So I finally got my custom carb back and now the car cuts out on me at around 4000. Its fine in neutral but with an actually load its another story. I had the car dynoed before the carb work and it ran up to 5000 just fine, but a short time after words I raced the car without the supercharger hooked up and it sputtered a little at top end but I thought it was due to having a supercharger carb tune on an NA engine since the blower was unhooked. Well now the carb has been pro tuned for my application and the supercharger is running, but now its worse. I checked the plugs and they are clean with a slight discoloring of the white which I believe is normal. There is no oil and hardly any gas fumes on them. I've tried different jetting in the rear too from 83s,86s, and 90s. I assume this would cover the range of lean and rich but no change with whatever I do. I found one cracked plug wire from header heat and I changed it, again no change. I have no vacuum leaks, no fuel leaks and Im stumped. Is it a fuel thing or an ignition thing. I'm using an MSD 6al, msd coil, MSD pro billet, and MSD wires with autolite plugs. What gap should I use with aluminum heads and 12 lb supercharger? Thanks, let me know if I forgot something or if you need more to go on.
Stang cuts out at 4000 rpms.
- Thread starter SmockDoiley
- Start date
mine had same prob when in neutral i rev it it started cutting out at 4000 but when in gear driving i could run it to 6000 no problem... figured out the cutting out was my MSD 6AL's rev limiter i had set on 6000. reason it cut out at 4000 with no load was the factory tach sux azz and couldn't keep up so when it said 4000 it was really at 6000 but the tach just couldn't keep up with the new motor
ECU5.0
Banned
yeah definetly check the gap.....and im pretty sure you want spiral wound wires with aftermarket ingnition because a single wire wouldnt be able to handle that much voltage
My car is N/A but I had this exact same problem. I had bad valve springs and valve float. I could rev the motor to 6500 in the pits (and did). As soon as I would get to about 4000-4500 in first, the motor would lay over and act as if it was running on 4 cylinders. Popping spititng. If I would shift right then, it would run a little bit better for a second, then same thing.
AFter I changed every plug and wire.
I changed the valve springs. When I retuned my motor, I went throught the lights sputtering and popping. This time my MSD rev limit chip went bad. After I got the timing back on track, it was clear as day what was happening as I went through the lights. I put an 8k chip in there and viola'. Back in business.
Even though these are similar I definately had to distincly different problems very close to the same time.
AFter I changed every plug and wire.
I changed the valve springs. When I retuned my motor, I went throught the lights sputtering and popping. This time my MSD rev limit chip went bad. After I got the timing back on track, it was clear as day what was happening as I went through the lights. I put an 8k chip in there and viola'. Back in business.
Even though these are similar I definately had to distincly different problems very close to the same time.
I doubt it would be the springs though because I'm using TrickFlow Trackheats with the upgraded .600 lift springs and my current lift is only .542. Also, the engine only has 3 passes on it, never seen past 5000 rpms, and only has 1000 miles on it. The likelihood of the springs going bad already is miniscule. I'm going to take the whole supercharger setup off. I'm sick of this crap, and the pro tuned carb I got back is making this car run worse.
