It's been a while - and no response to my last few updates but I have noticed something when driving (or rather idling) on the vacuum / economy gauge.

When starting from cold it behaves as expected, not quite fully to the left since the cold-start devices are functioning. However once the temperature reaches the magic number the engine revs lower but the economy gauge isn't quite all the way to the left, it's about 5-7% off. It's not until the engine is run for quite some time that it eventually sits to the far left at idle.

To me this would be an indication that the engine reaches temperature but the components further away take longer for the heat to raise, such things a seal or what-ever.

Am I on the right line of thinking with this? Could anyone offer a suggestion to determine what it is?

Many thanks,

Glyn B. - still lovin' the W124 experience, but hating the rising fuels costs

For what's worth, my economy gauge pretty much seems to behave the same way as yours, it stays pegged to the left during warmup, and then with a warmed up engine (82-85c) at idle and with the A/C on, the needle stays about between the "c" and "o" of the Economy label.

But I have to add that this was only noted last time I was following the behavior of that needle, and way before the recent replacement of a faulty Idle Control Valve hose, so I really have to look at it again and to make sure it is still doing the same.

__________________
W163 ML230 EURO SPEC 1999
W124 300E 1986

Hi Dr.

Just went over your images.
Pardon for saying so but a little bit of cleaning would be probably very beneficial. I see that the AFM plate has crud all over it. The throttle control plate below it probably is all crudded up also.

The Fuel distributor can be removed by undoing all of the fuel injection lead pipes, the fuel pressure vale pipes and fuel intake pipe.There are three screws that hold the FD to the AFM body. There is a small O ring between the FD and the AFM body. I suggest you get a new one before removing the FD. Getting the AFM off is simple also. Getting it back on is a little more difficult as you need to make sure the rubber AFM seal fits on the throttle body correctly. When removing the FD be careful of the plunger on the bottom. If you bend this you are in for trouble. If you take the EHA unit off the side of the FD, get the two small O rings seals and replace them.
While doing all this remove the IACV valve and give that a clean. Carbon gets inside and causes some idling problems. The IACV hoses get hard and brittle and ultimately split which will give vacuum and idling problems Replace these - good insurance.
There is a fuel filter in the side of the fuel distributor. Replace this.
The injector seals are cheap. They get hard and leak. Very easy to replace if you have the FD and fuel injector lines off.

All these O rings, hoses and filters are cheap, however you may need to get them at a dealer - make sure they are OEM.

If you don't change any settings when removing and cleaning all these components your car shouldn't need readjusting, however should have better idling response. Cleaning up all the components inside the throttle body and AFM plate may improve your vacuum gauge readings.

I hope you have somewhere warm to do this - to save your back.
We are suffering with cold weather here in Southern Australia at the moment +10c at nite and + 20c during the day

I wouldn't touch the sealed EZL wheel adjacent the ECU. It's sealed for a reason. I haven't actually been able to suss this switch out yet. If someone has a definitive description of what this extra adjustment wheel's function is I would be very interested.

I have been informed by a Bosch specialist that installing an O2 sensor would enhance the performance and fuel economy. However for the price of the change - Kat, O2 sensor and exhaust setup rework, it would be a long, long period of time before I would recoup the cost in fuel savings.

I recently received a load of dirty petrol from an outlet who had let his tanks run down. The response of the engine performance to this load of crap fuel was detrimental - to say the least. However it prompted me into cleaning out the fuel tank, running a load of 98 octane fuel laced with ATF and then replacing all fuel filters. The fuel pumps didn't need replacing however as I had the advantage to pick up a couple of near new OEM Bosch fuel pumps for $ 20.00, I changed them out. Also changed out the accumulator.
Huge difference.

Thanks azurite300E and Ivanerrol. Clearly posting in the evening ensures my post stays higher up the list - here's hoping this midday one is noticed

I have seen plenty of carbs in my time with similar looking dirt on them so thought nothing much of it being such a high-mileage motor, but having seen shots of other's AFMs I can see mine is definitely in need of a clean.

If I run the engine up with the air filter removed and therefore obviously have the oil-breather pipe off too (the venting pipe off the rocker cover) it's distinctly darkish-black smoky. No doubt a full oil change and filter is needed there (I did say it was neglected by its previous owner!). I'm surprised that the pipe doesn't vent into the outside of the air filter but instead it is drawn into the AFM unfiltered.

I am putting in lots of overtime in this month which I'll get paid in June so I will be in a position to go to the OEM dealership with your shopping list and do the overhaul on the injection system. Hopefully by then we'll have the same weather your 'suffering' with now. I mean, +20c, that's almost hat and scarf weather over your part of the world !!

I will ensure I take lots of photos of the work to post a guide to help other's , just as you have been so kind to help me - its much appreciated guys.

Kind regards,

Glyn B.

That's definitely a case of being at the right place, at the right time! Good catch there. I myself managed to bag four injectors off eBay, nearly-new for little over the cost of a single new OEM injector, though the only problem is the "6" in straight-six........

Regards,

Glyn B.

Hi Dr.

If you have a lot of black smoke emitting from the manifold pipe which feeds into the air filter, then I'd say you need your head pressure tested. Sounds like stem seals and or valve guides..
They maybe a lot of gunky oil in the bottom of your intake manifold underneath the throttle control.
If you have a fair amount of gunk around the air fuel plate this can affect the position of the plate and idle.

Whatever you do with the ignition and fuel injection, if you have really leaky seals your engine will not run correctly and idling won't be good.

Oil produces blue smoke, excess fuel, as in a overly rich mixture, produces black smoke.

__________________
W163 ML230 EURO SPEC 1999
W124 300E 1986

Coming from the valve cover?

No, I meant in general coming out the tail pipe because that is where you normally see any signs of worn valve seals or stems. If you get any pressure coming out of the valve cover vent, then that means you're getting blowby gases -combustion gases that are getting past the piston rings, and are blown into the crankcase. I doubt worn valve seals could produce that as the valves are obviously seated during the combustion phase.

In an engine with blowby, a compression test should shed some light on the condition of the cylinders.

__________________
W163 ML230 EURO SPEC 1999
W124 300E 1986

Got a 1993 300e that coughs and backfires thru the engine compartment. New fuel filter, MAF one year old, running premium fuel. Idles fine and revs up good in neutral, but under load it likes to "Pop" under the hood badly during acceleration, but on a cool crisp day it seems to run great. Hot humid days and the car won't hardly go down the road and shudders.

Very annoying. Suggestions appreciated.

Sincerely,
Rick Potter
Potters Barber Shop
Osage City, Kansas
barbershop@mchsi.com

Don't have much experience with 104 engines, but I would check for any possible unmetered air leaks getting past the air mass sensor that could be badly leaning out the mixture and causing back firing and loss of power under load. Also, ignition timing could be an issue.

__________________
W163 ML230 EURO SPEC 1999
W124 300E 1986

Okay, it's been a while. I had wanted to re-test the compression when cold and run-up warm however the exhaust has gone at the front box and I don't think any amount of Gun-Gum will fix this one...

So for now my continued input on this thread is on hold until I can afford a new exhaust

Hopefully return soon, best regards,

Glyn B.
DrModiford.

Just pipe in as you asked the question as to the factory BAR on the Cylinders. The factory specs were 180PSI +-5....

So your pressures are dead on.

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Good reading this, especially as you're in the British isles!

A simple question this but are you sure you've got full throttle? Worth a check! Especially as you stated the idle deceleration switch wasn't activated by the throttle, and as you said it didn't kick down too easily either.
Your problem sounds like a bothersome one, how're you getting on with it in the last month? From what you say your engine sounds fine - compression, check - electrical functions, checked with the X11 port diagnosis - it doesn't misfire or anything, so perhaps it's ignition timing related or fuel pressure/delivery related?

If you want to go one step further try unplugging the EHA, the black thing on the side of the fuel distributor. It will prevent the electrical systems from doing anything to the mixture at all, and you're running entirely mechanical injection then. Yet it should still run 95% normally once warmed up. Basically unplugging it shouldn't make a life-changing difference in my experience. If it does maybe something's up?

Can't help otherwise but keep us updated it was good reading!
By the way your timing dial should be on 'S' not 'N' - for 95 RON and above (that's UK ron rating, the US is different but they don't get the dial anyway I heard).

__________________
190E's:
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black 2nd owner
http://www.maylane.demon.co.uk/190esmall.jpghttp://www.maylane.demon.co.uk/190esmall2.jpg