Black98Z28

iTrader: (8)

I swapped out header gaskets just a few minutes ago, started the car after i did the driver side idled like normal....Change the passenger side and now the car starts up and idles right at 2500 and gradually goes up to around 3k rpm. Anyone know what could be the problem?


Edit: Today Car threw code P0507 Idle Control System, RPM Higher Than Expected

bastien

iTrader: (1)

I don't know what the problem is, but let the car relearn itself. Turn it on and off like 3 times. If that doesn't fix it, disconnect the battery for a few minutes.

Black98Z28

iTrader: (8)

We reset the pcm 3 times, we disconnected the tps sensor and turned the car on and idled fine for about three minutes. we reconnected the sensor and same symptoms. we tried running the car with the sensor unplugged again, and it is idling at 2500+.

01'WS6

Sounds like a vacuum leak of some sort. Did u happen to unplug the brake booster line for any reason that runs to the back of the intake and forget to plug it back in? Nothing that has to do with the exhaust will cause this.

Black98Z28

iTrader: (8)

I didn't touch the back of the intake so i dont think that is the problem. If that was the problem the car wouldnt have idle normal for the 5 minutes that it actually did.

Im going to take off the coil packs and take all the wires off and check all the plugs and re-tighten the bolts on the exhaust.....im lost as to what the problem is.

Black98Z28

iTrader: (8)

Looks like I may have solved the problem.

Issue UNKNOWN lol

I took the coilpack off on the passenger side, checked all the plugs and header bolts, all connections, brake booster etc...everything checked out, i reset the pcm for a few minutes, checked the eng sens fuse which was fine. Put it all back together, turned the car on, idled fine for a few momments then started rising and falling, shut it off and turned her back on she idled fine so i went for a drive, everything seems fine.

Exhaust leeks are gone and everything seems fine, im going to double check everything tomorrow and do an motor and trans oil change.

Thanks for the help fellas.

Black98Z28

iTrader: (8)

started happening again, i turned the car on today, i havnt driven it since the day i started this thread, and she idled fine and drove just like normal for over 25miles.

I go to leave my buddies house and here we go again, she starts to idle at 2500.

I swapped IAC and TPS sensors, reset the PCM, and unhooked the battery for 30 mins and still problem not fixed. I checked every connection i could and nothing is unhooked.

What could the problem be i am so lost. Thanks!

ssheets

iTrader: (1)

I'm having the same problem!! Did you replace your IAC and your TPS? I was thinking about that, but I don't want to just throw money at it without having any idea if will help.

I've unplugged my IAC and it drives great, it won't cold idle though.

Black98Z28

iTrader: (8)

I swapped IAC and TPS with my buddies, it didn't solve anything!

I havn't unplugged my IAC yet to check if that works i will do that in the morning. Your issue sounds like its the IAC since you disconnected it and it changed the way your car idles but im not 100% on that.

Is there a fuse/relay or something that could have blown? I have checked most of the fuses and they're all fine. Me and my buddies are lost, i might call TSP tomorrow to see what they say.

Black98Z28

iTrader: (8)

TTT Help is appreciated!

Russ K

iTrader: (1)

There has to be a vacuum leak. With the engine idling, spray water around the intake manifold. Also spray water at the EGR pipe & valve. When the engine starts to run rough, you found the vacuum leak.

Russ Kemp

Black98Z28

iTrader: (8)

If there is a vacuum leak wouldnt it always idle high? it idled fine for a 25mile drive and i romped in it a few times aswell.

EGR is deleted on the car.

ssheets

iTrader: (1)

I think I may have solved it. You see I have a custom tuned PCM that should be very close for my mods. It was a mail in tune as I don't have any dyno tuning services near by until the Mallory lab is back on line next month.

Long story short, the custom PCM had sever idle hang problems so I put my factory PCM back in and tuned it myself with my Predator. This isn't enough tuner to do what I need, but it gave me a false sense of accomplishment.

After a week of chasing my tail I finally found that my throttle body wasn't torqued down. I'd hung it on the manifold late one might to check the final assembly. The next morning I just kept assembling. It was snugged down, but not tight so it could have been leaking vacuum right behind the throttle body?

Ironically, my idle hanging issue only happened when I tried the new PCM...until last night. I know the new program handles the parameters differnet and perhaps this made the effect worse? If I unplugged the IAC the car ran great except for idle.
Late last night I went over all of the mainfold and TB fasteners and found the loose TB. I tightened everything down. Then I drove the car about 40 miles, but it still hung the idle badly. I unplugged the IAC and it ran great again...then I posted here.

This morning I went ahead and put the custom tuned PCM back in and other than a little learning adjustments in the first warmup period it seems to run right. Only time will tell. I'll try and drive it some more today if I get the chance...a snow storm is on its way in so it might be awhile.

If this indeed solves it I'll let you know. When I called Jesse about the first PCM hanging the idle he told me I had a vacuum leak. Though I was fairly confident I didn't, I kept looking for one and heopfully I found it.

ssheets

iTrader: (1)

I thought the same thing...but now I think this is the case. (Tuners can help me here) since we have an IAC the computer tries to adjust the idle speed and air. If you have a vacuum leak this control process is thrown out of whack. So the car may run well at times, but when the computer tries to adjust the IAC and the effect is something totally out of whack with what it should be it tries harder and the problem is magnified 100 times.

Black98Z28

iTrader: (8)

man i swear there cannot be a leak it happened randomly.

i guess ill go out there with a spray bottle. I just hope i can fix it because this is really frustrating!

ssheets

iTrader: (1)

I emptied an entire can of starter fluid and couldn't find a leak. I swore up and down I didn't have a leak too, but I did find my throttle body wasn't tight. I only have 6 miles on it since I tightened everything up so I can't say for sure if I fixed it, but it sure makes sense.

Good luck. I know how frustrating this is...trust me!!!

Black98Z28

iTrader: (8)

I went outside and started the car, NORMAL idle...

I got the spray bottle ready for when she started to idle at 2500, well she idled for about 5 mins so i shut the car off. Turned her back on and normal idle.

So i jump in the car to back out of the driveway, put it in reverse and bam she started to pull without me giving it gas so i put her back in park and here we go again 2500rpm idle.

I emptied 2 spray bottles all over the place and result did not change. Is there anything transmission wise that can be affecting the idle?

Black98Z28

iTrader: (8)

Just talked to Jon over at Texas Speed, they are clueless aswell lol

Im going to run out there and disconnect the IAC and see what happens.

andrew69_04

iTrader: (148)

I had an issue like that once on a trans am. just did it out of the blue one day, reset pcm and never had it happen again. kind of odd actually. This also might sound stupid, but if your car has TCS, did you move any throttle cables around? i know that they were in the way when i put headers on a camaro last week. just something you might look at.

Black98Z28

iTrader: (8)

thats something Jon at TSP informed me might be the problem however my car did not come with TCS. Is there anything else on the throttle body that could be out of line or missing something?