Turok

I started a similar thread on 6SO a while ago. Just want to explore every option so looking for fresh ideas.

After last winter (tranny rebuild) my car started giving flashing CEL:
P0300 - Random misifires
P0301 - Misfire on Cyl 1
P0302 and P0303
P0040 - Oxygen sensor signals swapped, bank 1 sensor 1 /bank 2 sensor 1


The CEL occurs on ~3000rpm in 3rd (around 80kmh) on light throttle. ONLY in these conditions. Car runs on all cylinders, no hiccups.

Spark plugs were changed about 2 months prior to that winter. During that time there were no CELs.

- done pressure test multiple times
- voltage runs at 14.08V (13.88V when warmed up)
- camshaft angles have slight difference (but within tolerance and better than most other cars at my shop)
- fuel pressure runs at 3.5 bars
- replaced variocam actuator (solenoid)
- replaced solenoid bracket (was ok)
- replaced coils (OEM)
- replaced N75 valve
- swapped oxygen sensors.

The errors remain on the left bank.

I've read literally everything there is on the Internet and I'm out of ideas. The guys at my shop are scratching their heads as well. I don't know what else I can do, I don't want to give up on my dream car Please help.

Carlo_Carrera

This is stretch, but you might need to try swapping ECUs with another 996TT.

If you are still getting errors then you might have a damaged wire harness.

Macster

I re-read your thread in 6Speed. You were advised to replace the plugs. Bosch plugs apparently aren't up to the job. And be sure the gap is correct.

(My stock 2003 Turbo gets Beru plugs and these appear to work just fine.)

Misfires confined to one bank can be plug related. Banks are not identical and often require different fueling which is why each bank has its own #1 and #2 O2 sensor. Marginal plugs may be tolerated by the better (for the lack of a better word) bank but cause the other bank grief.

I think at this point by not changing/replacing the plugs you are leaving a rather large stone unturned in your search for an answer.

"02996ttx50

by "swapping" 02's did you mean "replace" or just swap? id replace with new...and you could still have a cracked coil. i'd check those again also in spite of their relatively new installation.

clue might be found here:

What the P00040, P0041 code means

P0041 means that the engine control unit (ECU) is seeing the signals for oxygen sensor 2 has switched between the left and right banks. The bank 1 sensor 2 signal is swapped with bank 2 sensor 2 causing the ECU to trigger a Check Engine Light on the dash.

What causes the P0041 code?

P0041 has a few common causes:

Swapped connectors between oxygen sensor 2 left and right bank
May indicate ECU failure or error
Wiring damaged, open, or shorted
Swapped oxygen sensor wiring between banks

Kevin

I would swap the inlet low lift/high lift solenoids. See if the misfires move to Bank 2

I would also Replace the Wideband O2 sensors> new Bosch units..

When you have replaced them, I would datalog your short term and long term fueling.. Make sure both banks are recorded. I would also log your intake camshaft movement/deviation Bank 1 vs Bank 2..

Carlo, you can't swap ECU's between cars without a full reprogram> the vehicle codings will not match the gauge cluster and immobolizer..

Kevin

Another thing to check is the Crank DME trigger wire connections and actual air gap between the crank trigger sensor and flywheel. A improper gap or damaged DME sensor has produced these errors. A failed dual mass flywheel has also produced these misfires..

Carlo_Carrera

This would make sense since the issues arose after the trans was rebuilt.

Carlo_Carrera

I said it was a stretch.

Turok

Kevin, thanks for your advice. The left solenoid was replaced, the problem remained. Same thing after swapping O2 sensors.

I'll try to do some data logging and ask the shop to check the trigger connections

Fishey

What sparkplugs did you use and what gap level were they at when you installed them? It wouldn't be the first time I have seen a plugs installed with the wrong gap level. Hell, it could even be that they left the sparkplugs loose installed all 6 and tightened one bank and forgot to tighten the other bank as we are human this type of mistake happens.