What am I missing?

[PST]

I have a strange instance happening on the dyno. The car will not make a WOT pull without getting into a "Cut" scenario.

All I can see happening in the log is a HUGE jump in injector duty, followed by a large drop in duty, and so on for as long as I let it continue.

This car made several clean pulls yesterday, I broke for lunch, then came back and it was acting up. I litterally cannot figure out why, as I didnt make any tune changes between the last clean pull and the first bad pull.

Here's a tune file and log. The tune file is basically a quick slap together file that I am using to try out disabling different limiters.

So far, I ruled out all torque management, Burst knock, regular knock, etc.
I also noted on one of my logs that engine torque goes through the roof simultaneously with the injector duty. Ive even tried messing with the max torque timing table to see if I could get the reported torque to come down. No luck there.

Im thinking its just something stupid that Im missing. Please help me get this car rolling. I only have until 5 today with the dyno rental.

Almost forgot, car is a 2010 Camaro SS/RS with the L99/A6. Running 60# shorty's, ZL1 fuel pump, and a Granatelli Twin Turbo System.

[PST]

For what its worth... And its not set this way on the above tune, I have gone and disabled P0068, and P0101 etc. tests and maxed out the airflow and map limit tables to no avail.

I have also ruled out REP, and confirmed that the Throttle is not closing.. Its just litterally dumping fuel and chocking itself out.. But my AFR's are in the mid 11's right before the cut.

[DSteck]

Can't see your logs while I'm at work, but is the manifold pressure stable? What do the narrowbands look like when it cuts out? Post a screen shot of the log if possible.

Is the car in pure MAF mode? I'd check for a boost leak.

[PST]

It is pure MAF.. The kit has the sensor approx 12-14" from the throttle body..

The manifold pressure is stable.. It climbs with boost, levels out, and then the car starts to buck.

The injector duty cycle sky rockets, and before I disabled burst knock, it would also start making the timing jump up and down by as much as 6 degrees.

As for the narrowbands, they are rising and falling basically along the same trend as the injector pulse width.

[Chris@HPTuners]

looks like it's something airflow related, the MAF is dipping low. There are PIDs you can log called:
- Air Calc Mode
- MAF Sensor State

Maybe they will add some additional info.

It could be mechanical problem or intake pipe etc. Not sure how much boost the engine should make or if its turbo or s/c.

I also noticed you have aq lot of the MAF DTC's set to MIL on 2nd error, this can make troubleshooting failures tough becuase the failure will only set a code every 2nd key cycle.

[PST]

Will try logging those items now... The MAF DTC's were left stock, so I changed them to 1st error along with the MAP codes.
The dyno was logging a peak of about 7psi before and thats in line with what the wastegate springs are rated at..

[PST]

Air Calc Mode and MAF sensor state show "High Speed" and "No Fail" during the cut.. No check engine light either.. Not that I would be able to read the DTC if it had one, this beta doesnt seem to have that functioning.

Checked the Plumbing over and all seems to be in good shape. Could I have a bad MAF sensor and not report an error?

[PST]

Can't see your logs while I'm at work, but is the manifold pressure stable? What do the narrowbands look like when it cuts out? Post a screen shot of the log if possible.

Is the car in pure MAF mode? I'd check for a boost leak.

As Chris alluded to, the MAF data is the only thing jumping around. Just did one last pull and saw it jump from 8400hz to 10,000hz which definitely induced an increase in fueling.. Hope thats not the issue, as I really do not want to go SD with this thing. Its weird because the MAF hz log shows a nice smooth curve until this happens.

[turbo 6l]

how about etc traction control enabled since you are on a dyno rear tires are spinning front are not ..unless you are turning it off in the car hth

[PST]

Yep, its off.. After a few pull attempts it fails and stays off anyway.

[turbo 6l]

your second scan posted 67.725 frame 346 and 352 .it looks like you are maxing out the airflow ceiling in the ecm.

[PST]

I don't see how I'maxing it out.. Plus I've tried a scaled tune and got the same results.

[PST]

So before driving home last night, I fudged the MAF numbers to make it less of a drastic jump in lb/hr when the MAF was doing it wild swings. It broke up still.. But on the way to work this morning, it full on went wot without hesitation. And I didn't even change the tune. Wtf!

[PST]

Just got released from work and heading back to the dyno. Will post datalogs from my driving when I get there.

[DSteck]

If your MAF frequency is breaking up, then either something is contaminating the MAF or there's a leak happening. Just do SD and end your woes.

[PST]

That's probably what I'm going to do. She ran great on the road, but on the dyno it's breaking up again

[PST]

SD tune licensed. I just used the VE generator program to build a starter VE. Hope that works out.

[PST]

That VE generator is a pain in the ass! But I'm just about to start making boost sweeps!

[PST]

Everything went well today. Put the 2bar OS in, built a VE table to start with, and she fired right up. Took quite a while to get the VE dialed in, but managed to get full wastegate pressure pulls handled. It made 500rwhp, and 460ftlbs on a DynoJet at 6psig with little very conservative timing numbers.

Tomorrow, I'll head back to the dyno and up the boost to 9psig!

[DSteck]

Good luck! I'm a huge proponent of the MAF, but sometimes they just don't want to play ball.