Tuning issues with FAST 90 on vette
09-11-2006, 10:19 AM
#1
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Tuning issues with FAST 90 on vette Installed a FAST 90 and LS2 throttle body. I'm using HPtuners to tune the car.
My previous tuneup showed ltrims with the MAF enabled around 4-5 at idle and zero at part throttle cruising around, the ltrims with MAF disabled were 0 +/-1.
The only change that I made was the intake/throttle body.
The car idles right around 900 rpm where I desire it to, but the ltrims go sky high... around 20-25 or so.
I do NOT have a hole drilled in the LS2 throttle body so the ease of idling concerns me a bit, but perhaps with more butterfly area, this is normal?
The ltrims at idle/part throttle on my car go skyhigh to around 20-25. I believe that I have a vacuum leak of one form or another... does this sound right?
I didn't have a throttle body gasket so I made a paper gasket... will this have any issues sealing on a FAST intake vs. the rubber oring?
TIA for any advice/thoughts!
My previous tuneup showed ltrims with the MAF enabled around 4-5 at idle and zero at part throttle cruising around, the ltrims with MAF disabled were 0 +/-1.
The only change that I made was the intake/throttle body.
The car idles right around 900 rpm where I desire it to, but the ltrims go sky high... around 20-25 or so.
I do NOT have a hole drilled in the LS2 throttle body so the ease of idling concerns me a bit, but perhaps with more butterfly area, this is normal?
The ltrims at idle/part throttle on my car go skyhigh to around 20-25. I believe that I have a vacuum leak of one form or another... does this sound right?
I didn't have a throttle body gasket so I made a paper gasket... will this have any issues sealing on a FAST intake vs. the rubber oring?
TIA for any advice/thoughts!
09-11-2006, 11:07 AM
#2
When I changed to FAST/LS2 the car idled fine without tune changes as you note. (on 346) I found constant intake air leaks and futzed with it for a month. In the end I had cracked my LS6 valley cover and never did cure the leaks.
I wish you better luck, but look for leaks.
I wish you better luck, but look for leaks.
09-11-2006, 12:02 PM
#3
a quick way to find out if you are leaking arround the intake gaskets is to spay it down with wd-40 arround the intake runners, if the engine smoothes out there is your leak... good luck
09-11-2006, 03:14 PM
#4
Did you replace the valley cover bolts with the ones allen head bolts FAST provided? Thats the issue I ran into, didnt replace the bolts and my intake would seal all the way. I got lucky and it didnt crack the bottom, just dented it in. The stock bolts stick up to high for the FAST intake to clear.
May also want to check the MAP sensor.
May also want to check the MAP sensor.
09-11-2006, 05:04 PM
#5
The FAST bottoms out on the raised nubs on the LS6 valley. The allen button heads are nice but it is toward the center that problems occur and why the seals suck (literally). I have pics of my destoyed cover. It is lots worse with milled heads because the V created by the heads gets shallower.
