Turbo LS1 Help

[djb97ek]

Well long story short im running a fairly simple setup; stock 98 ls1 with twins at 7 psi, 85mm maf, siemens 60# injectors, kb bap, lingenfelter pump. the issue im having is a miss only when in boost at wot. im still running the 98 pcm which i was told isnt great but should work. anyways ive tried swapping to another 98 pcm, new tr6 plugs ive tried gapping them from 20-30 which never does much runs a little better with the gap down low, got new msd wires, new truck coils. my mind is getting the best of me on this one. car revs awesome if help under boost or just a hair into boost but full boost and she cuts out but the wierd thing is sometimes its ok and sometimes its terrible. im getting no knock and no misfire codes with the scanner which seems odd to me. done comp test and about everything i can think of so now i come to you guys for advice or recomendations.

i attached a copy of the tune if someone could take a peak at it and lmk how it looks i would greatly appreciate it and i can make a log of it no problem to post but if someone can let me know all the pids to select to help narrow it down i would appreciate it.

thanks in advance for anyone willing to help out


10948

[ScarabEpic22]

First off, you're going to be guessing at spark without running a Custom OS that lets you properly define fuel and spark. The BAP is ok, but if you ran a true COS you wouldnt have to deal with solutions like that to guess at fuel delivery, you could define it in your PCM.

Have you thought about going with a 99-02 PCM and run COS3/5 with it and a 2Bar MAP sensor? Im pretty sure it would take care of any spark issues unless its mechanical. If its cutting spark, what is your A/F ratio at that point? Not commanded, what a calibrated wideband says? You could be either blowing out the flame (doesnt sound like it if you've tried a smaller gap with no luck) or you're dumping too much fuel.

Im not a boost guru, but these seem like the logical places to start.

[djb97ek]

sorry forgot to mention that under full boost the wideband reads a right around 11.5-11.7. i have been seriously thinking about going to the newer pcm and a 2 bar

[ScarabEpic22]

Ok good info there, thats solid for a turbo'ed engine. What spark timing are you commanding under boost? Have a log?

[djb97ek]

dont have a log at the moment ill have some more tom my comp took a shit with my logs on it. at full throttle it shows right around 15-16 degrees

thanks again for the prompt help

[johnv]

Do you have heavier valve springs ?
if just running factory springs your more than likely seeing valve float.
also double check leads are in good shape.