can't get it to idle
Thread Starter
Advanced
Joined: Jun 2003
Posts: 58
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From: miramar florida
can't get it to idle
did a head and cam job on my 88, SR manifold with base, patriot heads 195 runners, crane cam 214/221 with488/508 lift, 1.6 rollers ect. took it to a tuner to do the ECM but I can get it to idle, rode around with the lap top hooked up to the car and noticed the IAC counts all over the place, one minute the car will idle at 700rpm's the next minute it will rise to 1400rpm or just die, replced the IAC followed the instrucion to set it up and still no good, Iam running the car with the IAC unpluged but it idles at 1400 rpm a PITA when driving in the city other than that it feels strong and drives good. any ideas out there ?
Supporting Vendor
Joined: Mar 2008
Posts: 1,762
Likes: 14
From: Cumming Ga
did a head and cam job on my 88, SR manifold with base, patriot heads 195 runners, crane cam 214/221 with488/508 lift, 1.6 rollers ect. took it to a tuner to do the ECM but I can get it to idle, rode around with the lap top hooked up to the car and noticed the IAC counts all over the place, one minute the car will idle at 700rpm's the next minute it will rise to 1400rpm or just die, replced the IAC followed the instrucion to set it up and still no good, Iam running the car with the IAC unpluged but it idles at 1400 rpm a PITA when driving in the city other than that it feels strong and drives good. any ideas out there ?
Supporting Vendor
Joined: Mar 2008
Posts: 1,762
Likes: 14
From: Cumming Ga
Team Owner
Joined: Jan 2003
Posts: 20,290
Likes: 238
From: Summerland B.C. Canada
There is no setup for the IAC, other than the extended pintle measurement, for installation.
Have you set the minimum idle and TPS ??
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
Have you set the minimum idle and TPS ??
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
Thread Starter
Advanced
Joined: Jun 2003
Posts: 58
Likes: 0
From: miramar florida
There is no setup for the IAC, other than the extended pintle measurement, for installation.
Have you set the minimum idle and TPS ??
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
Have you set the minimum idle and TPS ??
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
Team Owner
Joined: Jan 2003
Posts: 20,290
Likes: 238
From: Summerland B.C. Canada
yeah I did followed all the steps mentioned in this site, disconecting the ignition advance, adjusting idle to 450 rpm,turn off engine hook up IAC,adjust tps to.54 vlts let it run for 20scds shut it off for 5scds and try again, and still the same probelm, I am starting to think that something got screwed up in the ECM and it si not sending a correct signal to the IAC
After you unplugged IAC and started motor, did the motor struggle to run, or was it still revving high ?
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
Get a long piece of hose hold one end up to your ear and use the other end to probe over every inch of the intake while listening for a tell-tale suction sound.
Also, it is possible to have a gasket leak going from the intake to the head and it is sucking extra air through from inside the block.
How to know: Start the car. Pull the hoses that run from the intake to the valve covers and stick you thumbs over each valve cover hole and ensure that there is no heavy vacuum being generated inside the block....remove 1 thumb at a time....you hear it suck heavy if you have a problem.
Also, it is possible to have a gasket leak going from the intake to the head and it is sucking extra air through from inside the block.
How to know: Start the car. Pull the hoses that run from the intake to the valve covers and stick you thumbs over each valve cover hole and ensure that there is no heavy vacuum being generated inside the block....remove 1 thumb at a time....you hear it suck heavy if you have a problem.
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Supporting Vendor
Joined: Mar 2008
Posts: 1,762
Likes: 14
From: Cumming Ga
get a long piece of hose hold one end up to your ear and use the other end to probe over every inch of the intake while listening for a tell-tale suction sound.
Also, it is possible to have a gasket leak going from the intake to the head and it is sucking extra air through from inside the block.
How to know: Start the car. Pull the hoses that run from the intake to the valve covers and stick you thumbs over each valve cover hole and ensure that there is no heavy vacuum being generated inside the block....remove 1 thumb at a time....you hear it suck heavy if you have a problem.
Also, it is possible to have a gasket leak going from the intake to the head and it is sucking extra air through from inside the block.
How to know: Start the car. Pull the hoses that run from the intake to the valve covers and stick you thumbs over each valve cover hole and ensure that there is no heavy vacuum being generated inside the block....remove 1 thumb at a time....you hear it suck heavy if you have a problem.
Advanced
Joined: May 2003
Posts: 96
Likes: 0
From: Moreno Valley CA
If you are certain you have no vacuum leaks and the IAC motor runs when you jumper "A" and "B" sockets on the ALDL, then disconnect the MAF sensor. then see if it starts up and idles correctly. If so, your MAF is bad.
Hope this is helpful,
Gary
Hope this is helpful,
Gary
