Why is it doing this
Thread Starter
Member
Joined: Nov 1999
Posts: 429
Likes: 0
From: Fayetteville, Arkansas, USA
Car: 1994 Trans Am
Engine: 5.7L LT1
Transmission: 6-speed
Why is it doing this
OK, I tuned up my car. New Ac Delco plugs, Taylor SpiroPro wires, and an Accel cap and rotor. Set the base timing to 8* BTDC. adjusted the IAC and set the TPS at .57 volts. Now everytime I start it up the rpms suddenly shoot up to 1500-1600 then come back down to whatever is normal for the engine temp. Usually like 600-700 rpm. What's causing this? I can't think of any reason why it should be doing this. tahnx in advance 
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'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler
Taylor SpiroPro wires
Accel cap and rotor
------------------
'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler
Taylor SpiroPro wires
Accel cap and rotor
Junior Member
Joined: Jun 2000
Posts: 84
Likes: 0
You might try disconnecting the battery for about 30 seconds to reset the computer. Might be that the computer has not adjusted to all the tune-up mods.
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'89 GTA, Ported Plenum, BBK throttle body, 24lb Motorsport injectors, Jet stage 2 chip, AFPR, no cats and a Flowmaster.
'95 GMC soon to be 383 daily driver w/Howell multi-point injection conversion
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'89 GTA, Ported Plenum, BBK throttle body, 24lb Motorsport injectors, Jet stage 2 chip, AFPR, no cats and a Flowmaster.
'95 GMC soon to be 383 daily driver w/Howell multi-point injection conversion
Moderator
Joined: Jan 2000
Posts: 19,659
Likes: 310
88,
That's fairly normal. It's a sign that the IAC is actually doing its job, stepping open while the ignition is on but the engine is not running, then stepping back down to target idle once the engine is running. Mine has done this since 1986.
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Later,
Vader
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"Make Me Bad"
Adobe Acrobat Reader 4.0
That's fairly normal. It's a sign that the IAC is actually doing its job, stepping open while the ignition is on but the engine is not running, then stepping back down to target idle once the engine is running. Mine has done this since 1986.
------------------
Later,
Vader
------------------
"Make Me Bad"
Adobe Acrobat Reader 4.0
Thread Starter
Member
Joined: Nov 1999
Posts: 429
Likes: 0
From: Fayetteville, Arkansas, USA
Car: 1994 Trans Am
Engine: 5.7L LT1
Transmission: 6-speed
I disconnected the battery but no change. Another strange thing happend today, the idle speed suddenly became slower by itself, around 450rpm in drive. I remember it wasn't acting like this when I set the IAC earlier -it was after the last adjustment after setting base timing to 8* that the motor revved up on its own at startup. Before that I had accidentally set the timing at 12*. Don't ask why? 
Isn't this unnecessary revving harmful especially during cold starts when most engine wear occurs?
------------------
'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler
Taylor SpiroPro wires
Accel cap and rotor
Isn't this unnecessary revving harmful especially during cold starts when most engine wear occurs?
------------------
'88 IROC 305 TPI
Gutted airboxes
160 degree T-stat
Advanced base TPS voltage
Relocated IAT sensor
Momo steering wheel
Ram-air setup coming soon
Flowmaster muffler
Taylor SpiroPro wires
Accel cap and rotor
