help rpms wont drop!

GotRidOfTheHemiForThis

GotRidOfTheHemiForThis

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:dontknow: Was out playin around in the truck and i noticed the engine got really loud.
The Rpms wouldnt drop from 2000 not matter what i did???? They would fluxuate when i pushed the gas and shifted but would always return to 2000. Yet when i turn the truck on and off the rpms seem fine until i start driving her???? It seems the supercharger is also racing while this is happening any help here please!!!!!

-no leaks (checked)
- mods are paxton/heads and cam/exhaust

Could something be stuck or even triggering the paxton to keep going making air rush into the motor upping the RPMS maybe????

could this Throttle get stuck???
 
throttle position sensor? good idea im gonna go look at it now.

possibly could it be that i used full boost and the fuel injectors are taking a while to drop down?
 
GotRidOfTheHemiForThis said:
throttle position sensor? good idea im gonna go look at it now.

possibly could it be that i used full boost and the fuel injectors are taking a while to drop down?
Click to expand...
sounds about right.:rock:
 
Its the idle air control valve, already had to change 2 of them out. 45 dollar fix. the stock dodge ones are crap. when you run a high boosted car and you dont have the blow off set just right the IACV is always under more then normal stress. thats wat causes them to go out.
 
Try disconnecting the battery for ten minutes and then start it up. It resets the IAC.
 
avmech said:
Its the idle air control valve, already had to change 2 of them out. 45 dollar fix. the stock dodge ones are crap. when you run a high boosted car and you dont have the blow off set just right the IACV is always under more then normal stress. thats wat causes them to go out.
Click to expand...
How do you test if it's the IAC or the TPS?
 
unplug the ts and manually hold the throttle open a little to keep the engine running. i removed my tps a year ago and just turned the screw on my throttle body a little tighter to let it idle. that will tell you if it is what is causeing the problem. or you can check the sensors with a ohm meter
 
I had this problem on my sandcar. After a hard run, or good hill climb, it would not return back to idle.

Mine was a combination of the TPS sensor, and fuel table settings.

So I replaced the TPS, and the problem got better, but not completley gone.

So I hooked up my laptop and looked, and adjusted the injector pulse settings for the 0-1200, and 1200-3600 rpm ranges, in the the 20, 30 and 40% load settings.

Making these changes took care of the problem completly....

I know this doesnt help here... but maybe something to have your tuner look at. These are just the images from the saved calibrations, and not while the engine is running... as you can see by the diagnostics info in the lower portion of the window.

ingenius2.jpg


ingenius1.jpg
 
Thanks guys, either way im just gonna have dodge test out the IACV, TPS and most likely as Randy said replace the IACV and hopefully it will stop and be normal. I figure since he built it hes gotta a good chance at being the lucky bingo winner on this problem. Additionally I unattached the neg battery terminal already and let it sit off. I'll probably let it sit a day or two before this rain ends and have a chance to get her out to see what if anything that did. Hope for no tuning currently due to well im broke right now and that would suck currently! Either way first stop is dodge and then on i guess. OH hey Randy or anyone, does anyone know of a better iac that will work or am i stuck with the same one from dodge???
 
Last edited:
avmech said:
Its the idle air control valve, already had to change 2 of them out. 45 dollar fix. the stock dodge ones are crap. when you run a high boosted car and you dont have the blow off set just right the IACV is always under more then normal stress. thats wat causes them to go out.
Click to expand...

Where is the IACV located and is it difficult to change out?
 
Marc T said:
Where is the IACV located and is it difficult to change out?
Click to expand...

Looking at the engine bay picture in your sig it is one of the three sensors going into the box just behind the throttle body. I believe it is the one on the right but I cant remember for sure. Easy to change but may need to be calb with a StarScan...
 
TNVIPER said:
Looking at the engine bay picture in your sig it is one of the three sensors going into the box just behind the throttle body. I believe it is the one on the right but I cant remember for sure. Easy to change but may need to be calb with a StarScan...
Click to expand...

Must be the one furthest to the rear!!

The 1st one is the TPS, the middle one is the MAP sensor so I am guessing it's the third one!!

Thanks
 
Marc T said:
Must be the one furthest to the rear!!

The 1st one is the TPS, the middle one is the MAP sensor so I am guessing it's the third one!!

Thanks
Click to expand...

You are correc!...I knew it was the lrft or right but could not remember without lookin..I knew the center was the MAP sensor since we just changed it to a 2 BAR when the SCT tune was flashed in..
 
TNVIPER said:
You are correc!...I knew it was the lrft or right but could not remember without lookin..I knew the center was the MAP sensor since we just changed it to a 2 BAR when the SCT tune was flashed in..
Click to expand...

Yep, Sean had to change my Map sensor also. How are you liking your SCT tune as apposed to the VEC tune?

I am luving mine!! My only complaint now is that I have this annoying idle problem. Sticks at 1500 RPMS sometimes, not all the time. It goes right back to normal with a little blip of the accelerator but it is annoying!
 
Marc T said:
Yep, Sean had to change my Map sensor also. How are you liking your SCT tune as apposed to the VEC tune?

I am luving mine!! My only complaint now is that I have this annoying idle problem. Sticks at 1500 RPMS sometimes, not all the time. It goes right back to normal with a little blip of the accelerator but it is annoying!
Click to expand...

I do not have my final tune yet. I am scheduled to be on a dyno Thursday where we will email results and tunes back and forth to Marty.

I had the idle problem at first but Marty fixed it with the 3rd tune he sent me. I do have a problem with the A/F going off the scale lean when you first lay into the throttle. Does it for a second then back to ~11 where it should be at WOT.

Marty sent me a about 10 different tunes before we got it where it would not do it at the slightest touch of the throttle. Still goes lean for a second if you just floor it from idle. If I ease it to about half throttle and then nail it I am instantly layed back in the seat. Marty seems confident that he can fix this issue.

I did find something that might have been some of the problem. I had forgotten that I had put a resistor on the temp sensor wiring. Sean had suggested this last fall to help the truck run better in hot weather. Worked fine with the VEC but made the SCT tunes irratic.
 
Went through the same high idle problems that you described including running lean. Idle would stick at 1500 rpm and idle down after goosing the throttle a little. Very annoying. Got all the same good advice from the RBC but nothing worked. Even went to the point of buying 60 lb. injectors,new aeromotive fuel system, and adding lots more fuel to try and correct the lean condition. Actually made the situation worse. Modern Performance finally found the problem while checking and comparing cylinder temps. Number three was running hot--hot enough to burn out the header gasket. Seems that the fuel injector has two little electrical connections that when plugged in make the injector fire. One of these was bent and caused the injector to fire sporadically -- if at all. Because the air/fuel is read from the drivers side this came up as a lean condition. I could have dumped half of OPEC in the motor and still would not have corrected the condition. Spent lots of money trying to fix this and lots and lots of frustraton. Thanks again to Modern Performance for finding the problem.
 
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