idle issue

[ed666]

i now have an issue hope someone can direct me in the right way i have a 94 f250 2wd with the 5.0 in it the problem i now am having that whenever i shut off the truck and then restart it no matter how long it sits the idle kicks way up like i have my foot on the throttle and revs way up for at least 10-15 seconds i have replaced the tps twice now the vacuum sensor and all was OK for a couple of weeks there are no check engine lights and mileage once again is suffering badly any help is greatly appreciated thanks all

 

[Twiceblown351]

TPS is bad. Check the voltage at the TPS at idle. Its should be .99 or lower.

.99 or lower is idle. 1.00 or higher is run. so if the computer see 1.00 or higher and its idling the computer thinks its running and has the IAC open more then it should.

If its under .99 and its doing it. you have a bad IAC or a air leak after the TB.

theres 3 wire at the TPS one back thats the ground. a orange and one green.
One the 5 volt in and one .90 to 5 volt out. Not sure which one which. a volt meter should be easy to find out whats what.

Had this happen on a truck a month ago on a customer truck. But its the same on any OBD1 or 2 ford car and truck.

Hope this helps.

 

[Twiceblown351]

sorry should of read you post more closely . didnt see that you change the TPS twice,

still check the voltage of the TBS. of its right. its the IAC or a air leak after the TB. it could be a hose or the intake gasket lower or a upper gasket.

or take the vacuum line off the Fuel Psi reg. and make sure there no gas coming out of the vacuum line of the FP reg. if there is then its the FP reg.

And make sure you have about 37 to 41 PSI of fuel PSI at idle. Any thing over 41PSI would make it idle high.

Or the timing over 13 after TDC with the spot unplug.

check the timing,TPS volts, And fuel TPS, and vacuum leaks before you buy any parts. thats the only way your going to find out whats wrong.

there the only things that could really make that happen.

 

[ed666]

thanks alot will ck those things out