Mwyatt23

Good Afternoon guys. I posted on here about a yr and a half ago about my 1990 Mustang Lx (Fox body) running bad and shutting off after getting warm. Had a new engine built and installed in the car and have no clue whats wrong with it. Here are the details again....

Replaced parts after engine install
*computer
*distributor, distributor cap and module
*coil
*egr
*all vaccuum hoses
*fuel filter, pump, regulator
*injectors
*radiator with electric fans
*water pump
*both O2 sensors
*alternator
*selenoid
*ignition switch
*headers
*cold air filter

and probably some more stuff that I'm forgetting. Needless to say. The car misses and after running for about 30 min, it'll shut down and won't crank again until it cools down. After all that, I got discouraged and parked it for about a yr and a half. I decided this morning to run some codes on it and here's what I found.

*Key on
84 - EGR Vacuum Regulator (EVR) Control Circuit Failure (O)
14 - Profile Ignition Pickup Circuit Failure (CM)
33 - EGR Valve Opening Not Detected (CM,R)
66 - , MAF signal below minimum test voltage of .4vdc (O,CM,R), Transmission Fluid Temperature Circuit Grounded (CM,O)

*Cranked
21 - Engine Coolant Temperature (ECT) Sensor Out Of Self Test Range. 0.3 to 3.7 volts(O,R)
92 - o2 Sensor Circuit Indicates Rich -driver side(R), No o2 Sensor Switching Detected. always rich -driver side(CM), Shift Solenoid 2 Circuit Failure (O)
33 - EGR Valve Opening Not Detected (CM,R)

*Cylinder test
70 - Cylinder #7 Failed Cylinder Balance Test

Does any body out there know what it's going to take to fix this as you can see I've already spent a fortune. Or if a mechanic that works on Mustangs in the DWF area that I can let them come get it and keep it until it's fixed. I'm very discouraged and any help is well appreciated!!!

88 orangepeel notch

I'm not one of the smart guys here, but now that you've got codes, they can help you figure out where to go from here.

My only question is you said the motor won't even crank over when warm. Just to clarify, do you mean it actually won't even spin over ? If that's the case, you may have a bad battery cable. Check them over good, I've seen them corrode from the inside out from a little cut in the insulation. I'll assume all connections are clean and tight.

A bad ground can really screw with these cars. I had similar problems a couple years ago that turned out to be a bad ground on the neg. cable to the block.

Boss_Hotrod

If I were to take a guess, id say your issue is with code 14. Iif the computer cant see an ignition signal it wont fire the plugs. Look into that. One thing that comes to mind to try, is when the car does not crank after being hot, is to check for spark. I had a pip sensor go out on me while driving once and it felt like the car just shut down or hit a pot hole. Nursed it back home and swapped dizzy. Problem solved.

Mwyatt23

Thanks for the reply 88 & Boss. Just to clarify the car turns over when hot, it just won't start. After cool down, it will start on the 1st turn of the key. Boss, I think the same thing. It seems when it shuts down, and when trying to crank it, it sounds like there is no spark or no gas. It kinda just spins over, not even making a attempt to start. I'm not sure why the #7 cylinder test. The engine is new. Any ideas; based on the codes what needs to be done to fix it?

yurizx6r

It almost sounds like a TFI module the way you're explaining it, but the codes does not fit and you say you swapped it. Never rule out the possibility of multiple issues though. Also, with those damn TFI modules you must use some really good heat sink or they will fail immediately. Orange Peel is correct, a bad ground somewhere will really throw the fox off. Either way, I'm interested to find out with you what the problem(s) is/are.

dawson1112

Im leaning towards a ground or connection issue. But the lack of a PIP signal will halt the computer from signaling injectors and spark.

I would check your salt-n-pepper shakers and make sure every thing is clean and makes good contact.

Mwyatt23

OK. Will re-check everything again. I'll be sure to post what the issue is incase it may help somebody else. If I can't get it, I'll be forced to take it to a Mustang person and see if they can help. I have 1 offer to look at it so this nay be the way. Will let you guys know and again, thanks for your help!!!

Mwyatt23

OK. Went and bought another TFI and installed it as I hear alot of you guys saying that this is what it sounds like and they can go bad quickly. Installed it and added double the heat sink on this one. The car is running a little better but still seems to have a little miss to it. It did not cut off after letting it run for about a hour and driving it around the block a couple of times. Although it is 30 something degrees here today. Not sure if this helped it or not. Run codes again and got 84-66-14-33 on key on test. 33 on cranked test. And it's still showing cylinder #7 is failing. Not sure how the code thing really work...but should I have cleared the last codes before running a new test. Got kind of the same results. Not sure about the EGR becuase its new too. Could the ignition pick up failure be that I changed from a standard coil to a msd coil. And does the cold air filter make a difference. I read somewhere that you need a cold air computer to use these filters on these cars?? Any help with suggestions or recommendations will be appreciated!!!

dawson1112

disconnect the battery for about 10 min or so to clear the codes then run the koeo/koer tests again. There is no such thing as a cold air computer, and no you don't need to have it tuned or other wise for a cai.

As far as failing the cylinder balance test on # 7 , it could be several things. It is just detecting a misfire or lack of power on that cylinder. It could be a fouled plug, or bad wire, low compression or a failing injector. Pull the plug and see if it is fouled, it will have a black tarnish on it if its really bad, other wise it should be a nice tanish/brown color.

Mwyatt23

OK guys, here's an update. Turns out, the car doesn't need to get warm before just shutting down. Went out today and crankled it, let it warm for about 30 seconds. Attempted to pull off and it sputtered and went dead. Haven't crunk back up since. Just turns over. My neighbor put a test light on it to see if the light would blink. He put the wire from the test light on the coil wire and told me to turn it over. The light blinked 1 time at the hit of the switch, then nothing after that. I went and bought ANOTHER ignition coil and fuel pump relay to continue the process of elimination process, and no luck. Seems like fire rather than gas issue. Any ideas would be helpful.