2001 V70XC - struggles to idle when coming to stop light Topic is solved

[xHeart]

Intake holes can be seen in fuel trims. Small ones will drive LTFT (long term) up, large holes will drive STFT and cause idling/driveability problems. ECM relies on front H2OS for this loop to work.

STFT/LTFT can be read with any OBD-II scanner, DiCE/VIDA setup is not necessary.

If you see fuel trim off, but can't find the hole (smoke test is strongly suggested) AND the car works fine for a few minutes after cold start - that might be a bad front H2OS sensor. It does not work properly until heated to a working temperature, ECM knows that and ignores its readings for a few minutes. The moment ECM switches to a bad oxygen sensor you'll be getting engine troubles.

If you find someone with DiCE/VIDA, you can run a ETM test and see whether it reacts to ECM commands well.

Other common problem is a coolant temperature sensor. Most of engines don't work well if this sensor lies.

Thanks again.

I ran the ETM test over VIDA/DiCE today.

The ETM signal 1 = 16.74 & TM signal 2 = 16.58, so the Difference value is 0.26. Not sure what it exactly mean, but Maximum difference 0.53º and previous ETM test notes suggest that the ETM passed, unless you say otherwise.

YES, as you suspected there are two, ECM 6806: Turbocharge - Flow to high, and ECM 262A: Long term trim - Upper limit.

I'll read the details for each in the morning.

FWIW: the DTC is present for 13 drive cycles (?)

[abscate]

Did you clear codes after the snorkel work? I would clear them again and monitor.

Snorkel Tear would cause both of those.

[vtl]

ECM-262A alone would be a hole in intake or bad MAF. Not sure if you still have an old original MAF or got a replacement. Sometimes people get a wrong Bosch MAF that works OK at idle, but has a lot of divergence with the correct one under the load.

ECM-6806 is suspicious. Did you touch vacuum TCV hoses? Any chance they are incorrectly assembled? Or, maybe, pinched or anything else that causes TCV to malfunction? Turbo has a compressor bypass valve that acts as a safeguard, however ECM still wants to be able to lower the pressure. That is what wastegate and TCV are for. I can imagine malfunctioning TCV would make ECM unhappy.

These two errors probably say that the engine gets more air than it commands, which points to the turbo control. I would check MAP sensor as well (mounted on the intercooler, near exit) - it measures air pressure and temperature closest to inlet manifold and is more important to ECM than MAF.

Also did you do a smoke test? It is very handy in leaks diagnosis and can surprise you. For example, I had to replace a PTC rubber grommet, because it was letting smoke out despite all my attempts to seal it.

[xHeart]

Did you clear codes after the snorkel work? I would clear them again and monitor.

Snorkel Tear would cause both of those.

Thanks!
I'll clear the error codes. Explore vtl's directions if issue returns.

[xHeart]

ECM-262A alone would be a hole in intake or bad MAF. Not sure if you still have an old original MAF or got a replacement. Sometimes people get a wrong Bosch MAF that works OK at idle, but has a lot of divergence with the correct one under the load.

ECM-6806 is suspicious. Did you touch vacuum TCV hoses? Any chance they are incorrectly assembled? Or, maybe, pinched or anything else that causes TCV to malfunction? Turbo has a compressor bypass valve that acts as a safeguard, however ECM still wants to be able to lower the pressure. That is what wastegate and TCV are for. I can imagine malfunctioning TCV would make ECM unhappy.

These two errors probably say that the engine gets more air than it commands, which points to the turbo control. I would check MAP sensor as well (mounted on the intercooler, near exit) - it measures air pressure and temperature closest to inlet manifold and is more important to ECM than MAF.

Also did you do a smoke test? It is very handy in leaks diagnosis and can surprise you. For example, I had to replace a PTC rubber grommet, because it was letting smoke out despite all my attempts to seal it.

Yes, replaced the MAF and TCV when putting new pipe between MAF and turbo. The tcv hoses are the colored IPD silicon hoses for easy routing and connection, also made sure that the three hose connection and sensor at PTC were snug.

ERASE ALL procedure on error codes captured on 9/25. And followed by a warm engine ETM test, and then the 3-minute x 2 ETM reset procedure -- the Difference value 0.32 with Max Diff at 0.58º.

I can capture additional set of parameters, meanwhile, here is a vehicle information on following parameter at idle:

MVS_V70XC_1157.jpg (116.96 KiB) Viewed 1167 times

[abscate]

No leaks with they LTFT. The threshold on later engine management is about 20%, for the code to set.

[xHeart]

The test drive returns ECM 6806: Turbocharger control system flow fault - Flow too high. Would the Flow Too High due to Signal too high OR Signal too low, cause?

For Signal too high, it reads, air leakage after turbocharger
For Signal too low, it reads, hoses between turbo and tcv

Here is the Frozen data for ECM 6806:

MVS_V70XC_1166.jpg (78.49 KiB) Viewed 1161 times

[vtl]

Do you have your old TCV?

[xHeart]

Do you have your old TCV?

Yes!

[vtl]

Yes!

Try to swap it back?

Also did you do a vacuum test for membranes in wastegate and in CBV? When they tear the pressure coming from turbo becomes erratic, not what ECM expects.