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Discussion Starter · #1 ·
Hey guys, I picked up a 1999 9-5 SE v6 from a buddy that had what seemed like a rev limiter at around 3k rpms cold, and 3.5k rpms hot. I thought it was the MAF however a new one didnt fix the issue.

Now the fuel cut is occuring exactly at 2k rpms hot, which prevents me from going past 60mph. The engine runs perfectly before the cut off point of 2000rpms. I have checked all vacuum hoses, routed the PCV system to vent to atmphosphere, tested the bypass solenoid to hold vacuum and it does.

Ive changed plugs- also regapped (went from .44 gapped to 0.39) no change so I dont think its the DI's. Changed fuel filter, Unplugged all sensors individually and ran car to see if the problem changes - no change. Removed AC. Checked all vacuum and turbo pipes. New hose clamps. Cleaned all sensors. Flushed coolant. Unplugged all electrical connectors and coated them with Vaseline. Cleaned TB, and seafoamed the car. I also swapped the DI's around to see if anything would change.

Jacked the car up and removed Primary o2 sensor to see if the cat was clogged up, and the extra relief would change the bucking - no change.

I do have a 3" AEM dry flo installed, could this be throwing off the MAF?

The car will NOT go a hair past 2k rpms when warm, in any gear or neutral/park. Its exactly like hitting a rev limiter. NO CEL's, no codes. Sometimes when it starts to buck it will stall the car at 2krpms. I can not control the problem to troubleshoot and make it buck at a higher or lower RPM, I have reset the ECU almost every time I made a change to test it.

Anybody have any clues?
 

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The only thing I can think that would cause something like that is a bad crank position sensor. If you can get the car tech2'd that would reveal it immediately. If it's the CPS like I think, it'll lose the RPM reading at 2000 rpms which causes the ECU to think the engine is not turning so it cuts fuel.
 

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Discussion Starter · #4 ·
Thank you soo much for the replys. I too have recently thought that its the CPS.

However when cold, it can hit 3k rpms, untill about 5 minutes of driving. I removed the o2 sensor from the DP, and the car was able to rev untill 3k on a solid 6 minute drive.


After about 5-10 minutes, it cuts exactly on 2000rpms on the dot, any throttle position, any speed or gear.

Thanks again ill see if I can get it tech2'd, however theyre going to charge me 130 just for the visit.
 

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Discussion Starter · #5 ·
Pulled off the CPS and saw the end had alot of metal shavings on it. I cleaned the shavings off and reinstalled. No Change still cuts out at 3k rpms in park. I still havent reset the ECU or taken it for a long test drive on back roads..
 

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when my CPS went on my c900, it could rev, but I would be going like 60 MPH and it would just die on me, I'd have to wait 30-45 minutes, and then it would start and drive for another 30ish minutes.
 

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Siezed/binding turbo? Sure sounds like a big air leak, but you've already checked IC hoses. Have you tried running it with the AMS unplugged? Any codes?
 

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Discussion Starter · #8 ·
I dont know about a siezed turbo, since the fuel cut is exactly on the dot at 2000rpms, up untill that its good, a little surging while on the highway, but idle is rock solid. Ive unplugged the AMM and the same thing. There are no codes.


I cleaned the CPS from the metal shavings, cleaned it and it didnt change a thing. I should probably get a heatshield for it since the dealership didnt reinstall i guess when it was changed a year ago (different ownership). I bet it was cooked by the turbo maybe?

Hot restarts are no problem, it has never failed to start. So Im a little lost here.


Thank you guys for your responses!!!!
 

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any throttle fault would result in a check engine limp mode. I would look with a tech2 for anomalies in the data. Not completely wrong that would throw a code but something off just enough to cause this. Without seeing the live data it will be very hard to diagnose.
 

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I dont know about a siezed turbo, since the fuel cut is exactly on the dot at 2000rpms, up untill that its good, a little surging while on the highway, but idle is rock solid. Ive unplugged the AMM and the same thing. There are no codes.

I cleaned the CPS from the metal shavings, cleaned it and it didnt change a thing. I should probably get a heatshield for it since the dealership didnt reinstall i guess when it was changed a year ago (different ownership). I bet it was cooked by the turbo maybe?

Hot restarts are no problem, it has never failed to start. So Im a little lost here.

Thank you guys for your responses!!!!
OOOH you are using the wrong plugs!!! I just saw you other post GET THEM the HECK OUT OF THERE!!!!
 

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Yes, no crazy v-plug nonsense. Also, just because the CPS looked fine doesn't mean it is fine. When mine was bad it looked exactly like the one I replaced it with. I'm still putting my chips on the CPS for this one if the spark plugs are not it.
 

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Yeah don;t know why you would go to al lthe trouble of taking the CPS out only to replace it with the same one ( its a 50 dollar part IIRC)

Although when I had DI issues my car would pull back at 3500 RPMS, so I was thinking spark
 

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Discussion Starter · #14 ·
ill pull the plugs out and put the bkr7es-11's back in.

So today I took out the laptop with the WIS to troubleshoot.

CPS SENSOR resistance was around 500ohms (should be 850ohms)
CPS HARNESS Pins 1&2 resistance was around 7mega ohms (should be around 250k ohms)

Resistance from harness pins 1&2 to the ECM was spot on, which the WIS says its a faulty ECM.
 

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Hmmm Start easier and cheapest first, do the plugs, you would be surprised how many things they can F up, and the CPS, its easy and cheap enough, and what year car do you have,. there was a bad batch of DIs that caused all sorts of problems too...
 

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Discussion Starter · #16 ·
Put the standard plugs back in, the rev limiter is now at 2.5k cold, 1800-1900 warm.

The car is a 1999 Saab 95SE OBDII V6.

I went for a drive, and put it in 1st, and accellerated down a hill and let it coast till the rpms got to around 2k rpms. the tach wouldnt even register past 2k rpms as the speed picked up. Weird, im not pressing the gas but its still bucking.

Thank you for your responses guys!
 

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CPS. It's out of spec electrically and it's the only problem that won't cause CELs.
 
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