BLOWN91VERT

I'm hoping someone can help me figure out a problem I have currently with my idle. My motor is just rebuilt with aluminum heads, trick flow stage 1 cam and a vortech blower. Everything has run really good until around 900 miles. Now it's pig rich at idle and occasionally lean pops through the intake. At start it up it almost won't run at all. Once it's up in the rpm's all is fine. Still makes tons of power. But the idle is getting worse. Could this be bad O2's? They have about 80K on them. The only thing I've changed recently was add a Boost Cooler with methanol/nitro injection. Could the nitro have killed my O2s? I'm not getting an engine codes either. Also I do have the idle air by-pass plate and it doesn't help. Any ideas?

leadfootdriver

I'd say it's the bypass plate. Doesn't it bleed air into the motor from the outside? Any air that goes into the motor, needs to be metered by the mass air. Otherwise the air/fuel mix won't be right.

BLOWN91VERT

The idle air bypass bleeds air from before the throttle plate into the intake directly. It doesn't let any outside air in. It is supposed to help increase idle speed. I tried closing it completely and opening it fully. No change. Still a crappy idle. I've just installed brand new Denso Irridium plugs too. No change. I'm lost.

leadfootdriver

Okay then, cool. I was under the impression that it got air from the outside. I've read on other forums, where guys drill holes in their T-Body, to try and fix their idle problems. That's just dumb for the reasons I stated earlier.

As for the O2's, it wouldn't be a bad idea to change them after 80k! Check out the sensor package from the Ford Motorsport catalog. You can get 2 O2's, relays, and smog solenoids for real cheap. I think it was like $60 when I got mine. That's the price of the 2 O2's alone at a parts store.

BTW, my car runs crappy as well at cold starts. I bet a computer flash, to change the cold start maps would fix the problem. Because once my motor is warm, and the computer is taking readings from the 02's, it runs like a champ. Also, I had vacum leaks that gave me probs. They're sometimes hard to find, because the motor is loud.

Your motor probably just needs as fine tune, if all else is right. BTW, what volume fuel pump do you run? I run a 190, which is more than enough for my stock bottom end. [8D]