IAC Brand?
Thread Starter
Racer
Joined: Mar 2018
Posts: 432
Likes: 128
IAC Brand?
I've got a '96 with the LT1. I've got a rough/erratic idle, and have narrowed it down to the IAC. I took off the throttle body, took it apart, cleaned everything, replaced the gaskets, and put it back on the car. And yes, I cleaned out the IAC passage and the IAC. The car has 90K miles on it, and the IAC is done for. The passage way was beyond filthy, as was the pintle. No doubt it was sticking. Anyways, looking at the various brands, the price difference is huge! I see Airtex/Wells for around $16, and the Delphi and ACDelco's are around $60-80. Any experiences with the different brands? Recommendations?
Thread Starter
Racer
Joined: Mar 2018
Posts: 432
Likes: 128
Thanks, I had forgotten all about the Duralast stuff. Checked out their site, and the $100 one is made by Wells. The $80 one is made by Walker, no idea if there's any relation to the exhaust company. At least they say who makes the parts now! Used to be you had to open up the box and look, haha!
Team Owner
Joined: Jul 2004
Posts: 28,424
Likes: 3,276
From: Hartford WI
Thanks, I had forgotten all about the Duralast stuff. Checked out their site, and the $100 one is made by Wells. The $80 one is made by Walker, no idea if there's any relation to the exhaust company. At least they say who makes the parts now! Used to be you had to open up the box and look, haha!
Le Mans Master
Joined: Aug 2015
Posts: 6,090
Likes: 1,972
From: St. Charles MO
The only thing the IAC controls is idle speed - not mixture or spark. If you have an erratic idle speed, that could be a failing IAC. However, if the idle is actually rough or erratic in quality (as opposed to just speed), then the IAC won't cause that. Are your idle problems also happening at cold start, before the car goes into closed-loop mode? Is your car idling higher at cold start?
Thread Starter
Racer
Joined: Mar 2018
Posts: 432
Likes: 128
Oh, so maybe it's not the IAC then. It doesn't do it when I first start the car, when it's holding a higher RPM. The car starts easily too. Shortly after the idle drops, it'll start to act up. It's more frequent once the car is good and warmed up. Other than that, it runs great. No hesitation off the line, pulls hard throughout the rev range. I did replace all the spark plugs too, as they were in bad shape. Plug wires are in very good shape too, no corrosion on the contacts, and the outer insulation is still soft and pliable. I replaced the EGR valve as well, just for good measure, as they're pretty cheap and easy to replace.
Last edited by novaks47; Dec 15, 2018 at 02:42 PM.
Le Mans Master
Joined: Aug 2015
Posts: 6,090
Likes: 1,972
From: St. Charles MO
Oh, so maybe it's not the IAC then. It doesn't do it when I first start the car, when it's holding a higher RPM. The car starts easily too. Shortly after the idle drops, it'll start to act up. It's more frequent once the car is good and warmed up. Other than that, it runs great. No hesitation off the line, pulls hard throughout the rev range. I did replace all the spark plugs too, as they were in bad shape. Plug wires are in very good shape too, no corrosion on the contacts, and the outer insulation is still soft and pliable. I replaced the EGR valve as well, just for good measure, as they're pretty cheap and easy to replace.
Thread Starter
Racer
Joined: Mar 2018
Posts: 432
Likes: 128
No trouble codes stored, pending or present. Checked that before I got the car, and again a few times after, just in case the dealer or previous owner cleared them out. I'll clean the MAF next, that's easy enough. I suppose that could be it, as the air filter when I got the car looked like it could've been the original the car was built with, it was so dirty! Intake tract looked clean though. I had thought about the O2 sensors, but dismissed them as the car has 90K, so seems a bit early for them to quit. Who knows, maybe one of them is slowly dying. All the vacuum likes look ok, sure there's a few on the way out, but no visible holes. I'll have to spray them with something while the car is running to be sure.
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Team Owner
Joined: Jul 2004
Posts: 28,424
Likes: 3,276
From: Hartford WI
This isn't the 60s anymore. You really should buy an OBD2 scanner and it can be used on other cars. Codes don't mean that much other than the sensor is out of the set parameters. You need to see what the sensors are saying and match them against known values that someone might have gotten for that vehicle.