O2 sensor
02-12-2007, 01:27 PM
#16
Addict
Rennlist Member
Rennlist Member
Art,
OK, you just passed a pretty tough emissions test, so I would bet your cats, O2, and MAF are in at least decent shape. Each coil fires 2 cyl per bank,so if both cats are glowing red (burning off raw gas) one coil may not be firing when you feel that "running less than 8 cyl" happening. I would start with the coils--grounds, wires, then finally the coil itself. Pull the small grounds and clean/reassemble. Pull the coil wires and do the same--make sure they are firmly seated. If you can isolate which cylinders are not firing, it will make it easier to troubleshoot.
A quick check of the spark plugs condition when running poorly (shut down and pull plugs) may give you the answer of which coil to look at--wet plug, follow the wire back to the coil. Nice tan dry plug, look somewhere else.
How old are the plug/coil wires--do they put on a "light show" in the dark?
There are many other possibilities, but that is an easy place to start and a very cheap/easy fix.
Jim
OK, you just passed a pretty tough emissions test, so I would bet your cats, O2, and MAF are in at least decent shape. Each coil fires 2 cyl per bank,so if both cats are glowing red (burning off raw gas) one coil may not be firing when you feel that "running less than 8 cyl" happening. I would start with the coils--grounds, wires, then finally the coil itself. Pull the small grounds and clean/reassemble. Pull the coil wires and do the same--make sure they are firmly seated. If you can isolate which cylinders are not firing, it will make it easier to troubleshoot.
A quick check of the spark plugs condition when running poorly (shut down and pull plugs) may give you the answer of which coil to look at--wet plug, follow the wire back to the coil. Nice tan dry plug, look somewhere else.
How old are the plug/coil wires--do they put on a "light show" in the dark?
There are many other possibilities, but that is an easy place to start and a very cheap/easy fix.
Jim
02-12-2007, 03:57 PM
#17
Three Wheelin'
Originally Posted by Garth S
Because there appears to be an erratic nature to this issue, I would try to find a buddy with a good running S4 that you can swap your MAF and LH module into: if his car continues to run well, no damage done, and your more $$$ components are OK.
I'll second Garth here. I'd try the MAF and LH swaps before investing too much time on anything else. I'd do the LH first.
I tried to compile all the idle issues things into one list:
http://members.rennlist.com/fabric/i...eshooting.html
02-13-2007, 01:21 AM
#19
Instructor
Thread Starter
I have had Porsches since 1989: 86 911, 84 944, 86 944 turbo, 87 944 turbo and 928S4. Last one drove me to the point of thinking of leasing Hummer H3( for my wife that is).
Last edited by Art20c; 02-13-2007 at 02:36 AM.
