Woodard2589

I just put gt40p heads, trickflow stage 1 cam, and a rpm II intake, and when it was first put together it started up fine and would run right when cold, but i had to take it all back apart after it stopped wanting to turn over, and ended up being a chunk of metal on the no. 8 cylinder. anyways i put it all back together and it ran as strong as ever but when its cold, usually less than 125 it runs like crap. it has no power, barely can stay running, and when i give it gas it backfires. my friend told me before when we first put it together that it was the throttle body backfiring cause it sounds different than a normal backfire, yet i can feel it through the exhaust. he thinks it might be a leak on one of the heads, and the metal in the gasket is expanding when it gets hot and stops the leak. im not really sure. i cleaned the iac, even thought its the same one i had before, and the throttle body and mass air meter are also new on this setup but are used from a buddy. neither should be dirty enought to cause the problem seeing how htere pretty new. i've also changed the coolant temp sensor,(i forget the name) thats on the black hose for the heat in the car cause i had another laying around. so does anybody have any ideas what it might be?

67mustang302

Have you had it tuned yet? My guess is no

mjr46

what year mustang?? and have you/ how did you set the timing??

Woodard2589

the fuel pressure, idle, timing,tps and what not have all been roughly setup by a friend of mine that owns a speedshop so i dont think it is anything with the tune. it needs to be tuned more just to get a few more .10's off my 1/4 mile but, it should run fine off the tune. I'm thinking its a sensor but idk.

mjr46

your not giving us much to go on??? is the car mass air?? if so is the mass air calibrated to the injector size??? what year mustang is it????? we can't make a educated guess through osmosis....you need to provide some specs and what's been done to the car other than H/C/I

67mustang302

Then you're just not pressing your face against the moniter hard enough [8D]

mjr46

the car should run just fine without a tune installed.....the tune will maximize his potential.....with the backfiring through the intake the best guess I'd say is possibly the timing is off or the distributor is a tooth off...I 'd double check the timing with the spout connector out and check the balancer to make sure it hasn't spun on the rubber

TTGreenSN95

Let me know what this thing runs thats the exact same setup I have on my my motor
gt40p rpm2 and stage one cam
all I can tell U,mine is cold natured for about 30 seconds then runs fine I had a harder time getting the thing to idle and that still acts up sometimes.
might be that used mass air meter.Mine ran fine without a tune
it also doesnt like alot of timing if that helps you any..more than 12* and she starts pinging
do you have the same size injectors in it??if there bigger its going to be a cold natured B#$%@! without a tune
I had 36#injectors in mine and it was hard to start and cold natured for about a month in hot summer heat...so i went back to the 19#injectors

AdderMk2

this is the most retarded thread I have ever seen

you car will not make good power UNTIL its warmed up.. otherwise its gonna run rediculously rich, have no timing... and yea..

let it warm up before you whomp on it.. and stop bitching

TTGreenSN95

It is certainly not the most retarded thread!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!--->>https://mustangforums.com/fb.asp?m=3945286
The guy who ported his heads on the car is the most retarded thread I have seen so far!! Now thats RETARDED!!!!