1986 Engine problems

[Matts ford]

Originally Posted by tazzmann One question though, just to make sure. Is the TPS under the throttle body on the left side as looking at it from the front of the truck? or is that something else? yes the tps is right on the bottom of the tb, it has a little harness on it. Originally Posted by tazzmann Ok. I took a break and went out and ran the KOEO diagnostic and it returned an error code of 83. The continuous memory shows codes 18 and 22. Now, according to the book, a code of 83 is: EVP/EGRC/EGRV Code 18 is: Loss of Tachometer input/IDM Circuit Failure/SPOUT circuit grounded Code 22 is: MAP or BARO Sensor out of range. Code 22 could be due to the fact that I had the MAP sensor unplugged while driving it. Code 83 has something to do with the EGR Valve position sensor (Whatever that is) and 18 has to do with the TFI. So still not sure what to look at first. Mike the evp is the sensor right on top of the egr valve. Originally Posted by tazzmann Yeah, that is what it is doing currently. I had heard that unplugging the vacuum line to the egr valve should make the engine run better if the egr valve is faulty. Don't know if this is true or not, but i might give it a try after work today. when you take the vac line off the egr at idle it will be testing the evr. if the evr is leaking then it will hold the egr open a little bit causing the rough idle, and also cause the code 83 possibly(i dont have the code definitions in front of me so i dont know which code it is exactly). what all has been done recently? how are all the basic ignition parts? plugs, wires, dist cap and rotor, etc?

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[tazzmann]

The only thing I have done recently is put in a new distributer cap, rotor, coil and MAP sensor

[tazzmann]

so if I take off the vacuum line at the EGR valve, could the engine idle then smooth out if the EVR(?) is leaking?

[tazzmann]

Ok, I did some more tests last night and I also replaced the EGR Valve Position Sensor and it still had problems, though it cleared up the code 83. I did notice, however, during testing, I hooked up a timing strobe and noticed that the flashes from all the cylinders had a skip every so often while running. This is leading me to believe that the TFI is going out and not sending the signal to the coil consistantly.

Other tests: I unplugged the TPS as well and no change.
I unplugged the vacuum line from the EGR valve and put various amounts of vacuum on the EGR valve and found that with more vacuum, the smoother it idled which doesn't seem correct.

So what do you think?

Mike

[glc]

That would tell me that it's idling excessively rich.