W124 e220

[mark9208p]

Hi,

I'm new to this forum but have been reading some of the threads since 2009 and find the topics informative and helpful.

I live in Malaysia and own a 1994 E220 with about 112k mileage. The car has stopped a few times on the highway and left me as anxious as hell to be stranded with people honking me

These are the circumstances the car is put under before it stalls:
- car driven with the airconditioner on for about 30 mins
- in long jam and the temperature outside is hot and I also notice the gauge rise above 80. It happens when its hot.

Car will then jerk very very violently and rpm also goes up and down and there is absolutely no response from the throttle and I just manage to guide it to the side of the road where it either just dies or on the latest occasion it slowly (15mins) stabilized itself while on "N" and the jerks stopped and car is driveable again. When it did stall on the last few occasions the car would not start and turning the key doesn't do anything, no cranking nothing, just silence. Had it towed once and after an hour started like normalafter it cools. The mechanic suspects the OVP, throttle body's do the dreaded ECU. If it's the ECU I may have to give up on the car as it costs a fortune here. But for me it's about preserving it as I appreciate the cars legendary w124 history.
I would appreciate any help from the forumers. Thank you

Mark

 

[grober]

Sounds like a fuel vapour lock due to high underbonnet temperatures. You car will have 2 main cooling fans- an electrical switched one in front of the radiator and a viscous coupled one in front of the engine. I suspect one of these isn't working properly. The viscous coupling can lose fluid over the years or the bi metal control strip fails/seizes and eventually stops engaging. Check these first.

 

[mark9208p]

I recently installed a larger electrical fan and changed the radiator. So it must be the other fan if at all. But on idle with the ac on. The car would idle away happily. It's only when it is moving and stopping in traffic will the car jerk and rev up and down like crazy and I will lose all control and power so it's very dangerous and scary. I love the car but it's just nerve wrecking to drive knowing it will stall anytime. I just hope it's not the harness or ECU.

 

[grober]

If you are happy with the cooling- you mentioned for example--- the temperature rising in traffic--- to what temperature --- a slight rise is to be expected ?? You can do the "carrot test " on the viscous fan to test it - [ you may have to switch off the air con for this ] and try carefull cleaning the bimetal strip - an old toothbrush and wd40 is good for this. Otherwise symptoms do point to problems with the engine loom wiring or the throttle body- this in particular if the throttle mechanism is fly by wire rather than throttle cable.

 

[mark9208p]

Mine is the multivalve engine so it must be throttle cable. Can an OVP? Or coolant sensor? Or CPS cause these symptoms?

 

[grober]

Mine is the multivalve engine so it must be throttle cable. Can an OVP? Or coolant sensor? Or CPS cause these symptoms?

I doubt a faulty OVP, coolant sensor, or CPS would cause the symptoms you describe. Wiring loom insulation degradation is a known problem - goes brittle and flakes off leading to short circuits although I can't see that being temperature related.

 

[hotrodder]

Having a throttle cable is a bit of a red herring in that the throttle body is still full of leccy stuff. The ETA (electronic throttle actuator) controls the idle by moving the throttle butterfly, this vid explains the principles better https://www.youtube.com/watch?v=oluUNq4Yznc

As Grober said the comedy wiring looms on these can result in short circuits and all sorts of weirdness although not usually temperature related.

Hunting (wildly fluctuating idle speed from too low/stalling upto 1500 - 2000 rpm) can be a symptom of various problems from a vacuum leak to a problem with the fuel tank EVAP system that feeds petrol vapours from the tank into the inlet manifold under certain conditions. Temp could exaggerate these symptoms but i can't see them triggering them for example the EVAP system is only supposed to work after the engine has warmed up (when it then pulses) but if the valve is seized open it's like having a vacuum leak i.e. unmetered air/petrol fumes enter the engine which throws off the mixture and raises idle speed. This can then result in a feedback loop at idle where the ecu trys to correct things resulting in hunting.

The CPS on these cars is pretty reliable but when it does misbehave it's usually temp related. That'd only explain stalling and then refusing to start (although it'll still crank over) until it's cooled down though as what happens is the CPS goes out of spec/open circuit as it heats up and the engine cuts out

 

[mark9208p]

Thanks Grober and hotrodder. I will ask the mech to check the wiring tomorrow morning and then the evap system and also the CPS. He thinks its the OVP.

Early morning starts are not a problem, when the a/c kicks in the car judders and dies sometimes which he managed to pull a wire into the ECU? so the car now doesn't judder or dies when a/c kicks in.

When driving with the a/c on and in hot and jammed conditions only then will the car show problems.

So am I on the right rack to check the wiring,
evap system, vacuum leaks and CPS and OVP?

Tq

 

[grober]

He thinks its the OVP.

Early morning starts are not a problem, when the a/c kicks in the car judders and dies sometimes which he managed to pull a wire into the ECU? so the car now doesn't judder or dies when a/c kicks in.

When driving with the a/c on and in hot and jammed conditions only then will the car show problems.

So am I on the right rack to check the wiring,
evap system, vacuum leaks and CPS and OVP?

Tq

I am assuming what you mean is the mechanic managed to bypass the OVP and supply a separate 12v supply to the ECU. This solves the problem temporarily till the car gets warm. This might point to a problem with the cars voltage supply- meaning either something is drawing too much current and dragging the voltage down [ wiring shorts could do this] or maybe your alternator is not generating enough current. Check the wiring carefully for signs of flaking insulation[ you may have to slit open some of the black sleeving to do this] the evap system can be temporarily disconnected by blocking off the the pipe from the manifold to the valve on the wing. [ won't do any harm for a short time] vacuum leaks tested as suggested previously and replace the OVP.