Roush Something happened to my motor - Could use some help!!!!

When driving my car a around 80-90 mph on the freeway I got on the gas pretty hard through the power band through about 5500 rpm. When I engaged the clutch to down shift, I noticed the car wasn't able to idle w/o pushing the gas pedal. I slowed down to pull the car over at which point the car seemed to sort of come back to life. The idle was really rough and sounded like it was misfiring. After checking all my gauges I continued to dive the car real slow back home. From that point forward, the car would backfire pretty bad down in the lower rpms until around 4000rmp at which point the car seems to come alive again. However, the idle is really rough, it back fires in the lower rpms under load, and doesn't seems to have the same exhaust note it had before (it's almost like there isn't the same flow through the exhaust that there was before - almost weak). Anyhow, if you have any suggestions as to where I might start to troubleshoot, I would greatly appreciate the help.

Car details:
2001 S281-S/C
Chicane 66mm Blower Pulley
Chicane RIPP Kit
SCT Custom Tune

00-Saleen said:

May have blew out a Spark Plug under load.

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Plugs might be the problem, I just had someone, other than myself, install new ones for me.

Thanks for the tip.

wsbrigham said:

Plugs might be the problem, I just had someone, other than myself, install new ones for me.

Thanks for the tip.

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OK. Here's what happened:

My piston somehow hit my plug. No damage to my piston, but the plug needs replacing.

How exactly does something like that happen when the correct plug is being used?

Mstng2 said:

DId you run a compression test on that cylinder? As posted above it's a good bet there is a chunk of piston missing and floating around in there. Exact same thing under the exact same load happened to my car. After tear down I found a second piston going the same way, just not there yet. (Mine is a 2000 Replica w/series II and chicane pulley.)

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We ran a comparative compression check (compares compression on all cylinders) and everything was equal.

BTW, it was cylinder #2 with the problem.

Looking at the plug, the electrode was pushed-in, but not to the point of contact. Also, the electrode didn't show any signs of metal-to-metal (or hard surface-to-hard surface) contact. There was, though, an awful lot of carbon on the top of the piston. I had the cylinders flushed to remove the carbon and everything seems to be ok. The Saleen Foreman at the dealership that worked on my car here in Albuquerque said there have been cases similar to mind (carbon build-up making contact with the plug). I do have to say though, I am not convinced that is what was the cause. There is some data supporting that fact, but I'm not too sure. Any thoughts?

Anyhow, I went to the dyno shop here today to get some results after a new SCT tune. We had to cut the run short at about 3500 RPM because the car was running way lean. However, the car was making almost 300 hp at 3500 rpm. Hopefully, that is a sign that things might be OK.