m20-E hesitation in 3rd and 4th gear with throttle mostly open

[87' 325]

Hey I got a 1988 bmw 325e. The car has started to hesitate with the throttle fairly open. Most apparent on the highway. Only seems to happen in 3rd, 4th, and 5th gear at high speeds and the gas pedal down more than a tad. If I only slighty press the gas it doesn't hesitate but anymore and it hesitates bad. It's like a millisecond erratic hesitation.

it goes hesitation--normal--hesitation--normal in like a 2 second span.


I'm think fuel delivery since its only when the throttle is fairly open and the engine is dumping more fuel? I was also thinking possibly spark but I figured that would happen at all times.

I was gonna do fuel injector cleaner, fuel filter, then fuel pump.

problem just began within the last week and half becoming more and more problematic

Let me know what you think. Thanks.

[frolf]

I'm still facing a similar problem, but haven't started throwing parts at my car yet.

In for some more wisdom from the M20 gurus.

[atmobenzin]

I was gonna do fuel (2)injector cleaner, (1)fuel filter, then (3)fuel pump.

In that order. My money is pump though


Edit: It also could be running rich, Check O2 sensor before changing pump.

[Swanny]

^ whats up with the o2 in these systems? On my m10 I just deleted the sensor when I had to buy a new cat and it didn't cause any problems.

How vital are they to an m20i/e?

[M-power1989]

has a similar problem with my 86 bmw 635csi turned out to be my cap and rotor

[atmobenzin]

^ whats up with the o2 in these systems? On my m10 I just deleted the sensor when I had to buy a new cat and it didn't cause any problems.

How vital are they to an m20i/e?

If ECU renders O2 failed, it "turns on safemode" - making the engine run mega duper rich to prevent it from leaning out in case somthing else fails and O2 sensor is not there to correct it.

But it this case u would probably have noticed the huge difference in mileage.

[Swanny]

God damn! Everything in that system triggers safe mode.

[atmobenzin]

That is the reason why 20 years later you can still get a strong running original engine for cheap, you know. As opposed to piece of shit audi motors and such

[87' 325]

Well the odometer is broken so I wouldn't be able to track gas mileage very accurately. I'll change that out and fix the odometer. Then report back. Thanks