Vehicle running poorly

Tiny
UGLYONE
  • MEMBER
  • 2004 PORSCHE CAYENNE
  • 4.5L
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
Vehicle listed above is a turbo. Can anyone tell me why my truck runs very poorly when I clear check engine light, but then runs okay when check engine light is lit? It just had $8,000.00 in engine repairs but I still cant get it running good. Codes say lean condition off idle some lambda code brake booster faulty and like 5 others. I have found couple vacuum leaks, can't find any more though I hear a hiss. When you step on it to go it bucks like a bronco.
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Thursday, September 26th, 2019 AT 6:22 AM

5 Replies

Tiny
94 TRANSAM
  • EXPERT
Hi Uglyone, Welcome to 2CarPros.

The bucking you describe is generally caused by a timing issue.

It would be helpful to me if you could post the code numbers so I can look them all up. Then Ill see what we can do to get you going.

Rich
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Thursday, September 26th, 2019 AT 6:59 PM
Tiny
UGLYONE
  • MEMBER
Hi thanks for your help. Codes are P1201 P3901 C1921 and C3000.
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Friday, September 27th, 2019 AT 6:08 PM
Tiny
94 TRANSAM
  • EXPERT
And off we go!

P1201 OBD Code Definition:
P1201 Injector Circuit Open / Shorted Cylinder #1
P1201 OBD Code Description:
OBD Code P1201

Injector Circuit Open / Shorted Cylinder #1

OBD Code P1201

(Alternative Fuel) Gas Mass Sensor Circuit Range/Performance

OBD Code P1201

Fuel injector No.1 circuit malfunction

OBD Code P1201

Injector circuit open/shorted cylinder #1

OBD Code P1201

Injector circuit open/shorted cylinder #1

P3901 reads as again injector #1 issue and cam position sensor circuit low.

I have found info on both the C1921 and the P3901 that refer to variable valve timing. If your car has a VVT system Both these codes would apply to it.

C3000 is a code for unauthorized or illegal system modification. IE aftermarket chips or having someone use a scanner to alter computer performance functions.

I dont know if you have had this done, but if you have this is likely your issue. PCM reprogramming can cause many issues and even damage if done wrong or incomplete. If it is incomplete the PCM will try to compensate for the changes which could result in damage to many things. Or it could just confuse the PCM and by it trying to fix things kills performance.

If you have not had this done and you are not using a plug in aftermarket chip I would suggest having the dealer try re-flashing your PCM. If that does not fix it, Given the odd codes and situation I would look at a new PCM.

Let me know what you find out.

Rich
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Friday, September 27th, 2019 AT 9:17 PM
Tiny
UGLYONE
  • MEMBER
Thank you guys very much appreciated.
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Sunday, September 29th, 2019 AT 12:43 PM
Tiny
94 TRANSAM
  • EXPERT
You are very welcome. Let us know if you need anymore help.

Rich
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Sunday, September 29th, 2019 AT 1:54 PM

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