RPM question after tb and plenum install

MustangLife · Jul 19, 2007

I just installed the accufab plenum and 75mm tb on my 03 gt. I let the car idle for about 5 minutes and than drove it home about 2 miles. I didn't reset the battery.
But my rpms hang a little when I'm slowing down. Hang at like 1200-1300 and than when i come to a complete stop it drops to 700 or so rpm. But again at idle it idles perfect.

So do I just need to drive it some more or is something wrong.

Thanks
Josh

mustanggt3685 · Jul 19, 2007

I believe that the computer needs to get used to the new increased airflow into the engine? I'd say that the more you drive, the idle will level out.

COramprat · Jul 20, 2007

The idle control sensor may not be installed correctly. Make sure you have the throttle body blade inserted into the sensor so it manipulates the prongs inside of the sensor.

helty · Jul 20, 2007

If the IAC is installed correctly, and there are no vaccuum leaks, just give it time.

96GTstang46 · Jul 20, 2007

Just rally it... should be fine... Only kidding..

Well you could always make an IAC plate like i did.. its a piece of tin that replaces the little templet on the inside.. there are 2 8mm bolts holding it on (in case you didnt know) and just make a copy of it, but make the RIGHT (drivers side) hole smaller when you drill out the piece of tin... there was a thread about it a long time ago and cant seem to find it.. but it makes your rpms DROP like a rock when you make it just right.. for some reason all stock mustangs dont rev down fast at all.. maybe i am just stupid lol jkjk

MustangLife · Jul 20, 2007

I really don't see how the iac can be installed wrong, heres a pic

COramprat · Jul 20, 2007

Bah...got the terms screwed up. The throttle position sensor. That black sensor just to the left of the IAC attached to the throttle body.

scupking · Jul 20, 2007

Mine does the same thing. It will hang at 1200-1300 then drop and idle fine. Mine also does something strange around 4,000-5,000 RPM. It’s as if my engine falls flat on its face but then picks up again, I don't get it. Never did that with the stock TB and PL. I think I might put my stock Plenum back on and keep the 75mm TB to see if that will solve the problem.

COramprat · Jul 20, 2007

scupking said:
Mine does the same thing. It will hang at 1200-1300 then drop and idle fine. Mine also does something strange around 4,000-5,000 RPM. It’s as if my engine falls flat on its face but then picks up again, I don't get it. Never did that with the stock TB and PL. I think I might put my stock Plenum back on and keep the 75mm TB to see if that will solve the problem.

The 1st problem I bet is the TPS...I ahd mine installed incorectly and even bought a new one until I figured out that the sensor wasn't installed correctly. I does throw a code though.

The second problem might be a small vacuum leak somewhere. Just check all the connections to the TB and plenum and make sure there are no leaks between the two via loose bolts.

stangvert · Jul 20, 2007

TPS Sensor Adjustment

I know you guys may be done with this, but this document may help with the idle after installation of a new TB. From the Accufab website, but would pertain to any TB replacement. Please note the section on the TPS (sensor) adjustment. This definitely makes a difference, since I experienced the weirdness before I made the adjustments according to the article. Everything is fine now.

http://www.accufabracing.com/article_1.htm

scupking · Jul 20, 2007

I looked at that article and it says "DO NOT ADJUST THE STOP SCREW ON THE THROTTLE BODY UNDER ANY CIRCUMSTANCES. This screw has been pre-set at the factory to insure a proper air gap around the throttle blade in the fully closed position. If by chance this stop screw has been adjusted in the field, please call our TechLine for further assistance."

I did adjust my stop screw because my TB was sticking. I changed it till it wouldn't stick (probably about a half a turn). Why does it say not to do that?

RPM question after tb and plenum install

MustangLife

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mustanggt3685

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COramprat

...I can take it. I think.

helty

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96GTstang46

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RPM question after tb and plenum install

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