Ty Crawford

Hey everyone, its been a while. I've been having a gnarly sticking idle problem since the summer really kicked in. Seemed to happen more with heat as it got more and more hot. I know I've got an exhaust leak on both my manifolds and its just cranking my bay temps.

PROBLEM: Car idles low at stop. Talkin, like 600RPMs. Its been adjusted in the tune. But whenever I'm driving on the highway and I get off at an exit, or just shifting in the city, my car's RPMs would skyrocket. I usually shift around 2000, and when I was coasting, they'd peak at about 3000 before they started coming down. It would come down as soon as I got to 0mph. I understand that the ECU has a separate idle speed for Drive, or when the vehicle speed is greater than 0. This helps with shifting so the idle doesnt fall out from under you. Someone on the forums I was reading asked if blipping the throttle made it come down any faster, and it did. So I was thinking sticking TPS.

I replaced the IAC when this was happening as summer ended last year, thinking I had fixed the problem. Now that its starting back up with summer, I'm wondering if the weather was what 'fixed' it. But at least I have a fresh IAC and I can rule that out.

This week I replaced my Throttle Body Position Sensor at the suggestion of some forums. Made sense. I took the TB off and took it inside and just took the opportunity to just sit down and really clean it out from both sides. I installed a fresh TBPS, and in the morning I put it back on the car. I let the battery die to clear all learned memory, and I reflashed my tune because after starting once my idle was going so low that the car was loping pretty bad. My tuned idle was now actually coming out as opposed to being 100 or so RPM higher than what it always said on the tuner. After the install, I started getting this WICKED whistling noise from the throttle body area. Throttle body bolts are well tightened down, I didnt have a torque spec so I just got them pretty tight as best I could. I replaced the IAC gasket as from the side it looked cracked and it was, but it didn't change the problem. And get this: Its still sticking.

The whistling I suspect is caused by turbulence from a NAPA gasket. But the gasket doesnt stick in the way of the air, it actually creates a trough all the way around. I don't suspect its an issue, its just annoying.

Long story short:
Idle sticking and now car is whistling.
Replaced IAC
Repaced TPS
Cleaned MAF
Cleaned Air Temp
Cleaned Throttle Body.
Need HALP

dawson1112

That whistling is likely the effect of the new gasket not being flush on the inside of the TB , the trough you describe creates turbulence and it whistles .

The high idle could be the effect of leaking exhaust , any exhaust leaks before the O2 sensors will show lean conditions to the PCM. Something to get buttoned up and rule that out first.

Ty Crawford

Quite interesting!

I ran it in a rallycross weekend, because that's the poisonous abuse I pick for my car. During a run I threw a DTC and sure enough, bank 1 was lean. And I think in running it as hard as I was, my broken manifolds cracked even more, because my bay is getting hot.

I'm not concerned about the whistling at this point. When I get time I'll just try to find an OEM gasket.

At this point, and it may be separate-thread worthy, I'm debating between getting fresh stock manifolds, which would run 200 bucks new, or going with some shorty headers for a bit more. Do I care about my high end HP? Only so rarely do I even take it about 4K.

dawson1112

Quite honestly if your going to go through all the work of pulling the stock manifolds off, it would be worth it to just throw some shorty headers on there. Get some good ceramic coated ones and they will keep the heat moving out the pipes instead of radiating it under the hood as much.

BabyGT

Grab some used 94-98 manifolds, they are factory shorty headers in essence. They flow much better than the new edge manifolds and are about the same as any aftermarket shorty headers for the v6. If you're going aftermarket you might as well do it right and go long tube.

Ty Crawford

Awesome! What's insane is that I was actually thinking to myself, "Man, I really did a number on these stock manifolds and I need to make it my priority to get it fixed." And I looked locally on Craigslist to see if anything was available, and sure enough a set of older 94 stock v6 headers for sale for 50 bucks. Gonna snag it tomorrow, and start looking into installing them.