Uneven power delivery, they all do that?
Posted by Milo
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Haven't had a day off in a couple of weeks so not much progress. I did manage to pry the top off of the AFM and stared at it while scratching myself.
 Google told me that the 5mm allen on the body was a rich/lean adjuster, it was all the way down (clockwise) to the stop...is that bad? I now I should wrap my head around the AFM testing but my brain hurts from trying to figure out stuff at work.
It starts the same hot or cold, not instantly but not bad. When I quickly feed it gas it bogs out badly, I'm guessing too much gas too quickly. I'm back to my assumption that I need a shop with an exhaust sniffer to diagnose it. Matt Hey Bob, would you be willing to drive my car around the block and giving your opinion? ---------------------------------------------------------------------------------------- Matt in Everett, WA BMW n00b with a 1987 325e |
The only thing about that is that the pressure regulator is purely mechanical and fairly simple. I wouldn't think a failure would cause erratic fuel pressure. I might suspect a partially clogged fuel filter first, but even that seems unlikely. Usually fuel issues create very rich or very lean issues that cause even power loss across the entire band, or high/low RPMs. For something to come and go like that I would really suspect a sensor or electrical. Arbitrary flat spots really sounds like the AFM, but we think that is good, right? Milo or Bob, does The power loss feel like the loss of a cylinder (power wise), or more than that? Could it be as simple as moisture in the distributor? Or a really bad spark plug wire?Something would generally cause lower power, but given an occasional increase in frequency of failure would cause it to feel "flat"? Or does it feel like an on/off switch of rapid power loss/gain? ...always lurking, rarely posting... Tyler ----------------------------------------------------------------------------------- 1989 - E30 - M20 - Manual. Approximately 270,000 miles 2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles 
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Some other guys can correct me if I'm wrong here, but there few about like 4-8 ECUs for the E30, and they are all compatible with each other. 173 and 154 being the two most common by far. There are some difference between them (I think the stomp test ability is a feature added later), but they should all work. Now, there might be a difference between which ECU matches with a motor. But not having the exact one specified by your VIN does not automatically mean that something is wrong with it. ----------------------------------------------------------------------------------- 1989 - E30 - M20 - Manual. Approximately 270,000 miles 2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles
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Tyler, I wish I still had my Bentley and my mind but I have to caution against your logic. There are incompatibilities between most of the Motronics versions. Some are just non starters while others are A-ok with a bunch in between. Case in point; we used to have a member here; 'Djumanji'(Andrew Schluckbier) who had a 1988 super eta that someone had put a later model DME into it. He had no end of detonation(pinging) problems, until he replaced it with the proper one. Some of the DME's were only timing control units and required the ICM(Idle control modules) to work. I miss my stuff or I could tell you exactly which ECUs were compatible and which were not 
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My logic should always be questioned, but in this case I think it was sound. Because most E30 models had were produced with multiple different and BMW compatible ECUs, than just because the ECU in your glovebox doesn't match something like RealOEM doesn't mean it is the wrong ECU. I did some searching for an ECU E30 compatability list. I found a list over at PelicanParts. The summary though, is that the 325e has two compatible ECUs, the 027 (which Milo has) and the 154 which is what his search returned. Now, I don't know if all the ECUs are forwards compatible, but I know they are backwards compatible. i.e. An older ECU may not work in a newer car, but a newer ECU will work in an older car. In any case though, Milo should probably research the matter to his own satisfaction, especially if he intends on replacing it with something else. In the mean time, the issue is more likely to be something other than the ECU since it is an intermittent problem. ----------------------------------------------------------------------------------- 1989 - E30 - M20 - Manual. Approximately 270,000 miles 2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles
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That is correct; except the shut off time is more like 30 to 90 seconds depending on the year and model of E30. The proper test is to check it when the engine is running 
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