'02 Z06 Turbo has sudden problem when transitioning into boost

[JeremyBlackwell]

I am suddenly having some problems that I cannot figure out. The car is a '02 Z06 with STS twin turbos and 60lb injectors, running HP Tuners version 2.1.14 with enhanced 2-bar and RTT.
Here is the background of what's happening:
- I had the car running great at 5psi of boost, with low-mid 10:1 air:fuel and +1a4 degrees of timing advance. It would spin through 2nd gear no problem and pulled very smooth.
- installed a 160 degree thermostat, and lowered the #1 and #2 fan actuation temps. during this time, the battery was already weak, and died several times. I tried jump starting it with a jump box, no luck. So I took out the battery and put it on a trickle charger for a day, reinstalled, and the car cranked right up.
- since doing the thermostat and having the battery die completely twice, the car now has a problem. The only thing that has changed since it ran fine was the average engine coolant temperature because of the thermostat (went from about 220 down to 185 or so), and the ambient air temperatures outside dropped from about 80-90 degrees down to 50-60 degrees or so.
-The problem is....When the car starts to get above 95-105 kpa of manifold pressure, it will violently buck like the car momentarily shut off and will flash the check engine light for about a second like it hits a rev limiter. On one pull I stayed on the throttle, and after it missed, it picked back up, missed badly again, etc and made it up to 135kpa. The car drives well at part throttle and manifold pressures lower than 95kpa or so at ANY RPM, so it's not RPM dependant. I noticed the air:fuel ratio when it started go get into boost was low 11's (I assume due to the lower coolant and ambient air temperatures leaning out the mixture due to higher oxygen concentration), so I added 0.010 to the 140-194 degree cells in the POWER ENRICHMENT 'add vs ECT' map to help compensate for this, and it did bring the air:fuels back down where they should be at ~100kpa. I also did the following to the ECU:
p0106 error map calculated max upped, and changed p1514 zones by +0.03 from 43% to 100% TPS zones and 2000rpm to 8000rpm zones.
I also checked the MAP sensor to make sure it hadn't popped out, and it seemed fine. I also ran out all of the fuel in the car and put fresh 93 octane in, didn't help. I pulled one of the plugs out which I had recently changed, and it was clean. So, I am at a loss as to what the problem is.
-At this point I'm guessing either a crack insulator on a spark plug causing a cylinder not to fire (which I wouldn't think would feel so violent), or possibly a problem with the ECU, or maybe the fact that the low octane spark advance table only goes to 1.20 g/cyl and I'm logging more than that when the car misses. Also, just to make sure there wasn't some sort of lean miss the wideband wasn't picking up, I added 5% fuel and then 20% fuel to the 'boost enrichment' map with no luck.

Attached you will find the current map, datalogs (anytime you see the MAP pressure get to around 95kpa and see it suddenly drop off, that is when the problem is occuring.) Also, here are the DTC file of current codes. ANY help is appreciated!:

[PCM] P0103 - Mass Air Flow (MAF) Sensor Circuit High Frequency (Pending) (Old) (Current) (Immature)
[Convenience] B0851 - Unknown (History) (Immature)
[Unknown] B0432 - Unknown (History) (Immature)
[Brake] C1241 - Variable Effort Steering Circuit Malfunction (History)
[Unknown] B2587 - Unknown (History) (Immature)
[Restraints] U1000 - Class 2 Communication Malfunction (History) (Immature)
[Unknown] B2588 - Unknown (History) (Immature)
[Brake] C1278 - TCS Temporarily Inhibited By PCM (History)
[Unknown] B2592 - Unknown (History) (Immature)
[Entertainment] U1064 - Loss of Communications with DIM (History) (Immature)
[Unknown] B2593 - Unknown (History) (Immature)
[Brake] U1000 - Class 2 Communication Malfunction (History)
[Restraints] U1016 - Loss of Class 2 Communication with VCM (History) (Immature)
[Entertainment] U1016 - Loss of Class 2 Communication with VCM (History) (Immature)
[Convenience] B2202 - RF Window Switch Stuck in Up Position (History) (Immature)
[Convenience] B2283 - Unknown (History) (Immature)
[Convenience] U1160 - Loss of Communications with DDM (History) (Immature)
[Entertainment] U1096 - Loss of Communications with IPC (History) (Immature)
[Convenience] B2206 - RR Window Switch Stuck in Up Position (History) (Immature)
[Convenience] B2285 - Unknown (History) (Immature)
[Convenience] U1255 - Class 2 Communication Malfunction (History) (Immature)
[Convenience] B2282 - Unknown (History) (Immature)
[Restraints] U1096 - Loss of Communications with IPC (History) (Immature)
[Convenience] U1064 - Loss of Communications with DIM (History) (Immature)
[Convenience] B2284 - Unknown (History) (Immature)
[Convenience] U1096 - Loss of Communications with IPC (History) (Immature)
[Convenience] U1064 - Loss of Communications with DIM (History) (Immature)
[Convenience] U1096 - Loss of Communications with IPC (History) (Immature)


Continuous Tests
Misfire: Complete
Fuel System: Complete
Comprehensive Component: Complete


Once Per Trip Tests
Catalyst: Incomplete
Heated Catalyst: n/a
Evaporative System: Incomplete
Secondary Air System: Incomplete
A/C System Refrigerant: n/a
Oxygen Sensor: Incomplete
Oxygen Sensor Heater: Incomplete
EGR System: n/a

[JeremyBlackwell]

oops, I had forgotten to attach the log file and the map! I attached them to the first post now.

[HoP]

AFR's in the 10.1 to 11.1 is really rich for boosted cars. I try to keep cars that are forced inducted to AFR's under WoT to the mid 12's. I have seen a case where rich running cars in forced applications can blow out the spark. Try pulling some fuel out, and re-gap the plugs to perhaps a closer gap. Also I didn't see what codes where thrown when you mentioned the CeL light came on after the episode happened.

[JeremyBlackwell]

I know the AFR is overly rich, but I am using this as a caution of thermal management more than anything. I have a good bit of experience with forced induction on Supras, etc and don't feel comfortable with mid 12's unfortunately. In my opinion the optimal air:fuel lies somewhere in the middle. Besides, the car ran great even at richer air fuel ratios when I was dialing it in, so I don't think that's the problem. As I mentioned before, after the thermostat and cooler weather arrived, the air:fuel was in the 11's because the ECT trim wasn't quite enough at lower temps and the car still had the problem. So, it's had the problem with air:fuel ranging from 10 to 11.4:1. Thanks for the suggestion though!
The plug gap is what everyone seems to run with this set up, 0.035" on a colder copper plug, so I don't think that's it (unless a plug insulator/porcelain broke somehow!) I made some changes tonight, we'll see how it goes tomorrow.

[EC_Tune]

Email Ken your stock, modified & VCMSuite Info file.

[03Sierraslt]

AFR's in the 10.1 to 11.1 is really rich for boosted cars. I try to keep cars that are forced inducted to AFR's under WoT to the mid 12's.

Mid 12's AFR at WO for boost is lean, most seem to get max power in the 11.8-12.0 range and many tune for 11.6-11.8 for safety.One little hickup in the mid12's at higher RPM could be bad.

[NTIMID8]

I try to keep cars that are forced inducted to AFR's under WoT to the mid 12's.

Normally I would not post anything, but you posted mid 12s for a boosted car and 13.8 on N/A cars?

Those are both way out of line and dangerous to the reader

[HoP]

On the contrary. I have a dyno that loads 224 LX dynojet. Every tuner I know including myself targets AFR's on boosted cars to 12.1 to 12.5.1., with NA cars running very well from 13.1 to 13.8.1. Take a look at the new Audi 2.0 S's and Mercedes Benz 55 AMG Kompressor motors, you ever see what their AFR's are under WOT? Try this, 13.5.1 to 14.7, they try to get the car to run as close to stoich as possible. So yes imop and what I have seen daily on a dyno being logged and loaded with a wbo2, cars running below 12.1 boosted is very much so on the rich side of the spectrum. Curious as why you seem to think NA cars that run in the mid 13's is dangerously lean? Do tell..


Remeber the saying "Lean is mean"? To lean is disasterous I agree. A NA car that runs 14.2 or higher is in the danger zone imop. I believe alot of people target a richer zone because of a few variables..

1. They are logging info while on the street, which is dangerous and frankly sometimes you have no room for good pulls to redline e.g. traffic or congested city streets.

2. A richer AFR i.e 12's on a NA motor is easier to target then pushing for 13's. (From what I've seen) so many tuners settle for less.

[NTIMID8]

On the contrary. I have a dyno that loads 224 LX dynojet. Every tuner I know including myself targets AFR's on boosted cars to 12.1 to 12.5.1., with NA cars running very well from 13.1 to 13.8.1. Take a look at the new Audi 2.0 S's and Mercedes Benz 55 AMG Kompressor motors, you ever see what their AFR's are under WOT? Try this, 13.5.1 to 14.7, they try to get the car to run as close to stoich as possible. So yes imop and what I have seen daily on a dyno being logged and loaded with a wbo2, cars running below 12.1 boosted is very much so on the rich side of the spectrum. Curious as why you seem to think NA cars that run in the mid 13's is dangerously lean? Do tell..


Remeber the saying "Lean is mean"? To lean is disasterous I agree. A NA car that runs 14.2 or higher is in the danger zone imop. I believe alot of people target a richer zone because of a few variables..

1. They are logging info while on the street, which is dangerous and frankly sometimes you have no room for good pulls to redline e.g. traffic or congested city streets.

2. A richer AFR i.e 12's on a NA motor is easier to target then pushing for 13's. (From what I've seen) so many tuners settle for less.

For starters, you original metric posted failed to identify the conditions at which you recommend that air fuel ratio's in itself is extremely dangerous.
Second, Loaded vs non load dynos, placement of the 02 all have significant impacts on the air fuel readings.

The bulk of all vehicles will make peak power at ~13.0:1 which coincides with the known chemical ratio for the peak ENERGY from petroleum based fuels.

Arbitrarily stating AFR targets this aggressive are flat out dangerous.

[HoP]

For starters, you original metric posted failed to identify the conditions at which you recommend that air fuel ratio's in itself is extremely dangerous.
Second, Loaded vs non load dynos, placement of the 02 all have significant impacts on the air fuel readings.

The bulk of all vehicles will make peak power at ~13.0:1 which coincides with the known chemical ratio for the peak ENERGY from petroleum based fuels.

Arbitrarily stating AFR targets this aggressive are flat out dangerous.

Agreed loaded vs inertia dyno's will yield AFR % differently but the % error is minimal. I know I have one. The "bulk" of the vehicle's that you reffer to is broad so we will go with that. They are designed to make peak power above a 13.1 afr. I have no idea where you are getting your information but this is the year 2006 not 1968. Cars are designed now to be as efficient as possible, hence the reason why I stated Audi targets a 14.7 or as close as possible afr while under boost at WOT. Again afr targets for boosted cars at 12.1 or even 12.5.1 are far from dangerous, remember you still have timing that plays a major factor in afr. I really believe you should spend some money and book some dyno time on a dyno and play with afr/timing under controlled settings. I would be willing to bet that if you are runing your car NA at an afr of 11.5.1 that it will make more power and yield a more linear curve at an afr of 13.1. You mentioned the placement of the wbo2, again the afr% of error be it at the collector or after the muffler yields a small %. If it was so important companies like dynojet would not have wasted time and money engineering a AFR monitoring station that is as close as one can get to 0% error after the muffler. Rather they would send you a $1.00 bung and say "Have at it".

[EC_Tune]

HoP:
Just going to throw 2c in here on the headpipe/tailpipe wideband readings from my experience. I have seen as much as 1.5 ratios difference (extreme case) between my wideband in the collector and the tailpipe wideband on the DynoJet on a car with catcons.

Theory:
The efficiency of the exhaust system determines the ratio of the collector wideband to tailpipe wideband.

The gasses have cooled substantially by the time they reach the tailpipe wideband and because of this I have *generally* seen a richer mixture at the tailpipe vs the collector wideband on cars with catcons. Without cat's things *generally* reverse.

In your experience, which is truly the most accurate representation of AFR Pre-cat (collector Wideband) or tailpipe?

I personally prefer the pre-cat wideband for accuracy.

EC

[HoP]

Hello EC_Tune,

I would always prefer the pre-cat location especially on race cars. I've found the variance using the "new" afr monitoring station from Dynojet to be off from pre/post cat to be @.2 to .5 of a %. Honestly it's not that big of a difference to make me worried over. Of course the testing I performed was on cars that had under 14k miles on.

[EC_Tune]

What is different about the new version? Any pics?

[HoP]

The old system used a wand and the wb02 was inserted into a block that was attached to the wand. Problem with this was the fact that you could not keep moisture/condensation off of the wb02 and this caused a high failure rate of the wbo2's not to mention inaccuracy of true AFR. Enclosed is a pic of the new AFR monitoring system.

[EC_Tune]

That's the one we have here. Thought there was something even newer.

Thanks!
EC

[Casey]

Jeremy,


We had a bug with that RTT operating system that would cause the PCM to reset if it used the Boost AFR table.

There is an update and you will need to download it and re-do your RTT conversion. Then just do a compare and copy over your old values with a few right clicks. Email support your serial number and I will get you the udpated version.

The quick fix for this if you do not want to use the boost AFR table is set the map enable value to its higest limit.

-Ken

[jmoody66]

Jeremy,


We had a bug with that RTT operating system that would cause the PCM to reset if it used the Boost AFR table.

There is an update and you will need to download it and re-do your RTT conversion. Then just do a compare and copy over your old values with a few right clicks. Email support your serial number and I will get you the udpated version.

The quick fix for this if you do not want to use the boost AFR table is set the map enable value to its higest limit.

-Ken

Ken,
I ended up buying this car and would like to know if this serial number was ever sent to you for this updated version?
I just happened to be looking through this forum trying to find out what is wrong with the car and find that the seller had the exact issues I am having now.
Thanks