ZR8ED

86 na. Was running fine this morning. Go to come home, and it won't rev past 2000rpm. If I floor it, the rpm will start to bounce between 2 and 2.5k rpm.

I dropped the car off at the shop and I noticed that it drives fine as long as i keep it under 2k. Even in third gear. No other sysmptoms. The only other issue I had was yesturday, when I almost flattened the battery getting it started in -30 weather.

Not sure where to start looking. I'll stop by the mech in the morning to see if he has any ideas..

kev951

check tps and afm

VirginiaF1

Sorry mate...
Spare DME to swap out?
Could DME have been impacted by cold crank?
Crank sensor & throttle position sensor original?

ZR8ED

Thanks guys. I have a rogue tune maf kit, so my first thoughts are that is the only thing that has been changed...but I installed the kit a couple of months ago and has been working flawlessly. Crank sensors are likely original. I am ordering both anyways as I was already planning to change them.
I have a spare dme and afm that I am planning on swapping back to eliminate the maf kit as suspect. I thought that a afm issue would cause this type of symptom, but I didn't think about the tps. I'll have a look.

944Ross

I used to have a GTi, an '88 with the same EFI system pretty much, and it would behave just like that except when the A/C was on. Then it would rev to redline with no problem. Never did figure it out. Would be interesting if yours ran OK with the A/C on, too!

dirtyTurbo

I had the same issue and it turned out to be a ref sensor.

Dougs951S

Agree with above, definitely sounds like a VR sensor issue.

ZR8ED

You may be right. I swapped the ecu/maf with zero effect. I got it to rev beyond 2k rpm sometimes, so we are now suspecting the ref sensor. The car still starts and idles perfect. We will see on monday and I will report back.

Van

Ignition rotor?

Rogue_Ant

TPS... or possibly reference sensors/wiring.

Try unplugging the TPS sensor and see if that 'fixes' it. If so, then you have a bad TPS.

odonnell

Could also be a blockage in the exhaust system. Your cat ever rattle?

+1 on ref sensors though. Protip on getting some cheap: get them off a 80s BMW 5 series at a junkyard. Same part number.

Dougs951S

^^ also available off a 7 series of the same vintage.

admiralkhole

And the 6

Any m30 equipped bmw.
On a side note, I recently found a 6er at the junkyard...wish I had one as a dd.

ZR8ED

Small update. New reference and speed sensors..no go.The car still starts and idles fine. Still only revs to 2k, and I can occasionally get it to fully rev to redline. This is making me still lean towards electrical.
I have a brand new exhaust with new highflow cat and a N/A tune maf kit (tested a stock ecu and afm to be sure)
Now its back to basics. Will check the tps, check condition of spark/ignition system, will also have a look at fuel pressure. I am personally starting to think cap/rotor or tps.
I will keep you informed where I end up tommorow. Its going to be another cold one with temps well below minus 25.

shortyboy

I had a similar issue and it turned out to be a faulty TPS. Make sure it's properly adjusted to click when throttle body is moved. If set correctly, seek a loaner or new unit.