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Discussion Starter · #1 ·
90 mustang gt with a couple basic bolt ons. Car drove fine then all of a sudden check engine light and battery light came on and it quit. Car would crank over but sounded different than normal (like it was out of time?). Had the towtruck haul it home and put on my handheld code reader. I had a code 15 and 84. I changed the computer and now only have the code 84 (other computer had a chip in it). Car still wont start and still sounds funny. Would only a code 84 cause the car not to start? Any ideas? The car has all new sensors, a new fuelpump and filter, the motor trans and rear were all recently rebuilt.
 

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Discussion Starter · #2 ·
Wow, I know there are some really smart people on here that can help me out. bump
 

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The 15 code indicates a PCM problem or a loss of voltage at the keep alive memory pin #1. Don't worry about the 84 EVR code for now. Go to the basics, put a dumpy spark plug on a plug wire and spin the engine over. Do you have spark? If not, remove dist cap, spin the engine to see if the rotor turns, if not, broken timing chain. If rotor turns but no spark, check for voltage at the R/LG wire on the coil with a test light and key on. If it's hot, then put the test light on the other coil terminal, spin the engine to see if the light blinks and get back with us.
 

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Discussion Starter · #4 ·
The 15 code indicates a PCM problem or a loss of voltage at the keep alive memory pin #1. Don't worry about the 84 EVR code for now. Go to the basics, put a dumpy spark plug on a plug wire and spin the engine over. Do you have spark? If not, remove dist cap, spin the engine to see if the rotor turns, if not, broken timing chain. If rotor turns but no spark, check for voltage at the R/LG wire on the coil with a test light and key on. If it's hot, then put the test light on the other coil terminal, spin the engine to see if the light blinks and get back with us.

spark plug wire has no fire. removed dist cap and rotor turns fine. touched both posts of the mds coil and nothing. no fire. I checked the posts because there is an aftermarket msd box installed and im not sure which color wire goes where. WHat does this mean? Sorry, im not very good with this stuff.
 

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Discussion Starter · #5 ·
bump
 

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Can you take the MSD out of the system and just use the stock ign? If so, it will be easier to troubleshoot.
 

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No spark is often a bad coil. You said you have MSD stuff on it, if it's an MSD coil do you still have the stock one to put back on to test it? If it's a stock coil currently with an MSD spark box, this is a great time to upgrad to an MSD coil. :)
 

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spark plug wire has no fire. removed dist cap and rotor turns fine. touched both posts of the mds coil and nothing. no fire. I checked the posts because there is an aftermarket msd box installed and im not sure which color wire goes where. WHat does this mean? Sorry, im not very good with this stuff.
as crzy as this souns i have had two msd boxesa 6a and a 6al go out for no appernt reason . take and hook your wiresfrom the carstraight back in to your coil and perform volt test again f red and green have power check the other to make sure as you are turning the car over that it pulses . let me know what you find .
 

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Discussion Starter · #10 ·
bump. could this be the pick up on the distributor causing the coil not to have fire on either side? I read this somewhere i think.
 

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Discussion Starter · #11 ·
bumpity
 

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Discussion Starter · #13 ·
If you're still EFI, replace the TFI module.
Thanks soo much for the reply. I will try it and let you know if it works.
 

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Thanks soo much for the reply. I will try it and let you know if it works.
You can test the TFI module instead of buying a new one to determine if it's completely bad. The following site has some great information about it:

http://www.therangerstation.com/tech_library/TFI_Diagnostic.html

The problem with this is, however, that a TFI module can test good while cold, but then when the engine warms up the module will stop functioning. So, this test is only valid to troubleshoot a module that's at 100% failure.
 

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Discussion Starter · #15 ·
You can test the TFI module instead of buying a new one to determine if it's completely bad. The following site has some great information about it:

http://www.therangerstation.com/tech_library/TFI_Diagnostic.html

The problem with this is, however, that a TFI module can test good while cold, but then when the engine warms up the module will stop functioning. So, this test is only valid to troubleshoot a module that's at 100% failure.
Thanks for the reply! I will try to check it tonight. The car doesnt start at all so it has to be at 100% failure if this is the problem. Will let you know. Once again, thanks!!
 

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Discussion Starter · #16 ·
Changed the distributor and it fired right up!!

I just want to take the opportunity to thank everyone who helped in this thread. You are all an asset to this forum!! I do not know alot about mustangs but i come on here to learn and hope to help others someday as well. There are some people on here who know more then i would ever hope to know about mustangs and do not take the time to help out but you guys did. Thank you again!!!
 
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