This is the first time I have seen a car want this much air. Its a 427, pretty mild cam, 200r4 tranny. When warm, in park, it only wants around 8-9g/s. When you put it into drive, it is wanting 21g/s. It does fine with that transition, but when you go back into park, there is all this extra air that must be taken out, causing a huge surge. LTIT in P/D are zero. When you go into drive, it maxes the IAC out to 310.
I'm stumped and have no idea where to fix this...if it can be fixed.
Thanks
Idle speed may be too high or the converter too tight for the idle you are commanding.
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Originally Posted by EC_Tune
Idle is 975 and the converter is pretty loose, NA car. Not sure what size it is though.
975 is probably OK for P/N but my *guess* is that it's too high for Drive. Try dropping it by 100 or so RPM in drive and see what happens. How mild is mild? What converter? (I won't suggest converters because I have no clue there...)
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The cam is an MTI grind...C1 or S1..244 duration. Its not large for the CI's. I have no idea what size the converter is. MTI built the car and a local guy bought it. I'm just skeptical of the whole car, when we got it, it had two major vacuum leaks. This thing has been a real PITA to get it to where it is now...which sucks..lol.
Unknowns are the real PITA... LOL
BTW: That is a fairly big cam. Definitely not what I would call mild, even for the cubes and especially for your idle speed.
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I have the same issue on my LS1 with PRC heads and Torquer 2 Cam.....
Car won't allow me to idle over 800 RPM in drive and it stumbles sometimes going into gear, in P/N its fine, but I have the same little surge when going from D to P/N.
I'm almost positive its my converter, so I have a 3600 Stall coming in this week, hopefully that will allow me to idle it a little higher without all the extra engine load.
2004 Impulse Blue A4 LS1 GTO
PRC Stage 2.5 5.3L Heads, PatG Custom Cam (227/232 .610/.604 111LSA), 1 7/8" Kooks LTs w/catted mids, FAST 90/PTM90, Yank 3600 Stall, Custom 4" Fenderwell CAI, BMR Drag Bags, Magnaflow Cat-Back, PBMFIsMe tune.
410/362 at the wheels
[email protected] - Woohoo ! ! !
I knew something was not right with the motor. They finally did a leak down... #5 and #7 almost blew the radiator up when they pressurized them..lol. That could be why this car was such a whore
Wow !
Yep....methinks you may have determined the root cause of the problem...Haha.
2004 Impulse Blue A4 LS1 GTO
PRC Stage 2.5 5.3L Heads, PatG Custom Cam (227/232 .610/.604 111LSA), 1 7/8" Kooks LTs w/catted mids, FAST 90/PTM90, Yank 3600 Stall, Custom 4" Fenderwell CAI, BMR Drag Bags, Magnaflow Cat-Back, PBMFIsMe tune.
410/362 at the wheels
[email protected] - Woohoo ! ! !
(Where's the lightbulb smiley around here)
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