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  #16  
Old 03-21-2008, 12:01 PM
The Geezer
 
Join Date: Mar 2008
Location: Guernsey, Channel Islands
Posts: 28
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.

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  #17  
Old 03-21-2008, 01:55 PM
Roger Jones
 
Join Date: Mar 2008
Location: Harpenden, England
Posts: 14
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
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  #18  
Old 03-21-2008, 09:16 PM
azurite300E's Avatar
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Quote:
Originally Posted by tvpierce View Post
I don't know about Euro cars, but I don't understand how the fuel injection system can function properly without an O2 sensor.
The system needs to have some means of measuring fuel/air mixture. If there's no O2 sensor, how does it do it?
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
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300E 1986 - 117KMi
Sikkens Metallic Azurite Blue
Member #120 of MB Club VE
Caracas, Venezuela

Last edited by azurite300E; 03-21-2008 at 10:50 PM.
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  #19  
Old 03-22-2008, 02:39 AM
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Posts: 46
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)
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  #20  
Old 03-26-2008, 09:51 AM
The Geezer
 
Join Date: Mar 2008
Location: Guernsey, Channel Islands
Posts: 28
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.
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  #21  
Old 03-26-2008, 09:55 AM
The Geezer
 
Join Date: Mar 2008
Location: Guernsey, Channel Islands
Posts: 28
Quote:
Originally Posted by DrModiford View Post
Furthermore I disconnected a device on the front-side of the fuel distributor and the revs dropped right down from around 8000rpm to 6000rpm...
...erm, yes, of course, umm, I meant 800rpm to 600rpm, and not flat-out red-lining to just under , but I guess y'all realised what I meant!
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  #22  
Old 03-26-2008, 09:59 AM
azurite300E's Avatar
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Quote:
Originally Posted by DrModiford View Post
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.
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.
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  #23  
Old 03-26-2008, 11:47 AM
The Geezer
 
Join Date: Mar 2008
Location: Guernsey, Channel Islands
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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 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.
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  #24  
Old 03-26-2008, 01:31 PM
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Join Date: Jun 2002
Location: Charlotte, NC
Posts: 102
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
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77 Euro 350SL - 67k miles
94 Explorer 147k miles
2009 Hyundai Genesis - 65k miles
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  #25  
Old 03-26-2008, 03:53 PM
The Geezer
 
Join Date: Mar 2008
Location: Guernsey, Channel Islands
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Quote:
Originally Posted by DAVID LEE View Post
I hope you don't mind someone else jumping in here...
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.

Quote:
Originally Posted by DAVID LEE View Post
The reason I bring it up is that it sounds like you may have removed it to "see what would happen".
(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).

Quote:
Originally Posted by DAVID LEE View Post
...although on these 300's 100000miles is really not many miles and would normally be much too early to worry about a timing chain.
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!)
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  #26  
Old 03-26-2008, 04:20 PM
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Join Date: Jun 2002
Location: Charlotte, NC
Posts: 102
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.
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92 300E - 116K miles - Sold
77 Euro 350SL - 67k miles
94 Explorer 147k miles
2009 Hyundai Genesis - 65k miles
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  #27  
Old 03-26-2008, 08:23 PM
The Geezer
 
Join Date: Mar 2008
Location: Guernsey, Channel Islands
Posts: 28
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 . Looks like next month's pay day is already spent before I get it, but that's life I guess!

Kind regards,

Glyn B.
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  #28  
Old 03-26-2008, 09:04 PM
azurite300E's Avatar
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Quote:
Originally Posted by DrModiford View Post
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).
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.
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300E 1986 - 117KMi
Sikkens Metallic Azurite Blue
Member #120 of MB Club VE
Caracas, Venezuela
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  #29  
Old 03-26-2008, 09:11 PM
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Quote:
Originally Posted by DrModiford View Post
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 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.
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300E 1986 - 117KMi
Sikkens Metallic Azurite Blue
Member #120 of MB Club VE
Caracas, Venezuela
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  #30  
Old 03-27-2008, 04:55 AM
The Geezer
 
Join Date: Mar 2008
Location: Guernsey, Channel Islands
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Quote:
Originally Posted by azurite300E View Post
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.

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