Engine mis-firing, but I don't know why :(

[enildeR]

Okay. I was driving a friend home one night from work. It had been fine the entire day. I was just about to crest a hill when I started to smell burning electronics, and I'm like "OMG! WTF? On noes!" As I was coasting down the hill, it seemed normal, and the engine still sounded like it was running (of course that is because it was in gear while I was going down the hill). No mis-fire or anything.

I reach the red light to make a left, and the engine starts to stumble. Just as I shot my foot over to mash the gas pedal to keep it alive, it dies.

I try starting it, but no go. We get out and start to push the car over to the right where there is a parking lot.

I get it towed. The next day I try starting it, and it acts as though it doesn't know where the timing is. I mean, sometimes it would fire what seemed to be like 60degrees after TDC and then other times right after TDC (fires but produces no power, and no backfire).

I started to look at the wiring, but the previous owner made a rats nest out of the under dash wiring to install the keyless entry/alarm (alarm doesn't even work). I decided to take it to a shop down the street that does BMWs.

It's been almost a week, and the guy tried replacing the cam sensor, but didn't fix the problem. Now he says he's going to try replacing the coils. I'm like WTF? I'm thinking at least try a new ECU?


Ideas? My wife is bitching my ear off about having the car fixed by the time I head out of state, so she has something to drive. I'm thinking of going to the shop and working on it there lol

Thanks in advance!

[roundel318]

Okay. I was driving a friend home one night from work. It had been fine the entire day. I was just about to crest a hill when I started to smell burning electronics, and I'm like "OMG! WTF? On noes!" As I was coasting down the hill, it seemed normal, and the engine still sounded like it was running (of course that is because it was in gear while I was going down the hill). No mis-fire or anything.

I reach the red light to make a left, and the engine starts to stumble. Just as I shot my foot over to mash the gas pedal to keep it alive, it dies.

I try starting it, but no go. We get out and start to push the car over to the right where there is a parking lot.

I get it towed. The next day I try starting it, and it acts as though it doesn't know where the timing is. I mean, sometimes it would fire what seemed to be like 60degrees after TDC and then other times right after TDC (fires but produces no power, and no backfire).

I started to look at the wiring, but the previous owner made a rats nest out of the under dash wiring to install the keyless entry/alarm (alarm doesn't even work). I decided to take it to a shop down the street that does BMWs.

It's been almost a week, and the guy tried replacing the cam sensor, but didn't fix the problem. Now he says he's going to try replacing the coils. I'm like WTF? I'm thinking at least try a new ECU?


Ideas? My wife is bitching my ear off about having the car fixed by the time I head out of state, so she has something to drive. I'm thinking of going to the shop and working on it there lol

Thanks in advance!

It might be worth swapping the ECU out, do you have any idea what wiring was dammaged? It seems like the coils would be good to rule out, but there are a variety of other things, including items on the ECU going bad due to electrical shorts, cross conections, etc during the course of you smelling burnt electronics.

[enildeR]

The mechanic tested coils from another car, but the same problem persisted.

He found a guy local that was selling an ECU (he couldn't find anyone willing to loan one out). He tried putting it in two days ago and said that the fuel pump wouldn't run. He swapped ECUs again (putting the old, bad one in), and the fuel pump work, but screwed up timing.

I didn't get a chance to look much at the wiring. The mechanic said he didn't see any burned wiring. When he was going to swap the ECU in, he said he ran through and checked for ground faults but didn't find anything.

[RED IS 91]

Have you checked (tested)the crank position sensor?
You say he tried replacing the cam sensor but that wasn't it. Did he test it or is he just another parts replacer.......................

[enildeR]

On the phone, he said that he replaced the cam sensor. He tends to be rather brief on the phone.

However, he did call on Friday to tell me that they were able to figure out why the new ECU wasn't driving the fuel pump. He said that the alarm/keyless entry was disabling it. Which I did find rather odd, considering that he said the pump would run when they swapped the old ECU back in.

He added that they were running wire to isolate and troubleshoot the fuel pump, and that's how they figure it was the alarm. *shrug* dunno. I'm going to stop by the shop on Monday and see what's up.

It kinda sucks, too, because now my truck is throwing a lean code for the MIL, and I'm trying to track down a vacuum leak. What is that saying? When trouble happens, it comes in doubles?

Meh.

[enildeR]

http://www.pelicanparts.com/bmw/techarticles/E36-DME-Repair/E36-DME-Repair.htm

so I'm beginning to think the guy picked up on ECU for a different year M42.

He said that he had to run new wiring for the fuel pump to run correctly with the new ECU. I say bull, cuz the old ECU pressurized the fuel system just fine, even though it's fried to the point that timing is off.

Anyone know if the fuel pump pins are diff between the diff ECUs?

[Ramblin MAn]

Not sure about the pins, but you put number one up on compression stroke, mark the crank pulley if it isn't already, hook up a timing light and start cranking. Then watch to see where the light blinks.

If everything seems to work except the timing is effed with the old DME, then unplug the cam and crank positions sensors one at a time and see if the blinking changes.

I'm pretty sure (not positive) that the cam sensor is mainly providing input for the injector pulses and the crank sensor is providing the input for the spark. So replacing the cam sensor may have been a waste of time.

When the hall sensor in the distributor of my SAAB went out  it acted just like what you are saying. Erratic spark, if any. I replaced every other component and finally fixed it with a good used distributor. The crank sensor is basically the same thing.

[enildeR]

Well, I finally got my car back today. He said that the remote keyless entry/alarm was shorting out the ECU, and he took out all the shit.
He also said that he had it running earlier this week, but it had stopped running right after walking away. It made a loud clank and sputtered. Seems that the vibration damper on the front of the crank came apart and took out the crank pos pickup. Went in yesterday to look at it. The rubber had separated.

I landed up paying 1600 for the deal. :\

Thinking back on it, I think it may have been the original problem. I figure it moved, and that's what threw off the timing.
That's what I get for being lazy and not checking basic things on my own first. You live you learn. Meh.