Chugging and sooty spark plugs

[Peace_Power]

325i m20b25

I've got new spark plugs, a recently cleaned 02-sensor and rotor.

But the car doesn't want to rev very high and starts to chug and looses power.

It started at 4000rpm and got worse and worse down to 2000rpm.

I get soot on my spark plugs and O2-sensor, but a clean fixed the problem for a short while and now it's back.

Is it safe to assume it's the AFM that's gone bad?

[dnguyen1963]

Too much un-burnt fuel. Have you checked the injectors for leakage?

[Peace_Power]

Right after the O2 sensor clean it ran pretty good. But it's running rich for sure. And now it's so bad I don't dare drive it.

When I first checked the spark plugs after I bought the car recently they were a little worn but perfectly clean. It "was" running flawless for a while. And the car doesn't have a lot of miles on it so I doubt it's the injectors.

[Peace_Power]

Some more things; I guess the problem appeared when engine got up to temp and then got worse. When I finally made it home the temp gauge was sitting a little high (still under 3/4 mark).

The spark plug leads do look a little old but the engine runs fine on shorter trips.

I also got a warning light for the low beams, but they both lit up fine. Maybe I've got a short somewhere..

[EatsHondas]

Go through this list.

[Peace_Power]

Go through this list.

Thank you, this is awesome!

On the first list:
Is there both a coolant temp switch and sensor? I've checked the blue sensor on the thermostat housing and got normal ohm values at the ECU.

[Peace_Power]

I'm an idiot, pulled the spark plugs and they look just like new and the O2 sensor is still as clean as when I cleaned it.

[Peace_Power]

It won't even cold start easy now. It must be that it's running too lean. It used to be too rich and now too lean, I'm so confused. =(

[Peace_Power]

The f-ing AFM is from a m20b20 and has part # 0280202083.
I should have the 0280202082 for the m20b25...

Argh...

[EatsHondas]

Is there both a coolant temp switch and sensor?

Not for your whip, only the 318's and M20B27 (eta/seta motors) have a switch. The B25 has what you tested, and the single prong sender unit that tells your coolant temp gauge what to display. The single prong does not effect engine behavior.

How do you have the wrong AFM installed?

[Peace_Power]

Not for your whip, only the 318's and M20B27 (eta/seta motors) have a switch. The B25 has what you tested, and the single prong sender unit that tells your coolant temp gauge what to display. The single prong does not effect engine behavior.

How do you have the wrong AFM installed?

It looks like it may have come of a scrap yard car. It has some writing on it. And the previous owner had done some real poor repairs other than that. They look identical other that how they pair with the ECU i s'pose.

I found an AFM with the right part number that'll go on there.

It must be one of the following issues now;
Fuel pressure regulator
Fuel filter
Fuel pump

[EatsHondas]

How does it run with the correct AFM?

[Peace_Power]

How does it run with the correct AFM?

I haven't tried starting it yet, I'm waiting for a new fuel pressure regulator and fuel filter. I'll report back once I get the parts installed.

I'm fairy certain the FPR is the problem.

[Peace_Power]

I put a new FPR and fuel filter on and now it runs like it ought to! (=

I'm so relieved it wasn't the pump or something else more complicated.

I think it revs better now than when I first bought it.

But strangely enough there was nothing weird going on inside the old FPR that I could see.

When I opened it up. There was a little fuel on the wrong side of the diaphragm and also no fuel pressure at the FPR when I disconnected the fuel line.

Oh well, it works now and I got to destroy the old one, so I'm happy. (=