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Car randomly says reduced engine performance and won't move!

662 views 8 replies 4 participants last post by  TGO 
#1 · (Edited)
2 weeks ago I went to the store, came back out and started the car. I was greeted with "reduced engine performance" in the DIC and an EXTREMELY rough idle, as well as the throttle not working at all.

I shut the car off, started it again, and all was well.

1 Week ago I parked the car on Friday after work, went to go out to an appointment Saturday morning, and had the exact same issue. Except restarting the car didn't work. And after a few restarts the check engine light came on as well. The car feels like it's running on 2 cylinders and will not move when you hit the gas. Had it towed to me mechanic and they told me there was a hose loose that connects down by the firewall..I guess to the throttle body. I picked up the car and everything was fine.

This past Sunday morning I went to go out again and had the EXACT same problem. Drove the car the night before with no issues. Had it towed again. Called them today and they said the car drove off the flat bed under it's own power and has been running and driving ever since. No codes stored in the computer.

Any idea what the issue could be? I asked them to check the grounds before I pick the car up but I really don't need this happening to me far from home where I will be stranded. So far I've been lucky. But yeah some sort of electrical issue seems to be the only possibility to me.

EDIT: Doing some GOOGLE FU and it seems to be either the ETM has failed or I also found another post about the crank position sensor being an issue.

Youtube videos seem to confirm that you can still rev the car with a failing ETM.

Symptoms of CPS problem are hard starts. Which occasionally I do have to crank longer than normal. Jumpy tach, which occasionally I have noticed the tach jump around when I crank the car. Also I have cranked the car to start the engine and once I let go of the key the car shuts right off. Starts normally on the second try. Most importantly it supposedly won't throw a CEL

Perhaps even more importantly, when I first got this car I had a similar issue where I couldn't go over a certain mph and would get random reduced engine performance messages. Not really a rough idle though but perhaps some breaking up when the engine revved. And when I brought it to the shop they have noticed that the CPS bracket had broken and so the sensor wasn't reading right. They ordered a new sensor but the bracket had been revised. It was a huge job to replace the bracket so they just repaired the old one with epoxy I think. Whatever they did I haven't had another issue until now. I can't believe I forgot about that! Anyway I'm hoping it's that and this issue can be resolved quickly.
 
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#2 ·
"reduced engine performance"
I shut the car off, started it again, and all was well.

Had it towed to me mechanic and they told me there was a hose loose that connects down by the firewall..I guess to the throttle body.

Any idea what the issue could be?
The throttle body is in the front (nearest the radiator) , the firewall is between the engine and you -

Are you sure this is a 2002 with a bosch throttle body? 2001's have a Magnetti Marelli (sp) throttle that fails. 2002 throttle bodies rarely fail but I have seen poor electrical connections where the throttle body plugs in and have solved those very erratic, very frustrating problems with replacement wiring. Perhaps it was part# 31409380

Swedespeeders have talked about that here

https://forums.swedespeed.com/showthread.php?257161-Throttle-body-wiring
 
#3 ·
It's a 2002 for sure. I don't know if the TB is a bosch or not.

Sorry the offending loose hose must attach to the turbo or something then. It goes down by the firewall along with a plastic accordian tube off the intake. I can't really see but anyway it seems the hose is irrelevant.

I'm gonna bring my laptop with VIDA down there and see if anything pops up in there. I know they use one of those rather expensive scanners and they work on all types of cars, so I doubt I'll see anything that they can't, but it's worth a shot I guess.

I don't need to get stranded somewhere far from home. This happening in front of my house is one thing...but being stuck far from home with work the next day is something I don't have time for.
 
#6 ·
Yeah so VIDA didn't have anything stored except a couple of BCM codes. I guess I'm just driving around with my laptop until this happens again and I can get a live reading from VIDA as it happens.

Car is idling rougher than normal. Drives and accelerates fine but definitely more vibration at idle than normal.
 
#8 ·
I had similar issues and it was the mount for the CPS. I was able to fix it road side with some epoxy and I haven't had an issue again. The mount is a complete pain to replace with the transmission mounted to the engine, hence the epoxy.

You should be able to reach your hand back in there without removing anything to see if you get any play or not. For me, the sensor was literally resting on the flywheel, slowly being worn down.

This would be the first thing I check, but cleaning the throttle body is important too if you haven't already done it.
 
#9 ·
This is exactly what happened to me after I got the car. The problem wasn't as bad though. It would just say reduced engine performance and maybe rev a little slow but I could still drive. And then like magic the error would just go away and the car would start running fine while driving.

They found the CPS mount was cracked and same as you say, it was a major pain to replace so they fixed with epoxy. Haven't had an issue again until now.

I had completely forgotten but when I asked them about it when I remembered and they told me they were poking at the sensor while the engine was running and also scoped out the wires and sensor itself and everything was within spec.

I feel like if the issue was a dirty TB then it wouldn't be so intermittent. But I guess I'll add that to my list of things to check.
 
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