I have read a lot about how they go out when they get hot and how they can make cars stall and all that..My car has a lot of the same symptoms and I was wondering if we had one and if we do where it is located and what exactly it does
AutoZone and Advance also test them. If it passing be sure you put some dieletric(sp?) grease on the underside (metal faces the fender) before putting it back on (or replacing it). It helps with heat, you should see some white residue or power from the dried out dieletric grease...
and it burns burns burns..... the ring of fire.... the ring of fire.
Back on topic, as these guys said, almost any half-decent parts store should have the machine to test them. When I used to work at one, I would cycle them 3 or 4 times until they feel very hot to the touch. If it passes 4 times then thats probably not the problem. Try doucing the PIP (profile ignition pickup) sensor in the distributor with electric contact cleaner (remove the cap and the rotor and you should see it near the bottom of the bowl). If this helps with the cutting-out then its a sign a new PIP is in your future. Also don't forget to inspect the regular stuff like your plugs and wires, and you can also ohm-out the coil on the primary and secondary circuits to see if its showing signs of failing.
A TFI has a critical temp of ~257*F and when they get too hot, the car generally stalls and will not restart until the module cools off. A bad TFI leaves a no spark condition. A TFI or IDM code can be generated.
I do as Stephane does with the PIPs. A bad PIP will leave you with no spark or injector pulsing. Ferrous metal found in the dizzy bowl is a sign that a PIP or dizzy bushing is going south (when the latter does, it takes the PIP with it).
The repeated TFI testing is very good advice. A hair dryer can be used to simulate hot TFI temps if you're doing 'high desert testing' in your driveway.
Heat sink grease is a better alternative to dielectric grease, but definitely use one or the other in there. Too much = bad connection. Too little = overheating.
Tom, you might want to tack it down for vibration concerns (I'd do it to 'sink' the TFI's heat-sink as well).
Mike, You're absolutely right - a bad TFI can still cause issues. The base electronics on the car all still need to function - then the aftermarket box just augments/amplifies the signal (you can kind of think of an ignition-box like an amp in a stereo system - all the underlying elements still need to work. The amp just enhanes things).