I just pulled the codes on my 90 LX 5.0, and i got 131 or 31, not for sure which, also got 66, 94, and 21. I know the 21 was from testing on a cold engine. The other ones I searched for but could not find anything. Any help will be greatly apperciated,
BTW.- the 131 or 31 and the 66 was KOEO
and the 21 and 94 was KOER
Thanks..
Grover
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Grover
1990 LX 5.0 HO-- center force clutch(heavy duty);Hurst competition short throw shifter; 3.55's;Pro-M air w/ K&N; 65MM throttle body and spacer;1.72 Roller rockers; 1/2 inch plenum spacer; Big Tube Headers; pizza box kit??; Fuel pressure reg and gauge; GT-40 heads(ported and flow tested); Pulley Kit; 24LB injectors, Chip(not sure which one); 180 thermostat; Flowmaster off road X-pipe(no cats); 110 lph fuel pump; mobile1 5-30 synthetic; Corbeau VX2000 racing seats.5 lug conversion..
For the KOEO 131, 31 was probably a 13 and/or 31. You wouldn't get two and three digit codes. A 13 is RPM out of spec during normal idle operation, you should only get this for a KOER, so focus on the 31. A 31 code is an EGR problem. A 66 is a MAF sensor voltage too low. A 94 is a Thermactor system problem. I would solve the KOEO code first then work on the KOER codes.
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93 LX Notch 4 cyl conversion, Vortech SQ, TF TrackHeat, AFR 185 heads, .125 over Boss Block w/3.25 stroke, COMP blower cam, MAC 1-3/4 shorty, 3550 Tremec, 3.73s, Tokico Struts, Steeda Sport Springs, etc...11.3 at 129.9 through the cats.
Ok, i just updated my sig, maybe some of that will help.. anyhoo, the cover on the pro-m by the sensor fell off the other day- i got it back on, could that be a problem?, also, what is a Thermactor system, i've google it and can't come up with anything? haven't had a chance to check the egr though- does the valve just need replaced?
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Grover
1990 LX 5.0 HO-- center force clutch(heavy duty);Hurst competition short throw shifter; 3.55's;Pro-M air w/ K&N; 65MM throttle body and spacer;1.72 Roller rockers; 1/2 inch plenum spacer; Big Tube Headers; pizza box kit??; Fuel pressure reg and gauge; GT-40 heads(ported and flow tested); Pulley Kit; 24LB injectors, Chip(not sure which one); 180 thermostat; Flowmaster off road X-pipe(no cats); 110 lph fuel pump; mobile1 5-30 synthetic; Corbeau VX2000 racing seats.5 lug conversion..
Im not sure what you mean by Pro-M cover. The MAF code could also be because of a cold test since it has to heat up. I dont think the computer uses it on a cold start. The thermactor system has to do with the smog equipment. Every once in a while I will get codes for them since mine have been deleted. They wont effect running issues unless you have a vaccum leak.
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91 GT Hatchback- 3.73 Posi, Flowmaster O/R H pipe, Flowmaster 40 series mufflers, Tremec TKO, Pro 5.0 Shifter, Center Line 15s, Upper & Lower Control Arms,Weld-on Subframe Connectors, Eibach Lowering Springs
03 GT Coupe- Roush CAI and Jack Roush classic shifter, 40 series mufflers, Hooker Long Tube Headers, Hooker O/R X pipe, Custom Tune
the cover that is highlighted was gone for a few days- exposing something copper, I later found the piece on a part of the suspension and put it back...
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Grover
1990 LX 5.0 HO-- center force clutch(heavy duty);Hurst competition short throw shifter; 3.55's;Pro-M air w/ K&N; 65MM throttle body and spacer;1.72 Roller rockers; 1/2 inch plenum spacer; Big Tube Headers; pizza box kit??; Fuel pressure reg and gauge; GT-40 heads(ported and flow tested); Pulley Kit; 24LB injectors, Chip(not sure which one); 180 thermostat; Flowmaster off road X-pipe(no cats); 110 lph fuel pump; mobile1 5-30 synthetic; Corbeau VX2000 racing seats.5 lug conversion..
Mine is held in by two T-20 Torx screws and the harness connects to it. I don't have any cover that Im aware of. If the harness came off, then thats why you are getting the code. If you are not experiencing running issues, I wouldn't worry about code 66. Usually if not always, when there is something wrong with the MAF you will definately know it. My friend had a 94 and had to keep the car at about 5k to get it home one night, below 5k, wouldn't run. See www.fordfuelinjection.com for a complete listing of 2 digit codes. There is also a lot more information on there about sensors, ECCs, and more if you really want to learn how EFI works.
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91 GT Hatchback- 3.73 Posi, Flowmaster O/R H pipe, Flowmaster 40 series mufflers, Tremec TKO, Pro 5.0 Shifter, Center Line 15s, Upper & Lower Control Arms,Weld-on Subframe Connectors, Eibach Lowering Springs
03 GT Coupe- Roush CAI and Jack Roush classic shifter, 40 series mufflers, Hooker Long Tube Headers, Hooker O/R X pipe, Custom Tune
a quickie update to the question... ive been tryin to resolve the egr problem, is there a way to test it?.. Also i didnt realize, till lookin at other posts, the coolant lines have been removed.. everything else ok, will this cause it?, and where does the back one go?. i cant find a place to hook it back up. front one is visible. anyhoo, thanks again
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Grover
1990 LX 5.0 HO-- center force clutch(heavy duty);Hurst competition short throw shifter; 3.55's;Pro-M air w/ K&N; 65MM throttle body and spacer;1.72 Roller rockers; 1/2 inch plenum spacer; Big Tube Headers; pizza box kit??; Fuel pressure reg and gauge; GT-40 heads(ported and flow tested); Pulley Kit; 24LB injectors, Chip(not sure which one); 180 thermostat; Flowmaster off road X-pipe(no cats); 110 lph fuel pump; mobile1 5-30 synthetic; Corbeau VX2000 racing seats.5 lug conversion..
The 31 is for voltage below minimum specs in the EGR Valve Position sensor circuit.
The 94 means that the O2 sensor is not detecting the fresh air from the smog pump on the left (driver's?) side. Check the hoses from the pump to the dump and divirter valves, and on back.
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1992 Deep Emerald Green Mustang GT Hatch, 5 speed, 2.73s, Mac fenderwell cold air intake, '93 Cobra MAF, Mac 70mm throttle body & spacer, Explorer intakes, Mac unequal headers & offroad pipe, Magnaflow catback, Walbro 110lph fuel pump, Jet adjustable FPR, MSD Blaster coil, Accel 8mm wires, FRPP aluminum quadrant, UPR firewall adjuster, stock cable, Granatelli upper control arms.
Waiting to go on: Granatelli lower control arms, and GT40 Iron heads!
couple code questions 
