need help, out of ideas!!!

[mac7290]

my problem is when i'm over 3k and near WOT and up to WOT it will start missing. I changed the feul filter, plugs, feul pressure regulator, coil, had the TFI tested and good, ohm tested the wires and all are good. Can't find any vacuum leaks(checked with propane and also ether) Timing is good. Air filter is clean. Throttle body is clean. codes are clean just pas codes. Did the cylinder test and it was a pass. I'm out of ideas and everything else is to expensive to replace without knowing for sure if it bad or not. Also no wobble in the distributer shaft. Cap and rotor are clean and only supposed to be a year old.Check all electrical connections seem to be good but no telling though. Feul pump has a steady tone to it. Thanks for any help.
oopa, it' a 87 speed density all stock except for cold air in fender and glass packs.

 

[HISSIN50]

how is FP at higher rpm's? still sounds like TFI. dont forget the pick up too. just stuff to remember - not that any of it is the cause.

how do you like the glass packs?

good luck.

 

[90pony302]

sounds like the pickup in the distributor if the tfi checked out good. Is the tach jumpin around??

 

[stang22]

What kind of plugs are you using? Is your air filter inside the engine bay (cone) or is it a CAI kit?

Tim

 

[Michael Yount]

Uh - have you pulled the diagnostic codes to see what the computer can tell you about the problem?

Edit - sorry - just saw the codes note in your post; you pulled key on, engine off and key on/engine running codes and there was nothing at all?

 

[mac7290]

No codes at all for KOEO, KOER and cylinder balance test.
It has a CAI the air filter is inside the fender. The TFI was tested 3 times. Don't know what the feul pressure is yet, trying to get a hold of a gauge. Also when I changed the plugs they seemed a little white like it's lean. Not tan or grey. The only code I've gotten before was the TPS out of range, I set it and the idle. code is gone for over a month now. and code 67 comes and goes but I think that is because I forget to put it in neutral during the test. The glass packs are ok for the cost of them would prefer something else though. The plugs are autolite platinums, just the stock replacement.when I got the car in the begining of july the tach did jump when I got over 3k. I got another cluster from the junkyard and it doesn't do it. Goes smooth all the way even with the miss.

 

[v8only]

my brother had a bad miss at high rpms, only when warm. Drove this way for a while till it quit. It was the ignition control module on the side of the distributor. If yours is original issue, wouldn't hurt to replace it anyhow.

 

[dromeda]

MY friend's stang ran rough like that. Did you ever have the distributor shaft out? His was off by one tooth, and he also replaced the ignition control module.

 

[Michael Yount]

Most contemporary efi/elec. ignition cars run the plugs white when everything is just fine; they run less rich than older carbed cars - you can't really read the new car's plugs like you can an older carbed/leaded fuel car.

 

[jrichker]

MY friend's stang ran rough like that. Did you ever have the distributor shaft out? His was off by one tooth, and he also replaced the ignition control module.

The "One tooth off" fable appears again... There is no such thing as one tooth off. As long as you can get the timing marks to line up when you use a timing light, everything is good.

Your friend's problem was probably fixed when he replace the ignition control module or as it is known on Mustangs, the TFI module.

 

[HISSIN50]

ill toss out that i noticed your said you run platinum plugs. more than one 5.0 has had problems with plats - often a slightly lower idle and cutting out at higher RPM's.

i have no idea if that could be a problem with you (i.e. if you have been running the plats for years with no problems). but that did jump out at me.

good luck.

 

[v8only]

generally speaking, at least in my experience, if you're one tooth off, I don't think the timing marks are going to be able to line up.

 

[HISSIN50]

i respectfully disagree, V8. the relative position of the dizzy shaft to the housing can be changed by turning the dizzy (as if adjusting timing). the limiting factor is if the TFI or other dizzy items have interferance with their surroundings.

 

[Michael Yount]

V/8, Hissin - I think you may be both trying to say the same thing. What's commonly referred to as being 'one tooth off' (which has a whole different meaning here in the mountains of east TN) is most folks way of indicating that you can engage the distributor with the cam gear in a way that you can't rotate the housing far enough to get the timing correctly set due to interference between the dizzy housing/module/wiring harness/distributor wires and hard objects that prevent it from rotating any farther.

But for those interference points, you could stick the distributor in anyway you liked - and simply rotate the housing until the timing is correct. But the interference points are real - so it's kind of like saying except for THAT Mrs. Lincoln, how'd you like the play?