Jumpy throttle take off

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Oct 11, 2011 | 04:16 PM

Oldsmoky92

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From: Idaho

Jumpy throttle take off

Well my 95 psd has a very jumpy throttle all the time. I am guessing it has somethin to do with my ZF swap. I was wonderin if anyone else had this issue and what the remedy is. I asked Ford shop about Flashing my rig and they said it shouldnt need it goin from auto to manual. I really notice it when i am taking off its either idle or too much! Thanks, Chad.

Oct 12, 2011 | 09:58 AM

madpogue

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From: Madison, WI

So you didn't get the PCM from the donor truck?

Oct 12, 2011 | 10:08 AM

DIYMechanic

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From: Orrville, Ohio

Sounds like you may need to adjust the throttle pedal assembly. The pedal is a totally fly by wire setup with two separate sensors in it. One of the sensors is essentially a rheostat that changes resistance depending on the position of the pedal and it is called the TPS (Throttle Position Sensor). The other sensor is essentially a safety switch that signals that the throttle is or is not in the idle position and is called the IVS (Idle Validation Switch). In my truck you can hear the IVS "click" when you start to put the throttle. What you should look for is whether you can ever so gently push the pedal until you hear that "click" without actually increasing the engine RPM's. If you cannot you need to adjust the location of the IVS.

HERE is a link to look at. You'll need to open the file in the first post.

If that is not the issue, then occasionally the TPS just needs to be cleaned. Spray it out really good (while it is unplugged) with electrical contact cleaner and see if that helps.

Also, my understanding is that there is indeed a subtle difference in the fueling map between the PCM in an auto truck and those in a ZF'd truck. Not sure if that will solve your issue or not, but there IS a difference.

Oct 12, 2011 | 02:42 PM

Oldsmoky92

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From: Idaho

Well i installed my 6 pos yesterday and now the throttle is totally different its not so jumpy and now the power really comes on early on as in there is no need to floor board it. I will check into cleaning the pedal sensor. Thanks!

Oct 12, 2011 | 03:01 PM

madpogue

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From: Madison, WI

Just a WAG, but if you['re still running the auto PCM, and it's obviously not "seeing" any tranny in any particular gear when you launch, it may be overriding, in part, the pedal position. And the chip, presumably pre-set for a manual, is now trumping the PCM programming.

Dunno if you checked this, but withOUT the chip, and the truck NOT moving, just sitting in the driveway in neutral working the pedal, is it jerky then, or does it respond to the pedal as expected?

Oct 14, 2011 | 02:25 PM

Oldsmoky92

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From: Idaho

The only problem i had was trying to go slow through rough areas, it would get to buckin a little more than i liked. Either way it is better now with Chip installation but i really do appriciate all the input guys.

Oct 14, 2011 | 08:47 PM

3wildboys

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My truck is doing kinda same thing when on bumpy brick street at slow speed throttle seems ultra sensitve which causes a guys foot to bump and grind everyone in vehicle,kids like,wifey,not so much.