1992 300E Cold Running and Emission Problems

[biobenz617]

Hey all,

I have a friend at work who has a 1992 300E which has trouble starting when cold and also runs very poorly until up to operating temperature. He also failed emissions with high NOx (7 g/mi over limit of 5), and he had very low CO and HC levels so it's most likely running lean.

Could it be the CIS-E computer is not enabling cold start and cold enrichments and also running the engine lean at op temp? I'm trying to give him some advice where to start. Are trouble codes available from the fuel computer? If so, how do you access them? Does the engine fail lean or rich when the EHA valve is unplugged?

Thanks for the advice

[pawoSD]

In my case unplugging the idle control valve solved most of my problem.... Not a recomendation, but probably something worth trying. I still plan on fixing mine properly...eventually.

[biobenz617]

Originally Posted by pawoSD

In my case unplugging the idle control valve solved most of my problem.... Not a recomendation, but probably something worth trying. I still plan on fixing mine properly...eventually.

He says it runs well after warmup, but I'll bet he probably needs to clean the idle valve anyway.

[pawoSD]

When I cleaned and reinstalled mine it made my problem worse, it would not idle at all, it just shut off unless you gave it fuel with the pedal.....unplugged it, and problem went away. Weird.

[Oracle12345]

For the engine hard to start when cold try this:

test fuel pressure
test coolant temperature sensor
test starting device of KE fuel injection system

For the other problem it could many things causing the rich condition. An cold engine will always run rich not lean. You will have to test the KE injection system and see what it is wrong.

[biobenz617]

Originally Posted by Oracle12345

An cold engine will always run rich not lean. You will have to test the KE injection system and see what it is wrong.

Not necessarily if there is a problem with the cold enrichment logic either in the computer or the EHA valve. Could possibly be the temp sensor sending false warm temperatures.

Can you test the KE computer for fault codes? I've told him he needs to run through the basic tests of the system as well (fuel pressures, etc).

Thanks,

[pawoSD]

In my case I ordered a new temp sensor (the 4-pin one) and am going to see if that makes a difference.....it won't be here till the end of the week, but for now the car seems to be running fine without the valve connected....still has tremendous power. Easily pulls to the max of each gear.

[Oracle12345]

Originally Posted by biobenz617

Not necessarily if there is a problem with the cold enrichment logic either in the computer or the EHA valve. Could possibly be the temp sensor sending false warm temperatures.

Can you test the KE computer for fault codes? I've told him he needs to run through the basic tests of the system as well (fuel pressures, etc).

Thanks,

a cold engine will always run rich. Just hook a tool such as the snap on solius or modius and monitor the oxygen sensors if you dont believe me...

a faulty temperature sensor will cause the car to stay in a rich condition.

You can get fault codes from the ke control unit and mas. Search the forums on how to build it.

[babymog]

There is no MAS on a KE-Jetronic car.

[Oracle12345]

Originally Posted by babymog

There is no MAS on a KE-Jetronic car.

1990 and on....

not part of the fuel injection directly but affects the fuel injection system greatly

[babymog]

Are you thinking about the airflow meter / airflow sensor? The Mass Air Sensor is a later item, not CIS-E/KE.

[biobenz617]

From what I've read, my friend needs to check his lambda duty cycle and possibly the LED if his car is from CA. I crawled around and can't find any table of fault codes & duty cycles (on-off ratios). Can someone point me in the right direction? What years of KE gave fault codes in this fashion?

Thanks,