Car will start only if accelerator not pressed

[Me22]

The only way to start my W124 from cold is to turn the key WITHOUT pressing the accelerator.
Sometimes I have to try this few times to get it to start.
If the accelerator is pressed, it will not start and will have to wait say 10 minutes before trying again.
THIS ONLY HAPPENS WHEN STARTING FROM COLD. it will work like any other car during the day.
Any idea why?

 

[rayhennig]

My 124's fuel and ignition system is new and working, in the words of a 124 expert, "Like new".

It starts from cold with no accelerator. I have never tried it with accelerator from cold.

When hot, with no accelerator, it needs more churning or a second attempt to start. But, with light accelerator it fires up immediately - very light, just taking up slack, if that makes sense - that's what it feels like but there is no undue slack.

I found this hot start a bit frustrating until I read the user manual for the CIS/distributor ignition cars. In the manual it clearly states no accelerator at cold and light accelerator when hot. It also says something about longer churning when hot.

So, your condition may be normal, almost. Almost? I cannot explain why you need to wait 10 minutes so something must be amiss.

Sorry that's not a great deal of help.

RayH

 

[rifiki]

I don't know what your problem is with the car, I have always started a cars with electronic fuel injection without pressing the accelerator for years and never had problem, hot or cold.

 

[Me22]

My 124's fuel and ignition system is new and working, in the words of a 124 expert, "Like new".

It starts from cold with no accelerator. I have never tried it with accelerator from cold.

When hot, with no accelerator, it needs more churning or a second attempt to start. But, with light accelerator it fires up immediately - very light, just taking up slack, if that makes sense - that's what it feels like but there is no undue slack.

I found this hot start a bit frustrating until I read the user manual for the CIS/distributor ignition cars. In the manual it clearly states no accelerator at cold and light accelerator when hot. It also says something about longer churning when hot.

So, your condition may be normal, almost. Almost? I cannot explain why you need to wait 10 minutes so something must be amiss.

Sorry that's not a great deal of help.

RayH

Thank you for the reply. When my car starts from cold, the revs are very low, then gradually accelerates to normal engine rev speed. Does yours do the same?

 

[Me22]

I don't know what your problem is with the car, I have always started a cars with electronic fuel injection without pressing the accelerator for years and never had problem, hot or cold.

Thank you for the reply. When my car starts from cold, the revs are very low, then gradually accelerates to normal engine rev speed. Does yours do the same?

 

[rorywquin]

I thought it was normal to not press the accelerator (fuel injected) when starting the car (hot or cold).

 

[rayhennig]

Thank you for the reply. When my car starts from cold, the revs are very low, then gradually accelerates to normal engine rev speed. Does yours do the same?

No, mine springs quickly to life with an aggressive surge and then immediately settles to fast idle at around 1000 rpm (cold) or 600 ish rpm (hot).

There is something amiss with yours. It is time for you to start measuring duty cycle, temperature sensors etc. And ensure that your ignition system is 100% fine condition. These cars depend on excellent ignition.

Finally, what car do you have? I am talking about the M104.98x engine.

R

 

[Ron240]

As above the gas pedal should never be pressed when starting a modern fuel injected engine.
Im pretty sure it states this in the handbooks.

 

[Me22]

No, mine springs quickly to life with an aggressive surge and then immediately settles to fast idle at around 1000 rpm (cold) or 600 ish rpm (hot).

There is something amiss with yours. It is time for you to start measuring duty cycle, temperature sensors etc. And ensure that your ignition system is 100% fine condition. These cars depend on excellent ignition.

Finally, what car do you have? I am talking about the M104.98x engine.

R

Not sure of the M??? of the engine. It is a W124, 3 litre, petrol, 1991.

 

[Ron240]

. It is a W124, 3 litre, petrol, 1991.

Just to clarify my post about a "modern fuel injected engine"...your engine is definitely not modern.
I believe I (rightly or wrongly) routinely pressed the accelerator when starting 1986 and 1989 fuel injected engines.
It is definitely not to be done now though.

 

[rayhennig]

It is a W124, 3 litre, petrol, 1991.

It will be either an M103 or twin cam M104. Either way, I would expect similar starting regime as they both use distributor ignition and Bosch KE Jetronic injection, albeit with changes for the later M104 engine.

So, I stick to my earlier comments/suggestions. Something is amiss.

By the way, your engine is an M104.98x if it looks a bit like this.



Good hunting.

RayH

 

[mattkh]

When my car starts from cold, the revs are very low, then gradually accelerates to normal engine rev speed.

To me this means that the engine sensors have not realised that it is a cold start.
Is it a 3li V6 engine..?
Any chance of a photo of what is under the bonnet..?

 

[DREAMER NO2]

or like this M103

 

[rayhennig]

Is it a 3li V6 engine..?

Not for that vintage. My feeling is that it's an M103 or M104 straight 6.

R

 

[rayhennig]

or like this M103 View attachment 70135

Equally possible, an M103.

R

 

[rifiki]

Thank you for the reply. When my car starts from cold, the revs are very low, then gradually accelerates to normal engine rev speed. Does yours do the same?

It starts and idles at 1000RPM. It's designed to do that to get to running temperature quicker.