1987 BMW 325e running rich?

[davvik]

My e30 is running rich. I just picked it up a few months ago and it's unknown exactly what mods have been done to it but it's not totally stock.

The car runs rich to the point that after long drives I get residue on my bumper. I am going to get to testing things like the MAF and the coolant temp sensor to see why it could be running rich but I was hoping for other suggestions to look into. The fuel economy isn't terrible. It was something like $60 in gas for 8 hours of highway driving (in Canada, so a bit more expensive fuel than the states).

I believe it is running rich because I am getting smoke from the exhaust. I know it's not burning oil because there hasn't been any consumption, it doesn't smell like burning oil, and it isn't blue at all. It smells like unburnt fuel basically.

I am not sure if the ECU has been tuned, it is possible that I need to replace it or retune it but I don't think I should start there with troubleshooting.

Any suggestions would be greatly appreciated. Thanks in advance.

Edit: also, the previous owner removed the catalytic converter. I'm assuming this is because it probably died from running so rich all the time.

[NoM54me]

Does it run/idle rough as well? Coolant temp sensor could be suspect too, as well as cold start injector, if you have one. What condition are your ignition parts in? Your previous owner sounds like a tool.

[davvik]

Your previous owner sounds like a tool.

That's for sure! Terrible work done by him everywhere. Random exposed wires behind the dash. A wire with two switches in it that seemingly ran nowhere. Wire that ran from the driverside kick panel to under the back seat then under the carpet up to behind the radio (instead of just going up the one foot up around the guage cluster).

An unfused wire running from the battery with lots of breaks in the insulation to the stereo. It also wasn't even stripped, he put the wire between the battery terminal and the battery clamp and tightened it until it broke the insulation.

Idles and runs smooth. No stumbling on acceleration or anything. Lots of power. I get smoke out of the exhaust like it's running rich though. Not consuming oil or coolant so I don't think there are any bad gaskets internally.

The ignition parts seem to be in good condition. The plugs were okay when I pulled them for a compression test aside from the small build up (likely due to it running rich). The wire insulation is still nice and soft with no visible wear/aging.

Coolant temp sensor could be suspect too, as well as cold start injector

How would I know if I had a cold start injector and where would I find it? Does it inject extra fuel somewhere into the manifold/throttle body to give let it run rich on cold starts?

The only other symptom I have noticed is that on very cold starts (-30C or so), when it fires after cranking the RPMs will jump up to about 2.5k and then it will idle it's way back down to about 1100RPM. It will always idle around 1100RPM when warm. I thought that cold start jump was common though. My old car did that all the time.

[NoM54me]

I now see you have an eta, so your cold start injector is above the valve cover on the intake manifold, opposite the intake side. Sometimes they leak. You'll have to remove it to check, search for test procedure. Fairly simple. Yes, they give a little extra fuel on cold starts, but should stop after a few seconds. Sometimes they don't, causing that rich running condition.

[davvik]

Thanks, I'll add that to the list of things to look for. I checked out my air filter and it was pretty clean. Ordered up a new one still just in case because looks aren't everything.

I found on this forum that the cylinder injector o-rings get too hot when the engine is running and can leak some compression. They can also leak extra fuel into the cylinder by leaking. I think the cold start injector might be the easiest to check though at this point. So I'm going to try that first.

[Gary Horneck]

Check the values on the temp sensor. When I got my eta, it did the same thing. Changing the sensor cleaned it right up.

[davvik]

I assume you don't mean the temp sensor that controls the gauge on my dash, right? There is one that sends the info to the ecu?

[Gary Horneck]

There are two sensors down in there. A brown one, and a blue one. One for the dash gauge which is brown, and the sensor for the ECU which is blue. Check the resistance with an ohm meter if you have one, or try a new one, they are cheap.

[davvik]

Yeah the one for my gauge was giving me an issue. I think the ecu temp sensor is like $10. And I believe its also on the thermostat housing so it shouldnt be too hard to get to.

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[Gary Horneck]

You are correct.

[davvik]

I believe this part number: 13621357414 is the one that I need. I can't seem to find any information on what the resistance of it should be for different temperatures so I won't know what to make of it when I measure it's resistance.

Do you know where to find this information? If not, I'm likely going to just buy one.

Also, the one I found on ebay is a blue connector, the one on bavauto is a white connector. There isn't a blue connector one on RockAuto either. Should I get the one on ebay if I need to buy one?

[davvik]

Well, I switched my cluster out recently which involved switching my coding plug... I believe my old coding plug was from a 325i and my new one is from a 325e. The engine isn't running rich, it's smooth and at the proper idle RPMs now and it accelerates fine.

Only thing though is, the car has such little acceleration now. I don't know why but it just doesn't go like it used to. I am finally starting to see why people think the 325E is so much slower. My throttle response just dropped off the face of the earth. When I have more time I'm going to try switching back to my old cluster to see if that was what made the difference.