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Old 11-26-2016, 09:16 PM
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Originally Posted by cerial View Post
The IAC, can fill full of soot. Pull it off and shoot it with some carb cleaner pushing the plunger in a few times. That will "refresh" it. The sensor itself is cheap as well as the TP
S sensor.

If you are getting a over rich condition you should have a o2 sensor yelling at you somewhere. Or a Egr silionoid/egr sticking.
I removed and cleaned the IAC valve about three days ago with carb cleaner. It was rather grimey-looking. I think the plug connector from the harness to the IAC might be damaged. The plug has four prongs, and one them is missing a plastic cover but the other three have it.

I replaced the O2 sensor back when I did the tune up a few months ago.

Originally Posted by cerial View Post
Between your TBI and distributor you have a vacume line leading to a TVS switch. If this is clogged with oil it will tell the distributor your engine is cold. If your TPS is working properly it will adjust the fuel and the IAC will limit the fuel. But the distributor is only receiving vacuum signal that tells it the engine is cold and to keep it timed to warm up the engine.
Pull that TVS and check to see if it is full or oil/gunk.
I checked but did not see a TVS, or a vacuum hose on the distributor. I also did not find any info on my truck having one. Its a 1994. I'll try to dig in tomorrow.

Originally Posted by cerial View Post
Run your hand along the harness going to the transmission checking for any burns or cuts.
Check the pig tail connections and wiring going into the connections for any loose or damaged wiring. If they are full of oil and gunk hit them with your ex girlfriends toothbrush.
Got it. Was thinking of checking the speed sensor while down there.

Originally Posted by cerial View Post
Ok check your transmission fluid color(google it). I am guessing your engine is getting hot and that gauge with 300k on it is no longer reading correctly. You could also have a air bubble in the sensor area giving the pcm false readings. Pull the temperature sensor and check it electrical wise(google). Then if it reads good reinstall it, after filling the port to the brim, inserting the sensor till fluid comes out, installing some liquid silicone, then inserting the sensor in place you know you will not have any bubbles.
I would run the engine with a aftermarket gauge with the aftermarket sending unit installed in a non factory position(so the computer reads the stock sending unit correctly) checking the cluster temperature vs the aftermarket temperature to let you know if your gauge is working correctly.
I checked the transmission fluid when I got the truck a few months and again three days ago. It is pretty clean. I have feeling both the engine and transmission were replaced at some point.

I replaced both the Coolant Temperature Sensor (AC-Delco) and the Temperature Switch (AutoZone's Duralast brand).

Originally Posted by cerial View Post
Does the engine rev higher in any gear like it is in neutral for a bit when driving?
No higher revving when driving or warming. It drives along just fine, especially on the street. Its when I start accelerating past 60 mph that it either the transmission stay in third, or bounces back and forth between third and fourth. It only a has a bit of a "thump" every few seconds or so when stopped at a light.
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