NoGo95GT

For the last few weeks, when under boost the Mustang will make pop and almost seem to shut down. But it doesn't. It's really becoming a pain. I pulled codes and got one: CYL 4. So I pulled out the spark plug on #4 and tested it. It produce negative ohms. I replaced it and the problem seemed to be solved. However, when I was at the track yesterday it started back up. So I replaced all plugs and wires. Still no fix. The car seems to have no miss or anything like that. Could it be a bad coil, bypass valve, dizzy(replaced in Sep.), maybe even an injector? Any help would be appreciated.

PRO50SC

Has this always been an issue, did it just start and if so, have you done something and then this started?

What is your fuel set up?
How much boost?

The more info you supply, the easier it will be in helping you. Be exact w/ all your info.

NoGo95GT

Ignition wise I am running an MSD Blaster Coil(bought in Aug), stock plug wires, Autolites 3924 gapped to .30. I was running Accel plug wires w/champion 2 heat range colder plugs gapped to 30. However,I thought the plugs were fouled up and was not getting a good reading with the Accel wires, so i though that was the problem. It was not. My fuel pressure it set to stock. As you know the FMU takes care of the rest, by bumping up fuel pressure. I was running a stock MAF for a while while I had the problem and then replaced it with a Lightning MAF. The problem still persisted. I am making 8lbs of boost through a 2.95 pulley. Total Timing is 18 degrees. I have 0 detonation or a miss. At higher rpm the car just pops and and sounds like it shuts down but it doesn't. It is really hard to explain. And since it just started happening randomly is what has me stumped. Also, the code reader points to CYL. #4 which also has me puzzled. Thanks for the reply.

PRO50SC

So out of no where, this is happening correct? What size injectors? And is the mass air calibrated to your injectors? I see in your sig about a tune, was it dyno tuned? I had a similar issue, mine ended up needing a blow-thru mass air. I went to larger injectors(42's and ditched the fmu), the mass air and a custom burned SCT multi tune chip. The car has never ran better.

NoGo95GT

30lb injectors hooked to a MAF and a 255lph fuel pump. We are using a Tweecer R/T so the Injector size is already calibrated into the tune. No, the car was not dyno tuned, however, it was taken to a dyno. , where it was running pig rich. During this time however, the car was using the stock MAF, running on 7cylinders, and had a slipping AODE. I have a AFR wideband currently in the mail and will be ordering 42lb injectors and an AFM Powerpipe next month. The thing is, I know the car is getting enough fuel. I am just wondering why all of this occurred all of a sudden.

NoGo95GT

Slight update: I was looking around the motor when I happened to look at the coil. The electronic plug did not look to be fully seated into the coil. I took it out and saw that the two wires were not creating full contact. I played with it and got the wires to contact. The plug is still slightly loose, but I'll work on it. Took the car for a ride and it ran fine. This would explain why the car would "pop" only intermittently, although most of the time under boost. Fingers crossed I fixed the problem. Thanks Pro for your help!