mstr3ttcmp
03-05-2008, 06:30 PM
I own a very clean, 1986 BMW 528e - 5 speed- in great condition. I bought it just over a month ago, and have had nearly no problems up until now.
If you feel like cutting to the chase - Scroll down to "The Current Problem".
Since I bought it, I noticed the idle was a little bit low and slightly rough occasionally, although I never thought much of it. I did adjust the screw on what i believe is the throttle body, only a couple turns, which did fix it. Although, over the course of a few weeks, it slowly seemed to come back.
A couple days ago I noticed the idle becoming a little bit more rough, and actually fluctuating, or racing, up to about 1000-1500 rpm. It still started up fine, and ran fine, especially at higher revs. The only noticeable change was at idling rpm's. It slowly became more noticeable over the course of an hour or so, while idling and driving to test it.
Later that evening, the problem progressed. It went from fluctuating higher than normal, to lower. The rpm's would fluctuate from 1000 down to the point of stalling. At first, it wasn't stalling, but revving up as soon as it almost died. This behavior only existed at low revs, especially lower gears. I also noticed that the gauges would all be a little...jumpy. If I provided gas in neutral at a slow steady pace, the tachometer would go up in small jerks rather than smoothly. The gas gauge also fluctuated back and forth a tiny amount.
Later that night, the more I ran the engine and tried to solve the problem, the worse it got. It was to the point where it could barely idle without stalling. If I gave it gas, it would be okay once at higher RPM's but as soon as I let off, it would drop back down and probably stall.
Whenever I accelerated, it had a weak sound and feel, a lot of vibration, and clouds of dark exhaust which smelled like rotten eggs and possibly gasoline.
I started investigating the Idle Control Valve and Idle Control Module, but was unable to find out much that night. I did notice the ICV had the vibrations felt by touch, with the key turned to the ignition stage, indicating it was powered. I unplugged the electrical connection to the ICV, and started the engine, resulting in the idle operating at a constant ~3000 rpm.
I reconnected the ICV, and the original problem returned.
The next morning, it took a few seconds longer than usual to start, and had a very weak, rough, and smokey idle. It stalled over 5 times in a drive less than a half mile - every time it was not in gear and no gas was provided.
While driving in lower gears at lower rpm's, the whole vehicle would jerk, more violently the lower the revs.
I also noticed a whining sound seemingly coming from the rear of the car ever since the problem started, maybe even before - it might have always been there - but I've noticed it more lately.
Mid-day, it was running just about the same, although it seemed like it may have gotten better after warming up. It might just be me, but after being parked in the sun and driven some, it wasn't stalling as easily, although still fluctuating between 800 and 1200 rpm.
I removed the ICM and tested the outputs for resistance on the actual unit. Supposedly, there are supposed to be 9-10 ohms of resistance between pin's 1 and 5. I read Over Limit on the meter.
So - I'm not sure if the Idle Control Module could be the problem...
I started it without the ICM installed and it performed the same as with the ICV unplugged. After reinstalling it, the original problem came back.
The current problem:
The problem since then for a couple days now, is very rough idling, and stalling, but particularly when the engine is cold. Sometimes it is hard to start, where the starter cranks and the tachometer shows the RPM's raising very slowly up to about 500 revs over ~5+ seconds. Until it reaches normal operating temperature, the engine will stall if gas is not provided constantly. It is also weak during acceleration, and produces large amounts of exhaust, which smells like rotten eggs and gasoline.
After reaching operating temperature, the engine will idle at around 1300 rpm, and fluctuate back and forth down to around 800 rpm. If I turn on the A/C, it will usually regulate the revs down to the normal ~700 and fluctuating less. While at normal operating temperature, there is still some smoke and lack of power during acceleration in low gears at low revs, along with a rough and jerky ride at low revs.
I have done a couple preliminary checks for vacuum leaks, with none found so far.
I'm thinking it could be an idle control component, or possibly a faulty fuel injector?
Any ideas help...
Thank you!!!
If you feel like cutting to the chase - Scroll down to "The Current Problem".
Since I bought it, I noticed the idle was a little bit low and slightly rough occasionally, although I never thought much of it. I did adjust the screw on what i believe is the throttle body, only a couple turns, which did fix it. Although, over the course of a few weeks, it slowly seemed to come back.
A couple days ago I noticed the idle becoming a little bit more rough, and actually fluctuating, or racing, up to about 1000-1500 rpm. It still started up fine, and ran fine, especially at higher revs. The only noticeable change was at idling rpm's. It slowly became more noticeable over the course of an hour or so, while idling and driving to test it.
Later that evening, the problem progressed. It went from fluctuating higher than normal, to lower. The rpm's would fluctuate from 1000 down to the point of stalling. At first, it wasn't stalling, but revving up as soon as it almost died. This behavior only existed at low revs, especially lower gears. I also noticed that the gauges would all be a little...jumpy. If I provided gas in neutral at a slow steady pace, the tachometer would go up in small jerks rather than smoothly. The gas gauge also fluctuated back and forth a tiny amount.
Later that night, the more I ran the engine and tried to solve the problem, the worse it got. It was to the point where it could barely idle without stalling. If I gave it gas, it would be okay once at higher RPM's but as soon as I let off, it would drop back down and probably stall.
Whenever I accelerated, it had a weak sound and feel, a lot of vibration, and clouds of dark exhaust which smelled like rotten eggs and possibly gasoline.
I started investigating the Idle Control Valve and Idle Control Module, but was unable to find out much that night. I did notice the ICV had the vibrations felt by touch, with the key turned to the ignition stage, indicating it was powered. I unplugged the electrical connection to the ICV, and started the engine, resulting in the idle operating at a constant ~3000 rpm.
I reconnected the ICV, and the original problem returned.
The next morning, it took a few seconds longer than usual to start, and had a very weak, rough, and smokey idle. It stalled over 5 times in a drive less than a half mile - every time it was not in gear and no gas was provided.
While driving in lower gears at lower rpm's, the whole vehicle would jerk, more violently the lower the revs.
I also noticed a whining sound seemingly coming from the rear of the car ever since the problem started, maybe even before - it might have always been there - but I've noticed it more lately.
Mid-day, it was running just about the same, although it seemed like it may have gotten better after warming up. It might just be me, but after being parked in the sun and driven some, it wasn't stalling as easily, although still fluctuating between 800 and 1200 rpm.
I removed the ICM and tested the outputs for resistance on the actual unit. Supposedly, there are supposed to be 9-10 ohms of resistance between pin's 1 and 5. I read Over Limit on the meter.
So - I'm not sure if the Idle Control Module could be the problem...
I started it without the ICM installed and it performed the same as with the ICV unplugged. After reinstalling it, the original problem came back.
The current problem:
The problem since then for a couple days now, is very rough idling, and stalling, but particularly when the engine is cold. Sometimes it is hard to start, where the starter cranks and the tachometer shows the RPM's raising very slowly up to about 500 revs over ~5+ seconds. Until it reaches normal operating temperature, the engine will stall if gas is not provided constantly. It is also weak during acceleration, and produces large amounts of exhaust, which smells like rotten eggs and gasoline.
After reaching operating temperature, the engine will idle at around 1300 rpm, and fluctuate back and forth down to around 800 rpm. If I turn on the A/C, it will usually regulate the revs down to the normal ~700 and fluctuating less. While at normal operating temperature, there is still some smoke and lack of power during acceleration in low gears at low revs, along with a rough and jerky ride at low revs.
I have done a couple preliminary checks for vacuum leaks, with none found so far.
I'm thinking it could be an idle control component, or possibly a faulty fuel injector?
Any ideas help...
Thank you!!!