Ok, been dealing with a 97 Jeep witha ho 5.0 maf from a 91 mustang. Went though everything basic this morning, but didn't start buying sensors and such.
the TFI ignition thing seems to be a pretty common problem, however, would i have any spark is this was bad?
I think thats gonna be the first part i purchase, its only like $30 and seems like one of the bigger issues with this motor.
Josh

Excuse me for not knowing what you are talking about, but does your TJ not start?? Where are you getting spark at? The coil, plugs?? If the TFI is bad, you will get no spark. Does it have fuel pressure? Is it getting an injector pulse? More info required;)

yeah, the tj won't start.
I get spark at the plug, meaning the tfi is good. Howver, The injector is supposed to ground when i fires. I put a voltmeter to it, and when its cranking, it reads ~6...i'm wondering if the voltmeter can't read a change that quickly though and it just skips the ground instant.
I'm thinking the ecu might be bad now. I'm not really feeling a pulse on the injector either, although i'm not sure how strong this "pulse" is.
Josh

yes the TFI CAN go out and still have spark.

It's usually a pretty safe bet to just assume it's always the cause of a no-start condition if you have fuel.

if you want to make sure the injector is getting a signal, go get some noid lights. they plug into the injector plug and are LEDs, you can watch them blink if they are getting a signal.


BTW, a $30 TFI is junk before you ever buy it.

I've had good luck with AC Delco (yes, AC Delco) brand and Borg-Warner premium, but they're gunna set you back ~$75 or so. Especially if you buy the $30 TFI, make sure you buy an extra. Sooner rather than later, you'll be needing it to get home.

TFIs can definitely still throw a spark and still be bad. I had one go bad on my old 95' 5.0. When it acted up, I'd get a no start. I'd pull a plug and have intermittent spark, but it wouldn't fire the plug every other revolution of the motor like it should.

The last one I had go bad would only fire right at 3/4 throttle or more. Wouldn't even start with less than 3/4 throttle.

Ended up having a crack right down the front half, dunno the exact issue beyond that, though.