HELP! IDLES WAY TOO HIGH!
02-24-2011, 06:20 PM
#1
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Join Date: Jan 2011
Location: Mansfield, Texas
Posts: 73
HELP! IDLES WAY TOO HIGH!
1993 MAX GXE AUTO 126K
I bought it after sitting 3yrs. It had 3 4th gen injectors put in it. Then was parked in '08. I put a new battery in it and drove it home. It idled good, and ran smooth. However, it had no power at all and it ran so rich, the catalytic converter would glow cherry red.
WORK DONE BEFORE IDLE ISSUE SURFACED
A) I replaced all 6 injectors and rail along with replacing all related gaskets and o-rings.
B) I cleaned intake plenum parts, TB, and IAC while apart.
C) I replaced the spark plugs.
D) I replaced the fuel filter.
E) I replaced 02 sensor.
F) I replaced the MAF.
G) I changed oil & filter.
HIGH IDLE AND IDLE PULSING STARTED IMMEDIATELY AT START UP.
TROUBLESHOOTING DONE UP TO THIS POINT.
A) I cleaned IAC again, then lubed the IAC o-ring with vaseline in case of vacuum leak.
B) I attempted to adjust the TPS. Very slight idle changes noted when adjusted full forward and full backward.
C) I completely disconnected the TPS. High idle did not change.
D) I disconnected MAF and engine died. "Should be normal"
E) I sprayed all possible vac leaks with brake cleaner. Idle did not fluctuate according to sprays.
F) I got frustrated and came here to beg anyone with experience with this problem.
I am still leaning to IAC, but it sure looks clean.
I bought it after sitting 3yrs. It had 3 4th gen injectors put in it. Then was parked in '08. I put a new battery in it and drove it home. It idled good, and ran smooth. However, it had no power at all and it ran so rich, the catalytic converter would glow cherry red.
WORK DONE BEFORE IDLE ISSUE SURFACED
A) I replaced all 6 injectors and rail along with replacing all related gaskets and o-rings.
B) I cleaned intake plenum parts, TB, and IAC while apart.
C) I replaced the spark plugs.
D) I replaced the fuel filter.
E) I replaced 02 sensor.
F) I replaced the MAF.
G) I changed oil & filter.
HIGH IDLE AND IDLE PULSING STARTED IMMEDIATELY AT START UP.
TROUBLESHOOTING DONE UP TO THIS POINT.
A) I cleaned IAC again, then lubed the IAC o-ring with vaseline in case of vacuum leak.
B) I attempted to adjust the TPS. Very slight idle changes noted when adjusted full forward and full backward.
C) I completely disconnected the TPS. High idle did not change.
D) I disconnected MAF and engine died. "Should be normal"
E) I sprayed all possible vac leaks with brake cleaner. Idle did not fluctuate according to sprays.
F) I got frustrated and came here to beg anyone with experience with this problem.
I am still leaning to IAC, but it sure looks clean.
Last edited by txsilverado1; 02-24-2011 at 06:24 PM.
02-25-2011, 06:59 AM
#4
The tps is really only there for the ECU to do other things..
how high is the idle? is it hunting, or does it stay high?
4th gen injectors? or are you running 6 3rd gen injectors now? I don't remember if they're different, but if they flow more than 3 gen injectors, then there's your problem. too much fuel and you're running it pig rich.
Otherwise I'd guess you have a major vacuum leak somewhere you just haven't found yet and it's causing the car to run so lean that it's not burning the fuel at all on a couple cylinders, then it's getting clogged in the cat and burning up there. not good at all.
keep looking.
how high is the idle? is it hunting, or does it stay high?
4th gen injectors? or are you running 6 3rd gen injectors now? I don't remember if they're different, but if they flow more than 3 gen injectors, then there's your problem. too much fuel and you're running it pig rich.
Otherwise I'd guess you have a major vacuum leak somewhere you just haven't found yet and it's causing the car to run so lean that it's not burning the fuel at all on a couple cylinders, then it's getting clogged in the cat and burning up there. not good at all.
keep looking.
02-25-2011, 03:15 PM
#5
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Thread Starter
Join Date: Jan 2011
Location: Mansfield, Texas
Posts: 73
Replaced all injectors with 93-94 single cam pink injectors. It is idling high and intermittently hunts between 1500-2000 RPM. It runs good otherwise. It actually passed a tail sniff emissions test today with flying colors.
02-25-2011, 08:02 PM
#6
I noticed you haven't mentioned that you tried to adjust the idle. There's a screw on top of the idle control valve which controls the idle. You gotta turn the ECU screw completely clockwise before adjusting the screw to get the proper idle. Make sure to turn it back when finished.
I should mention that when I changed an injector, my idle was high too. But when I adjusted the screw, it idled normally.
I should mention that when I changed an injector, my idle was high too. But when I adjusted the screw, it idled normally.
02-26-2011, 07:07 AM
#7
Junior Member
Thread Starter
Join Date: Jan 2011
Location: Mansfield, Texas
Posts: 73
Really! Very interesting! Ok, so turn screw in ECU completely clockwise, then adjust screw on top of IACV to correct idle speed. Then turn ECU screw back.
Couple of questions. Start engine before ECU screw or after?? and shut engine off before or after ECU screw return to normal??
Couple of questions. Start engine before ECU screw or after?? and shut engine off before or after ECU screw return to normal??
I noticed you haven't mentioned that you tried to adjust the idle. There's a screw on top of the idle control valve which controls the idle. You gotta turn the ECU screw completely clockwise before adjusting the screw to get the proper idle. Make sure to turn it back when finished.
I should mention that when I changed an injector, my idle was high too. But when I adjusted the screw, it idled normally.
I should mention that when I changed an injector, my idle was high too. But when I adjusted the screw, it idled normally.
02-26-2011, 07:10 AM
#8
air leak....................vacuum leak ...................check initial ignition timing, and make sure you connected all your plugs properly!
Last edited by CMax03; 02-26-2011 at 07:12 AM.
02-26-2011, 11:08 AM
#10
Really! Very interesting! Ok, so turn screw in ECU completely clockwise, then adjust screw on top of IACV to correct idle speed. Then turn ECU screw back.
Couple of questions. Start engine before ECU screw or after?? and shut engine off before or after ECU screw return to normal??
Couple of questions. Start engine before ECU screw or after?? and shut engine off before or after ECU screw return to normal??
02-26-2011, 05:33 PM
#11
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Thread Starter
Join Date: Jan 2011
Location: Mansfield, Texas
Posts: 73
Ok, I started back at square 1 and checked for vac leaks with a stethescope "tubes open" listening for the suction noise. I traced it down to a local area and doused it with carb cleaner. I found a substantial split in the vac hose at the fuel pressure regulator. It was hard to spot because the split was on the underside of the hose and carb cleaner was having trouble getting into it. I replaced the hose, and reset the computer. This helped some. Then I replaced the IACV with a salvage unit, then set computer into diag mode, then adjusted idle screw at top of IACV. This helped some more. Then, leaving the computer in diag mode, I adjusted the throttle stop on the side of the TB. Idle finally dropped down to 800rpm. Then I put the computer back into normal mode. The idle sped up to 900. Then after driving a while the idle drifted up to close to 1000. I think it is close enough. I am no longer worried about damaging the transmission and at least it doesn't bang when put into gear. The surging problem is gone too. I don't guess there was a silver bullet. But thanks to your help and posts in history from searching. I think I am good to go. 
BTW, there is more room to play with the throttle stop if I decide to go back into it. "Any bets on how long I can leave it alone."
BTW, there is more room to play with the throttle stop if I decide to go back into it. "Any bets on how long I can leave it alone."
Last edited by txsilverado1; 02-26-2011 at 05:36 PM.
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