Need Help!!!

[bwawuz02]

So for the past few days I've been trying to get my build to run with no luck

I have 150psi compression across all four cylinders, spark, and fuel. The car barely starts, sputters for a few seconds at most then stalls out. If I hold the throttle open and crank her over she gets a little more rpm then lets out a few backfires thru the intake (dBilas ITBs) before completely stalling. I've checked the timing and everything looks good there, but she just doesn't seem to be firing properly. Swing away with ideas, I'm all but fed up at this point.

[Ryann]

You're kind of in uncharted territory there, man. What are you using for your FI setup?

[bwawuz02]

Stock ecu. This should at least be able to crank her over. I've tried making changes to the idle spark timing thru the ostrich emulator and it doesn't really do anything. I've tried adjusting the fuel tables for the larger 24lb injectors and that's not helping either.

[Ryann]

What are you using for a TPS?

[bwawuz02]

All sensors are currently stock. WB O2 sensor going in tomorrow.

[mr ilia]

Check list if you're starting a cold motor:

ICV
AFM
Battery

Make sure these are pluged in in good working comdition...this is assuming the built motor has the rest of things properly setup.

Ohh...I've heard that plugs for some sensor plugs are identical and can be cofused with one another, so ensure these bits are plugged properly.

[bwawuz02]

FML!!!

Today I put all the stock pieces back on the motor.

Intake manifold
Cams
Injectors

I can't pull out the M44 crank/pistons, so those will have to stay. I know the TPS works cuz the stomp test still works to get trouble codes. I know the AFM works cuz I can see it tracing different load addresses in tunerPro RT.

But alas, she still only cranks and diesels for a few seconds at best, never more than bouncing the RPM gauge.

PLEASE HELP ME!!!

[bwawuz02]

I think I might have fouled the spark plugs. Will try another set and report back mañana.

Would it still be dieseling with fouled plugs? The weird thing is that the wide band O2 sensor always shows as running lean... What do u guys think?

[bwawuz02]

Okay, so def fouled plugs = dieseling... I still don't know why the wide band shows lean...

[bwawuz02]

Bad (brand new) crank position sensor. Intake, cams and injectors going back in tomorrow.

Oh and for all the haters, I found my answer in the archives of M42club.com

[Ryann]

So the crank sensor was sending SOME kind of signal but not a readable one? An unplugged CPS gives you an engine that won't start at all. Nice work btw.

[bwawuz02]

Apparently E36 and E30 CPS are different. Word to the wise, try to get a genuine BMW piece. BMW spec for E30 is 640 ohms, my new one showed 503 ohms and so did the one I tested that came on my E36 core motor. Funny tho, the E30 one only showed like 550 ohms... who knows.

[Ryann]

The only real way to test a cam or crank sensor is to back probe the connector for AC volts while the engine is running. I realize you've got this resolved and I'm dragging this out but I'm curious as to the mode of failure in the other sensor that would cause a poor running condition and no codes.

[bwawuz02]

Read up on M42club nay-sayer!!!

The E30 motronic won't throw a fault code for a bad CPS, but it will cut the fuel pump. I realized this, which i had read about on previously mentioned forum, when the car would try to start and then quickly go lean (due to lack of fuel). I was perplexed by this at first, but once I read that no/failing/wrong CPS signal cuts the fuel pump it made sense. And it was literally the only thing I hadn't tried, after resetting the mechanical timing multiple times, swapping out all coils, watching the plugs arc on top of the engine to make sure I had them on the right cylinder, etc.

Unplug your CPS from the central wiring box under the intake and try to start the car... it won't. Stomp test will give you 1444, no errors.

[Ryann]

The reason for my confusion is that in your original post you said the engine actually started. I've inadvertently tried to start mine without the crank sensor plugged in and got nothing but starter.