Dying stang

[StangNut86]

So a few days ago, i went to start my car after driving it around a bit (up to operating temperature for a while), and it cranked forever and wouldn't start. i tried playing with the timing a little bit as i didn't have a spark tester... after about 5 or 10 minutes it fired right up. a couple days later, i was driving around and it just died for no reason i could see... not my fault. same story... play wiht the timing a little bit, but it was time that made it start up. and it did it again today, left me in traffic and almost got me towed (except the cop was really cool about it). just today, i noticed that it was actually trying to die while moving below 1500 rpms, then would fire back up, did this a couple times. when this happened, i noticed that the tach dropped to zero for a moment, leading me to believe that the whole issue is centered around the spark being dropped. My plan is to replace the TFI module and see if that fixes it. if that doesn't work, i'll have to see if i can find a problem with the wiring or the computer. if anybody has any suggestions as to what i can do to resolve this, please speak up. thanks.

[silverstangs]

Well, I would start with Cap and Rotor and then the coil and keep going from there. It's a Ignition issue, so it shouldn't be too hard to trace.

[StangNut86]

Originally Posted by silverstangs

Well, I would start with Cap and Rotor and then the coil and keep going from there. It's a Ignition issue, so it shouldn't be too hard to trace.

brand-new MSD cap and rotor on an MSD dist with less than 1000 miles on it... the TFI unit is also labeled MSD.

[silverstangs]

Wow, then check the ground cable from the engine block to the chassis.

[351wStang]

Originally Posted by silverstangs

Wow, then check the ground cable from the engine block to the chassis.

Yup, sounds like a loose connection.

[StangNut86]

Originally Posted by 351wStang

Yup, sounds like a loose connection.

i was eyeballing some of the wires today... the small ground strap on the negative battery cable terminal seems to be corroding away. i dont' know if that has anythign to do with the ignition, but i intend to replace both battery cables and that ground strap as soon as i get a chance. any tips or tricks to make that easier?

[StangNut86]

Originally Posted by StangNut86

i was eyeballing some of the wires today... the small ground strap on the negative battery cable terminal seems to be corroding away. i dont' know if that has anythign to do with the ignition, but i intend to replace both battery cables and that ground strap as soon as i get a chance. any tips or tricks to make that easier?

well, i replaced both battery cables and relocated the negative engine block ground to the a/c bracket due to a broken bolt. this improved little, which frustrated me. in fact, it was getting worse. so i thought i'd take the ignition module from my stock distributor and install it on my msd dist to see if that fixed anything. when i removed the cap to check the rotor position, i found that each and every one of the brass terminals on the underside of the cap was caked with corrosion, at least 1/16 of an inch thick. this was what stopped my spark. after an initially angry call to MSD tech support, following their advice, i used a low-rpm dremel with a small wire wheel to clean the corrosion from the brass surfaces, and sandpaper to clean the backs. I applied generous amounts of vaseline (closest i had to dielectric grease) to all of the terminals inside (and outside, in all the plug boots). after installing the cap and resetting the timing, the car ran a hell of a lot better than it did before, and even seemed to pull harder on the subsequent test drive. i'm very happy that my solution worked so well, and saved me the hassle of ordering a new cap and rotor. when i have time, i'll wash all the vasoline out and redo it with real dielectric grease.


by the way... i performed compression and cylinder leakdown tests on the stang today... 100,000 miles and it still meets factory specifications!