need help backfires and stalls after dyno

[douniasg]

I have a 98 c5 with 408 mild cam and 40lb injectors. Did a mail order tune and the car ran decent. Decided to get a dyno tune and now if I go wot it dies and backfires. The tuner put the original tune back in and same thing happens. The afr drops to 10 once you wot. The afr is real erratic when driving normal jumps to 17 and goes straight to 10. I am getting a p1133 code o2 bank1 sensor 1. Did change the crank senor and checked for any exhaust and vacuum leaks. Not sure what to look for if its a tune issue or mechanical. I attached a scan log and tune file. I appreciate any help. Thanks
cutt off scan.hpl 98 c5 408.hpt

[mecanicman]

Try reposting your log, appears to be an error with it, I cant open.

[douniasg]

I finally was able to get another scan.I was talking to a few people and they think it might be the pcm. Let me know what you guys think before I spend more money. Thanks

[mecanicman]

Have a maf you can swap?

[douniasg]

Have a maf you can swap?

I bought another brand new one and replaced it. It didn't change the problem.

[SultanHassanMasTuning]

tune SD

[mecanicman]

Your pegging your maf and injectors by 5000 rpm. The above advice is correct.

[mowton]

Again, what is the AFR at WOT pull? Most of log shows very rich. If super rich, you need to get that in-line before declaring defeat at wot. Not saying that you won't have to scale the tune for air flow (Tune right now is MAF only), but might save you the cost of a set of injectors.

Ed M

[douniasg]

This problem happened after taking the car to the dyno tuner something he changed in the tune or damaged the pcm is causing the car to shut off at wot?
Car ran extremely rich before taking it to him (afr pegged at 10)but did not die and cut off going wot. Injectors pegged because the computer is telling them to dump so much fuel? I tried running the car open loop by disconnecting the front 02's ( no change ) I turned off the maf (no change ) I am going to install new denso 02 sensors this weekend but doubt that could be the reason it's cutting off. The first dyno pull was a clean pull all the way to redline no shut down or backfire after he "tweaked" the tune the problems happened. The tuner claims all he did was add some timing and take away some fuel. I don't know

[POWERZONE]

Did a certain Tuner in Houston do this tune?

[2xLS1]

Look where I have the cursor in your log. Your TP is still at 100%, your IPW is still 19ms, and your O2 sensor voltages are dropping like a rock. I think that for whatever reason you are losing fuel pressure.

log.JPG

[douniasg]

Look where I have the cursor in your log. Your TP is still at 100%, your IPW is still 19ms, and your O2 sensor voltages are dropping like a rock. I think that for whatever reason you are losing fuel pressure.

log.JPG

losing fuel pressure even though my fuel pressure gauge never drops below 60psi?

[douniasg]

Look where I have the cursor in your log. Your TP is still at 100%, your IPW is still 19ms, and your O2 sensor voltages are dropping like a rock. I think that for whatever reason you are losing fuel pressure.

log.JPG

But don't it look like the sensor voltage drops after the engine has cut off?

[douniasg]

yes runs very rich at wot the afr is pegged at 10 even before it goes wot
why is it doing that shouldn't it be in open loop at wot and go by whatever is entered in the tune?

[douniasg]

Again, what is the AFR at WOT pull? Most of log shows very rich. If super rich, you need to get that in-line before declaring defeat at wot. Not saying that you won't have to scale the tune for air flow (Tune right now is MAF only), but might save you the cost of a set of injectors.

Ed M

yes runs very rich at wot the afr is pegged at 10 even before it goes wot
why is it doing that shouldn't it be in open loop at wot and go by whatever is entered in the tune?

[xrelapse13]

it will only follow what is entered in the tune if the airflow is properly modeled (maf or ve)

[LSxpwrdZ]

Did anything physically change on the car? Are you positive your wideband is reading correctly? Log idle airflow and idle adapt PID's to see if the idle trims are out of place. Send me the logs when you get that done and I'll modify the file for you.

I sent you an email with some information as well.

[Jabbott]

Ok, first off sometimes they will cut off when you are MAF only on the dyno with a big cam and you have not got your fuel right down low. Don't worry about that right now, fix the fuel every where else, then fix the VE table from 3600 and down turn your high speed air to 2500 and you will be fine. You shouldn't have to tell your tuner to do this. You have to check that WBO2, just a sanity check to make sure it is good.