I posted up in Drag Racing Tech and PCM Diagnostics and Tuning and haven't been able to get an answer to resolve my problem, so i'm hopin maybe my nitrous brothers could help me out!

I just installed a fast 90 mm intake and nw 90 mm tb on the car last weekend (no nitrous yet) and it's having major issues at wot. I've tried everything, been logging and making changes all week, every night after work and all last weekend and now all this weekend so far and nothing is working. The car will start out ok and go to fuel trim cell 22 (wot) and the lterms will 0 out and the o2's will be up around 910ish, then all the sudden it will pop out of open loop, and goes to either ftc 20 (seems to be idle while cold before getting to operating temp) or 19 (idle) and the lterms will unlock and o2's will start switching again at low numbers and the car gets down on power. I can't figure out what the hell is goin on with the car and am getting very frustrated and very upset, any you guys have any insight for me that could help me out, i'd really appreciate it!!!! Thanks for any help!

 

try PMing a builder/tuner like mikey from rapid.

 

Thanks, i'll give that a shot and see what I can come up with, in the meantime, anyone else have any ideas?

 

TTT, for ya.
Robert

 

Thanks Robert, i'm gonna throw a fuel pressure gauge on her and take her out today and make sure i'm not losing fuel pressure, just to rule out the pump possibly goin bad (even though it's a racetronix that I just put in less than a year ago).

 

OK, pump is ruled out, fuel pressure is perfect all the way through the end of third gear!

 

Here is a shot in the dark for you. When I switched my intake to the Fast 90/90 setup, my MAP sensor did not seal right. I also had a few vacuum leaks from the DP setup. I had to take it back off and re-seal everything. I doubt that is what is wrong with yours though.

 

yeah, the map sensor doesn't sit right, I took it off and put sensor safe silicone around it and then plugged it back in and let it sit for a day and that didn't solve the problem either and the direct port isn't on the intake yet, haven't gotten it yet. Thanks for the advice though, i'm almost positive it's in the tune somehow, it's really weird, it all of the sudden goes super lean around 5200 - 5500 rpm and kind of like the computer can't keep up, the injector pulse width like doubles when it happens and drops out of open loop, like the comp is tryin to just dump fuel to compensate for goin lean but can't keep up. I may end up having to take a trip to Louisiana to have Allan @ Futral tune it in, cuz I know he can get this car right, he knows his ****!

 

Good luck with it. I am computer tuning illiterate. When some says they adjusted their tune, I thought they just changed the radio station.

 

what MAF is on the car???

SLP? if so, take it off, try the stock MAF see if that works.

worst case send me the intake and some $$ and i'll send you mine. hehe

 

Are your heads milled? Sorta sounds like a vacuum leak, did you use new gaskets & the valley cover bolts?

Matt

 

It's the stock maf with thunder ported ends, been on there since hte car was bolt on's.

 

They're TEA stg 2.5 5.3 castings unmilled, gave the guy I sold my old intake too the gaskets that were on it and he had new comp gaskets that he gave me and I put those on, they were red, looked just like the gm ones, could they be a problem? And I put the little button allenhead bolts that came with the intake in the valley cover, at first it wouldn't seat right but then I realized the front was hittin the coolant crossover pipe, so I bent that out of the way and it seems to be seated perfect, made my rounds on the bolts in the order that it says and just kept goin till they were all snug and stayed tight. I reused the stock bolts instead of the ones they gave, cuz I didn't have a short enough allen head socket to get under the cowl to tighten them, is that ok? And then for the tb, put the gasket on that came with it and the nuts and bolts and tightened her down.

 

I had to rescale the MAF on my car when i went to the 90mm intake.I also diched the front o2s and tuned open loop best thhing i ever did when my car was a H/C car.Do you have tuning software if so you can try pm redhardsupra he knows his **** and if you have any logs you can e mail them to him and he will go through it for you.I know he uses hp tuners and he knows his ****.He loves doing this kind of stuff and he won't charge you a thing.

 

That all sounds good, although I'm not sure on the intake bolts as we've always used the supplied ones.

Matt

 

Thunder racing sells the fast intake gaskets there alot fatter and fit in the grove nicely.You might wanna give that a shot.

 

I use autotap for the logging and ls1edit for the tuning. Quick question, this is the longest i've been driving the car around on the same tune w/o reflashing cuz I finally got the idle pretty good, and I just noticed she threw a po135 twice, could the o2's cause the issue i'm having with popping out of open loop? I'm gonna try and grab some tomorrow and replace them and see if it solves it.

 

If you had access to a wideband id ditch the 02s unless your lookin for the best gas mileage.As far as poping out of open loop it could be a fueling problem and i don't think it's going to be the o2s.Whats your afr you know your tune is going to be off with the 90mm.

 

Don't have a wideband, usually do my tuning off the o2's and then check on dyno (except on spray, will never go back on the dyno on spray, fucked trans last time I did that). I know the tune is gonna be off, that's why I started with the idle, got that down pretty good, then got the part throttle down, then wot was issues, so I added 10% fuel at wot just to see if it helped, still a problem, so added another 10%, still a problem, when it is working and in open loop, it's rich, o2's are at 950's to 970's, so I don't know why it's poppin out. I don't start work till 2 tomorrow, so i'm gonna pull the intake back off and just make sure everything is ok with the gaskets and that it's seated perfect and all, and then i'll try and get my hands on a set of o2's and then see if she's still havin the issue.

Also, I don't know how to tune in Speed Density and I heard ur constantly having to change the tune for the weather and that it's a pain in the ***, is that true?

 

Man if i remember right i had to take fuel away in the pe vs rpm table.Sound stupid but it has alot to due with the maf and map reading.I would go back to were you started off and then take out %5 and see if that starts to clean it up.Like i said i had to take fuel out.