Hey guys I just installed a set of hooker LT's and their matching off road Y pipe. I fired it up and it sounded AWSOME! after warming up the car and performing the idle learn procedure, no SES light!
so then I took a drive and everything went fine...for about a half hour. then out of nowhere the rpm's dropped to about 500 in the middle of the road! and the car wouldnt respond to the throttle, no matter how far I pushed it. A few seconds later, the motor revved up by itself and the car was running pretty good, so I took it home
the next morning i fired up the car and noticed the idle speed would go from 1100 rpm to 800 to 600 and then bounce from 200-400 rpm.with the car barely staying on, and all within 10-15 seconds. and at the same time when the car goes down to 200-400 rpm., the intake makes a very loud "sucking" sound. kinda like a very strong industrial vacuum sucking air....
next thing you know, the ses light came on, and then to my surprise the
"ASR OFF" light comes on. WTF IS GOING ON! LOL.
SORRY......I know this post is long but I would greatly appreciate any feedback about how this problem was caused, how to fix it, or even just your 2 cents.
thanks in advance.

p.s. its a 2000 Z28, M6, ported MAF/throttle body, I did the 99 EGR mod for this install, new felpro metal gasket, o2 simms on the two last sensors,

 

well first i'd pull the code and see what that is and go from there. could be that you burnt a sensor wire or something on the header.

 

I agree with jrp, pull the code, check your o2's and your plug wires.

 

First like they said is check that code. Next if you hear a sucking sound make sure you do not have a leak. If you messed with the EGR at all make sure that that is not leaking(little rubber O-ring), if it were it would make a sucking sound. Check the header to head gaskets for leaks as well.

 

as for the sucking noise, could it just be the AIR coming on, mine is loud like a vacume since it is just sitting there. as far as the choppy idle goes, did you check your maf conection, when i changed my parts over from my old car i was in such a hurry i forgot to plug it in and i idled like crap. and like everyone else said, check for a burnt wire, it happens more often than you think. i have the same headers, and the wire are close to alot. use tiestraps to secure them out of the way.

 

Sounds like a EGR problem to me. Happened to me. First check the Egr tube leading into the intake. Take it out make sure the little rubber seal is there and not kinked. Put the tube back in and bend it as best you can to make it seat back in the hole *it should sit in the intake without the bolt even holding it in* Go ahead tighten that bolt. Start up the car. If the idle still drops. I would check the EGR valve itself. Disconnect it unbolt it check the gasket make sure its not damaged. If everything looks good put it back together and double check ALL your connections. Star the car up again. Idle still drops, Egr is defective. ANY kind of vacuum leak will make you car idle like crap. Egr should ONLY come up during cruise. Sounds like the EGR is not closing at all..thus putting exhaust into your intake at idle and off idle accleration. Check all this. Let me know how everything goes. I had to replace my egr a couple of days ago. So I know what your going through and the symptoms you have decribed.