92 Mercedes 190E 2.6 Loading up?

[mechjames]

I was just given a 92 Mercedes 190E with the 2.6 Inline 6 motor. Apparently the motor had no compression, and the shop wanted to put a new motor in it. Only 160,000km.

I pulled the plugs, and they were all fouled. Cleaned them up a bit, but they were still in poor shape. Car ran for a few minutes and then died. Thought maybe they were right, maybe the rings are worn and oil is fouling the plugs, but I decided to go get a new set.

Car starts up and runs alright, although not perfect. It only lasts for 15 minutes this time. It seems to be loading up with fuel, because while cranking after a long time, it sounds like the cylinders are just filling up with fuel. You get the odd fire from the plug that works. It's not oil on the plugs, it's definitely too rich.

You can clean the plugs and it'll fire up right away.

Now it just occured to me before I came inside and wrote this post, that it seemed like there was an air flow sensor in the air tube, which I have taken off, because it looked like it had mechanical fuel injection (with that mechanical fuel distributor). Looking online at rockauto, seems like it has o2 sensors too. Is this EFI? Will it run extremely rich if it doesn't detect air in the intake?

It's overly complicated for what it is, but the car is in nice shape. Just not famaliar with these systems. I'm a pro at ford EFI.

 

[oggb]

I think you might've just unplugged your MAF (mass airflow sensor)...

Plug that sucker back in. Or put it back in, if you removed it from the intake plumbing.

Perhaps try cleaning it as well.

 

[mechjames]

Originally Posted By: JRed
I think you might've just unplugged your MAF (mass airflow sensor)...

Plug that sucker back in. Or put it back in, if you removed it from the intake plumbing.

Perhaps try cleaning it as well.


I wasn't even running intake plumbing. Never thought it was fuel injected. Guess it is. There's injectors, but it still has a fuel distributor.

 

[mechjames]

Air plumbing is on, and it still loads up and dies when the engine gets warm. It starts up fine when it cools down though.

 

[CBR.worm]

Did you do a compression check to see if the original diagnosis was valid?

I think those did have a completely mechanical fuel injection system, I would check for any intake leaks (splits in the plastic possibly) and if it has a flap that moves based on air volume you could make sure it travels smoothly and that it's mechanical linkage to the fuel distributor is good. You might be able to pull it up slightly and see if the idle comes up and/or runs longer I have heard people say that those cars last forever, I have heard others say they couldn't keep them running.

Some of those systems had a single electrical fuel injector that would spray fuel into the manifold for starts and cold enrichment. If that is staying on it would foul the plugs pretty quickly. As I recall they were supposed to spray for a few seconds normally, longer in cold temperatures. I don't remember if they we computer controlled or if it was a bimetallic strip.

I don't know what kind of adjustments there are, or how the O2 sensor data is used to trim the fuel delivery.