97 wont idle

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Aug 5, 2012 | 07:57 PM

97FRD1TN

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From: Mason Michigan

97 wont idle

Hello everyone,haven't posted on here in a while,but I been having problems with my 97 f350 not wanting to idle. I pulled codes and only thing that came up was up was bad air charge temp sensor. I put a new iac valve on but I'm leaning towards a tps. It has a 351 with an automatic trans. Other than idling low it seems to run fine. But it just surges and has been sucking gas lately and getting sluggish. Any help would be appreciated. Thanks.

Aug 6, 2012 | 08:14 AM

rla2005

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From: Kentucky

So the code was for a faulty ACT sensor, but you changed the IAC? Seems a little odd. IF you did not warm up the engine/transmission before running the KOEO/CM and/or KOER tests then you may have triggered a false ACT failure. A hunting idle as you described can be cause by a faulty IAC, the aftermarket versions are notoriously bad out of the box, a vacuum leak TPS or a few others. I start with the easy things first. Before going hog wild replacing parts take a few minutes to verify if the sensor is bad by using a meter.

Aug 6, 2012 | 03:15 PM

97FRD1TN

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From: Mason Michigan

The truck was up to normal operating temp when I pulled codes. The iac was just one I had pulled off another truck along with throttle body and tps. It baffles me why if those were bad that it wouldn't show any codes. Also I have checked and cannot find any vacuum leaks. My truck also did this before and it was a bad o2 sensor. Could that be it again?

Aug 6, 2012 | 06:43 PM

rla2005

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From: Kentucky

If the truck was up to operating temperature and you still got a code for an ACT temperature out of range then you may have a bad ACT sensor. The easiest way to tell is measure it with a meter.

Many times a TPS can be faulty but never trigger a code. That is why it is highly suggested to check the output linearity with a meter before tossing parts at a problem.

Same can be said for most of the sensors. That is why you measure them before tossing more unknowns ($$parts$$) at a problem.

Aug 6, 2012 | 07:44 PM

97FRD1TN

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From: Mason Michigan

Yeah that's why I haven't bought any new parts for it just junkyard which may or may not be helping my cause. I just didn't wanna drop a bunch of money on new parts like you said. So far what I've read it doesn't sound like act even effects the vehicle,it just throws the cel.

Aug 7, 2012 | 08:09 AM

97FRD1TN

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From: Mason Michigan

I was just messing around this morning and the truck won't even idle at all. So I got it to stay running and unhooked both iac and tps one at a time and then together and no change. Does this mean anything?

Aug 7, 2012 | 08:52 AM

rla2005

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From: Kentucky

Not to me, does not mean a thing. You have a code for a faulty ACT, measure the dang thing to verify if indeed the output is incorrect. If it measures good, then you need to move down to the PCM connector to verify the signal is good there.

Start with the things the computer is trying to tell you it thinks is wrong. The PCM relies on several sensors for correct engine operation. If any one of them is out of whack then anything is bound to happen.