Always use stock OEM Porsche belts!
07-26-2010, 03:40 AM
#31
Burning Brakes
Unbelievable story. How on earth such small difference can cause CEL light? If the belt is wider, it sits higher on both wheels and doest cause any alteration for alternator speed, I believe? Mystery for me, engineer as I am. Doesn't upgraded pully cause CEL?
Jack
Jack
07-26-2010, 07:55 AM
#32
Rennlist Member
I just had my belts replaced with the pulley update. All contis, new pulley and my wrench who says that the small difference in diameter and width makes no difference. I watched him perform the update and belt replacement. I mentioned that there were many that had problems with CEL afterwards and he responded that it had to do with the tension of the belts not the belt itself. He said if improperly installed, you may see a problem. I have about 1500 miles and no problems.
07-26-2010, 10:14 AM
#33
Three Wheelin'
I'd never heard of this issue and I've just bought new Contis. Have not put them on yet. Wanted to have spares in the trunk, just in case. On a side note, how often are you guys changing belts? I have 30000km and 8 years on my Porsche belts.
07-26-2010, 01:56 PM
#35
Rennlist Member
Mine were cracked with only 25k miles.
07-26-2010, 04:06 PM
#38
Race Car
Thread Starter
FWIW, 95's may not have this issue as they are ODBI. Also, the CEL with Conti's belts seem to occur under heavy acceleration and reving over 5K RPMS. Some seem to baby the car some, so they may never get a CEL even with the Conti belts.
07-26-2010, 05:03 PM
#41
Race Car
Thread Starter
07-26-2010, 05:46 PM
#42
Burning Brakes
okay, another stroy of a well-known issue. I have a dilema and wonder what would you do...my car has a conti belt now...no idea if the shims were played with. The belt has been on the car since I bought it and I am planning on doing them soon. Anyway, I have both a conti and a porsche belt but am wondering if I should just use a conti since it is on the car with no issue (possibly re-shimmed to make work by a mechanic that knew of the issue and compensated)...or, to go with the porsche belt. Car is a 1997 so obd-II 
07-26-2010, 06:58 PM
#43
Burning Brakes
Don't worry. Alan at German Car Repair now only uses OEM belts after what happened to me. Alan thank me later since he was able to fix other 5 993 clients of his with CEL issues by just changing their belts from Conti's to OEM's.
FWIW, 95's may not have this issue as they are ODBI. Also, the CEL with Conti's belts seem to occur under heavy acceleration and reving over 5K RPMS. Some seem to baby the car some, so they may never get a CEL even with the Conti belts.
FWIW, 95's may not have this issue as they are ODBI. Also, the CEL with Conti's belts seem to occur under heavy acceleration and reving over 5K RPMS. Some seem to baby the car some, so they may never get a CEL even with the Conti belts.
07-26-2010, 07:25 PM
#44
Race Car
Thread Starter
Read my post #20 about it for more details.... It is also documented on another thread in which was discussed in greater length.
Basically, It is not the wrong/lower alternator speed but rather the pulsations it makes when the belts slips rapidly due to incorrect size and being "pinched". At higher rpms, the belt slips ever so slightly and then it catches again once the tension from the "pinch" is released.
Due to the rotational inertia of the alternator, those pulsations are transfered to the crank, where they are detected by the crank sensor and the ODBII logic reads it with a multiple misfire in a all cylinders.
Basically, It is not the wrong/lower alternator speed but rather the pulsations it makes when the belts slips rapidly due to incorrect size and being "pinched". At higher rpms, the belt slips ever so slightly and then it catches again once the tension from the "pinch" is released.
Due to the rotational inertia of the alternator, those pulsations are transfered to the crank, where they are detected by the crank sensor and the ODBII logic reads it with a multiple misfire in a all cylinders.
The following users liked this post:
ElCid86 (04-18-2023)
07-26-2010, 10:16 PM
#45
Three Wheelin'
Read my post #20 about it for more details.... It is also documented on another thread in which was discussed in greater length.
Basically, It is not the wrong/lower alternator speed but rather the pulsations it makes when the belts slips rapidly due to incorrect size and being "pinched". At higher rpms, the belt slips ever so slightly and then it catches again once the tension from the "pinch" is released.
Due to the rotational inertia of the alternator, those pulsations are transfered to the crank, where they are detected by the crank sensor and the ODBII logic reads it with a multiple misfire in a all cylinders.
Basically, It is not the wrong/lower alternator speed but rather the pulsations it makes when the belts slips rapidly due to incorrect size and being "pinched". At higher rpms, the belt slips ever so slightly and then it catches again once the tension from the "pinch" is released.
Due to the rotational inertia of the alternator, those pulsations are transfered to the crank, where they are detected by the crank sensor and the ODBII logic reads it with a multiple misfire in a all cylinders.