Ported Throtle Body Problem....need help !
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Joined: Jan 2002
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From: Chicago Suburbs
Ported Throtle Body Problem....need help ! So, 6 moths ago I ported my Throttle body: smoothened the surface, epoxied the holes and drilled new ones, etc.
I fired up my car, and the idle was bumping "up-and-down" a little bit between 700-1000 rpms on a cold start for about 10 seconds. Then it would "catch the idle" and was stable. I thought it was "good enough"
A couple months ago, I did am F10 cam swap 228/228, and the problem escalated: It is now VERY unstable on cold startups, with idle jumping up-and-down for about 2 minutes between 600 and 1100 rpms. Once it catches it, it's fine and stable for the whole day.
Any idea, why I'm having those problems ?
Is it possible that my IAT/Air holes are two small and it "chokes" ?
Would drilling it more help a bit ?
I'm considering getting an 80mm BBK unit, or just buying a used stock unit to put back in. I'm on a budget, so I can't really afford a 90/90 combo....
THANKS,
Adam
I fired up my car, and the idle was bumping "up-and-down" a little bit between 700-1000 rpms on a cold start for about 10 seconds. Then it would "catch the idle" and was stable. I thought it was "good enough"
A couple months ago, I did am F10 cam swap 228/228, and the problem escalated: It is now VERY unstable on cold startups, with idle jumping up-and-down for about 2 minutes between 600 and 1100 rpms. Once it catches it, it's fine and stable for the whole day.
Any idea, why I'm having those problems ?
Is it possible that my IAT/Air holes are two small and it "chokes" ?
Would drilling it more help a bit ?
I'm considering getting an 80mm BBK unit, or just buying a used stock unit to put back in. I'm on a budget, so I can't really afford a 90/90 combo....
THANKS,
Adam
Pretty sure your IAC isn't getting enough air to it. (hole too small now) IAC is probably maxed out trying to get more air.
It's best if you have scan software to see where your IAC counts are. I decided it was easier to drill a little bigger hole in my TB blade instead of the IAC hole. Got my counts close and now it idles fine.
It's best if you have scan software to see where your IAC counts are. I decided it was easier to drill a little bigger hole in my TB blade instead of the IAC hole. Got my counts close and now it idles fine.
You could drill out the IAC hole to give it a little more
authority but it seems most people with larger cams
have the same problem, and you need to tune the
lower end of the VE table and perhaps shave on the
open loop fuel air table as well to get the cold idle
enrichment more sensible.
There's no point in removing the epoxy now.
authority but it seems most people with larger cams
have the same problem, and you need to tune the
lower end of the VE table and perhaps shave on the
open loop fuel air table as well to get the cold idle
enrichment more sensible.
There's no point in removing the epoxy now.
Yeah, your epoxy holes are too small - just make them a bit larger, and also make sure there is not any epoxy blocking the holes in the little "chamber" in the tb they lead to. Good luck!
The easiest (and cheapest) thing to do is to drill the tb blade hole a size or two larger. My friend had that issue with his F15 cam and the larger hole cleared it right up. I have 20 seconds of idle hunt right now, I plan to drill mine a size larger. Bolting on my true duals with h-pipe tonight!!! Woot woot!!! 
