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Discussion Starter · #1 · (Edited)
Today I installed one of Matt Blums bored out stock TB's. Transferred the IAC sensor and the
TPS sensor from a spare stock 48 mm Throttle body. Checked the IAC with multimeter and it was 54.2
and 53.1 DC/AB pins. So I started the car and followed the FSM procedure for resetting the
IAC and it won't idle down. Goes to about 2,000 and stays there. Tried disconnecting the
battery for 10 minutes and then ran the FSM procedure again. Same result.

Checked the Helms manual for Grins and Giggles. It says that when replacing IAC you just
start the car and the PCM relearns the correct idle over time. How much time? This is in
direct contrast to the FSM. Granted the procedure is for a new IAC but I assumed it would
work with a used IAC sensor from another throttle body.

Any thing else I should do before spending the big bucks for a new IAC.
 

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When I put on my 52mm throttle body I had high rpms also. It took about 2 weeks for it to settle down to normal .

I did as you did transfered the IAC and checked voltage. Just give it a little time------thats what worked for me
 

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Discussion Starter · #4 ·
Sometimes its the simple stuff

Roger;

Yep, sure did. Found the problem thanks to a suggestion from a friend. When I installed
the 58mm TB I checked the slack in the throttle cable and the position of the blades.
All good. Later when I was buttoning everything up, I hooked up the Cruise Control Cable.
It was a tad shorter and pulled the throttle open slightly.

Upside is I can R&R a throttle body in Fifteen Minutes or less.

Down is I have a check engine light and an off idle bog with the larger TB
 

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Discussion Starter · #6 ·
Update

The car has a TKO-600 Five Speed transmission. Emailed Bryan Heter and he said my current tune should be fine.

I scanned the code last night. I have low voltage from the TPS and suspect that may
be contributing to the off idle bog. Hope to have time tonight to check voltage on the
wires. Ground should be ok because the ETC sendor uses the same one in the PCM.
Either a bad wire or bad sensor most likely.
 

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Discussion Starter · #7 ·
52mm Throttle Body

Bought a new GM TPS and installed it tonight. Scanned and cleared the code and
the check engine light is out. Hopefully, the new sensor solved the problem. It occurred
to me that the Stock TB was operating perfectly and therefore it was unlikely to be
a wiring problem.

Both problems the high idle and the Low Voltage TPS were caused by my errors.
First I had the cruise control cable too tight and second I tried to save some money
by using old sensors with an unknown history.
 
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