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Car missing

1438 Views 16 Replies 5 Participants Last post by  Jon.kin96
just completed a cam and head swap on my 95 GT. Put in an E303 cam and GT40P heads. The car has been sitting for abt 4 months while this happened. Now I have a miss I can't fix. I have replaced the plugs, wires, distributor cap and rotor, coil, fuel filter, put in new fuel with sea foam and a can of heat in case there was any water. The car sounds great, you can rev it up no problems but out on the road it misses. I ran the timing up little by little to 20 BTDC and it got rid of a lot of the miss/dogged feel. BTW did remove the spout when adjusting the timing. Had it in the dark rev'ing to see if I had any arching and can't see anything. I did have the #8plug wire get hot enough to burn the boot up. (Actually caught on fire). Only have about 3/16" between the 90degree boot and the header. Put a new boot on and a sock.

I've run out of options so any help would be greatly appreciated.

Thanks in advance.
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What octane do you use? The computer may also not like the cam if it isn't tuned.
I plan on getting it chippedi
but wanted to get this problem fixed first. After 4 months of throwing $100 bills under the hood would like to know the engine runs prior to dumping any more into it.
Sounds like there may just be a bad injector, you say it revs up good which says there's a lot of fuel pressure at the time, and misses at idle when it drops.
In the garage can't get it miss. Rev's up no prob. Get it out on the road and it starts missing.
I don't get an eng light.
Run your codes anyway. You don't always get a CEL
Run your codes anyway. You don't always get a CEL
Especially with obd I
Got some high speed spark plug wires. Will run the code tomorrow when I get them on. Let you know what kicks out. Thx
My number 4 plug with these heads has no real clearance to speak of. Already dimpled the header. Called kegs and they say the Accel P526S is a little shorter. Ever actually tried it? I know the Shorty Header Plugs were the exact same size as what I already have.
Ok first sorry for taking so long, the job sucks. Tried to run the codes and can't get the ck eng light to flash at all. Got on line and tried some different things with no luck. The car still is missing. Put a new distributor today also. Didn't change anything.
I could be wrong because mine does throw an engine code after about 20 mins of driving. I have been having this issue, as far as I can see what is happening is the rocker arms do not have enough clearance with the stock valve covers. So the valves can't properly open above 4200rpm, then the engine starts missing. everything is torqued properly etc. All my rockers have scratches, and my valve covers do to from them rubbing on each other. It seems ridiculous, but I'm 95% sure that's what my problem is. I've done everything you have done chasing my high rpm misfire.

The other issue you could be running into is the springs in the heads. gt40p heads have **** springs and have to be replaced even with a stock mustang cam.

*edit* the more pedal you give it under load i.e. in gear pushing weight, the more the valve train will show it's weakness.
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Had the springs replaced when they did the valve job and cleaned the heads. My issue starts almost from pulling out of the garage. Last night I cranked the fuel pressure up 10psi over stock and ran the timing up to 20 BTDC. It doesn't seem to be missing but still feels like it's not pulling like it should. I think I may have had an injector issue. I put in some Lucas fuel treatment and while I was checking the temp on the headers to see if I had a dead cylinder the idle jumped up.

Not knowing the prob or how/if I fixed it not real confident driving it.

Will check that rocker clearance deal.

did you ever get this figured out?! i'm having the same exact issue but dont have a cam..stock cam with some major head work done to my E7TE's, 24# injectors, gt40 upper and lower ported to fel-pro 1250, heads portmatched to intake, 70mm TB, BBK longtubes with offroad X-pipe...just spent 4 hours replacing the lower intake gasket last night to no avail and got pulled over leaving the shop...was it an injector issue? also my #2 plug was carbon fouled to hell and back....
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