This is topic Need Help - replacing parts but no fix in forum Tech Talk at Northern California Ford Owners  .


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Posted by Andrew G. (Member # 7930) on :
 
I'm an old fart with a 91LX hatch, stock motor, Lentech AOD, 3.73 gears, subframes and a few other minor things. Oh, yeah, Magnaflow cats about four years ago, if I recall correctly. New O2 sensors at the same time. The car has 81K on it.

Started missing under load at speed when freeway hot, got worse until once it was hot it would miss at 2500 rpm or more with no load. There's a long saga here, but I don't wrench on it and took it to a dealer for diagnostics, after replacing the mass air, cap, rotor, plugs, wires and coil. New idle control valve didn't help either.

So the dealer tells me I need a PCM, which they'll sell me for $800. So I get one shipped for less than half that, they put it in, declare it fixed. NOT. Meanwhile I'm renting a car. So then they replaced the distributor, and declared it fixed again - at least it doesn't miss at rest. But once it's hot it still won't take any throttle, like pulling away from the toll booth. If I feather the throttle it runs OK, and it runs great when it's cold.

It seems the TFI is a likely culprit, but for some reason the dealer didn't replace it when they put in the distributor. If they bench tested it, how can that show what it does when it's real hot?

So here we are replacing parts one after another, which is what I was trying to avoid by taking it to a dealer. Next they'll be telling me I need an ECU, or who knows what. I haven't named the dealer, but they don't inspire confidence.

Can someone recommend a Mustang-savvy shop in SF? Or have any other ideas?

Thanks!
 
Posted by JohnB (Member # 969) on :
 
It needs a TFI...


Bring it to Fairfield, I'll fix it. [Wink]
 
Posted by 92stangLX (Member # 3252) on :
 
Try adjusting the TPS. What is your timing set at? Have you scanned for codes?

It could very well be the TFI module. They are easy to change. I would suggest borrowing one from one of your buddies and test it.
 
Posted by Andrew G. (Member # 7930) on :
 
I kept asking the damn dealer about the TFI, but they just don't listen to the customer, I guess. No codes that I know of. I'm gonna check the TPS myself right now.

Timing and everything is right on - we just checked all that - it passed smog at a test-only station here.
 
Posted by Beasty5.0 (Member # 2935) on :
 
quote:
Originally posted by Andrew G.:
I'm an old fart with a 91LX hatch, stock motor, Lentech AOD, 3.73 gears, subframes and a few other minor things. Oh, yeah, Magnaflow cats about four years ago, if I recall correctly. New O2 sensors at the same time. The car has 81K on it.

Started missing under load at speed when freeway hot, got worse until once it was hot it would miss at 2500 rpm or more with no load. There's a long saga here, but I don't wrench on it and took it to a dealer for diagnostics, after replacing the mass air, cap, rotor, plugs, wires and coil. New idle control valve didn't help either.

So the dealer tells me I need a PCM, which they'll sell me for $800. So I get one shipped for less than half that, they put it in, declare it fixed. NOT. Meanwhile I'm renting a car. So then they replaced the distributor, and declared it fixed again - at least it doesn't miss at rest. But once it's hot it still won't take any throttle, like pulling away from the toll booth. If I feather the throttle it runs OK, and it runs great when it's cold.

It seems the TFI is a likely culprit, but for some reason the dealer didn't replace it when they put in the distributor. If they bench tested it, how can that show what it does when it's real hot?

So here we are replacing parts one after another, which is what I was trying to avoid by taking it to a dealer. Next they'll be telling me I need an ECU, or who knows what. I haven't named the dealer, but they don't inspire confidence.

Can someone recommend a Mustang-savvy shop in SF? Or have any other ideas?

Thanks!
A few years back I had a similar problem, and if I recall correctly I don't remember the car throwing back any codes, but I ended up taking it to a shop in South San Francisco, since I didn't know JohnB at the time [Big Grin] . Anyways, the shop ended up replacing the TFI and the problem was solved. It's a matter of marking where the distributor sits because it will be moved when you loosen the bolt which holds it down , then removing the two Torx screws which hold the TFI to the distributor. Fianlly, apply the silcone which comes with the new TFI and just re-install. Where are you located in SF?

Edit: Forgot to mention, you may have to buy a special tool at a parts store to remove those two Torx screws, unless for some reason you have it already. Also, disconnect the battery before attempting to remove it.

[ October 02, 2007, 01:17 AM: Message edited by: Beasty5.0 ]
 
Posted by Andrew G. (Member # 7930) on :
 
I am in San Francisco's trendy Mission District, and I say that only partly ironically.

I may replace that TFI myself, if I can bend over long enough (no jokes, just a bad back!).

I read somewhere that it's held on with two 7/32" bolts and you need a super thin-wall socket (or the special little wrench) to get 'em out. I might just grind down a cheap socket. If they're torx I dunno.

I don't see any reason to move the distributor, but then again, I haven't started working on it yet.

Thanks for your help, everyone!
 




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