IAC problems
IAC problems I can't seem to figure out the problem on the IAC. Upon start up it's maxing out at 160 and doesn't want to take any throttle. And will creep down to around 130 -120.
Some of the things I've done :
1. Played with the Idle adj. screw. ( still high)
2.Sprayed starting fluid around the intake no spike in the idle.
3. Took the TB apart cleaned it put all new gasket's on it (still no change)
4. Checked the resistance on the IAC I was getting 50 ohms (in range)
5. Reset the IAC position (no change)
The only thing that has changed is when I had the motor rebuilt it had to be bored .30 .I have talked to Solomon he seems to think it need's to be updated but need to figure out the IAC problem first.
I am out of ideal's with what to do.
Some of the things I've done :
1. Played with the Idle adj. screw. ( still high)
2.Sprayed starting fluid around the intake no spike in the idle.
3. Took the TB apart cleaned it put all new gasket's on it (still no change)
4. Checked the resistance on the IAC I was getting 50 ohms (in range)
5. Reset the IAC position (no change)
The only thing that has changed is when I had the motor rebuilt it had to be bored .30 .I have talked to Solomon he seems to think it need's to be updated but need to figure out the IAC problem first.
I am out of ideal's with what to do.
Can you give some further details. What is the idle rpm when cold and then when warmed up? When you tried adjusting the idle screw how far down were you able to get the IAC down. Did you then try to readjust the TPS back to about 0.56V ?
TECH Veteran
Joined: Apr 2008
Posts: 4,985
Likes: 112
is this a stock TB?
if you adjusted the TB stop screw (really never should touch it) adjust it back so the TPS then reads .67vdc (+/-)
EDIT: CAPS
heads/cam cars WITH AFTERMARKET TB often need A idle hole LIKE THE stock TB drilled out 1/64" LARGER THAN THE 1/8" STOCK SIZE HOLE...but generally because the car won't idle (stalls) while IAC counts are pegged at 160
Is your car stalling because of low idle or does it have a high idle RPM?
if you adjusted the TB stop screw (really never should touch it) adjust it back so the TPS then reads .67vdc (+/-)
EDIT: CAPS
heads/cam cars WITH AFTERMARKET TB often need A idle hole LIKE THE stock TB drilled out 1/64" LARGER THAN THE 1/8" STOCK SIZE HOLE...but generally because the car won't idle (stalls) while IAC counts are pegged at 160
Is your car stalling because of low idle or does it have a high idle RPM?
Last edited by BALLSS; Jan 30, 2017 at 11:10 AM.
When it's first fired up it idles around 1100 then it will jump around 650-850 rpm's when warmed up. When adjusting it I got the counts down to around 130. But I didn't check the volts on the TPS.
is this a stock TB?
if you adjusted the TB stop screw (really never should touch it) adjust it back so the TPS then reads .67vdc (+/-)
heads/cam cars often need the stock idle hole of a stock TB drilled out 1/64" more...but generally because the car won't idle (stalls) while IAC counts are pegged at 160
Is your car stalling because of low idle or does it have a high idle RPM?
if you adjusted the TB stop screw (really never should touch it) adjust it back so the TPS then reads .67vdc (+/-)
heads/cam cars often need the stock idle hole of a stock TB drilled out 1/64" more...but generally because the car won't idle (stalls) while IAC counts are pegged at 160
Is your car stalling because of low idle or does it have a high idle RPM?
TECH Regular
Joined: Nov 2011
Posts: 471
Likes: 14
From: Tucker, GA
Didn't have to drill my stock TB with a cammed 383, either. What year/make/model LT1? Is this the 92 in your sig?
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You should not have to do drill a hole into a stock TB. It should already be there. And don't try to enlarge it. That can lead to further idle quality issues. That only applies to those TB's that do not have it already there, and even if it isn't there, it would not cause your idle to go high, but rather low/stumble. If your throttle position sensor voltage is out of whack that can make the engine idle high.
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Verdad Gallardo TECH Veteran
Joined: Apr 2008
Posts: 4,985
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so you cleaned your stock TB. I assume you also cleaned the IAC & orifice. It is possible that the IAC itself is bad...If you pushed in the tip of the IAC by hand, it is dead now
If I understand your problem...the car will not idle (due to low rpm) and IAC counts are high (130 if you crack open blades some with stop screw) or pegged at 160, right?
"stock" TB...than don't drill it. I edited my previous comments. Must have been pre coffee as I meant to refer to aftermarket, larger, TB's
so you cleaned your stock TB. I assume you also cleaned the IAC & orifice. It is possible that the IAC itself is bad...If you pushed in the tip of the IAC by hand, it is dead now
If I understand your problem...the car will not idle (due to low rpm) and IAC counts are high (130 if you crack open blades some with stop screw) or pegged at 160, right?
so you cleaned your stock TB. I assume you also cleaned the IAC & orifice. It is possible that the IAC itself is bad...If you pushed in the tip of the IAC by hand, it is dead now
If I understand your problem...the car will not idle (due to low rpm) and IAC counts are high (130 if you crack open blades some with stop screw) or pegged at 160, right?
And when it warms up the counts will go down to around 130.
crack the blade open some and do a tps reset... iac counts will come down some
