vacuum problem

worm · 03-28-2006, 08:13 AM

HI TO EVERYONE. Loks like a good site. Hope you guys can help me out. I have a 97 350 w/ around 154000 on it. I'd left the oil fill cap off awhile back and have had alot of problems ever since. I reserched some sites and figure I have a bad vacuum problem now. I had the codes ran and it gave me a 507 code wich is the IAC. So replaced it and nothing changed. I did spray carb cleaner all around the TBI and intake. Right around the front left on lower intake I got a mild increase in rpms. I replaced the intake gasget around 120000 miles and all tune up at the same time. The engine goes to arond 1800 to 2500 rpms at start up depending on hot or cold then it slowly drops to around 1100 to 900 rpms at idle. When driving it will be so high that I have use the breaks to slow it down. I took the vaccum line off of the pcv and it sucks like a shopvac. Not the normal kind of vacuum. It is sucking into the intake and into the valve cover as well. Could this be the lower intake gasket again?

chevyguy · 03-28-2006, 06:10 PM

Sounds like you need to train the IAC . I replaced mine a short time back for high idle and had to retrain it. Turn ignition swith on for 10 sec, then off for 10 sec, then start and let run for 5 min, shutoff and wait 30 sec, and then start again.

worm · 03-29-2006, 09:15 AM

Well I put the choker chain around it and everytime I pulled at it the chain would slip off. lol No, I tried 3 times to train it like you said chevyguy and it had no effect at all. Thinks. Any other idea what it could be before I dump it off to a mechanic for a bunch of money. I know I can fix it if I can figure out what to do to it.

chevyguy · 03-29-2006, 09:00 PM

I think a vacuum leak.

03-28-2006, 08:13 AM	#1
worm Junior Member Join Date: Mar 2006 Posts: 7	vacuum problem HI TO EVERYONE. Loks like a good site. Hope you guys can help me out. I have a 97 350 w/ around 154000 on it. I'd left the oil fill cap off awhile back and have had alot of problems ever since. I reserched some sites and figure I have a bad vacuum problem now. I had the codes ran and it gave me a 507 code wich is the IAC. So replaced it and nothing changed. I did spray carb cleaner all around the TBI and intake. Right around the front left on lower intake I got a mild increase in rpms. I replaced the intake gasget around 120000 miles and all tune up at the same time. The engine goes to arond 1800 to 2500 rpms at start up depending on hot or cold then it slowly drops to around 1100 to 900 rpms at idle. When driving it will be so high that I have use the breaks to slow it down. I took the vaccum line off of the pcv and it sucks like a shopvac. Not the normal kind of vacuum. It is sucking into the intake and into the valve cover as well. Could this be the lower intake gasket again?

03-28-2006, 06:10 PM	#2
chevyguy Senior Member Join Date: Sep 2005 Location: ALABAMA Posts: 3,160	Sounds like you need to train the IAC . I replaced mine a short time back for high idle and had to retrain it. Turn ignition swith on for 10 sec, then off for 10 sec, then start and let run for 5 min, shutoff and wait 30 sec, and then start again. __________________ When i die, i dont want to walk gracefully thu the pearly gates and turn in a unused body. i want to go sliding thru sideways and turn in a body that has been completely used up.

03-29-2006, 09:00 PM	#4
chevyguy Senior Member Join Date: Sep 2005 Location: ALABAMA Posts: 3,160	I think a vacuum leak. __________________ When i die, i dont want to walk gracefully thu the pearly gates and turn in a unused body. i want to go sliding thru sideways and turn in a body that has been completely used up.

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03-29-2006, 09:15 AM	#3
worm Junior Member Join Date: Mar 2006 Posts: 7	Well I put the choker chain around it and everytime I pulled at it the chain would slip off. lol No, I tried 3 times to train it like you said chevyguy and it had no effect at all. Thinks. Any other idea what it could be before I dump it off to a mechanic for a bunch of money. I know I can fix it if I can figure out what to do to it.