Car acting strange.
07-12-2005, 10:48 AM
#1
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Car: '99 HO Z28 / '03 Trailblazer
Car acting strange.
The car is a 350 TPI that was converted from LG4
It runs fine at speed, and with everything connected it idles at 1200-1400 RPM
I tried to set min idle, per the instructions I've found during a search - but the car will not idle at 650 rpm...not even close.
It may be missing, but there is no backfiring...just doesn't run.
I tested the vacuum at the 1200 RPM idle - and am getting a 19-20 Hg.
I have the FMS injectors on there (24#) and I have the FP dropped down to around 35# to try to compensate for the larger injectors.
It is also very hard to start, but runs ok when started.
I just bought a cable and am getting ready to connect a scanner, but I wanted to post up to see about anything I may not have thought of.
Thanks guys!
It runs fine at speed, and with everything connected it idles at 1200-1400 RPM
I tried to set min idle, per the instructions I've found during a search - but the car will not idle at 650 rpm...not even close.
It may be missing, but there is no backfiring...just doesn't run.
I tested the vacuum at the 1200 RPM idle - and am getting a 19-20 Hg.
I have the FMS injectors on there (24#) and I have the FP dropped down to around 35# to try to compensate for the larger injectors.
It is also very hard to start, but runs ok when started.
I just bought a cable and am getting ready to connect a scanner, but I wanted to post up to see about anything I may not have thought of.
Thanks guys!
07-13-2005, 11:38 AM
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Car: '99 HO Z28 / '03 Trailblazer
I fiddled with the car and it appears that I may have some issues with the MAF (short in the wiring)
It still idles high, but it seems to be running "better".
Hopefully I'll be able to scan it in the next couple days.
It still idles high, but it seems to be running "better".
Hopefully I'll be able to scan it in the next couple days.
07-13-2005, 09:48 PM
#3
when one of my runner gaskets was leaking i was idleing at 1400 and still pulling 19 hg of vac, i would check all the gaskets and make sure ur not leaking anywhere, that would cause it to idle high, i know if i pull off the vac line from the tb to the vap canister it will idle higher and pull just over 20 hg of vac,
07-17-2005, 05:24 AM
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Car: 92 Form, 91 Z28, 89 GTA, 86 Z28
Engine: 5.7 TPI, LG4
Transmission: 700R4, 700R4
Axle/Gears: 3.27, 2.73
It's kind of a difficult concept for some people, but yeah, a vacuum leak that is COMMON to all cylinders (far enough away from the ports), acts just like the throttle plate, or the IAC so vacuum will be the same as if it were just revved to that higher RPM. The exception is on a MAF car that is still in open loop - it will be lean due to the fact that the MAF isn't reading that air that's getting in. Vacuum in park/nuetral, with all cylinders firing with good timing and good A/F, should always be high, except when snapping the throttle.
My point: a vacuum gauge doesn't report vacuum leaks. It reports misfire, retarded timing, uneven combustion between cylinders, and load. The cause of which is what troubleshooting is for.
My point: a vacuum gauge doesn't report vacuum leaks. It reports misfire, retarded timing, uneven combustion between cylinders, and load. The cause of which is what troubleshooting is for.
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