Codes, what do they mean?

Lifted2x · Feb 20, 2009

Puled the codes but dont know exactly what they mean, Its a 85 2.8 auto 4x4 all stock. Dont know if any of its worth fixing. It is getting bad mpg and doesnt idle very well.

KOEO
31 EVP??? whats that?
63 TPS signal low
KOER
12 Isc motor
23 TPS out of range
31
35 RPMS too low to test egr
41 system lean
58 Idle tracking switch
63

BeaterMan · Feb 20, 2009

31 evp is most like evaporative emission system
63 sounds like your throttle position sensor (TPS) use a voltmeter set on ohms and slowly rotat the throttle and observe the readings with the meter, any sudden jumps or fluxiations would indicate the sensor is bad.
same with code 23.
there is probably a test for code 12- isc motor, isc stands for idle speed control.
the other few i'm not so sure about. the code 35 is fine since you/computer can not apply egr at idle or the engine will die. try putting vacuum to it running and if it dies it working, but might be dirty or clogging up. try cleaning it out. hope this helps, these 1980's vehicles and there half ass computers are a royal pain to understand/ diagnose

Nipplechops · Feb 21, 2009

I'm not an expert on propane conversions, but aside from the TPS codes it seems that the others would be caused by the propane conversion. As far as I know the EVAP system code is normal due to the fact that the fuel is under pressure in a tank and isn't vented to atmosphere.

In my past experience in machine shops (if I am remembering right), propane engines that we built never retained any EGR function. The propane specific gasket sets the builders used had gaskets and plates to block off the ports.

The system lean code is most likely a side effect of the propane conversion as well. I don't have any experience in tuning propane converted vehicles, so I can't say for sure.

I think you are the first person I know of with a propane converted 2.8L.

Lifted2x · Feb 21, 2009

Nipplechops said:
I'm not an expert on propane conversions, but aside from the TPS codes it seems that the others would be caused by the propane conversion. As far as I know the EVAP system code is normal due to the fact that the fuel is under pressure in a tank and isn't vented to atmosphere.

In my past experience in machine shops (if I am remembering right), propane engines that we built never retained any EGR function. The propane specific gasket sets the builders used had gaskets and plates to block off the ports.

The system lean code is most likely a side effect of the propane conversion as well. I don't have any experience in tuning propane converted vehicles, so I can't say for sure.

I think you are the first person I know of with a propane converted 2.8L.

Sorry I havent added this truck to my info, I have two rangers (right now :icon_thumby:

) The 83 is the one on propane and it is durasparked so there is no comp or emissions stuff left on it. This one is my 85 and it is all stock pos feedback fuel system.

The clutch, waterpump and radiator need to be replaced in the propane truck so I just decided to start driving this one.

I want to duraspark it but I dont have the money for it right now so I thought I would see what I could do to get it running better. The gas mialage is not as bad as i thought, the guage is just not accurate.

The idle problems are the only thing I really wanted to try and fix. I was looking at the truck yesterday and it looks like someone has tried to mess with the base idle and I think that might be causing the hesitation at idle. I already replaced the accelerator pump diaphram and it helped. THere may still be some vacuum leaks that I havent found and that may be causing the lean code.

enginepaul · Feb 21, 2009

31 = EVP. Not exactly sure what the initials stand for, but it the sensor on top of the EGR (in front of the carb) that senses the valve's position. Now for the fun part, it may be an erroneous code. I spent hours tracing my 31 code, including a new computer to pass California smog. It turns out that Ford put out a service bulletin saying to make certain tests, and if it passes those tests, ignore the code.
You will need an emission manual and probably the 60 pin Rotunda test equipment to do the tests.
I think that the others can be tested with a Haynes type manual. Sometime it isn't easy, but mine now runs great and it was worth the work.
If you are allowed DuraSpark, you may want to look into that.

Good luck
(Exhaust Valve Position ?)

litleblue · Feb 23, 2009

I think your problems are pretty much with the ISC to start with. This device is on the left hand side of the carb and sets the curb idle (calculated by computor). Try to test is first, If you have troubble finding a new part try to match it up with a central fuel injection off af a 3.8 l unit. Code 63, the TPS could be out of range because the ISC isn't allowing the throttle to position itself correctly.

Code 41, 99% of the time is a vacuum leak or the feedback solinoid on the back of the carb is bad mechanicaly not electricaly. Ford dosen't support this part (feedback solinoid) however NAPA does, definitly a high wear item, and when the solinoid is not working it will make the engine seem like it needs a tune up.

EVP "EGR Valve Position" (EGR position sensor) code 31. There could be some junk underneath the seat on the EGR valve holding the EGR valve just a little bit open. This could also be the problem with the code 41 if the EGR valve isn't seating properly and leaking causing a lean condition. Start by cleaning the EGR valve.

First thing to do is test is the ISC. After the KOEO test is complete don't exit the test yet. The computor will enter the output state mode or test. this means every time you depress the throttle all outputs will change state including the ISC motor (this part will extend or retract and it is common for the part to break in one direction meaning that it will retract and not extend or get jamed), in addition the vacuum solinoids will change state underneath the plastic cover on the right hand fenderwell.

Lastly, Code 35 is linked to code 12, most likely.

Good luck and ask more questions or post your findings!

Codes, what do they mean?

Lifted2x

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BeaterMan

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Nipplechops

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enginepaul

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