Rough running engine, now no start

[redhatpat]

For the last couple weeks, my engine's been running rough in my 1990 325i. I took it to a shop where they replaced the injectors and plugs, and checked out some other things. It ran a lot better, but still slightly rough. It also had a hard starting issue to during the last few weeks. It would turn over fine, I could smell gas after a few minutes of cranking, but it wouldn't start up. Sometimes it would kind of catch, sputter, but wouldn't run. This tells me (I hope) that fuel is fine, but its a spark problem.

Today was the worst so far, I couldn't get it to start even after a jump, and ended up taking my bro in laws truck. Yuck. Needles to say, it drives like a truck. But at least it got me to work.

I've picked up a new dist. cap and rotor and will do some more trouble shooting this weekend to check out how the spark is, but does anyone have some ideas on what else I can check out? Is there a good way to check coil output?

BTW, there are no error codes, no CEL. In fact, I can't even get the "all clear" error code to come up.

[mmmjboner]

delete

[Dave]

Are you sure your CEL works? I once knew a guy who worked at a car dealer and one of his mechanics' usual tricks for the used junkers was to remove the bulb on the CEL on cars they wanted to flip quickly.

[redhatpat]

I replaced the fuel filter last week. On the test drive immediately after, it ran perfect. It also ran perfect the next morning until my first stop after driving for 20 minutes. After that, the stumble came back.

Saturday, I replaced the dist. cap and rotor. The cap had a fair bit of pitting on the electrodes, the rotor was dirty, but looked okay. After this, the car ran a lot better, but still had a stumble. I was getting inconsistent resistance readings on the coil, so I picked up a new one that afternoon. After it was in, I didn't notice much difference, but considering it was probably the original coil, it was most likely due to be replaced.

The stumble was very reduced at this point. It would come on around 2800 rpm, the engine would slowly rev up to about 3200, then take off again like normal. The amount of throttle I gave it didn't seem to make it any worse or better, though flooring it would get the engine to accelerate past that rpm range a little faster, making it feel less worse.

Are you sure your CEL works? I once knew a guy who worked at a car dealer and one of his mechanics' usual tricks for the used junkers was to remove the bulb on the CEL on cars they wanted to flip quickly.

I've thought it might be out or disabled. Which one is it? I've never seen it lit up, is it on the left side? And would I have to remove the gauge cluster to check it out?

Since the new cap,rotor, and coil, the start up is better, but still takes some cranking sometimes. Today I had to put the gas pedal down at least 3/4 to get it started. A couple times I had the gas pedal down 1/4 to 1/2 way the engine would catch, run rough for a few seconds, then quit. When I had the gas pedal down 3/4, it would catch after a little cranking, I'd continue holding the pedal down 3/4+ and it run rough for a few seconds at 1000 rpm (give or take some) then slowly rev up to where you'd expect it to run with a 3/4 pedal (3000+ rpm). After that, I eased up on the gas, and it ran fine. I didn't drive it, so I'm sure the ~3000rpm stumble was still there.

I still need to check out the throttle position switch, and other things giving signals to the DME. But would a bad fuel pump cause anything like this? It's occasionally made a loud whining noise in the last couple weeks and I'm going to replace it.

[mmmjboner]

Is there a good way to check coil output?

ah, i didnt catch that the first time around. my bad.

[redhatpat]

I have a shop looking at this right now. Monday night it was running so bad (bucking) I pulled over and had it towed to a local shop that's supposed to be very good. When I pulled over, so much gas had passed through the engine unburned, the muffler was glowing red hot! Luckily, nothing in there seems to be damaged.

The guys got it running almost perfect. Turns out it was several things at once which were bad: spark plug wires were in terrible shape, fuel pressure regulator was bad (overfueling the engine), the coolant temp sensor at the thermostat housing was bad (it fell apart into three pieces when it was taken out), and of course the plugs were so fouled from the extremely rich condition that they'll need to be replaced again (they're only 2 weeks old).

When I get it back I'll need to do the timing belt, and valve adjustment. Should be pretty much 100% at that point.

Damn, I hate taking my car to a shop, but this guy really knows these older bmw's so it looks like it was money well spent.

[porsche gt1]

check your fuel pump. you might not be getting enough fuel. I know you are getting fuel. It could also be your fuel pressure as I realised this week. Low fuel pressure = no go.

[MrK]

Yeah plugs can foul real easy from rich running... I've gone through like 6 SETS since I first got my e30 exactly a year ago.

[redhatpat]

check your fuel pump. you might not be getting enough fuel. I know you are getting fuel. It could also be your fuel pressure as I realised this week. Low fuel pressure = no go.

The shop measured the fuel pressure, and its good. But I've also heard the fuel pump making a loud whine off and on. It's been added to my "to do" list to replace it. Its funny, that list doesn't seem to get any shorter after owning this car for over a year now. :( Maybe if I didn't want everything to be perfect on the car. At least it runs and drives a hell of a lot better. :)

[euroshark]

Check your grounds, especially the injector grounds... I had a problem with this and the car would start and die intermittently, then finally no start.

[robmespeedy]

i think im going through the exact same problem.

[325iCabrio]

I was going to recommend the fuel pressure regulator, so I'm glad to see you replaced it. I'd also replace the cranshaft position sensor. My car died while I was cruising at 40, and after some questions board members recommended the CPS. I'm either running lean or have an ignition problem, but we have some similar symptoms. The CPS is on my list to be placed, along with rotor/distributor and ignition wires.

Oh, and my fuel pump buzzed really bad until I replaced my FP regulator. It still makes some noise sometimes, but it's much better.