[qwkvert]

I may be wrong about the spout, but I still dont think that is it. I would look into the pcm connectors, and also check ALL of the grounds. A missing/bad ground has f!@#$d me up many times, doing crazy stuff.

[kilby91]

Originally Posted by qwkvert do you have a fuel pressure guage in the car? I would look at that. it sure sounds like the factory rev limiter to me though, like it is hitting fuel cut.

I don't have a gauge mounted in the car but it is set @ 42psi with vacuum unplugged and holds constant under load.. It does sound like a rev-limiter, but it runs weak past 4,500 and when really cold will actually hit the factory 6,250 limiter??
Also i have replaced the PCM, redone every ground, and done a wire integrity check on all the inportant wires... It appears to check out..

[cptkng79]

don't listen to all these neg comment's lol i had the same problem plauge me for a long time put a msd box in and check your plug gap and i bet my car your problem will be solved
btw you really don't want my car cause i just blew the motor lol

[kilby91]

Originally Posted by Casper98GT +1. Youre correct darrell. Had a customer with a 1995 Cobra doing exactly what youre car is doing. says it wont rev very high, when it starts to climb it runs very shitty and also feels very sluggish. Says runs good until it warms up and also runs very good when the spout is out. This thread is kinda weird because its almost exactly what happend to him to a T. I ended up replacing the plugs and gapping them correctly and it ran fine afterwards. Im not saying this is youre problem, but it sure does sound the same. Good luck, unfortunatly online diagnostics sucks. haha.

I have changed the plugs numerous times and tried all different gaps, i wish it was something like that.. When i changed heads i had to run a completely different plug, and it still has the exact same problem..

[kilby91]

Originally Posted by cptkng79 don't listen to all these neg comment's lol i had the same problem plauge me for a long time put a msd box in and check your plug gap and i bet my car your problem will be solved btw you really don't want my car cause i just blew the motor lol

Yeah a MSD box is definately in my near future! Did that fix your problem on your car, before it blew?

[turbodgumby]

Have you changed the TFI module on the side of the distributor? That will also Cause the problem you are have. It will tell the computer that rpms are different in it will drop timing and injector pulse( like a rev limiter). If you have a buddy with another 5.0 borrow theirs and see what it does. And def. check that all the grounds are good. Also the ground connector by the battery. It will get corroded. It is the black ground connector that almost looks like a fuse holder It can also cause a similar problem. Its one of the main computer ground for loop. Hope you figure out and one of us helps you out!!

[cptkng79]

i changed my tfi module 3 times and still no change wen't through every sensor......no change still the same prob until i put the msd in no rev limit problem @ 5200
it wen't all the way up
prob why i blew my motor........lol

[kilby91]

I have also changed the tfi a couple of times with no luck, also redone and cleaned every ground on the car.. Thanks alot for everyone's input though.. I think before i do anything else i should get an ignition box for it...

[Darrell]

I don't see what an ignition box is going to do for you. If that fixes the problem then it is just masking a problem that is elsewhere. I've gone high 10s with the stock TFI ignition. The TFI ignition is a good set up from the factory.

[badshoe]

You say it works fine with the spout out and set at 32 degrees. I would say it's over advancing with spout engaged. Therefore try setting base timing to 10 or even 8 and take a ride. If that doesn't fix it, have you tried another dist. pickup or new dist?

[kilby91]

I have had the timing from 0-20 and the problem is still there it just changes what rpm it starts to miss.. I have tried 3 new distributors... With the timing locked @ 32*, and the spout removed it will rev to 6k in neutral, but still won't pull much past 5k under load... Also it isn't throwing any codes that would affect this and the computer is new.. But the spark plugs look completely clean?? They have about 4,000 miles on them and still look like they did when i pulled them out of the box? It looks to me like it isn't getting enough fuel, but it isn't throwing a lean code? Also i have replaced all the fuel components except injectors.. The wierd thing to me is that it misses at the exact same rpm every time when the computer is controlling timing advance?

Thanks, Richard

[kilby91]

Originally Posted by Darrell I don't see what an ignition box is going to do for you. If that fixes the problem then it is just masking a problem that is elsewhere. I've gone high 10s with the stock TFI ignition. The TFI ignition is a good set up from the factory.

I know that the tfi is a pretty good system, but i think mine is faulty. Would the MSD box bypass anything that could be causing my problem?

[cptkng79]

IM telling you i had the friggin same problem
pain in the ass MUSTANGS!!!!!
I changed everything 2 or more times
im talking distributers
tfi's wires coils and nothing seemed to help
put the msd in and it was fine!!!!!!! who cares if it maskes the problem as long as it
fixes it lol!!!!!!!!!!!!!!!!1

[badshoe]

I think you said your using a 70mm MAF from a SN95. If your still using a 90-93 PCM, it's not reading that MAF the same as an earlier unit. This mismatch could be causing a lean or rich high rpm and it's unlikely to flag a code because it's in open loop at WOT. If you have a stock MAF for the correct year car/PCM might be worth a try.

[kilby91]

Originally Posted by badshoe I think you said your using a 70mm MAF from a SN95. If your still using a 90-93 PCM, it's not reading that MAF the same as an earlier unit. This mismatch could be causing a lean or rich high rpm and it's unlikely to flag a code because it's in open loop at WOT. If you have a stock MAF for the correct year car/PCM might be worth a try.

Well i bought that MAF trying to fix the problem....But I'm 99% positive that these are compatible.. I've talked to numerous people on here and other forums about it..

[SALIV8]

Don't know if this was suggested, but I would check air/fuel ratio with a wideband.

[Darrell]

Originally Posted by kilby91 I have had the timing from 0-20 and the problem is still there it just changes what rpm it starts to miss.. I have tried 3 new distributors... With the timing locked @ 32*, and the spout removed it will rev to 6k in neutral, but still won't pull much past 5k under load... Also it isn't throwing any codes that would affect this and the computer is new.. But the spark plugs look completely clean?? They have about 4,000 miles on them and still look like they did when i pulled them out of the box? It looks to me like it isn't getting enough fuel, but it isn't throwing a lean code? Also i have replaced all the fuel components except injectors.. The wierd thing to me is that it misses at the exact same rpm every time when the computer is controlling timing advance? Thanks, Richard

What is the timing at 3500 rpm with the spout in?

[Darrell]

Originally Posted by cptkng79 IM telling you i had the friggin same problem pain in the ass MUSTANGS!!!!! I changed everything 2 or more times im talking distributers tfi's wires coils and nothing seemed to help put the msd in and it was fine!!!!!!! who cares if it maskes the problem as long as it fixes it lol!!!!!!!!!!!!!!!!1

I care. Putting a band aid on the problem is a half ass way of doing things. He obviously wants to find the problem and repair it instead of just throwing more parts at it.

[kilby91]

Originally Posted by Darrell What is the timing at 3500 rpm with the spout in?

I don't have a light right now to check it with, but i have checked it before and it was advancing like it was supposed to with no load on the motor.. I think it was around 34* @ 3,500 rpm....

[cptkng79]

just for shits and giggles check all your grounds i know someone mentioned it already but when i ripped down my motor tonight i found a really loose ground on the back of the header
i know darrell say i told you so prob was my problem and when i put the msd in i grounded it so the ignition system was good than
who knows can't test it cause i got a broken ass motor lol
really worth a try