Car cuts out/stalls over bumps and bucks when I let off the gas

[kbaszak]

I've got an 87 325is that has recently started acting up. Whenever I go over a decent sized bump on the passenger side of the car, it cuts out and the cel flashes on for a split second. If I hit consecutive bumps, the car will completely stall out.

Another problem I have is while at a cruising speed, if I let go of the gas, the car bucks and slows down quite a bit. I'm not sure if this is driveline related? I'm not really sure where to start looking for either of these problems.

[dnguyen1963]

Perform a smoke test.

[kbaszak]

It just happened this morning on my drive home from work. Completely stalled out and when I went to start it back up, it wouldn't. When trying to crank I smelled raw fuel. Seems to be ignition related. Checked all the spark plug wires and none of them were loose or anything. Checked the connections on the coil, they were fine. Went back to try and start it after looking at everything and it started back up.

The cps is new bmw oem so I know it isn't that. Maybe the distributor cap?

[Andy.B]

I would start looking around for a loose electrical connector or ground strap. If you smell raw fuel, carefully inspect for fuel leaks as well.

[kbaszak]

I only smelled raw fuel when the car was crank no start. Is there a diagram anywhere that shows where all the grounds are?

[dnguyen1963]

Search here...grounds locations were posted many times in this forum.

[kbaszak]

Ok thanks

[kbaszak]

After replacing most of the vacuum lines because they were old and cracked, checking fuel pump wires, checking grounds, and checking distributor and spark plug wires, my car was still doing the same thing. So I figured I'd wait 'til my 173 dme came in so I could pull the code it was throwing when it happened. It came in this morning and I replaced it and took it for a test drive to get it to throw the code.

The first the I notice when I'm driving down the street is that the bucking that used to happen when I would take my foot of the gas was gone. At this point I'm glad at least one of the problems are fixed. While driving, I'm trying to hit every bump I can and the car doesn't throw any codes or stutter or stall or anything. Hopefully this means that the problem is gone for good but with my luck, this wont fix it for good. But at least right now, it seems like it's fixed.

I also had a random idle surge/cel problem that didn't happen yet today that vacuum lines didn't fix. The ecu is from programa. Haven't found much info about the quality of their ecu's for this car but have seen that they're stupid expensive. Is their quality just not that good?

[kbaszak]

Took the ecu apart and found out it's chipped and had some modification to the bottom board. I tried to put a picture in the thread but it's gigantic so here is the imgur link: http://imgur.com/51NfpqD (If someone can help me out and put it in here in a normal size that'd be awesome.)

Can anyone tell me what that thing on the bottom board is for? And is there anyway to contact turner motorsports to figure out what it's chipped for or do they only have a 91 oct chip? The PO never said anything about it..