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2.4K views 22 replies 8 participants last post by  Mike in Kentucky  
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#1 ·
Hi guys,
Im new to modded Mustangs because, the folks over at Mustangforums aren't that friendly lol.
For the record, I have a 97 GT convertible that has been cloned into a 1995 Cobra. It has a 95 generation 5.0 in it, with the following: E303 Cam, GT40 upper /lower intakes port matched to 75mm throttlebody, BBk Cold air, Grannetelli #24 MAF , 24lb injectors, headers, no cats, magnaflow off road with x pipe, 255lph fuel pump, AFPR w/in line guage, 355"s in IRS out of 2003 Cobra, full cobra suspension and brakes, with eibach springs. Sub frame connectors and strut tower brace, aluminum radiator, full 2003 Cobra interior, 5 speed off coarse, yada yada...
Anyways.....I have n MSD ignition with ford racing wires, AUTOlite 25 copper plugs, proper gap, a new EFI module, new distributor, and cap and rotor AND fuel filter....
My problem is......Im getting a high RPM break up....around 4k at WOT. ESPECIALLY first and second gear , the car just sputters and losses all power, third gear it does it less, and 4th almost not at all....Entire ignition and fuel system is new, timing is good......Im at a loss....
Any help would be appreciated....
Thanks in Advance-
~Marco S.
 
#2 ·
Can you be more specific ? Such as...

Whats your timing set at ( did you pull the spout connector when you set it)..... whats your fuel pressure ( check it with vacuum line disconected)...... what are the plugs gap to...... have you ran your codes as of yet ?
 
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#3 ·
What computer is running this frankenstein? I love it, don't get me wrong. Also, pull spout, set timing at 30*, leave spout out, go drive car. Don't shut it off after advancing the timing, go drive it and get on it. It won't start with that much advance but if the sputter is gone, it will help me narrow it down.
 
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#4 ·
LOL! Frankenstein is right. It actually has an A3M computer with a MASS AIR conversion piggy back, yes a foxbody set up. I set timing with spout OUT. Its at 14.(tried everything from 10 to 15 to no avail) Fuel pressure is around 38 with vac disconnected, 40 connected.(played with that and didn't do anything). Plugs have been gapped at 42 and 50, neither helped. MAF is clean. Fuel filter is new....Im kinda new to Mustangs, don't know how to do KOER. BTW, EGR has been deleted, and no smog, or emission(charcoal canister)..tried 2 different diizzys and EFI"s...nothing. Still breaking up UNDER LOAD around 4k...

---------- Post added at 09:13 PM ---------- Previous post was at 09:10 PM ----------

Oh , and Ill try the timing at 30 spout out, and Ill go driving....will let you know...Thanks again to both of you for your input so far...
 
#5 ·
Well, for one, the fuel pressure with vacuum off should be 40, with vacuum on, it should be around 35 or less. If it goes up with vacuum on, well, there's an issue somewhere. Spark plug gap should be .052 to .056. What heads are on it?
I'm going to guess it's a lean break up you are seeing. Not positive, but what color are the plugs? Post a pic? Make a run with it breaking up and shut the key while it's doing it. Cost to a stop and pull a plug, take a pic and put it back in and continue motoring like nothing happened. Post pics here.
 
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#6 ·
Id be glad to do that for you although plugs have been pulled and are a nice dark almond like color. Not to dark and not to light. I will double check fuel pressure with and without vacuum, taking into consideration your numbers, and the gaps are at.50 now, runs the same (or slightly worse than when at say .43.)
By the way the tach jumps around real bad during the high RPM "break up". Some times its so bad, I can keep the pedal floored indefinitely and it will never climb, it just misses so bad, I don't even have to change gears , it will just stay at that speed , misssfiring. And it seems to do it less as you go up in gears. Third almost not at all, and 4th NOT AT ALL...First and second REAL BAD. Im going to pull the spout and take the computer out of the loop, like some of you suggested and see if that helps...btw I will post pics asap...
 
#7 ·
cobraclone1 said:
Anyways.....I have n MSD ignition with ford racing wires, AUTOlite 25 copper plugs, proper gap, a new EFI module, new distributor, and cap and rotor AND fuel filter....
Click to expand...
MSD ingition boxes, especially the cheap 6-series line, are notorious for going bad. Take the box out of the equation and see what happens. Honestly, for what you are doing there is no need for an aftermarket ignition box. The stock ignition system is more than adequate.

You did not list a new coil, maybe that was an oversight? It is possible for a coil to be faulty without all-out failing and it will cause high-rpm ignition break-up.
 
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#10 ·
Also, gentlemen, i just noticed a strange thing with this......if i go partial throttle into the upper rpm's, it does not break up/missfire???? Apearantly only at WOT??? Starts and idles fine, runs great at all speeds, just having this high rpm/ under load problem...does that ring a bell with anyone, is that a symptom of something particular? Maybe coil is going bad?.... I still havent looked at anything else that we have talked about yet, been working alot...i have off on Tuesday, so Ill look at it then....
 
#11 ·
Thinking back about 7 years, I had a TFI module cause the exact scenario you describe here. I could slowly rev-out the engine but if I stood on it the engine would break up bad at about 4k RPM, acting like a premature rev limiter. Back then I was under the impression that they either worked or they didn't, so I dismissed it as a possible cause. Ultimately the TFI module failed completely leaving the car on the side of the road. Once a new one was installed the car fired up and the ignition break-up was gone. After the fact I happened to talk to an engineer who worked for the company that made the TFI modules for Ford and he said absolutely it is possible for one to be faulty without all-out failing.

I know you stated that the TFI module is new. I also saw where you said multiple distributors have been tried. It just dawned on me that on your car the TFI module is not mounted to the distributor base like an '86-'93, it is remotely mounted on a heat sink. At least, that's how it should be if your using a '95 engine and related parts. If that's the case, when you tried a different distributor the TFI module was not changed with it.

It is absolutely possible for the TFI module to be faulty right out of the box, especially if it is an off-brand from an auto parts store.
 
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#12 ·
I did change the tfi on the heat sink, but with cheap advance auto stuff. I have stock heads btw.... I think after I try running her with spout out, Im going to look into a coil, maybe a motorcraft tfi....my problem is ignition related , Im sure of it...SO can someone tell me what the problem would be if the car runs better with spout OUT? Thanks again..
 
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#14 ·
UPDATE: Checked grounds, they are good. Ran it with spout out, same misfire. Checked all plugs for cracks, loomed wires away from each other, no arcing....Still missing badly up top. I was thinking, the MSD coil is the ONLY thing I haven changed. I was under the impression that they either worked or they didn't. Could that cause this? Remmeber, when I climb into the upper rpm"s slowly even to red line, there is no misfire, only at WOT...

---------- Post added at 02:11 PM ---------- Previous post was at 02:10 PM ----------

Note, I DO NOT HAVE MSD "BOX", only blaster coil...
 
#16 ·
Did this problem just start happening one day out of the blue? Or did you just get the car? If it was a recent development ... did it start suddenly or gradually. Is it getting worse over time?
 
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#17 ·
Its not valve float, that Im certain. Im gonna spring for a new coil(no pun intended), and see. As far as when this started happening. I had a different "no start" condition, and one of the things I replaced trying to fix that was the distributor. The distributor I replaced was one that fixed this problem before.....could it be another faulty distributor right out of the box??!! At this point it wouldn't surprise me.....Well, its either the coil or the distributor at this point. WPM distributor from Bennette(NEW) not a Reman. Had a Cardone didn't even start the car right out of the box, had to switch it out twice before going to a new one.
 
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#18 ·
I get paid Friday, so that's when Im going to get a new coil but, I hope that's it, if not, does anyone have a 1994/95 5.0 FORD distributor they want to sell? I was recently told a used oem distributor for this car is better than an after market new. Even better than an MSD or MAllory distributor. I can check Ebay, I Suppose. Trying not to spend $300 on it though. Anyways pray the new coil fixes my problem. No way gap on the plugs is causing spark scatter or blowout/misfire right? Some guys said .38 on the gaps and Im over .50.....just brain storming I guess...This is killing me that's all.
 
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#20 ·
Update: ok guys after trying everything. I decided to fiddle with timing again. It seems i have a slipped balancer or bad markings. Cause i retarded timing and it stopped breaking up, its actually pinging like its still to advanced. Running good though. Need to back timing off alittle more. I will get tdc re-marked on the balncer i guess and fine tune from there.....
Thanks again for all the input...
 
#22 ·
There should be a key way. So it should only go on one way. But i agree.... a new balancer is needed if you know its slipped
 
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