W124 3.0 300E Poor Performance
 

This is a long post, but I wanted to be very precise on the details:

Last December I finally bought a car I always had an interest in - a 300E W124 with the 3.0L straight-six automatic. Fantastic car and certainly shows the excellence that is German engineering. It only cost 300 quid, has 160,000+ miles on it, so it's not a show-room example by any means! As such, besides the rust, it wasn't without problems.

First up it was really rough running, that turned out to be a worn-out rotor-arm and distributor cap.

Then the fuel economy was seriously lacking, peaking at 16mpg. From the forums the recommendation was a new fuel filter. This was changed and I am now getting 21mpg, which also from the forums suggests that this is normal.

What I am finding now is the performance is seriously lacking to the point of being disappointed by it. Considering it is meant to have around 180hp and do a 0-60mph in 7.9s it wheezes its way to 50 in around 13s (the speed limit on this island is 35mph! So I'll have to find a quiet stretch of road long enough to get to 60mph). When traveling at a steady speed and I begin accelerating it edges up 100rpm at a time very slowly. My last car was the Accord Aerodeck 2.2i and that was rapid by comparison and that had just 130hp.

What I have done so far:
* New fuel filter;
* New air filter;
* New rotor arm;
* New dizzy cap;
* New spark plugs (Mercedes dealership OEM Bosch parts);
* Used lots of Redex and other injector cleaners;
* Inflated tires to Mercedes maximum guide specification;
* Tried 97 RON fuel, usually 95 RON - both unleaded;
* Compression tested (gives 13 Bar give-or-take per cylinder, hot);
* Checked o2 / lambda sensor - doesn't exist, wiring tucked away under carpet (some posts suggest euro-market cars don't have this fitted?);
* Checked EGR valve - (from reading posts) does not appear to exist;
* Became confused how an EFi car can run without either o2 or EGR... :confused: ;
* Got a per-unit price of new injectors - I multiplied by six, and got rushed to resus!;

I replaced the spark plugs as the NGK ones we dark black (dry, not particularly oily). They appear to be NGK's equivalents so I do not think being non-Bosch was the problem. The diagnosis of such spark plug conditions is non-clean burning of fuel or over rich mixture.

One thing I considered was HT leads however the pattern parts shop didn't have suitable replacements so guess that's a trip to the dealership.

So, here I am running out of ideas - perhaps the issue with the spark plugs might indicate something? As mentioned there is no o2 sensor and from reading posts the default action of a failed sensor (or indeed having no sensor connected) is to 'sense' lean and go rich, so how does the ECU know to lean the mixture on such a car?

The engine itself starts alright and runs smoothly at all speeds, most of the forums mention hesitation or rough idling - I am not experiencing that at all.

Would you forum members offer a fellow Mercedes fan your wisdom?

Many thanks,

Glyn B,

What year was it made. The 300E was shipped to the US from 1986 to 1993 or so. Many things changed in the emissions systems and the Euro cars were different from the US cars. For the most help, always give all the details about the car. Year, make, model, US/Euro, engine (there were 3.0, 2.6, and 3.2 I believe), trans, etc.
With more information, you may get more responses.
Thanks

Glyn, check the condition of the ignition wires. If original, install new Beru wires. Also, the coil may be suspect.

Thanks Fred, the leads are probably the last thing I can replace without costing the earth - I had a quick look for a Beru supplier in the UK but nothing yet, I shall take a better look later or failing that go to the dealership for OEM ones. It would be almost certain they are factory originals still in there.

pmckechnie - if it helps I can state the following from what I know:

The car is the 300E with the 3.0 straight (inline) six with what would appear to be the Bosch K-Jetronic system. The car was imported into Guernsey (Channel Islands, essentially part of Britain) in 1993. The motor office never signify the original manufacturer date of the vehicle when imported, so 1993 or earlier is the best I know of. It looks like this one whether that helps (albeit silver and with tin-worm):

http://www.peachparts.com/300e.htm

(is that what is referred to as the later 'face lift' version?)

When I replaced the fuel filter the parts supplier matched it to the early 90's model, which may help?

The chassis number is WDB 124 030 2B 246 816. I shall locate the log book to determine the engine number. It has the standard function automatic gearbox. Is right-hand drive so that limits its origins to key markets, but strongly suspect it to be a UK model.


I forgot to mention in my original post that I have adjusted the ignition timing dial through the seven positions with no noticeable difference.

Thanks once again,

Glyn B.

I have just been to my car and found the service manual. The car was originally owned by a leasing agent and first registered 1st August 1990. I still haven't found my log book (strange how all the log books of the cars I had in my past have turned up though!).

I also found the sales note from when I purchased the OEM Bosch spark plugs from the dealership - the parts guy noted down "Engine type M103" so I guess they have had this car in previously, prior to my owndership of it, and have that on record.

Hope that helps you with the details you need?

Thanks once again,

Glyn B.

An update 2008-03-14
 

Thanks to the people at:
http://www.ignitionleads.co.uk/
I have replaced all the HT leads with nice shiny new ones but the performance is still lacking. The engine starts and runs fine, however trying to accelerate while driving has no get-up-and-go.

From what I can determine my W124 has the basic CIS running in open-loop (no lambda), so is adjusting the idle mixture the only thing I can reasonably do?

As an aside, can someone clarify for me the 'continuous' part of CIS - does that literally mean that each of the six injectors are running like a tap left on? That is to say, it fills the intake port until the valve opens?

I don't know about Euro cars, but I don't understand how the fuel injection system can function properly without an O2 sensor. :confused:
The system needs to have some means of measuring fuel/air mixture. If there's no O2 sensor, how does it do it?

Does you car have a catalytic converter?

It could be possible that you have a huge vacuum leak...what does your "economy" gauge read at idle? From what I understand, it should be all the way to the left.

Thank you for your responses TVPierce and Johnatahn1.

There does appear to be a cat but certainly no position to fix a lambda sensor in. I have checked under the carpet and found wiring for one, attached to one side in a special holder.

I can only guess that the fuel injection on this car is no more sophisticated then the SU carb on my old Rover Metro!

As for the vacuum gauge it shows roughly 1/5th to 1/4 from the left when started from cold ('choke' on) and near-fully to the left once warm running idle.

Just to reiterate the fuel consumption remains around 20-21, consistent with urban traveling and the engine has none of the signs of hesitation or rough idling. It's just the get-up-and-go-go-go! There are kids around here with Nova's and Clio's that need knocking down a peg or two! (because I'm fed up of them being able to overtake me :mad: )

Thanks once again,

Glyn B.

I have a Euro market 190e 2.6 M103 engine. This car was exported from the channel islands to the U.K. and then to Australia, The car has no Cat or O2 sensor.(wiring for O2 sensor in place). It features the rotary EZL switch as mentioned above in your posts. My car suffered from lack of pickup power also. Had the fuel mixture adjusted a little bit richer and this improved things at the expense of consumption.

According to a Bosch Injection specialist I took my car to, by installing the O2 sensor, this will improve consumption and engine performance - depends on the cost to do this. As my car doesn't have a cat and also features dual engine pipes to the first exhaust muffler, installation would require some extensive work, so maybe not justified.

Settings for the EZL switch. S is for premium fuel - 95 Ron and above. N is for lower quality fuel 91 Ron. The EZL switch was designed for use in countries with some really crappy fuel and adjustments accordingly. The higher the number the lower quality fuel to be used - right down to 89Ron.
According to the user manual. Using the S setting with low octane fuel can damage the engine. - so make sure you set the wheel correctly for the type of fuel.

Cars not fitted with the cat can use unleaded or leaded fuels. Cars with a cat must use unleaded.

Getting the fuel distributor tuned correctly makes a big difference to performance. The coil can affect performance also. Only use Beru or original MB leads cap and rotor. NGK make the equivalent non resistive plug for the M103 - MP6ES.

Have you checked that the spark plugs are gapped correctly?
Should be 0.8-0.9mm gap.

Thank you for taking the time to respond Ivanerrol, and ps2cho.

Does that mean you were a former Channel Islander, Ivanerrol? (tell me you weren't a crapaud ;) !!) - sounds like I have the same model car as you feature-wise (or lack of features).

I read elsewhere that your present home country and other parts of the world have low octane petrol such as those you mention. In the UK and CI you cannot get lower then 95 at the pump and 97 is available as 'Super Unleaded'. The EZL is set as appropriate for 95 RON.

I twiddled the idle adjustment and now it sounds like its almost going to stall when stopped in gear - not a simple thing to play with, clearly... will have to tweak that back to normal now.

The air temperature recently has been around 5.0-6.5C according to the dash readout and I have noticed the engine temperature has not gone much above 40C and from reading other posts on this site the engine should be at 87C under normal conditions. I suspect the usual cheap-o-mechanic job of not fitting one when the water pump was replaced, if not simply rusted 'open'. Some replies to those posts suggest that fuel economy will suffer as a result of the temperature sensor not detecting a warm enough engine to switch off the cold-start injectors, etc. As this should be cheap to replace I will venture down this route next. Might driving with 'choke' effectively on impact on performance?

Regarding the spark plug gaps, ps2cho, I asked the parts guy whether I'd need to adjust them and he was fairly sure they were correct being OEM items - but I intend on checking the condition of the new plugs and cleaning them as necessary so I shall find the long-lost feeler gauge and verify.

As a general question on coils do they really become 'weaker'? I would have thought they either work or fail. I am happy to replace the coil if someone can confirm that changing a coil gives a definite improvement?

Many thanks,

Glyn B.

Not from the channel Islands - Cheltenham and Edgware- many many moons ago (with wet nappis on).

The car I bought was imported to Australia as an export model from the U.K. via Singapore. Technically this car should not be allowed on our roads as there is no cat fitted. In Australia we have 91,95 and 98 Octane. Leaded is now outlawed. The EZL switch can be adjusted to let the car run on the lower 91 Octane , However the 98 Octane has additives that "clean" injectors and fuel injection components. It's always better to run the car on the better petrol for this reason. Anecdotal evidence from Benz mechanics here have confirmed that cars run on 98 Octane have "cleaner components" than those which are run on lower octanes.

Coils can slowly deteriorate and the heat affects them. They are positioned in an area that can catch the heat from the radiator. Replacement is a good option. If the electrical system - plugs, leads, dissy and coil are not in good shape then the car can never be tuned properly.

The thermostats are cheap and easy to replace.The car should have the 87 degree one as OEM'd by Benz.

You car will not go over 40 degreesC. Last week we had 40 degreesC as an ambient temperature.(in the shade).

And I'm from Stroud originally.

You can pin down all the original details of the car by going to:

http://old.mbclub.ru/mb/vin/?lng=eng

Note: the VIN has 17 characters, including "WDB"; the one you have given doesn't.

Thanks for taking the time to reply again Ivanerrol. I tried a tank of 97 the other day - I was sure I could see the fuel gauge move with a distinctive cartoon-style sucking sound as I was driving! After checking the mileage it was only down to 19 from the usual 21MPG, give-or-take errors in my measuring.

My son's child minder is next door to an copy-parts supplier and considering the long weekend (Happy Easter folks!) I quickly went in and ordered one. If it doesn't work then it wasn't a great loss cost-wise and I'll go to the OEM dealership.

I re-adjusted my idle to get it back to normal, or as it was before, and then took off my air filter and poked around the various CIS sensors (the ones I could locate and get access to) using my trusty multimeter.

The engine temperature sensor is one of those with four-connectors and from reading the forums the the pins are diagonal and the resistance equated to the dashboard temperature reading (within reason) or both pole-pairs. There was also a single-wire temperature sensor ahead of that and seemed to show resistance too.

The air temperature sensor I didn't have a guide for however on testing it outside the car and moving it into the hot-air flow from the radiator fan it showed functionality.

The throttle position sensor (perhaps called something else on the Benz?) showed variation when moved.

At the same time I tested the X11 socket for the ECU's fault code. Since this is a non Lambda car / open-loop car the ECU presents a value representing an error code. This is steady at 50% normally but did show 70% with the engine temperature sensor off, 20% with the air temperature sensor off and either 60% or 90% value (can't recall which just now) with the throttle position sensor off.

Now I was puzzled by these values, since another article stated that failures in these sensors should generate 30%, 80% and either 10% or 40% respectively. Then I realised that these figures, when inverted, worked out right: 100% - 20% = 80%. This may be down to how my multimeter works, but it left me scratching my head for a bit!

Clearly this shows that the ECU sensors are not 'failed' and the ones I tested with references seem to be within tolerances.

Still with the air filter off I checked other components and found a switch on the throttle linkage. It never seemed to engage under normal usage but if I pushed it in by hand the revs would drop down a little bit. Should I somehow 'modify' (read: bend) the switch actuator with the roller to make better contact so it's activated normally? Or is it movable to reposition it?

Furthermore I disconnected a device on the front-side of the fuel distributor and the revs dropped right down from around 8000rpm to 6000rpm. I'm guessing this is the extra air enrichment device, the technical name of which I cannot recall. The engine seemed slightly more responsive when driving with this left off and, although I cannot determine until my next fill-up, the fuel gauge seemed to go down slower then usual.

Would I be right in thinking that this along with the cold-start injector are temperature dependent and therefore the current guess at the thermostat issue would be resolved next week upon fitting the new one? I know I'll find out when I fit it, but as is typical when you're keen to fix something a raft of bank holidays get in the way! (the workaholic in me can't cope with such long breaks off :eek: )

I shall keep you updated with progress.

Kind regards,

Glyn B.

Thanks for the website link Roger. I gave it a try and was surprised to read my car described word-for-word - Big Brother clearly knows too much!

I shall bookmark that and add it to my website when I finish documenting my car for it.

Kind regards, have a Happy Easter one and all,

Glyn B.

No problem, and thanks for the thanks.

Here's another site that throws light on the dark corners of a VIN:

http://tinyurl.com/7xoso

The mechanical part of the system is quite accurate, enough so a (warmed up) engine will run quite good without the o2 sensor (open loop mode), without any intervention of the electronic part, although mixture will be on the rich side. The electronics of the CIS-E injection system mainly contribute to refine and optimize the correct mixture ratio taking into account several variables (o2, temp, RPM, timing, vacuum, altitude, etc) when its running in closed-loop mode. It will also ease a cold start/run until the engine has had a chance to warm up to operating temp.

My car did not have a o2 sensor for about 3 years, and it ran just fine. Only thing I noticed was the black sooth that tended to accumulate on the tailpipes and also to some degree on the spark plugs. Nothing that an occasional "Italian Tuning" won't clear up. But there was never a performance issue. I can certainly tell you that.

The lack of performance of DrModiford's 300E sounds to me that the ignition timing might be way too retarded. I would check it with a timing light to make sure its correct. There is also a resistor on the end of a plug (usually found on the left hand side engine compartment) that presets the timing to a certain degree, and if you just pull it out it will advance timing and make your car feel snappier. But the car should run pretty good without doing this in the first place, so I guess your problem is somewhere else.

You can always refit the o2 sensor, it easy. Here's a tread I started when I refitted mine. But keep in mind that if the gasoline (petrol) has added lead, the sensor won't last long and become clogged.

http://forums.mbworld.org/forums/showthread.php?t=200680&highlight=sensor+300e+o2

21 mpg is excellent at your slow speeds of 35 mph, usually these vehicles optimum performance is at 120mph. Running temps of 40 deg C will definitely contribute to a rich mixture. Flush the system, change the thermostat and add Mercedes coolant and soft water mixture (50/50)

The replacement thermostat arrived and duly fitted - only to discover the housing cover, being plastic and obviously subjected to extremes of temperatures, cracked off at the hose part! Fortunately enough was left to cram down tight the Jubilee clip and hopefully last until a replacement is ordered.

The original was distinctly orange in colour and wide open when warm but failed to close completely when cooled so had clearly failed 'safe'. The new thermostat got the engine warmed up within minutes from cold this morning and reads around 87 degrees on the dash temperature gauge (the thermostat itself had 87C stamped on it).

While fitting the thermostat I reconnected the cold-start air-enrichment device as well as a pipe that was so awkward I left it off last time - the one that connects the fuel-return device to the rocker cover oil to air filter pipe (it's only been off for 10 days or so, probably explains the marginal drop in MPG for the fill-ups during that time).

The revs stayed around 1500rpm when testing it on a drive last night, but this morning it returned to 1000rpm cold and 800rpm warm.

I parked up at work and got my trusty 3mm Allen key out and started adjusting the idle to get it back down to the more normal 600-650rpm however each 1/8th turn lean increased the vacuum gauge (needle moving to red / to the right) a small amount and the engine progressively heading to 'stalling' out. So it's back to zero on the vacuum gauge and 800rpm.

The switch on the throttle linkage within the engine bay, if pressed, drops the revs to near 600-650rpm but as I stated in a previous post on this thread it never engages at idle - it is a manual press by hand that activates it. I shall see if it can be moved slightly so that it engages since adjusting the linkage screws did not make this happen (I did find the gear shift line and set that to 3000rpm before changing up a gear).

I have learnt a lot about engines over the years, I even stripped down an MG Metro engine and rebuilt it with tuned parts to wrap my head around how each part functions. Having bought this Benzo just a few months ago I know almost all there is to know about fuel injection and the particular oddities that these cars have - what a learning curve! May I give my thanks to azurite300E for clarifying how EFI can work without an o2 sensor since myself and tvpierce were clearly under the illusion you couldn't have one without the other.

And rorypff I nearly fell backwards off my chair when I read the idea of driving at 120mph to get maximum efficiency! Going just over 50mph will get you banned for a month, and finding a road long enough here on this island in which to reach 120mph is a challenge in itself! Typical driving is stop-start stop-start so its very much 'urban' driving all over the place.

Many thanks, and kind regards,

Glyn B.

...erm, yes, of course, umm, I meant 800rpm to 600rpm, and not flat-out red-lining to just under :o, but I guess y'all realised what I meant!

Instead of ordering the plastic part again, order 104-203-0274. This one is made of aluminum, and should fit your 300E. At least on mine if fits perfectly and is much stronger then the original part.

Thanks for the tip azurite300E I shall ask the dealership to determine whether that would work on my model as I'm sure they'll have 'microfiche' style details available to them.

I just went to one of our remote offices (well, as 'remote' as you can get for this island!) and after stopping there for a short while and getting back in the car the revs went to 1500rpm even in gear. After a short drive I pulled over, stopped the engine, restarted it where it then remained at 1000rpm. Grrr :mad: if it's not one thing it's another... two steps forward, one step back.

Where's my trusty sledge hammer.........

Yours truly, going mad,

Glyn B.

Hey Glyn:

I hope you don't mind someone else jumping in here, but your thread reminds me a lot of my 1st few weeks of 300E ownership about 7 years ago. I had some similar issues as you, and in particular - the "sudden fast idle" issue.

I hit upon my solution after reading one of Steve Brotherton's articles and so I'm going to suggest that you may possibly have the same issue I had, and that the fix might be the same as well. As you know the ECU gets feedback from a number of sources, and one of the sources is the temp-sensor at the very back of the head. As you stated earlier, there are two sensors - one for the temp gauge and one for the ECU. Not sure why it takes two. Anyway, the sensor would "intermittently fail" and then "un-fail" resulting in the exact phenomenon you mention - erratic fast idle. It's pretty easy to check the resistance on the sensor, but when it is intermittenly failing it is rather difficult to pin it down. The sensor only cost $20 USD (here in the states), so I simply replaced it (based on Steve's article) and the problem has not returned. Another idle issue I was having ended up being a clamp not being tightened on the hose coming out of (or into - I can't remember) to the idle air control valve - that thing you mentioned that is in front of the fuel distributor (I assume it exists on a Euro car). The idle might surge to around 900rpm and then return to normal 600rpm in a matter of seconds. Insuring all the hose clamps were tightened fixed that problem. The reason I bring it up is that it sounds like you may have removed it to "see what would happen".

Since the initial issues I had, the car has been one fantastic machine. I had a lot of "little" things to initially fix, and like you I thought there couldn't be one more thing that could "pop up", but eventually, the issues were resolved and I'm quite happy with the car. I get just around 20 mpg around town here in North Carolina, and I'm quite happy with that.

I'm somewhat puzzled by your accelaration issue and only have one thought. I've read over the years on this site about timing chains getting stretched to the point where the timing was actually retarded about 12 degrees. Someone else has eluded to that in one of the posts, so it might be something to think about, although on these 300's 100000miles is really not many miles and would normally be much too early to worry about a timing chain.

Hope you get things running to your satisfaction,

Dave

Not at all Dave, many thanks for taking the time to convince me I'm not really going stir crazy with all these issues! In fact I'm very grateful to all the fellow forum members who have contributed so far - many personal thanks to you all.

(Hangs head in shame) you're absolutely right, I had a moment of "Hmmm, I wonder what if..."

The device is electronic with what looks like two power pins on it (to the front of the car) and when removed I had to maintain the revs using the accelerator pedal until the engine had warmed up enough not to stall out. Does that sound like the same device? I will certainly check over the quality of the seals, etc.

I shall order a temperature sensor since its clearly a not an expensive part ($20 US would be about £10 UK there-or-there-abouts, although it never works out that way as we all know).

My 300E has just rolled past 164,000 miles but I did wonder whether the timing chain tensioner might be worn down as that would be cheaper then a chain to replace, particularly since a chain will have to be purchased from the dealership (but then a part that critical I wouldn't trust a pattern part equivalent).

Many thanks,

Glyn B.
(single handedly keeping the local Benz dealership in business!)

What you described as the 'electronic device with two pins on it" should indeed be the idle air control valve. When putting your finger on it, it should have a "humming" sensation. There should be an intake rubber hose about 1" in diameter heading down toward the manifold on the "left" side as you face the FD, and I can't remember what is on the right side - perhaps another rubber hose.

Ah - 164,000 "miles" - I was thinking "km", so indeed, there may be a timing chain issue. I would highly recommend the 29.95 CDs from MBUSA - they go into a lot of detail and are quite helpful. They are basically PDFs of the MB shop manuals.

Thanks again Dave - it's night time here now (twenty minutes gone midnight in fact) so I will do that tomorrow, my eyesight is going fuzzy and the bed is calling!

I have a Haynes manual to hand but I'm sure its no substitute for the shop manuals you pointed out.

I have searched for a supplier online for a timing chain to simply get a price (as I mentioned, I'd get an OEM one from the dealership). Are they really as cheap as £30 UK? What price, in $ US if it's easier, should I be expecting? I already have a new temperature sensor and azurite300e's recommended aluminium thermostat housing on the shopping list as well as the MBUSA CDs :eek:. Looks like next month's pay day is already spent before I get it, but that's life I guess!

Kind regards,

Glyn B.

Replacing the timing chain tensioner is cheap insurance, and is one of the first things they tell you to replace outright. Not sure what the mileage expectancy of the chain is, but if it is not making any noises yet its probably still fine.

I was lucky that my car had the aluminum part already fitted by the previous owner. Never knew the original was plastic until I read your post.

Or alternatively the previous owner of my car replaced the aluminium part with a cheaper, plastic one! I shall note the part number on it and post it here for reference.

Glyn:

I have purchased a number of things from this site - www.performanceparts4benz.com They have a catalog that is quite helpful that gets mailed out as you make purchases. Fastlane is very very good and Phil is extremely helpful, so that is normally where I make my 1st visit when looking for parts. There is also www.millermbz.com and I have visited them frequently because they are located right here in Charlotte NC.

BTW, I'm with azurite - I didn't know there was a plastic thermostat housing.

Also, if you get to the point where you really want to fine tune the adjustment on the IACV, Steve Brotherton has a fine article on how to do that. I was quite successful in adjusting mine when I 1st purchased my 300E. You can find the article here on this site (sorry, I can't seem to remember much of the details on how I found the article. Normally when I find these little nuggets I print them out and put them in a binder for later reference).

Well from the part number one can see the aluminum part is for the 104 engine, so its possible our 103 engines originally came with the plastic part. Maybe someone else with the same engine can chip in and post what type of part they have.

Glyn:
Woops, hope you didn't hurt yourself nearly falling out of the chair, but sorry about the 120 mph, should have been 120 kph - that's what happens when living in a metric country - good luck anyway.

OOPS - sorry, I meant to say - "It you get to the point you want to fine tune your idle mixutre", blah, blah, blah......

Hi Glyn; just a few thoughts - if I missed anything already answered, please ignore :)
Performance: are the part and full-throttle kickdowns both working? When you floor the throttle, the car should change down two gears and spin the tyres...
Emissions: don't think a cat was required until '92 on UK cars, although you may have the wiring fitted.
Cooling: mine has a plastic thermo housing, due for replacement along with the thermostat 'cos it never goes over 70C; I shouldn't need cardboard in front of the rad on a modern car!
And I get 25mpg out of my 1988 300E, 156,000 miles, 5,000 miles per litre of oil.
Cheers, Pete.

That link takes you to a page of generic searches, not a specific company. Maybe the correct link you meant to post was this?

http://www.performanceproducts4benz.com

You beat me to it azurite300E in figuring out some domain name squatter has scooped up yet another web address for themselves.

For reference my part number for the plastic thermostat housing is 103-200-0117 (also had 2-2815-000 beneath it) and azurite300E quoted 104-203-0274 in his previous post for the aluminium part (yes, the British spelling! I noticed the way you other guys were spelling it without the "i").

Ah yes, rorypff, being part of the Crown Dependencies we use the UK imperial MPH and even after conversion 70MPH (ish) is double our 'national the speed limit' for this island :D and probably three months off the roads.

David I looked at the pipes connecting the idle air device and they were very loose on it. They were only held in place by the way they fit. I shall buy some small jubilee clips to secure them down and see if that helps. The other end attaching to the engine manifold looks tricky to get at even with 'piano fingers'...

Thanks for adding your input 2mercspete (not inspired by a certain two Jaguar owning politician, by any chance??!). If I forcefully - like hammer - the accelerator pedal it has a good long think about it before dropping two gears and, in the wet at least, I get a slight sidewards step from the tail-end. However under normal driving, even being slightly demanding on the pushing, it will not shift down a gear, certainly not like my last wagon the Honda Aerodeck. That Honda worked almost like 'gestures' where it knew the difference between gentle acceleration, needing to kick-down a gear or a flat-out go for it.

Could that be part of the problem? If driving at 35-40MPH with revs around 1600-1700rpm (off the top of my head, and yes it's slightly speeding ;) shhh!) and I try to pull away the gearbox doesn't do any work and it simple tries to 'accelerate' away in 4th. In my mind a 3.0L engine should have the muscle to blast up the revs, perhaps I'm wrong?

I adjusted the gearbox cable at the throttle linkage and the up-change on the gearing is now set around 3000rpm and the gear changes are quite sharp (which I read is a good thing to save wear on the clutches) and I have no issue with that.

As a side question and from what I've read it pulls off in 2nd gear in "E" switch mode, which in some way improves economy. In a stop-start urban driving is it better to set it to "S" to allow 1st gear starting, or a better term, crawling?

Kind regards,

Glyn B., wondering if the weather will hold off this weekend to install the all essential boom-box in the Benz.

But that's the kind of engineering that made Britain great!

i'm surprised that nobody's suggested a clogged catalytic converter or exhaust yet, drop the exhaust from before the cat and see how it runs

Glyn, my nickname was indeed inspired by a certain politician - not my idea - some of my mates started it and it seems to have stuck!
It seems that your box's behaviour is at least partly to blame; with mine, a small increase in pressure on the pedal when I'm doing 35-ish results in an instant downchange and if I use full throttle (without kickdown) it will hold the lower gear to the redline. I was going to suggest adjusting the control pressure cable but you say you've already done that; also, with mine, the changes are almost imperceptible.
The S/E switch has been the subject of much debate; in theory you get a first gear start in S but if you blink you'll miss it, also the box holds on to lower gears slightly longer, in the end it doesn't seem to make a great deal of difference, on mine anyway.
My replacement thermostat housing just arrived from Eurocarparts, it's a nice alloy one for under £8, pleased with that.
Cheers, Pete.

I might be wrong, but I seem to recall that this is a non-"Kat" car.

[quote=DrModiford;1793769]Thank you for your responses TVPierce and Johnatahn1.

There does appear to be a cat but certainly no position to fix a lambda sensor in. I have checked under the carpet and found wiring for one, attached to one side in a special holder.

I

Running a Cat without o2 sensor being installed is a sure way to easily damage it if the max temperature of the converter is exceeded due to a continued overly lean mixture. In worst cases it may even melt down internally, and partially or totally block the exhaust flow.

Just to clarify the "has it got a 'kat' or not" the twin pipes drop from the manifold into a box beneath the drivers possition (British car, so that's the right hand side guys! ;) ) which twin pipes to the other side of the car at another box before going up and over in a single pipe to the rear box beneath the bumper / boot exiting as twin tail pipes. The first box has a heat shield over it but this has recently become lose and the rattling is driving me mad! That's a 'to do' for a dry day... Are there any characteristics that denote whether it's a cat by looking at it?

I have been pondering taking a learning curve in pipe bending and fabricating a homemade de-cat from ERW or similar steel tubing but that will be when I'm rich again (it's the being a new daddy money vanishing problem, sure most of us here know that feeling). Aside from the environmental (and possibly legal, such as certain US states) is there any need for the cat? Will an o2 sensor work without one? That is to say if I ever constructed the de-cat would I benefit from installing an o2 mount in one of the pipes?

Thanks for your continued input,

Glyn B.

P.S. the weather never held out for installing the sounds :(

Manifold -> KAT -> Central Muffler -> Rear Muffler

What you describe as the rattling box with the heat shield under the passenger side, that's you Cat converter. From what you say, its obviously deteriorated, probably damaged internally, and is most probably also blocking a great deal of the exhaust system.

Sorry azurite300E, I may not have been clear with my post - it is the heat shield that has come lose, like no bolts holding it in place kind of lose! It's only the shape of it that won't let it fall off and around the box. It happened when I had to mount and drive over a curb and as you know the 300's are quite low. A distinct 'clunk' and an "uh oh" from me resulted in it becoming lose. It is that which is rattling through-out the car at idle. I've not noticed any other rattling from within the cat prior to that.

The downside of working in IT is people find out and do the "oh, I think I have a virus...". Suffice to say have ended up with a computer to fix, but on the plus side this guy repairs cars as a side line so quid-pro-quo he's agreed to go over my exhaust and fix the heat shield. I put forward teezer's suggestion about dropping the exhaust to test the difference. I'll report back on his view of its condition.

2mercs' thanks for commenting on Eurocarparts - I've found their website and seen some of the prices, they seem quite reasonable. Pay day can't come soon enough...

Best regards,

Glyn B.

Glyn, we don't seem to have established for sure whether your car has a cat - what you are looking at may be just an expansion box - as far as I know you don't actually need a cat on your car, so you could eliminate it but the worry is what to do with the sensor. If I've read your previous posts correctly, the wiring isn't connected anyway? Perhaps you have a 'universal' harness, used on cars for many markets that may or may not need a cat? Did the site that described your car (like 'big brother') not tell you if a cat was original equipment? You (and we) really need to know....Cheers, Pete.

Hi Glyn,
I am sure you don't have a cat. If you have no O2 you wont have a cat. From what you describe about twin pipes from your manifold to the first exhaust muffler is exactly the same as my U.K. car. i.e. No O2, No cat.
You car was designed to run on either leaded or unleaded therefore no cat.
U.S. cars are a completely different kettle of fish to what the Euro models made for the U.K. were.
Another give away is the EZL wheel on the front passenger guard (RHD) Pictured. This is not in the cat cars (Euro). reading earlier posts - your car has this adjustment wheel. In an earlier post I listed the correct positions for this.
http://farm2.static.flickr.com/1376/...b96136.jpg?v=0

There is some heat shield metal insulation bolted to the body of my car that follows the exhaust pipes from the manifold to the first muffler under the (RHD) drivers seat area. If this metal insulation is loose it will make a rattling sound - in my case not in neutral but happens in drive at idle. In my case this was an easy to fix by getting under the car and tightening it up.

I recently changed my Fuel distributor in the hope that it was the cause of much as the same as your problems. One of the things I found was that there is a rubber grommet/seal between the fuel distributor and AFM body. Mine had stretched and was letting a little airleak and fuel into the air chamber. In the end changing the fuel distributor made no difference however the rubber seal replacement seemed to be a culprit.

I finally messed around with the air fuel ratio on the lambda tower. With a lot of trail and error eventually got the car running correctly. The car now accelerates like it never has before.

Because our cars are running open loop they require adjustment of this ratio to be spot on correct to function as designed. Adjusting the lambda tower can be very frustrating and really should be done with a CO2 exhaust analyzer by a professional.

The plastic thermostat cover was a boo boo by the designers - what were they thinking - It should be changed out Post Haste with a metal one.

Some cars designed for export were designed as a " global" car i.e. were designed to go to countries where poor quality petrol or leaded fuel was still commonly in use (at the time). You may find in your car manual (if you have one) that this detail is mentioned. Cats were not fitted obviously because the lead would destroy the precious metals used in cat construction. O2 units were superfluous if leaded fuels were used.

My car was exported from the U.K. to Singapore and then to Australia. Some Asian countries in the late eighties and early nineties still used leaded petrol extensively. Some petrol is rated at 89 octane.

regards Ivanerrol Australia with U.K. Import 190e 2.6.

Ivanerrol, hopefully the good Dr is sorted but you could help me with something if you would; the EZL adjuster - I've done a search but couldn't find the previous post you referred to. The adjuster on my 1988 300E, using English Regular 95 Octane fuel is nowhere near where the one in your picture is set; could you please refer me to your earlier post?
Also, as an aside, when I replaced the plastic thermo housing with an alloy one, the new housing has a threaded boss in its top which needs blanking off: it's an 8mmx1.0 thread - I bet anyone changing theirs hasn't got anything suitable in their toolbox! However it's a great bleed for refilling - just find a suitable bolt first.
Cheers, Pete.

That's correct, mine has it.