M42 Full Rebuild now won't start

[pklym]

I tried 3 different brands including Bosch.

The one that made it all run was an OEM BMW sensor from a known running m42 with original equipment.

Do you know the part number? My car wouldn't start with new CPS with the part # 12141721504, which superseded the original.

I also bought a used OEM CPS (off ebay), part number 12141721968, that did work.

[jpod999]

It is so amazing and runs so strong I'm super happy. Now I need a good
Muffler...

Years ago I had my stock muffler cut off and a 2.25" in/out Magnaflow welded in. Was quite at first but then it broke into an awesome deep sound. Cheap and sounded good!

[theTBLACK]

I tried 3 different brands including Bosch.

The one that made it all run was an OEM BMW sensor from a known running m42 with original equipment.

[pklym]

Well, it is finally finished :)

In addition to the clogged cat, the 2 crank position sensors that had been tried were incorrect. So we got an additional known working m42 CPS sensor and it fired right up!

DONE.

What was incorrect about the previous two CPS sensors?

I'm wondering if we had the same issue...

[theTBLACK]

It is so amazing and runs so strong I'm super happy. Now I need a good
Muffler...

[gespinal0301]

Well, it is finally finished :)

In addition to the clogged cat, the 2 crank position sensors that had been tried were incorrect. So we got an additional known working m42 CPS sensor and it fired right up!

DONE.

Congrats! I've been reading and lurking, but I'm glad that you finally got it. How's the difference from how the engine was before?

[theTBLACK]

Well, it is finally finished :)

In addition to the clogged cat, the 2 crank position sensors that had been tried were incorrect. So we got an additional known working m42 CPS sensor and it fired right up!

DONE.

[jaredmac11]

For everyone reading, it was resolved page 11 -- blocked exhaust

It was a bit frustrating to read that you had all these critical components working (i.e. 'fuel is present') when critical tests werent verified (i.e. injectors pulled and verified to be sending fuel). I think you went down so many rabbit holes because of that. You definitely WERENT getting fuel to the spark and thats a critical component. That was figured out at like page 10 lol

Glad its working....

edit: whelp apparently you have a whole other issue. good luck.

[benz-tech]

I apologize for not reading 12 pages of this thread but you do have the secret o2 wire connector at the fire wall disconnected correct?

[RobDog]

I don't know shit about M42's, but if this was a M20 I would think the coolant temp sensor or something that controls the mixture while the engine is cold. It seems like once it warms up and the O2 sensor takes over control of the mixture, everything is good. So you may have open loop issues.

[roguetoaster]

Wait, I thought you were selling your engine?

[theTBLACK]

Anyone still here?

R3v facebook has convinced me to keep going and figure this out - even though i'm on mechanic number 3.

Current status -

Starts and idles perfectly.

Upon cold start, won't really rev above 2.5 - Starts to sputter and bounce back like its being limited.

Once it warms up for 20 minutes - revs all the way up.

Ideas?

[theTBLACK]

running right now?

Yes sir.

[Dj Buttchug]

running right now?

[theTBLACK]

I forget, did you replace the coil packs? They can do weird stuff like not fire if they are failing, depending on if they are hot yet.

Otherwise, it sounds like the carbon track on the AFM is going bad. Can you borrow a known good one and try it?

Yup. Coil packs have been replaced. The AFM I replaced it with was a known working one - i'll see if I can get my hands on another one.