B34.5 CEL light.... no code readout with gas pedal?

[Erick]

Right now my car is idling like crap. It'll barely stay on when its warm.

There is a CEL light on at all times, but I cannot tell what it is. I tried to get the gas pedal stomp read out but I get no reading from it.

This is a B34 with all B35 electronics.

Anything I'm missing? It's a Motronic 1.3, so it should give a read out.

[yert315]

only when it's warm, or all the time?

edit:
did you use your e30 temp sensor?

[Erick]

Yes, I am using the e30 temp sensor since the e34 one I had was not giving me a read out.

As for the idle... it shuts off when cold, barely idles when warm.

[Flash]

First unplug the oxygen sensor and see if it changes operation when warm, next check the temp sensor with the multimeter, then make sure the TPS is adjusted, lastly the AFM.....well you cannot properly check an AFM period without messing with the adjustments. Those were the 4 codes that 1.1 throws at least, 1.3 stores more codes and will throw more but that is the basics.
Only other sensors are a bad injector (sticking or cracked), cranks trigger sensor, and thats pretty much it.
Make sure that none of your fuel hoses, ESPECIALLY the return at the FPR side, arent kinked. The b35 return is notorious for being short, i made mine like 4 times as long so there is no sharp bend, just loops around.
The car will run fine without the inductive pickup plugged in so that isnt a culprit, and remember your spark plugs will tell you a lot, if an injector isnt firing or sticking.
Lastly make sure all your connections to every sensor are good.

Those are the basics, no different from the 325i with 1.3 :)

[yert315]

Make sure that none of your fuel hoses, ESPECIALLY the return at the FPR side, arent kinked. The b35 return is notorious for being short, i made mine like 4 times as long so there is no sharp bend, just loops around.

what might happen if this hose is slightly kinked?

[Flash]

Ive had every problem known to man with my b35, one of them was the car not idling and running what felt to be 4 or 5 cylinders. By chance my hand pushed the line on the kinked hose and my idle smoothed out and i could drive the car. It felt like it was running on 5 cylinders and idles poorly. Its a stupid design how they have the hardline where it meets the fuel pressure regulator, its such a sharp bend.
When i let the fuel line go, the problems would persist and i found the issue. I just used about 10 inches of BMW fuel line and its been running fine ever since!
The funny thing is, is that when i cut the line originally to the factory length it was still too short and very hard to get off with the angle.

You can see how much longer i made it:

[Erick]

First unplug the oxygen sensor and see if it changes operation when warm, next check the temp sensor with the multimeter, then make sure the TPS is adjusted, lastly the AFM.....well you cannot properly check an AFM period without messing with the adjustments. Those were the 4 codes that 1.1 throws at least, 1.3 stores more codes and will throw more but that is the basics.
Only other sensors are a bad injector (sticking or cracked), cranks trigger sensor, and thats pretty much it.
Make sure that none of your fuel hoses, ESPECIALLY the return at the FPR side, arent kinked. The b35 return is notorious for being short, i made mine like 4 times as long so there is no sharp bend, just loops around.
The car will run fine without the inductive pickup plugged in so that isnt a culprit, and remember your spark plugs will tell you a lot, if an injector isnt firing or sticking.
Lastly make sure all your connections to every sensor are good.

Those are the basics, no different from the 325i with 1.3 :)

Well, I just solved the idle issue by putting the ICV back in and drilling the intake manifold to put in a fitting for the brake booster hose. Now I'm using all the proper hoses so I'm not having issues with vacuum lines flexing themselves completely.

The car idles straight now, although a bit high because my throttle cable is pretty stretched. Car is idling at about 1500-2000, but if you push the cable further forward it'll go down to about 1200rpm.

The check light is still on though. Why I have no idea... I cannot tell this 100% for sure, but I am pretty sure I was running the car with the CEL off at some point in time, but for the life of me I cannot remember what has changed since then.

I put in some temp sensors from my e30 T-Stat housing since the ones I got from the junkyard (off the E34 T-Stat housing) were no good... or at least my instrument cluster was not getting a reading.

Now with the e30 sensors I get a good reading on the instrument cluster, and I'm assuming the ECU is also reading because although it's running a bit rich, it's nothing too crazy.

- Erick

[Erick]

One more symptom. I'm breaking up really bad from idle to moving. Especially in reverse. The car almost bogs out... but once you start revving up all is good.

Doing a little bit more research, it seems that the blue temperature switch on the t-stat housing is different on the B35 than the B25 (although the B35 and B27, M10B18 and S14B23 all share the same one). I'm guessing that's the culprit.

Now if I can only find where the hell I put that damn sensor. I might've tossed it :slapforehead:

[Erick]

So I swapped sensors today... nothing's changed. Looking at it closely... the blue sensor that was on the 325i was the same as the one that the M30 uses. Go figure.

Back to square one.