Misfire and CEL cleared w/ Porsche Belts

[geolab]

23$ + $10 shipping on ebay, 60 euros at dealer, regards

[jimbo3]

Originally Posted by Avenger6

Geolab -

What did the belt tension tester doohicky cost?

That's a "Kricket". $11 at Napa auto parts. They'll probably need to get it from their local warehouse for you as it's usually not stocked in the stores. There are two versions- the one you need is the least expensive one. (I don't recall the number offhand.) I just got one a couple of weeks ago.

[geolab]

Originally Posted by jimbo3

That's a "Kricket". $11 at Napa auto parts. They'll probably need to get it from their local warehouse for you as it's usually not stocked in the stores. There are two versions- the one you need is the least expensive one. (I don't recall the number offhand.) I just got one a couple of weeks ago.

if it has the same scale, the price is excellent news, this is one should have items to all RnList

[aracer]

the crank sensor is on the flywheel.....how would the front pulley have anything to do with that?

[TheOtherEric]

Originally Posted by aracer

the crank sensor is on the flywheel.....how would the front pulley have anything to do with that?

An old thread, but I'll respond anyway....
I agree, that doesn't make sense to me either. Perhaps if the alternator belt is slipping, then the voltage fluctuations either screws up the spark or the ecu somehow. But I can't see how a slipping belt would affect the entire rotation of the ENGINE and thus the flywheel.

[Avenger6]

As I understand it, the vibrations transmitted back through the crankshaft to the sensor are enough to make it think there is an engine misfire, which would set up similar vibrations. I don't think it has anything to do with any possible voltage fluctuations.

[JasonAndreas]

Originally Posted by TheOtherEric

But I can't see how a slipping belt would affect the entire rotation of the ENGINE and thus the flywheel.

Misfire Detection By Evaluating Crankshaft Speed--A Means to Comply With Obdii

Methods of On-Board Misfire Detection

[Tour18]

Rennlist is the center of the Porsche universe. IMHO.

[Laura]

Lay a Porsche factory belt next to a Continental belt that is supposedly interchangeable and you can see the differences. They may be small but it does seem to make a difference. Our shop is adamant about using only factory belts.

[Sonic dB]

CEL can be caused by many things. My 97 had a "blowout" of the plastic shroud which covers above the fan area which immediately caused CEL. My mechanic said that the CEL was due to the valve guides, but I suspected it was not due to the fact that it came on when the shroud blew up....and this was proven correct once I cleared the CEL and replaced the shroud it went away for months.

It came back several months later....when I had an issue of a broken belt and bent pulley caused by a worn out fan bearing which went.....and required immediate replacement of belts over 100 miles from home. The out of town mechanic used non Porsche belts and fked up the repair (its a long story not worth getting in to at this point but it caused the second bearing to fail and massive fan and alternator failure within 2 weeks). After driving for a few days....the CEL came on and my mechanic (who is very good btw) and Hergershemires in OC said it was an issue that required at least a cleaning of the SAI ports and possibly a rebuild...

however, once I had the belts changed to Porsche with new alternator and bearing, correctly by my mechanic...and the codes reset...the CEL light went out and has been out for several months of heavy driving since then.

the moral of the story as I see it based on these experiences: dont let anyone tell you that CEL = immediate rebuild because it doesnt. This system is very sensitive and needs to be properly maintained.

[aracer]

WOW, this is one helofa thread>>>I have no choice but to now change belts to factory, however I still cannot grasp the true creation of the CEL misfire code; which, presumably is the result of the belt issue. JUST cannot justify causal issue. m

[cabrio993]

The problem with the Conti belts is not that they are lose, so this is not a belt tension or a complete slippage issue.

The problem with the Conti belts is that they are .5mm wider than the OEM's even though they are the same length. By being wider and of the same length, when they are at the correct tension, the cross section of the belt is not flat / even but they are rather "pinched" by the pulley.

Due to rotational force, as the engine reaches higher rpms, it flattens the cross section of the belt and by doing so, the 2 halves of the pulley lose grip with the sidewalls of the belt only temporarily until it grips it back rapidly once the tension is lose. This causes a "hic-up" effect on the crank and the crank sensor detects it as a misfire.

If the belt was just slipping due to being lose, it wouldn't throw a CEL, it is this rapid pinching and releasing of the belt due to the wrong width and cross section that it creates that causes the problem.

You can read more in my original post from a year ago.
http://forums.rennlist.com/rennforum...ighlight=belts