GSLSto S4 Intake Unique Idle Problems
11-21-13, 02:43 PM
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GSLSto S4 Intake Unique Idle Problems
Alright guys I've been trolling since I got it back together for an answer to this.
'84 GSLSE, just swapped in an S4 block and intake, still running SE injection system.
Problem: With headlights on, and brake depressed, idle surges up and down, gradually worse. This more or less happens with larger electrical loads such as heater/headlights, brakes/heater, etc.
I believe I've got the vacuum lines routed correctly, still using the SE BAC, however, all the vacuum diagrams point to the oil injector air lines being routed into the top front port of the uim (the largest port of the three). I've read that the oil injector lines should be run to metered air, not vacuum, and the top port IS vacuum. More specifically, it seems the vacuum in this port is controlled by the idle adjust screw on the top of the TB, which also logically explains why the idle adjust screw does NOTHING.
Long story short, where the heck do the oil injector air lines go, and what plugs into the port controlled by the idle adjust screw???
Thanks, and I'll clarfy anything that needs to be! Love this car but it's driving me INSANE!
'84 GSLSE, just swapped in an S4 block and intake, still running SE injection system.
Problem: With headlights on, and brake depressed, idle surges up and down, gradually worse. This more or less happens with larger electrical loads such as heater/headlights, brakes/heater, etc.
I believe I've got the vacuum lines routed correctly, still using the SE BAC, however, all the vacuum diagrams point to the oil injector air lines being routed into the top front port of the uim (the largest port of the three). I've read that the oil injector lines should be run to metered air, not vacuum, and the top port IS vacuum. More specifically, it seems the vacuum in this port is controlled by the idle adjust screw on the top of the TB, which also logically explains why the idle adjust screw does NOTHING.
Long story short, where the heck do the oil injector air lines go, and what plugs into the port controlled by the idle adjust screw???
Thanks, and I'll clarfy anything that needs to be! Love this car but it's driving me INSANE!
11-22-13, 07:37 AM
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Quick update to this, on the front of the throttle body, the air ports are as follows:
Top port-vacuum controlled by idle screw.
Middle port-can't blow or suck air through.
Bottom port- can't blow or suck air through.
I did remove and clean the throttle body a few weeks back, and I was very careful when I RTV'd it back on. I feel it may have plugged up an important air circuit. Can anyone verify these ports as correct or plugged?
Thanks!
Top port-vacuum controlled by idle screw.
Middle port-can't blow or suck air through.
Bottom port- can't blow or suck air through.
I did remove and clean the throttle body a few weeks back, and I was very careful when I RTV'd it back on. I feel it may have plugged up an important air circuit. Can anyone verify these ports as correct or plugged?
Thanks!
11-25-13, 07:58 AM
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Just to complete this thread for anyone else that may have a similar problem in the future, it turns out the idle passages were blocked up by mod dobber nests. They were deep enough in there that they could not be seen, however running a drillbit through each passage revealed un unbelievable amount of dirt and debris clogged inside. Blocking the main idle passage in the throttle body, effectively caused a vacuum to be drawn on the oil injector lines, rather than an air supply to both it and the idle passage.
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trickster
2nd Generation Specific (1986-1992)
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