Throttle Issue after Heads Cam and Accufabs

[Shiner]

So I picked up my car after my Heads, Cam, Tune and Accufab Install.

I noticed that the IAT sensor was left unplugged, no big deal, things get missed. I plugged it back in and cleared the CEL with my SCT handheld.

As I was driving the car, I noticed that the throttle was hanging somewhat almost as if the car came equipped with cruise control (it doesn't have). During this time I would let off the gas with the clutch in and the RPM would stay around 3-3.5k RPM for about 5-7 seconds and then drop down suddenly (similar to an automatic car going into overdrive). I noticed the car was low on gas, so I pull into the nearest gas station. As the car was coasting to a stop and towards the driveway to the fuel station, it just starts "running away on me", 3k RPMs again. Minded I have a brand new clutch and I had to slip it to get the RPMs down and into the station. Fill up with gas and start to take off in RPMs, again, starts climbing in RPMs as touch the throttle, back again up to 3k RPMs. Try to goose the throttle to see if the RPMs would settle back down and nothing, RPMs still hanging...Im still at the gas station.

I parked the car and just shut it down. I pop the hood and go back inside and start it back up, starts idling..go back under the hood and just touch the connecting rod between the TBs and here we go again, another run away and the RPMs are sitting back at 3k RPMs.

[dave6666]

So just to clarify a few things.

-> You take the vehicle to a shop. They install heads, cam, and tune it.

-> You discover an obvious sensor left unplugged that threw a code. You clear the code.

-> You have running issues with the engine hence this thread.

And per your statement about the sensor and the code, it's no big deal? Like when this shop was tuning the car they didn't notice the code? Or the fact that without an IAT sensor input that the tune is probably junk? No big deal right?

Sorry man. Go find a real shop and have them fix your car.

[Fatboy 18]

Have you tried to reset the tps throttle position sensor?

[GTS Dean]

Butterflies are not seating in the bores at closed throttle. As soon as engine vacuum is up, they are pulled open and the IAC has no control over idle speed. The OEM linkage pulls one butterfly open just before the other for a smooth transition off-idle.

[Shiner]

Took the slack out of the throttle body shaft. They are pretty much opening simultaneously now, just a very minute amount of "slack" in the cross shaft. I think all we need to do now is tune the issue out. If not then maybe need to block off some IAC.

[river rat]

Name of shop?, so I know who to avoid.

[Shiner]

Name of shop?, so I know who to avoid.

High Performance Connection

[Red Snake]

lol wow. Take it back to the shop that clearly didn’t fix it correctly and then don’t use them for anything else.

[GTS Dean]

Took the slack out of the throttle body shaft. They are pretty much opening simultaneously now, just a very minute amount of "slack" in the cross shaft. I think all we need to do now is tune the issue out. If not then maybe need to block off some IAC.

So, is it better now with the cable slack out? The IAC should fully control the idle speed with the stepper motor. It may take several minutes of idling and/or a drive cycle to "relearn."

[BK99GTS]

After installing the supercharger, I had issues with an idle hang and erratic idle. I did 2 things that solved the issue for me. One was resetting the ecm aka purging learned parameters. The other was installing a restrictor in the feed line for IAC. I found an old article (can't find it now) that described finding a plastic or wooden plug that would fit in the feed line. Then drilling a hole in that plug starting with a 3/8 bit and increasing as needed from there. I found that a small section of 3/8 fuel line would do the same thing and solved the issue. I understand that Dodge had done some updates to ECM programming over the years that may have also fixed the issue. I had zero confidence in my local dealer to handle reflashing my ecm, so did not pursue that any further. You could also try taking it to the dealer and installing the stock tune so the dealer can updated the ecm with the latest flash available. This may or may not be your issue, but all of the above could be worth a try if you are still experiencing the problem.

[Camfab]

Idle hang is a common problem with large cam duration on Gen II’s. This is where an experienced Gen II tuner can make all the difference. Idle hang will make you hate the car, and it will come right back if not tuned properly.