The Dreaded Mid to High RPM Cutout

[It's Soda Not Pop]

I appreciate the help and advice fellas. I will update as I try things.

[It's Soda Not Pop]

So I haven't driven or messed with the car in probably a week. Today I swapped the service interval back to the original. Shocker.......not fixed. I have a brand new harmonic balancer I can put on the car. But I'm still at a loss of why I'm losing timing data or fuel pressure or split sec power loss to the DME. Idk what happening to be honest.
I hope going full standalone will resolve this issue. I hate not knowing what's causing this.

[It's Soda Not Pop]

I'm going to undo my fuel pump wiring and restore it back to factory. That's the only other change I made.

[Panici]

I would expect a standalone ECU to have a high-speed crank/cam trigger log.
I know for sure the MS3X can do this, because that's what's on my E30.

You'd be able to see missing pulses straight away.


But I wouldn't swap to a standalone just to address this issue.

[It's Soda Not Pop]

I would expect a standalone ECU to have a high-speed crank/cam trigger log.
I know for sure the MS3X can do this, because that's what's on my E30.

You'd be able to see missing pulses straight away.


But I wouldn't swap to a standalone just to address this issue.

I was planning swapping anyway. This is just the issue that's come out of nowhere for me. Reading through this forum I've seen that others were having problems similar to mine and swapping to a standalone fixed their issues. Like I said I'm going to wire the pump back to factory. Right now power comes from the battery directly. There is another relay that clicks over when the original FP Relay gets power from the main relay. This (new) relay then sends power to the pump. I still use the factory ground to the pump.

[moatilliatta]

AFM flapper for getting full swing?

Cap, Rotor, plugs, plug wires all new?

[It's Soda Not Pop]

[QUOTE=moatilliatta;n10112981]AFM flapper for getting full swing?

Cap, Rotor, plugs, plug wires all new?

Flapper moves all the way. I even swapped out to another AFM to test. All new ignition. New cap, plugs, rotor, wires, and coil.

[bangn]

assuming this is an M20 on motronic 1.3 - With a coil or fuel load related break down the needle will still match the engine rpm and lower as the engine looses power unless its loosing signal to spark entirely from the DME. A complete loss of RPM feedback on the dash is a loss of crank position or rpm input from the DME which only requires a singular feed from the DME for engine speed if I recall. The engine position sensor is as reliable as they come as so long as you're seeing a voltage output from the sensor when you put a metal object against it you can confirm the sensor to be ok generally speaking. The feedback to the cluster seems quite erratic

looking at your video my first hunch is you have some form of interference in your electrical system, especially seeing its effecting your temp gauge which is measured by resistance at the engine.
First thing I would be doing is ensuring the ground strap on the tower is sound, as is the one from your battery to chassis and sump to chassis rail strap. Add jump lead if you have it to see if giving these points a better earth improves your symptoms.
nearly everything in the engine harness goes to the star point grounding strap on the tower so its important its mickey mouse.

what's the charge rate from your alternator out of interest when its running and revving? make sure the crank sensor wiring is well away from the alternator. Its almost as if as RPM increases so does the interference

failing above I would be doing resistance check on the following wires when cold and when the car is at operating temp (when its failing) as with older wiring resistance increases with temp

Pin 8 on DME - Black - CYL ID SENSOR DME INPUT - FROM H/T LEAD
Pin 1 on DME - Black - TIMING CONTROL EARTH TO COIL AND O2 SENSOR
Pin 37 on DME - RD/BU - ECU SWITCHED POWER FROM MAIN RELAY
Pin 31 on DME - Yellow - CYL ID SENSOR INPUT
Pin 48 on DME - Yellow - Engine speed (-) from crank position sensor
Pin 47 on DME - Black - Engine speed (+) from crank position sensor

If that all checks out as consistent I would be applying my own fused power input to the DME to rule out a weak power supply issue.

Also wouldn't hurt to do a voltage check between the cylinder head to chassis to check there is no stray voltage there from the alternator

[moatilliatta]

Injector harness connector free of corrosion?

[It's Soda Not Pop]

assuming this is an M20 on motronic 1.3 - With a coil or fuel load related break down the needle will still match the engine rpm and lower as the engine looses power unless its loosing signal to spark entirely from the DME. A complete loss of RPM feedback on the dash is a loss of crank position or rpm input from the DME which only requires a singular feed from the DME for engine speed if I recall. The engine position sensor is as reliable as they come as so long as you're seeing a voltage output from the sensor when you put a metal object against it you can confirm the sensor to be ok generally speaking. The feedback to the cluster seems quite erratic

looking at your video my first hunch is you have some form of interference in your electrical system, especially seeing its effecting your temp gauge which is measured by resistance at the engine.
First thing I would be doing is ensuring the ground strap on the tower is sound, as is the one from your battery to chassis and sump to chassis rail strap. Add jump lead if you have it to see if giving these points a better earth improves your symptoms.
nearly everything in the engine harness goes to the star point grounding strap on the tower so its important its mickey mouse.

what's the charge rate from your alternator out of interest when its running and revving? make sure the crank sensor wiring is well away from the alternator. Its almost as if as RPM increases so does the interference

failing above I would be doing resistance check on the following wires when cold and when the car is at operating temp (when its failing) as with older wiring resistance increases with temp

Pin 8 on DME - Black - CYL ID SENSOR DME INPUT - FROM H/T LEAD
Pin 1 on DME - Black - TIMING CONTROL EARTH TO COIL AND O2 SENSOR
Pin 37 on DME - RD/BU - ECU SWITCHED POWER FROM MAIN RELAY
Pin 31 on DME - Yellow - CYL ID SENSOR INPUT
Pin 48 on DME - Yellow - Engine speed (-) from crank position sensor
Pin 47 on DME - Black - Engine speed (+) from crank position sensor

If that all checks out as consistent I would be applying my own fused power input to the DME to rule out a weak power supply issue.

Also wouldn't hurt to do a voltage check between the cylinder head to chassis to check there is no stray voltage there from the alternator

Thank you. My last alternator was over charging. I checked the voltage at the battery with the car running and it was around 13.5-13.8. I didn't check while reving. I did restore the fuel pump to the factory setup. But again the car was acting up. I'll check my grounds. I have issues with the ignition switch sometimes. Meaning the starter will spin, but not engage the flywheel. But if I leave the key in the on position and jump pins 11 and 14 in the diag plug the starter engages everytime. Could my ignition be cutting out briefly causing this issue? Like it's turning the car off. Again I believe I'm losing a ground or something for a split sec.

[It's Soda Not Pop]

Injector harness connector free of corrosion?

Yes. Last time I checked it was good. I keep the car mostly in a garage and I avoid (or try to) water in the engine bay.

[It's Soda Not Pop]

So I ordered the standalone from jakeb. Hopefully I can pin point my issue with a more modern ecu. Plus it gets rid of the AFM, uses a e36 TPS, new wiring pigtail for the injectors, and allows me to run coil packs.

[packratbimmer]

Fuel delivery. My 89 325i did this years ago and the new pump solved it. It ran fine at lower speeds and bucked/cut out under heavier loads/RPMs.

[It's Soda Not Pop]

Fuel delivery. My 89 325i did this years ago and the new pump solved it. It ran fine at lower speeds and bucked/cut out under heavier loads/RPMs.

But would it magically buck and then pull to redline? Mine will still pull to redline. This pump is maybe 3 years old. And it's 255 walbro. Which is overkill for what it's delivering fuel to. I mean I guess at this point anything possible. I'm just extremely confused why the car started doing this out of the blue. Less than a year ago it never hiccupped.

[packratbimmer]

That's a weird one for sure, definitely different circumstances. Mine always cut out under load, but never cut out otherwise.