Just doing some tune-up projects on a 91 LX 5.0 that I recently picked up.
I will be setting the timing and adjusting my tps voltage and idle speed. What RPM should my car be idling at???????????
Is it a stick or auto? 675 rpm is idle in drive or in neutral with a stick. The sticks dont seem to idle there, mine is 850-900. You cant set the idle really, the computer controls it. What year is the car? Different steps for different years to set it up right. www.alldata.com is a place to check. Its not free, but its cheap for only one car. I have the idle proceedure for my 88 from them.
Jerry is right - some dont like to idle too low. then again, go too high and the puter will cut what it can to lower the idle back down.
here is a decent link for adjusting all that stuff - each page has a different aspect covered. http://www.muscularmustangs.com/iac.html
good luck.
Yeah, that's why an alternator produces ALTERNATING CURRENT
You do want to use DC voltage to check TPS voltage. I can't remember it, but there is a specific voltage that the EEC starts to change fuel delivery so you want to stay below that voltage. Pretty useless info since I can't remember the number though...
most set it at < 0.97V. the puter is supposed to zero-out the base setting upon start up, so as long as you are within the adaptive abilities (usually within 25%) you should be alright.
i still like to set it - the puter has enough stuff to do without needing one more task.
The idle on the 5.0 is non-adjustable. The computer controls it. If you try to adjust it down, the computer will try to raise it up by opening the blade on the IAC.
The only reason you should touch the idle screw is to set minimum idle. WHat you do is disconnect the IAC and set the idle with the screw so it idles as low as it possible can without stalling out.
Then you reset the computer and plug the IAC in and reset TPS to 0.95 volts.
The IAC will function only very slightly open at normal idle and can open further since it has most of it's range available.
Everything vehicle related is a 12volt DC system. The alt may produce AC internally, but all output from the power output should be about 14VDC. Also, when it comes to working on vehicle electrical systems, Black wires are grounds and red wires are usually 12V power source wires