Not a 500 but similar technology: 1991 300CE-24 stalling then immediate re-start

[rayhennig]

This is an interesting one for the brainy boys.

I bought my 1991 300CE-24 in 1997. And for the last 26 years it has suffered from occasional stalling. The engine starts immediately afterwards.

In the early days, performance was good and has continued that way. Now, the car is even better after renewal of many, many parts.

But occasionally it still stalls. Every 4 months, at a guess.

These stalls have always taken place at very slow speed, always under light braking and sometimes when turning.

The car has aircon, ABS and ASR. No cruise control. Over the years, I have stacked up replacement electronics, including:

• KE jetronic controller,
• MAS box,
• ABS module,
• ASR module,
• EZLs – many.

This stalling condition has not got worse over the years and today is only very occasional.

I am baffled and my thoughts turn to some marginal timing issue that prompts the various electronics to shut down the fuel pumps via the MAS box. Possible?

Almost every electronic box that I have received as a spare has been tested on receipt and left in place if found to be OK. They all seem OK.

But the stalling condition remains.

BUT, the only 2 modules that have not been changed are the ABS and ASR modules.

My plan is to swap these and then continue. Of course, I shall only know if this has fixed the issue when stalling does not happen. This could take years for maximum confidence.

I find it difficult to believe that it is a sensor as this would surely have died in 26 years. As said, baffled.

Has anyone else had anything similar?

Any and all suggestions will be most gratefully received.

Best to all.

RayH

 

[gsxr]

This engine has mechanical CIS-E injection, not electronic. I don't know what the issue might be, but I suspect it's unlikely to be electronic. I'd research the mechanical injectors and airflow/plate assembly. Maybe look at the EHA as well. @jhodg5ck might be able to point you in the right direction.

Oh yeah - the ABS/ASR modules likely won't have any effect. It's also unlikely that the fuel pumps are shutting off, but if you rig up a temporary remote fuel pressure gauge you can rule that out too.

 

[rayhennig]

This engine has mechanical CIS-E injection, not electronic. I dont know what the issue might be, but I suspect its unlikely to be electronic. Id research the mechanical injectors and airflow/plate assembly. Maybe look at the EHA as well. @jhodg5ck might be able to point you in the right direction.

All these have been changed over the years and the condition has remained.

Thanks for your comment.

RayH

 

[alabbasi]

starts then stalls? Likely to be losing fuel pressure. Clogged injectors, accumulator and check valves would be the cause, as well as a leaky cold start injector

 

[rayhennig]

starts then stalls? Likely to be losing fuel pressure. Clogged injectors, accumulator and check valves would be the cause, as well as a leaky cold start injector

New injectors, new cold start, new everything really. And it's been doing it for 26 years!!

Thanks.

R

 

[alabbasi]

26 years! don't worry. Someone on this forum will come along and suggest something that will fix it

 

[TerryA]

@rayhennig,

Ray, I had a Toyota that stalled and then would restart and go. Turned out the fuel filter was clogged. New filter no more stalling. Your issue my be similar maybe not the filter but something that’s restricting the fuel delivery.

 

[rayhennig]

@rayhennig,

Ray, I had a Toyota that stalled and then would restart and go. Turned out the fuel filter was clogged. New filter no more stalling. Your issue my be similar maybe not the filter but something that’s restricting the fuel delivery.

Thanks for that. Yes, could be but it's got a new-ish fuel filter. So much has been changed in this car that I still focus on the remaining 2 things that were never changed: the ABS and ASR modules. Easily changed but I'd never know for perhaps a year or more.

Oh well, not a major flaw.

R

 

[Steve119]

Has the idle valve been checked or changed? Worth a try to run it with the plug disconnected. Could be faulty and cause the stalling.

 

[gerryvz]

What you have to do is to identify the specific conditions as to when and/or where the stalling is occurring.

It is repeatable? Does it happen all the time at a certain time or place? Does it happen when the engine is warm, or cold?

Etc. etc.

Here is the saga of something similar I went through for some time (months) with my 560SEC when I lived in Texas. I finally found the issue when I identified the problem REPEATABLY happening in a single place (although it happened on rare occasions at other times).

126 fuel delivery system saga (long post) | Electrical and Wiring

Today was a significant milestone in my work on my 560SEC -- specifically because I was able to excise a persistent issue that the car has had over the past year, and I was able to solve an intermittent fuel delivery problem that's cropped up over the past few months. Interestingly, the cause...

126board.com

It turned out that it was the fuel pump bundle in the rear of the car bouncing slightly and a wire with insulation worn through, grounding itself on the frame of the car when I went over a specific set of railroad tracks at an angle on my way to work, or over a speed bump.

Once I identified the pattern as to when and where it happened, I did some digging and messing around and detective work, and was able to reason out the issue.

 

[rayhennig]

What you have to do is to identify the specific conditions as to when and/or where the stalling is occurring.

It is repeatable? Does it happen all the time at a certain time or place? Does it happen when the engine is warm, or cold?

Etc. etc.

Here is the saga of something similar I went through for some time (months) with my 560SEC when I lived in Texas. I finally found the issue when I identified the problem REPEATABLY happening in a single place (although it happened on rare occasions at other times).

126 fuel delivery system saga (long post) | Electrical and Wiring

Today was a significant milestone in my work on my 560SEC -- specifically because I was able to excise a persistent issue that the car has had over the past year, and I was able to solve an intermittent fuel delivery problem that's cropped up over the past few months. Interestingly, the cause...

126board.com

It turned out that it was the fuel pump bundle in the rear of the car bouncing slightly and a wire with insulation worn through, grounding itself on the frame of the car when I went over a specific set of railroad tracks at an angle on my way to work, or over a speed bump.

Once I identified the pattern as to when and where it happened, I did some digging and messing around and detective work, and was able to reason out the issue.

Has the idle valve been checked or changed? Worth a try to run it with the plug disconnected. Could be faulty and cause the stalling.

Yes, quite a long time ago. A brand new one was installed. The condition existed before and after the change.

Thank you.

R

 

[rayhennig]

What you have to do is to identify the specific conditions as to when and/or where the stalling is occurring.

It is repeatable? Does it happen all the time at a certain time or place? Does it happen when the engine is warm, or cold?

Etc. etc.

Here is the saga of something similar I went through for some time (months) with my 560SEC when I lived in Texas. I finally found the issue when I identified the problem REPEATABLY happening in a single place (although it happened on rare occasions at other times).

126 fuel delivery system saga (long post) | Electrical and Wiring

Today was a significant milestone in my work on my 560SEC -- specifically because I was able to excise a persistent issue that the car has had over the past year, and I was able to solve an intermittent fuel delivery problem that's cropped up over the past few months. Interestingly, the cause...

126board.com

It turned out that it was the fuel pump bundle in the rear of the car bouncing slightly and a wire with insulation worn through, grounding itself on the frame of the car when I went over a specific set of railroad tracks at an angle on my way to work, or over a speed bump.

Once I identified the pattern as to when and where it happened, I did some digging and messing around and detective work, and was able to reason out the issue.

The condition is not repeatable. Recently, after complete revision of the HT system, performance has been "as new", in all respects. Then it stalls and returns to perfect for another few months.

I would say that it happens when the engine is warm.

And it does not happen invariably at the same place. Several times it did stall as slowing for a speed bump, on a hot day. Thereafter, that speed bump has not caused misery.

So, I have to say that the condition is neither consistent of repeatable. Aside from the fact that it happens at slow speed, when braking lightly.

Hey ho!

R

 

[gsxr]

Don't forget that new parts can be defective out of the box... I know, not something you want to think about...

 

[rayhennig]

Dont forget that new parts can be defective out of the box.

True. However, it does seem unlikely to me that a new part would suffer exactly the same failure mode as the 20-30 year old part that it replaces. Not impossible though.

R