mr_bock

I went to have my Emissions test taken and received a Failed Test. I have used two different scanner tools to remove the codes that keep coming back.

Until this is fixed, I can't renew my car registration in Virginia!!!!

I will be checking a couple of things first. I have the TPC Supercharger kit on my car. All was well with the VA State Emissions testing until the State changed how the test is done (from spinning the driven wheels with a sensor tube up the tail pipe to just reading the OBD II codes). My car is showing faults for misfire in cylinders 3 & 6. Not too long ago, the plug wires, spark plugs, rotors/caps were replaced. I don't notice any misfire but maybe it is very slight.

The Supercharger 'black box' has a wire connection to the flywheel position sensor and may be compromised. I was told by TPC that the sensors are susceptible to EMI interference. I have to check to see it the wire shielding is messed up at the connection. Not sure if there is a software fix that I can do, nor did they offer one.

I am not sure if any other TPC Supercharged cars are having similar issues with emissions testing. If anyone who has this and found a fix, please let me know!!!!!

Thanks!!!!!!!!!!!!!!!!
George

e9stibi

Bad fuel? I had the same codes and when I got a fresh tank of good fuel I was fine.s

mr_bock

I don't think so. I always run Shell V-Power!!! I have refilled the tank more than a few times since this started. I did add Techron (sp?) once, but that was a couple of refills ago.

Other suggestions????

Don Plumley

I had random misfires for a while. I thought it was due to my habit of hitting the rev limiter on the track due to lack of cognitive skills.

Here's a general list of misfire causes:

Non OEM Fan belt
O2 Sensor, Wiring
Vacuum Leak
MAF dirty
Dirty Injectors
Ignition: Wires/Caps/Rotors/Plugs worn
Various Hall sensor issues
Failing DMF
Worn valve guides

In my case it was a failing DMF. I'm told there is a definitive test using a PST2 and watching the output of the flywheel sensor with the car in the air and in gear. You'll see excursions to 10K RPMs. When we pulled the flywheel out, I could rotate the outer portion by hand showing how much of the rubber has failed.

In a worst case, it's badly worn valve guides that cause this. Cross your fingers on that one. I did.

WTH4

For several years my 96 993 (no TPC) has had issues with inspection due to random misfire codes in cylinders 3 and 6. The car has always run perfectly. I've had a tune up, plug wires replaced, etc., but none of it has had any effect on the existence or frequency of the misfire codes. I've taken the car to two local mechanics - neither seems to have a clue, other than to suggest perhaps the dual mass flywheel, but it isn't noisy and I'm not keen on replacing it on the off-chance it might resolve the issue. Unfortunately, diagnosing the problem may involve the systematic replacement of everything it could be. If you don't think there is an actual misfire and haven't done so already, I'd re-set the codes, follow the directions on page 192 of the 993 Essential Companion on drive cycling to reset the readiness codes and hope you can get it through inspection. At least, that is my current strategy.

mr_bock

A massive amount of Thanks to Don Plumley and asda82000!!!!!

I will sift through this and see what comes up. There is a lot to look at here.

Thanks Again, what a wonderful community here!!!!!!

g_murray

Hi,
When u set your OBD-ii code reader to re-set or 'ERASE all CEL codes' (real and pending) -- all data gets set to 'zero' - which includes all the readiness monitors and, of course, the 'memory' for storing 'CEL codes'.
Several of the 'monitors' (8 in total, if memory serves me) get 'set' fairly quickly - and I mean fairly quickly - like within 10 mins. of driving. The misfire monitor is one of these! (The other ones, namley the catalyst monitor(s) take AGES, but that's a different thread.)
If there's a problem with 'misfiring' then you'll see the monitor staying at "inc" (for "inconclusive") when you connect your OBD-ii reader -- and, then first a pending code, then a full-blown CEL when the problem has 'occured' 'several times' over several 'drive cycles'.
Since you can spend a lot of time "chasing your tail" - when it comes to CELs - I would recommend first doing the obvious - like checking the spark plug and wiring, distributor cap/points, distributor BELT! etc. I would even go as far as to PULL out the distributor shaft(s) and check the TEETH of that little 'cog' way down at the bottom. Often if this is missing a 'tooth' -- or is very badly worn -- it can cause a 'timing problem' (obviously!). Having had this exact problem, in another car, I am speaking from experience!
Double-check the DMV site for Virginia. I may be mistaken but I do NOT believe they can FAIL you for a pending code. They can only fail u (OBD-ii) if the readiness monitors are not set or if the CEL light is on or if the bulb in the CEL is dead or it has been disconnected, etc.
If you get to a stage where you have "done your best" and have ALL the (8) readiness monitors set and only have the odd 'pending code' for a misfire - (but NO actual CEL !) then you should be good-2-go for your state inspection.
Good luck!
Gerry

99three

I had the same problem when I was low on gas enough for the gauge to light up. Filled up and the light was gone.

hkate

I had same misfire problem on #3 and #6. Turns out it was non-oem, Continental actually, alternator belt. Search 'Misfire and CEL cleared w/ Porsche Belts' for my original post. Post reply if it works. Good luck!

mr_bock

If this really is the cause, that will suck big time as I have a Supercharger installed and that has a completely different belt than OEM!!!!!

There is NO WAY that I will be taking the SC off!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I also don't remember getting any of these codes three years ago before the car was laid up.

The current faults;

Random misfire
Misfire in cylinders 3 & 6
Rear blower
Rear Blower, Stage 2

and the Airbag light on the dash comes on, blinks once, stays on for about one/two minutes. Then the ! and the airbag light go out at the same time. No airbag fault codes are shown.

Seems that the OBD II is so smart that it is dumb!!!!!!!!!!!!!!!!!!!

Deadeye

Can anyone explain to me how an non-oem belt triggers a misfire code in #3 & #6????

mr_bock

I think that it has something to do with vibrations that go through the engine and messes with the flywheel position sensor.

I am not sure if/how the sensor could be made a little sensitive and still not have adverse effects. I will 'try' and measure the sensor gap in the car and adjust as necessary if this can be done with the car up on a lift.