1BADLS1tuner

iTrader: (5)

OK guys i just swapped a 5.3 into my 69 C10...

setup:

2004 DBW 5.3
new dual valvesprings
new cam
new pushrods
new t76 turbo
new Siemens 60# injectors
new Built 4l80e
new yank 3600
new TR6 gapped at 28


PROBLEM:

Motor runs great till it gets to 130-140 kpa and BOOOOOOOOM!!!!!!!!!!!! (It s LOUD!) when it back fires the DBW quits working, but motor stay running... shut the motor off and restart it and its like nothing happened.

IT IS NOT THE TUNE, timing is very conservative and afr is good, not happening near the rev limmiter, open downpipe.....

Things i am thinking of checking over:
plugs/wires
intake (might be cracked)
vacuum leaks
ground wires
crank and cam sensors
compression test




I am open to suggestions and ideas!

ATEURZO6

Your on the right track with checking that... Do you have a log of when it does this???

ATEURZO6

also what is the AF when it does this????

6.0mustang

iTrader: (2)

sounds alot like a lean pop. check your fuel pressure when it occurs.

oange ss

iTrader: (50)

massive spark blowout re-igniting in exhaust ?

BadCompany VP WS6

iTrader: (6)

I was going to say crank trigger but looks like you got that. What about the verter being correctly installed?

2005vetteTT

iTrader: (1)

sound like that? if so.. spark blow out haha

1BADLS1tuner

iTrader: (5)

Thanks for the replies guys! I will check everything over as i have time and keep you updated.

Converter its new and was within tolerance.

Afr are from 11.5 to 10.5 in boost right now, its a little fat but haven't had a chance to tune it since its a new setup, timing 8 to 12. Ill try and post a log tonight.

Sounds just like a shotgun going off, almost identical sound..... And only one bang, then the dbw throttle shuts off immediately.

6.0mustang

iTrader: (2)

Sounds like you need to bump your timing to about 15 degrees for starters

1BADLS1tuner

iTrader: (5)

Timing should be fine where its at i will add more later, its just a baseline timing table....

I'm open to suggestions tho.... So i may just try it lol. I understand that 15* is still fairly conservative though, and know where your coming from.

Its just the 30-40 other turbo ls platform vehicles I've tuned have been fine using that as a baseline ...... Anything is possible though!

denmah

iTrader: (2)

with timing that low i have had trouble getting motors over 4krpms

sputter and lay over like crazy

8deg at 130kpa?! holy ****

i run about 20-25deg there thats like 4.3psi

with 10lbs of boost and 8deg LSX motors are a total dog.

i usually hit 14lbs and 12deg conservatively and then i throw timing at it till it quits making power.
usually ending up at 20lbs and 14-16 deg

1BADLS1tuner

iTrader: (5)

Hahaha i totally agree with you.....

This is my bad guys i should have clarified..... its 8-12 at 210... At 110 its19-22....

I guess i didn't even realize how it came off reading it.

1BADLS1tuner

iTrader: (5)

It is for sure backfiring from exhaust...

I pulled the charge pipe off and did a pull NA and it ran like a champ, no backfire!

so its deffinetally boost related...

replaced plugs and wires
cleaned all ground wires and added another ground

still backfiring....


This is frustrating lol...

if it was the crank or cam sensor it would have the issue NA also, so those should be good....

It backfires at such low boost I would highly doubt spark blowout....

I didnt see the voltage drop, and grounds are good...

AFR and Timing are ok, backfires well below rev limiter....


If the intake leaked it would backfire through intake wouldnt it?

ANY IDEAS???

NBM-LS1

iTrader: (7)

Do you have a log that you can show us?

1BADLS1tuner

iTrader: (5)

attached logs...

THIS IS NOT A FINISHED TUNE!!!! Its just a baseline i threw together...

black98ws6ta

iTrader: (77)

Does it throw a code for the DBW and go into reduced engine power? Ive have seen that before.

1BADLS1tuner

iTrader: (5)

It did that one time... and hasnt thrown the code since....

but EVERY time it backfires i have no throttle (dbw quits working completely)

1BADLS1tuner

iTrader: (5)

I know this is going to end up being something stupid and im gonna look like a complete jacka$$ hahahahaha....

im just at a loss of what to check now....

black98ws6ta

iTrader: (77)

Has it ever made a clean pull? The truck I was having problems with had a very quick spooling turbo and would only do it at part throttle making boost. Straight to the floor WOT worked fine. I bet if your scanning it and it happens if you clear the codes it will go back to driving normally without key off/on.

1BADLS1tuner

iTrader: (5)

Not 1 clean pull in boost, NA yes....

never tred to clear the code and see if it that worked but I bet your right, ll try it...


so are you suggesting the DBW is the source of the problem?