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88 k5 5.7 base idle

Old 05-03-2011, 12:07 PM
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deathman is on a distinguished road
Default 88 k5 5.7 base idle

setting my base idle on tbi ,iac closed and unpluged, set rpm at 700 ,warm engine, adjust tps to .50, my ? is does the timing advance wire need to b unpluged doing this ? engine timing is set at 0 with advance wire disconected, it still seems to idle a bit high , all sensors are new ,iac,tps,cts,esc,map,egr,o2,pcv,edelbrock intake, msd distributer,msd coil,no vacum leaks ,throttle body is rebuilt , 4000mls on new engine, its always done this even with the old motor , ecm has been replaced, does it need to b programed ?? any help or ideas ?
Old 05-04-2011, 03:22 PM
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I believe 700 is a bit high for the minimum air screw. My understanding is you need to set it as low as possible without stalling. The point is to get your IAC steps around 10-20 when you come to a stop and have a stable idle.

When you say it seems to idle high, at what speed??? Is this automatic or manual tranny?

If ECU is commanding 550 (in gear, auto) and you're idling at 800, your problem is not the ECU, but rather the minimum air screw has the blades open too far or the IAC isn't closing as far as the ECU is commanding it to.

You can find out actual rpm and what ECU is commanding with an OBD1 scanner (dealer), or DIY with an ALDL 1-transistor cable and winaldl/tunerproRTv4 (free OBD1 software). Search google... 1 transistor cable is cheap to build if you have an oldschool serial port.

Last edited by helo; 05-04-2011 at 03:24 PM.
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