New IAC Install

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HEMI_MEAT

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How much play should be in the unit's spring prior to install?
I've been reading around and went through the self diagnosis litany. Reset TB, per this forum. Replace battery, replaced TPS, Replace IAC. IAC was the last thing I tried because it was the hardest part to get a hold of. I first tried to clean the original and when I did, it was so stuck that the splunger/spring guy didn't even move by hand. Should it?
When I got a new one, it didn't move much easier prior to install.
Symptoms are occasional low idle RPM on start (500RPM). Usually, I'll shut it down, and restart and it's fine, but then the throttle seems to stick a little, almost like a vacuum leak. RPM around 1500-2000 while shifting with clutch depressed.
I checked for vacuum leaks, but couldn't find any.
Any thoughts would be greatly appreciated.


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how did you check for vacuum leaks?? on carbs we used to lightly spray carb cleaner around the intake runners and base of carb (TB) to see if the idle changed. I'm assuming that would still hold true for FI engines
 
Shouldn't move that much by hand.

Mine does exactly what you are saying from time to time. Although it doesn't go nearly as high as 2k rpm.

I have brand new TPS and IAC and TB.
 
HEMI_MEAT said:
How much play should be in the unit's spring prior to install?
I've been reading around and went through the self diagnosis litany. Reset TB, per this forum. Replace battery, replaced TPS, Replace IAC. IAC was the last thing I tried because it was the hardest part to get a hold of. I first tried to clean the original and when I did, it was so stuck that the splunger/spring guy didn't even move by hand. Should it?
When I got a new one, it didn't move much easier prior to install.
Symptoms are occasional low idle RPM on start (500RPM). Usually, I'll shut it down, and restart and it's fine, but then the throttle seems to stick a little, almost like a vacuum leak. RPM around 1500-2000 while shifting with clutch depressed.
I checked for vacuum leaks, but couldn't find any.
Any thoughts would be greatly appreciated.



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Click to expand...

Not sure what you are running for compression or a camshaft but it sounds like your IAC may be trying to compensate for your throttle body adjustment and it is doing (2) things. One would be not allowing enough air in behind the throttle body and it is giving you a slow idle (500 r.p.m.) and the other it is over-compensating for a throttle body that needs to be opened a bit more and is trying to compensate with too much air behind the throttle body giving you your 1500+ r.p.m. engine speed.

You could try to open your throttle body A TOUCH.

I don't know how long it's been since you changed the sensors (TPS/IAC) you said you changed; but you should try and perform an ECU reset as well: Disconnect both battery cables and hold them together briefly, then reattach. Even though your sensors were changed, the ECU could still be retaining info from the old ones.

The reset will reintroduce the ECU to planet Earth.

Good luck
 
Thanks Ronnie. I just put the sensors in a few weeks ago. I'll try working with the TB screw and reset again. Thanks for the help!

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Stock bottom end and Comp Coupe camshaft. I just got the truck in November with 13,500. I have changed all the fluids, plugs, wires. The current tune is a from mopar performance ECU to run the cam and mopar headers. I've got an SCT coming from Torrie this week.
I think the only thing I haven't done is a compression or leakdown check.
Is it possible that I got either a bad IAC or TPS?

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NukeGM/Ford said:
how did you check for vacuum leaks?? on carbs we used to lightly spray carb cleaner around the intake runners and base of carb (TB) to see if the idle changed. I'm assuming that would still hold true for FI engines
Click to expand...
I rechecked all the bolts from the valve covers and manifold. Retightened header bolts.
I think I check all the vacuum lines, including the two under the intake manifold.

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ViperPete said:
Shouldn't move that much by hand.

Mine does exactly what you are saying from time to time. Although it doesn't go nearly as high as 2k rpm.

I have brand new TPS and IAC and TB.
Click to expand...
Thanks Pete. I probably didn't explain that very well. During a shift, it will stay around 1500, but also sometimes climb (or Rev without throttle inputs) to about 2000 RPM.
All off this only happens once only 10-12 starts during the past two weeks. Eventually an engine restart will correct it.

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Do you know what kind of throttle body it has? Stock or?
 
Brace yourself... It's got the Ol' JH single blade... which I cleaned and visually checked during the reset procedure. It seems to function correctly, and I don't think it had these issues early on. Who knows, I've only put 700 miles on it since I got it in November.

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My BBK had throttle hang issues (after years of service) during a road trip last year. It looked clean and perfectly fine, except it was hanging. The only local replacement was a BBK for a viper. It worked perfectly, other than the throttle linkage was different. A little side of the road zip tie work, and I drove 800 miles home. I put the stock TB back on once I got home and have had no issues.

If Ronnie's fixes don't work...it's the TB.
 
HEMI_MEAT said:
Brace yourself... It's got the Ol' JH single blade... which I cleaned and visually checked during the reset procedure. It seems to function correctly, and I don't think it had these issues early on. Who knows, I've only put 700 miles on it since I got it in November.

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Click to expand...

Might be your problem, even your mopar ecm was tuned with the stock throttle body being in place. History has shown that aftermarket throttle bodies on these trucks can be hit or miss with the latter being more common. Alot owners report issues of the rpms hanging or the throttle sticking.

The TPS and IAC on these trucks tend to go out prematurely as well especially if you dont drive your truck as much. In the 1.5 years Ive had mine ive replace them both twice, I have a stock throttle body.

The good news, you can get a TPS and IAC from autozone and they will be OEM, you can check the part numbers between the two. Also autozone will give you a warranty so you can replace it if it dies within a year. The parts are also cheap thankfully.
 
oldcolt said:
My BBK had throttle hang issues (after years of service) during a road trip last year. It looked clean and perfectly fine, except it was hanging. The only local replacement was a BBK for a viper. It worked perfectly, other than the throttle linkage was different. A little side of the road zip tie work, and I drove 800 miles home. I put the stock TB back on once I got home and have had no issues.

If Ronnie's fixes don't work...it's the TB.
Click to expand...

Thanks. I'll try that and see what happens.
 
earl lee said:
Might be your problem, even your mopar ecm was tuned with the stock throttle body being in place. History has shown that aftermarket throttle bodies on these trucks can be hit or miss with the latter being more common. Alot owners report issues of the rpms hanging or the throttle sticking.

The TPS and IAC on these trucks tend to go out prematurely as well especially if you dont drive your truck as much. In the 1.5 years Ive had mine ive replace them both twice, I have a stock throttle body.

The good news, you can get a TPS and IAC from autozone and they will be OEM, you can check the part numbers between the two. Also autozone will give you a warranty so you can replace it if it dies within a year. The parts are also cheap thankfully.
Click to expand...

Thanks Earl. I didn't think of that. I don't know when these parts were installed, so your guess is as good as mine. Is that something I could ask Torrie to fix in an SCT tune?
 
Bump

Torrie can certainly set your base idle speed but if your TB and IAC motor are having a pissing match, it can still affect the idle regardless of where it is set by the Tuner.

As Earl Lee stated, these system ARE based on stock components.
 
So...to reset the tps and iac, do you only have to touch the battery cables together, or is there something else that needs to be done? Thnx
 
ralphie said:
So...to reset the tps and iac, do you only have to touch the battery cables together, or is there something else that needs to be done? Thnx
Click to expand...

Touching the cables together briefly, affects the ECU and is similar to performing a reboot on it.

The TPS and IAC do not have any systems to reset.
 
Last edited:
Copy... I'll try that and post an update in a few days. Thanks for all the support and responses.

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