Loss of power while driving

[sumrnitz]

Hello forum,
The past month or so I've had an issue with my '89 325i 5 speed.
While accelerating I get an rpm flatspot that will range anywhere from 3700 to 4300 where the car just falls on it's face, loses power and simply will not rev any higher. It happens anywhere in this range, but only when driving. When I sit still it will rev freely. It's a weekend car so it does sit up some. Yesterday, I put some fuel injector cleaner and premium gas in just in case it's dirty injectors (i've put 50 miles or so on it since, not enough to clean anything yet).
The car is completely stock except for one of those cheap ebay cone filters that I put on (yeah, like that actually helped anything :crazy: ) a couple of years ago. Didn't hurt anything, really didn't add anything unfortunately, just sounded cool. Filter is clean, plugs and cap look good. If there are any ideas I would sure appreciate it.

Thanks everyone for taking time to read my thread,

Chris

[lennon]

Afm?

[sumrnitz]

Would it be happening even when the car is sitting still if it was? I have no clue here.

[e30trooper]

Fpr

[Alpinweiße30]

Fpr

Both the AFM and the FPR would make a difference sitting at idle and while moving though right?

[sumrnitz]

Both the AFM and the FPR would make a difference sitting at idle and while moving though right?

That's my thought process too. It seems that if either of those parts had issues then it would happen while the car is sitting still and being revved up. Could be wrong though?

[e30trooper]

Both the AFM and the FPR would make a difference sitting at idle and while moving though right?

When my FRP was acting up , i couldnt pass 4k rpms . This happened due to me nearly running out of gas. Lots of blogging and back firing

[sumrnitz]

Mine never gets below 1/4 tank. Were you having the problem when sitting still too?

[I got it, yes!!]

I hope you get this fixed. I am having almost this same problem but mine happens at ~~5200 rpm. It feels like a fuel starvation issue. Doesnt happen when revved from a stop. Does your happen if the take the rpms up there at part throttle??? My next step is to do a fuel pressure test. You might want to do the same. I have changed out both the AFM and the FPR. It didnt change anything.

[sumrnitz]

It seems that we were thinking the same thing. When I was driving I tried it both at partial throttle and full throttle with the same result. Sitting still I can punch it or partial throttle with no issues. Really weird if you ask me.

BTW: I meant to add that I put a new fuel filter on about 1200 miles back. Has been doing fine though.

[lennon]

It could be lots of things. afm, tps, Intake leaks, o2 sensor, fuel system, etc etc

[sumrnitz]

It just seems like those things would affect the car while at rest too. I spent another hour messing with it last night. The check engine light came on for a second while it was bogging and immediately went back off. I'm really puzzled on this one.

[Streichholzschächtelchen]

No load and high fuel flow demand at rest vs under load, I bet a fuel volume with pressure drop issue.

[sumrnitz]

No load and high fuel flow demand at rest vs under load, I bet a fuel volume with pressure drop issue.

That makes sense. It's going to take more fuel while under load to reach those rpm's then it will sitting in the driveway.

New development: I went to start her (she's a she :) ) this morning and she took a long time to start...like there was no gas. The car normally fires up instantly. I wonder if the fuel pump is going south on me?

[E30_fiend]

if the check engine popped on for a little then you should run a stomp test to see which code you pull. This could very well point you in the correct direction for a fix.




Taylor