87 gn swap high idle problem
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87 gn swap high idle problem I swapped a 5.3 Lm7 into my 1987 Buick grand national an ever since then it gets high idle motor is bone stock 2006 van engine an it has a factory moded harness with a factory computer with vats removed an it's never ran well I replaced iac map an tps sensors it has a returnless fuel rail from the 06 van with a corvette fuel filter the problem is that it has hard start up it picks up to 2k or 2500rpms an drops back down then back up then it either idled or stalls I checked for vacuum leaks but I have seen non it's bolted to a chevy style th350 trans I have no clue what this is I'm just trying to get my daily driver back on the road
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Is it drive by wire? Ive seen this exact problem with bad DBW throttle bodies and/or after the throttle body has been cleaned. Usually have to do a throttle body/ idle relearn using a scan tool
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No it's drive by cable. I thought it might be a dirty throttle body. so I changed it an I still have this issue.
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Verdad Gallardo Have you checked fuel pressure with a gauge? If pressure is good Really need a scan tool on it to see what the o2s are doing.
It really sounds like a vacuum leak, and as the previous person said ive seen vacuum brake booster leak and cause this but its rare. Although in my experience if it runs fine with the maf unplugged the maf is prob bad, or dirty.
With vacuum leaks i always soak the intake down with some carb cleaner and see if it starts missing or anything diff. If it does you found it. However sometimes i have to watch the o2s on a scan tool and when you find the leak the voltages will go up.
Also look at your pcv system, a pcv valve stuck open can do this also. Or the hoses hooked up wrong etc
It really sounds like a vacuum leak, and as the previous person said ive seen vacuum brake booster leak and cause this but its rare. Although in my experience if it runs fine with the maf unplugged the maf is prob bad, or dirty.
With vacuum leaks i always soak the intake down with some carb cleaner and see if it starts missing or anything diff. If it does you found it. However sometimes i have to watch the o2s on a scan tool and when you find the leak the voltages will go up.
Also look at your pcv system, a pcv valve stuck open can do this also. Or the hoses hooked up wrong etc
Thread Starter
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Have you checked fuel pressure with a gauge? If pressure is good Really need a scan tool on it to see what the o2s are doing.
It really sounds like a vacuum leak, and as the previous person said ive seen vacuum brake booster leak and cause this but its rare. Although in my experience if it runs fine with the maf unplugged the maf is prob bad, or dirty.
With vacuum leaks i always soak the intake down with some carb cleaner and see if it starts missing or anything diff. If it does you found it. However sometimes i have to watch the o2s on a scan tool and when you find the leak the voltages will go up.
Also look at your pcv system, a pcv valve stuck open can do this also. Or the hoses hooked up wrong etc
It really sounds like a vacuum leak, and as the previous person said ive seen vacuum brake booster leak and cause this but its rare. Although in my experience if it runs fine with the maf unplugged the maf is prob bad, or dirty.
With vacuum leaks i always soak the intake down with some carb cleaner and see if it starts missing or anything diff. If it does you found it. However sometimes i have to watch the o2s on a scan tool and when you find the leak the voltages will go up.
Also look at your pcv system, a pcv valve stuck open can do this also. Or the hoses hooked up wrong etc