Mercedes 190 1989 2.0E Rough Idle and bad cold start

[derolivan]

Hello I've been trying to fix this for a year now and I've spent a lot of time searching and trying different things but none have helped so I figured I'd make a thread to get some help. It seems like the colder it is outside the harder it is to start it, it starts but I have to pump the gas to keep it alive and usually it takes 5-10 attempts if its below 10 degrees celsius. The idle is very rough 500-1300 rpm and doesn't matter if the car is hot or cold, what's weird is sometimes it runs fine sometimes not though. The abs light also comes on after 1-30 minutes of driving and when I brake on lower speeds my abs gets activated and vibrates the break pedal.

I have a spare parts 190 that runs fine so I've tried swapping a lot of parts.
OVP Relay tried swapping + bought a new with 2 fuses
Idle engine
Tried adjusting co2 and idle values (did it with a mercedes mechanic friend)
New plugs and wires
Air temperature sensor
Thermo vacuum valve
Microswitch

The car runs fine otherwise when driving normally but I will be moving to a colder climate soon and the fact that it doesn't cold start well is really annoying and looks dumb in traffic lights when the engine is revving.

I think the next 2 things I will try is to resolder the OVP relay cables and then try swapping fuel pump relay? If that doesnt help im considering taking it to a mechanic to do a smoke test to find vacuum leaks and after that I might just swap the injection system because I know these wear with time...


I would appreciate if someone would be able to help me.

 

[DREAMER NO2]

Did you try the IACV idel air control valve remove it and clean it out . Also you need to do a fuel; prtesure test . Swap out the coil for one in the spares car noteing the numbers are the same that goes for all the parts you change over.They might look the same but they are not .Look for any vacuum hoses split or damaged under the iacv and all over the engine compartment.

 

[derolivan]

Did you try the IACV idel air control valve remove it and clean it out . Also you need to do a fuel; prtesure test . Swap out the coil for one in the spares car noteing the numbers are the same that goes for all the parts you change over.They might look the same but they are not .Look for any vacuum hoses split or damaged under the iacv and all over the engine compartment.

Hi thanks for your reply yeah I tried swapping the IACV and I checked the cable and it was fine. Tried looking for damaged cables also but couldn't find any.

 

[DREAMER NO2]

Canyou see any bad wires in the loom that are cracked .I said vacuum pipes and the small nylon lines going to items .If vacuum is missing the engine wont operate right . Any fuel leaks in and around the fuel distributor ?. And the coil what engine is in your car ?

 

[derolivan]

Canyou see any bad wires in the loom that are cracked .I said vacuum pipes and the small nylon lines going to items .If vacuum is missing the engine wont operate right . Any fuel leaks in and around the fuel distributor ?. And the coil what engine is in your car ?

I found one that was cracked but I replaced it last year and I've tried several vacuum pipes with start spray to try to find the leak but no help. The wires run in hard to get places which is why I'm considering the smoke machine.

But you don't think it could be the OVP relay? The cables could be damaged? It surely has the symptoms since abs light is also on.

It's the 2.0 with automatic transmission and ke jetronic

 

[DREAMER NO2]

The engine has a model number . As your car got multi ciols or just one ?. You wont find vacuum leak with spray on the small bore pipes . Light up a good cigar and puff it and then blow the smoke down the vacuum pipe see if you can spot its entrance .Do you have the econo gauge on the dash if so where is the [pointer pointing at tick over .Have you got points in the distributor ?

 

[DREAMER NO2]

Is this like yours

 

[derolivan]

Hi, yeah my engine looks just like that! Not sure about the coils I tried googling but can't really figure out what it is, are they ontop of the cylinder head or?

I know its running on all 4 cylinders though because when I was adjusting co2 and idle rpm I had the car hooked to a exhaust test machine that gave me the motor values etc and the motor values were good. The air value kept jumping up and down though.

The cigar trick sounds good but where am I supposed to blow the smoke? There are so many cables and pipes there.

Yeah I got a economic meter I'll check tomorrow where it is at tick over but if I remember correctly its at the middle and when it has rough idle its moving from middle to red left and right.

 

[DREAMER NO2]

Use any of the vacuum pipes in turn . The adustment should never be changed but it to late

 

[DREAMER NO2]

Coils are the main reason these play up, and miss fire . The electrical side needs to be 100% for the engine to be spot on . 90% of problems come from poor electrics . Have you sprayed the injectors with starter fluid to see if the seals are leaking . And if i am right there is a large rubber seal under the fuel distributor spray under there also .

 

[derolivan]

" And if i am right there is a large rubber seal under the fuel distributor" Yeah I replaced that one already, old one was cracked but didn't help... and yeah ive tried starter spray.

And the adjustment was put back to default.

 

[mattkh]

You have not mentioned the
coolant temp sensor
injectors

 

[derolivan]

You have not mentioned the
coolant temp sensor
injectors

Have not done anything to those, injectors shouldn't have to be replaced and wouldn't they also cause problems on higher RPMs? Also my temperature meter is working fine in the dashboard so it should be fine? Correct me if I am wrong please.

 

[mattkh]

Please confirm how many injectors there are on your engine, and a picture showing the pipes leading from the fuel distributor to the injectors would be appreciated.

 

[DREAMER NO2]

4 Hard lines to 4 injectors , or 5 including cold start injector hIgh revs is down to vacuum leal or faulty IACV

 

[mioba]

Not read all the posts, but a vac leak somewhere.