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Hi,
New here, hoping for help. I have a 1988 Bronco 302. I started getting really odd idle/engine rpm problems. It tends to idle at around 2000 rpm and run in gear at around 1200. But its not consistent. If I leave it a few days it seems to be fine for a while before reverting.
The really strange part is if I start it with the accelerator floored it runs at normal rpms but the check engine light comes on.
I have swapped out the idle air controller and am about to put in a new TPS, but I have never heard of these symptoms and was hoping someone would have an idea what might be going on.
TIA
Chris.
 

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Roller rockers are gay
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check for vacuum leaks.
 

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X2 for vaccum leaks......:rockon

I would "pull codes" from the computer FIRST BEFORE throwing parts at a problem and see what indications there are initially especially code: 44 Thermactor Air Injection system fault where more then likely the "check valve" located on the exhaust cross over tube bolted to the cylinder heads has either rusted or burned thru from moisture and heat sucking in air....assumes you have this set up.

The check valves only cost $20.00 or so BUT you do have to pull off the C/O tube, stick it in a vice grip to unscrew the check valve as it's "pipe threaded" and will help with leverage etc.

Do a visual inspection of all rubber and plastic vaccum lines and repair any that may be cracked, broken or split and for plastic vaccum lines you can use small rubber vaccum hoses to "bridge" and I use small tie-wraps as clamps on each end of the bridge for a better seal.


Make sure the uppper fuel injection plenum and lower intake manifold bolts are snug.....

I also recently read here that the cruise control servo can cause high idle issues.....IDK?

For TPS, most sold today are plug & play with a slight CCW and CW turn in the hand for installation so there are no "slots" for physical adjustment but there's a Ford Racing Instruction sheet which explains how to drill out the TPS mounting holes in order to adjust voltage setting, ideally .93-.97 volts AND a simple procedure on how to set idle by disconnecting the IAC using the throttle body idle stop screw..

IIRC this sheet should be somewhere on www.bronclinks.com OR google, SORRY but I have over 300 saved posts and don't have time to search for the link.

Good Luck ~ :thumbup
 
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