I don't remember if I mentioned this in any of my earlier posts, but now that the temps here are starting to get up into the eightys, an old problem is rearing it's ugly head again. When my temp gauge gets up to around the "R" or "M" in NORMAL the idle jumps up high enough to go down the street doing 45mph without touching the pedal. Some time back I bypassed the hot water line away from the throttle body to see if that would solve the problem, but It still does it.
Second problem that started recently is the motor won't start unless I hold the pedal to the floor while cranking. This is something I shouldn't have to do since it's EFI. I recently put in a new fuel pump since the old one died on me, so I know it's not that. I put in F/I cleaner every couple of times I get gas, so I don't think it's the injectors, and if it was the regulator it would just run bad if at all.
92 E150 302ci EFI

 

Replace your TPS (Throttle Position Sensor).

 

Hi Nightowl

Did you fix your fast idle problem yet?
I have a '92 E-150 351ci EFI with the same problem, idle speed about 1200 to 1500rpm mostly after driving at speed it's worst, on slowing down it's fighting against the brakes. it's Ok again when cool then starts again when temprature rises

 

Haven't had the chance yet, been raining last couple of days. I wish I knew of some way to test it before spending the $35 on the part and time installing it.
The manual shows two different TPS's for this van. One of them you can take apart and clean, and the other you just have to replace, mine is the latter.
I read comments in here about guys spending hundreds of dollars replacing parts just trying to find the one that's causing the problem they have, I can't afford to do that.
I was thinking of unplugging it to see if that might tell me, but I think that would screw up the computer.
Unless one of these guys knows of a way to test it, I'll just have replace it and find out. I'm keeping my eye out for an older van in good shape that doesn't have all this computerized electronic crap on it and selling this one to some sap who doesn't know any better or has the money to take it to a shop every time there's a glitch in the electronics.

 

TO check it, get a multi-meter, set it to the 12 volt (or close to) range, get some straigt pins and put them in the black and green leads, then use an alligator clip or some tape to secure the RED probe to the GREEN wire on the TPS, and the BLACK lead to the BLACK wire. DO NOT cross let the two probes touch as this could cause potential damage to the computer. The voltage should be .7 ~ 1.0 volt at idle, and ~5.0 volts at WOT. It may be the IAC sticking when it gets hot.

 

Are we talkin key on, engine off ? I assume yes cause of the WOT.(wide open throttle Right ?) O.k, then if the readings are, or close to, as you say on my VOM is there a way to test the IAC ?

 

Yes, KOEO (key on engine off) the best way to test the IAC is unplug it. If it idles down then it's ok, if it stays high then it's stuck open.

 

I appreciate the info. If it ever stops raining here I'll get on those tests. Hey Bartat, you need to try what the man sez, and see if it helps you. If you get to it before I do report back. I'll do the same just in case someone with the same problem checks into this post.