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Discussion Starter · #1 ·
My GF's van had a dead miss at ALL speeds as if the coil wire was removed and quickly replaced. Some times it was longer. She took it to All Tune, Firestone then the Ford Dealer. No one could find the problem. I removed the PCM and found 3 capacitors blown out. I went to radio shack and found replacement caps. After replacement, the van runs Smoooth! But it runs at a high idle. I tried another PCM and had the same results. I have checked and replaced rubber vacuum lines to no avail. Second, How do I bypass the RABS valve? Thanks in advance!
 

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High idle is often a vacuum leak, and sometimes a faulty Throttle position sensor.

You might consider pulling diagnostic trouble codes.

Pull Diagnostic Trouble Codes (DTCs) From your onboard computer.
Your engine and transmission are computer controlled.
The computer uses sensors to tell it a number of different things and it controls actuators that push or pull mechanical levers (kinda). If one or more sensors aren't working properly, the computer goes "blind" and doesn't know what to do. If the computer can "see" but one of the actuators is broken and therefore can't follow the commands of the computer; the engine won't run correctly. The computer is preprogrammed with set values for each of its sensors, and each of its actuators. It will run a self check of all systems, like the space shuttle; it will compare its set value(s) to the value(s) it recieves from its sensors, and actuators. If any sensor or acutator is out of the "normal" range the computer will generate a "code." It will generate some codes on the fly, and others will be stored while you are driving. There is a simple method to "pull codes" out of the computer for one to use for diagnostic purposes.
Earlier versions of On Board Diagnostics OBD 1983-1995 can flash the error code to the dash board and can be pulled in one's driveway without any special tools.
Later versions of On Board Diagnostics OBDII some 1995, and pretty much all 1996 and newer, require one to use a code reader or scanner tool.
Some auto parts stores will scan your engine codes for FREE, you may want to call around. Some will scan OBDII but not the older (prior to 1996) OBD systems.
SO here you go...
How to scan FORD on board Diagnostic Trouble Codes (DTCs) in your driveway

HowTo Pull Codes 1983-1995 Broncos, Mustang, F series Trucks, Econolines, 302, 351 and more
Howto locate a vacuum leak
http://www.fordforumsonline.com/forum/engine-drivetrain/94-howto-how-locate-vacuum-leak.html#post423
 

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Discussion Starter · #3 ·
Thanks Poppy! I pulled the codes which were 121 then 111. 121 refers to the TPS which I will replace. I also pulled the IAC while the engine was H O T! The little cup at the end of the shaft was not in the closed position between the two ports hot or now cold. The spring seems to hold it in the open position. Is there a way to test/clean this valve? I did not trust putting 12V to it!
 

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Fourwayz,
You pulled codes! Good for you! :)
It's amazing how easy it is to do yet how few actually pull them in pre '96 vehicles.
:thumbsup:

See if this helps :)
HowTo check your IAC
http://www.fordforumsonline.com/for...lean-your-idle-air-control-valve-iac-iab.html

You should be able to clean the IAC with a toothbrush, and some throttle body cleaner.

I think they used locktite at the factory for the screws to the TPS, so be sure that you have a good angle on the screw head with a good quality screwdriver (not one that is worn out), or you might strip the inside of the phillps before it breaks free.
 
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