Need diagnostic help with my 325i

[Scott314]

Twice now while I've been driving, the engine has lost power for a split second, and the check engine light came on and went off just as quickly. Both times it was under acceleration. I'm pretty worried, what gives?

[jeffreyb4me]

could you give any more detailed info, anything relating to the conditions would help...................jb

[scott5598]

This sounds a bit familiar. I've just noticed my 2001 325i /w manual trans and 76K miles seems to lose power for a split second as you describe on accel in 2nd or 3rd gear between 1500 and 2000 RPM with a medium load. I'm not "lugging it", but if I wanted to accelerate more quickly I would downshift. I haven't noticed it over 2000 RPM. It has never triggered a dash light, but I've only noticed it for the last couple of weeks. I haven't noticed it when the engine is cold, so it may be calibration sensitive.

My current guess is I'm getting a misfire on one of the cylinders/plugs, and losing power, but not long enough in light the MIL light. At one time I thought it might be the clutch slipping, but I doubt that now.

Do any of my circumstances compare with yours?

[Scott314]

Originally Posted by jeffreyb4me

could you give any more detailed info, anything relating to the conditions would help...................jb

It was under fairly hard acceleration in 2nd or 3rd gear, in the 4000 RPM range. The loss of power is really noticeable. It will stop accelerating briefly, and then pick right back up, pulling hard.

Since I posted it hasn't happended again, but I haven't had to do much driving and I've been trying to drive it fairly gently. It's just when it loses power that the check engine light comes on. I don't think there are any fault codes.

The only things I've noticed about the engine are that it needs to be cranked for a while before it starts, and that one of the belts might be making a little bit of noise.

[jeffreyb4me]

'scott314' being an '89, i'd replace the DME [injection] MAIN and FUEL PUMP relays. the in the small rectangular box just ahead of the L/F strut tower under the hood. these are failure prone and may still be original on your car. If you can find an Independent shop in yor area with a BMW MoDiC or GT-1 they might be able to pull a code. Most generic scanners won't in these cases. The long cranking can also be caused by these relays BUT is also problematic of some M20 engines with M 1.1.3 DME and can take some time to isolate the cause.
try the relays UNLESS you've replaced them in the last 2 years............................................. .....jb.

[scott5598]

What you describe sounds much more dramatic than what I described in my earlier response. I did talk to the mechanic about what I have been experiencing, and he indicated it is probably misfire, as I suspected. I think the earlier post suggesting you check for codes makes good sense.