Is this a bad TFI module....

Nicks5.0 · 01-11-2001, 08:05 PM

ok, my car ended up sitting for about two weeks without being started in freezing weather(below zero most of the time) and of course it was hard to start the first couple times, but then it was fine for a couple days and now i have to pop the clutch or use starting fluid to even hope to get her firing. she will crank all day so its not the battery. i have checked all the wires and stuff like that and made sure the cap and rotor werent bad also. when i do get her running, its missing really bad at various rpms, part or wot, high, med, or low load on the motor. the tfi is the only other thing i can think of. please help!!! thanks in advance, nick

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1990lx coupe, 302, gt40p heads, wolv 1087 cam, 1.7rr's, 65mm tb, 75mm maf, comp box on top of cobra lower, anderson ford pms, full exhaust, drag type susp. and 3.55's. traps 105mph

mikew88gt · 01-11-2001, 08:33 PM

It could be a lot of things. How do your plugs look? Are they fouling or showing any signs of bad spark? Usually TFI modules just die in my experience. They don't usually go bad gradually. If you're certain that you are getting fuel then inspect your plug wires, coil connector and TFI module connector for corrosion. A bad connection could prevent adequate spark and seeing as you are in a rust belt area don't rule anything out.

------------------
Edelbrock heads, intake, 70mm, e303, 4.10's w/ auburn pro and Compucar.

My 1988 Mustang GT

01-11-2001, 11:44 PM

Take a look at your coil. Sometimes when cars with the new style coils are driven in the winter the laminated plates of steel that surround the coil get rusty, swell and cause problems. Check for cracks on the plastic part of the coil. If you know a buddy with another mustang, try his coil and see what happens. Post what happens, to see if this works.

exgmguy · 01-11-2001, 11:56 PM

Throttle position sensor?

My .02.

Capri306 · 01-12-2001, 09:55 AM

Well, if it's actually missing, then I'd say it's the module or the coil. Reason I say this is because the TFI is a big transistorized switch, and when mine went on my 4-banger, it did the same thing a little bit before it died. What usually goes first is the dwell, or how long it charges the coil between firing. Best thing to do is take it to a parts store and have them test it. Most will do it for free. Also take the coil along with you, and see if they can check for opens and shorts, at least.

If on the other hand the spark is just erratic, then like exgmguy says, probably a TPS. Again, you can test this with a DVOM. Good luck.

------------------
Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch

<--- New Timeslips

Skankin · 01-12-2001, 11:50 AM

TFI's will gradually die... but it usually causes stalling, and starting problems when it is warm.

01-11-2001, 08:05 PM	#1
Nicks5.0 Registered Member Join Date: Jun 2000 Location: Belleville Il, USA Posts: 234	Is this a bad TFI module.... ok, my car ended up sitting for about two weeks without being started in freezing weather(below zero most of the time) and of course it was hard to start the first couple times, but then it was fine for a couple days and now i have to pop the clutch or use starting fluid to even hope to get her firing. she will crank all day so its not the battery. i have checked all the wires and stuff like that and made sure the cap and rotor werent bad also. when i do get her running, its missing really bad at various rpms, part or wot, high, med, or low load on the motor. the tfi is the only other thing i can think of. please help!!! thanks in advance, nick ------------------ 1990lx coupe, 302, gt40p heads, wolv 1087 cam, 1.7rr's, 65mm tb, 75mm maf, comp box on top of cobra lower, anderson ford pms, full exhaust, drag type susp. and 3.55's. traps 105mph

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01-11-2001, 08:33 PM	#2
mikew88gt Registered Member Join Date: Jul 1999 Location: New York State Posts: 242	It could be a lot of things. How do your plugs look? Are they fouling or showing any signs of bad spark? Usually TFI modules just die in my experience. They don't usually go bad gradually. If you're certain that you are getting fuel then inspect your plug wires, coil connector and TFI module connector for corrosion. A bad connection could prevent adequate spark and seeing as you are in a rust belt area don't rule anything out. ------------------ Edelbrock heads, intake, 70mm, e303, 4.10's w/ auburn pro and Compucar. My 1988 Mustang GT

01-11-2001, 11:44 PM	#3
88GT5.013.02 Guest Posts: n/a	Take a look at your coil. Sometimes when cars with the new style coils are driven in the winter the laminated plates of steel that surround the coil get rusty, swell and cause problems. Check for cracks on the plastic part of the coil. If you know a buddy with another mustang, try his coil and see what happens. Post what happens, to see if this works.

01-11-2001, 11:56 PM	#4
exgmguy Registered Member Join Date: Feb 1999 Location: Utica, Michigan Posts: 2,631	Throttle position sensor? My .02.

01-12-2001, 09:55 AM	#5
Capri306 Moderator Join Date: Sep 1998 Location: Grand Rapids, Michigan, USA Posts: 1,001	Well, if it's actually missing, then I'd say it's the module or the coil. Reason I say this is because the TFI is a big transistorized switch, and when mine went on my 4-banger, it did the same thing a little bit before it died. What usually goes first is the dwell, or how long it charges the coil between firing. Best thing to do is take it to a parts store and have them test it. Most will do it for free. Also take the coil along with you, and see if they can check for opens and shorts, at least. If on the other hand the spark is just erratic, then like exgmguy says, probably a TPS. Again, you can test this with a DVOM. Good luck. ------------------ Capri306, Moderator, The Mustang Works Online 1979 Mercury Capri, 5.0L -- C4 -- 2.73 1987 Mustang LX Notch <--- New Timeslips

01-12-2001, 11:50 AM	#6
Skankin Registered Member Join Date: Dec 1998 Location: London, Ontario, Canada Posts: 1,349	TFI's will gradually die... but it usually causes stalling, and starting problems when it is warm.