M50 E30 3500 RPM bogging

[Habla]

Bump from the depths, but I have the same issue. There is nowhere to hook up the engine ground on the passenger side of the engine bay, so I put it on the drivers side. It is attached right on the block, and goes to the early model ground point on the frame rail.

I did hook up the cel and I have no codes. Cel does not light up at all, even when the engine hesitates.

Ive replaced knock sensors, o2 sensor, intake boot, maf, fpr vacuum hose, spark plugs, and tested my crank sensor at 520ohms.

Now Im thinking that I should try a new cam sensor, and do a fuel pressure/volume test under load.

Does anyone else have any ideas?

Thanks,
-Peter

[MaxBell]

Ok, so just to put an answer into this thread, my main engine ground was not making proper contact.

[MaxBell]

Same as me. Ok so Pin 2 goes nowhere.

However, I'm still getting this weird bogging issue!! It will do it randomly, nothing is constantly repeatable. It will idle but not rev up at ALL.

Turning the car off and back on will solve it for a bit.

Could it be lack of fuel?

[e30rapidic]

i connected mine like this..

pin 24 on the ecu goes to the red/yellow wire of the c104
pin 14 on the ecu goes to the black wire of the c104

[MaxBell]

Question: is there a wire (Pin 2) in the C103 (little white/square/3 pin connector in the glovebox) that has to be connected to prevent a 3500 rpm rev-limit?

In a guide I read, I was told that Pin 2 has to be connected, but it didn't say where.

Bump

[jrdeamicis]

You win! The hose from te icv to the intake had been knocked out. Plugging it back in fixed the problem!!

10 points for Gryphindor.

I'm hoping also that the intermittent bogging and temp gauge wackiness was solved by me moving the harness ground to a better spot.

Come on, I'm shooting for 2/2.

Hell yeah!

[MaxBell]

Question: is there a wire (Pin 2) in the C103 (little white/square/3 pin connector in the glovebox) that has to be connected to prevent a 3500 rpm rev-limit?

In a guide I read, I was told that Pin 2 has to be connected, but it didn't say where.

[MaxBell]

You win! The hose from te icv to the intake had been knocked out. Plugging it back in fixed the problem!!

10 points for Gryphindor.

I'm hoping also that the intermittent bogging and temp gauge wackiness was solved by me moving the harness ground to a better spot.

Come on, I'm shooting for 2/2.

[jrdeamicis]

Your timing was off and a backfire blew out the main vac line or popped your intake tube.

[MaxBell]

This engine was rebuilt before it was put in the car. I just reset the timing as per the Bentley manual.

I'm starting to suspect a bad ground. The temp gauge goes wild when this problem occurs and those gauges are sensitive to that kinda shit.

HOWEVER: I have a new greater problem. I went to start the car today. I turned the key, it started for a half second and then I let off on the key. A crack/pop was heard and now the motor will barely run. It stalls after a could seconds of chugging.

[mattrabbit]

Is your check engine light on? My car is sluggish above 3k when my check engine light is on for bad o2 sensor.

[M-technik-3]

Is your vanos working properly? Tested the solenoid?

[e30rapidic]

how confident are you in the cam/VANOS timing? Sounds like its either a VSS signal or the intake sprocket was not advanced as a far as it should have been when putting the VANOS back together.

[MaxBell]

Sorry read what you posted and did not see any mention of what had been apart. You must have edited that portion.

You had no cracked boots of vacuum lines?

Nope, nothing. I've solved the first problem it seems tho.

The MAF was excessively dirty, so I cleaned it and the car is running much smoother. However, it still lacks power, which is a constantly repeatable problem. That makes me think the timing is off.

[M-technik-3]

Sorry read what you posted and did not see any mention of what had been apart. You must have edited that portion.

You had no cracked boots of vacuum lines?