e30 cutting out.

[ashton]

My 88 325i is stock except it has a walbro 255 and an adjustable fuel pressure regulator. I just can't seem to get the fuel right. It keeps fouling my plugs and it just wont run right. Can somebody please give me some advice on adjusting fuel and what I'm doing wrong. It seems like my car is always down and I just wanna drive it because I love it. So please help me out. Thanks. It also has an o2 sensor check engine light code too..

[paperplane94]

Sounds like you are running overly rich. A new O2 sensor may help, but it may not if the O2 sensor has only breached the max limit of what it can read(i.e. too rich, triggers O2 sensor code).

Perhaps your AFM has been tampered with, try to use a MM on the O2 sensor(granted that the O2 sensor is working) to get a relative tuning of your AFM by turning the idle mix screw. Also check to see if the AFM has a worn resistor track under the black cover.

On testing the AFM:
http://www.iprimus.ca/~trauttf/temp/AFM/

And if your gutsy, adjustment(GRANTED that your engine is in otherwise good running condition!):

http://forums.bimmerforums.com/forum/showpost.php?p=18364832&postcount=16

http://forums.eurocca.net/showthread.php/35799-How-to-properly-Tune-the-M20-AFM

NOW HOLD ON, the AFM is just one part of how the DME controls the mixture. You will also have to check the ECT, TPS, and O2 sensor for proper functioning.
It sounds like you just want to drive the thing so that is why I suggested the AFM adjustment first, as opposed to proper replacement of sensors, but that is all up to the OP.


Post back with any results!

[jlevie]

The first thing to do would be to replace the adjustable FPR with the OE (new) part. Then check rail pressure to see that the pressure at idle in about 37psi and that it rises to 43psi when the vacuum line is disconnected. I don't know what plugs you are using, but the best choice would be NGK ZGR5A plugs.

Don't fiddle with the bypass air adjustment in the AFM. That would be treating the symptoms, not the cause. Do replace the O2 sensor unless it has recently been replaced.

[ashton]

The first thing to do would be to replace the adjustable FPR with the OE (new) part. Then check rail pressure to see that the pressure at idle in about 37psi and that it rises to 43psi when the vacuum line is disconnected. I don't know what plugs you are using, but the best choice would be NGK ZGR5A plugs.

Don't fiddle with the bypass air adjustment in the AFM. That would be treating the symptoms, not the cause. Do replace the O2 sensor unless it has recently been replaced.

The reason I put the adjustable fuel pressure reg on is because it was running too rich. The walbro is high pressure. But will the stock fuel pressure regulator do the job?

[jlevie]

There is a possibility that the Walbro will overwhelm the stock FPR, in which case you should remove it and install the OE pump.

[ashton]

There is a possibility that the Walbro will overwhelm the stock FPR, in which case you should remove it and install the OE pump.

Well I don't have that kind of money...but in the previous post you said to remove the adjustable fpr and put an oe one on it. So which one do I do?

[paperplane94]

If this is a bone stock setup then you should put an OEM FPR on there and start looking for other issues that might cause a rich condition.

[ashton]

If this is a bone stock setup then you should put an OEM FPR on there and start looking for other issues that might cause a rich condition.

It still has the oem one on it. The adjustable fpr is tapped in the fuel line right before the stock fpr because it's universal.

[jlevie]

Remove the adjustable FPR, then tee in a pressure gauge, zip-tie the gauge to the windshield wiper, and see what the rail pressure is while driving the car. If out of spec, replace the FPR and see if that results in normal pressure. If the pressure is still too high, install the OE pump.

If the fuel pressure is correct, something else is causing plug fouling. There could be problems with the engine management system that is causing a rich condition, or worn rings or valve guides/seals may be causing excessive oil burning.

[ashton]

Remove the adjustable FPR, then tee in a pressure gauge, zip-tie the gauge to the windshield wiper, and see what the rail pressure is while driving the car. If out of spec, replace the FPR and see if that results in normal pressure. If the pressure is still too high, install the OE pump.

If the fuel pressure is correct, something else is causing plug fouling. There could be problems with the engine management system that is causing a rich condition, or worn rings or valve guides/seals may be causing excessive oil burning.

This is how it drives. With no adjustable fpr and a walbro 255. I go down the road it'll be fine for about 2 minutes. Then it'll just sputter sputter sputter and it'll lose throttle. And cut out alot. There is no check engine light code or anything. I just put a new o2 sensor on it. I'm just lost. I just wanna drive my e30. :(

[paperplane94]

With any luck you can sort this out...

Now give us some more clues, does it start to sputter/cut out when the engine has warmed up or does it happen when stone cold?

Have you tried wiggling the connector in this photo while the car is running(its under the throttle body).

Can you follow what jlevie said by maybe renting a fuel pressure gauge at autozone or someplace and try to read the fuel pressure while driving.