Fe 427 hp?

[Excaliber]

As the above link points out: Shut off the engine at the end of a drag strip run, after a full throttle blast at high load and high rpm. Then tow the car back to the pitts to read the plugs. That would eliminate the problem with the Multiple Spark Discharge changing the plug coloring.

That would sure be tough to do with a typical Cobra though. How are you going to tow it, or get it back to the pitts after a 1/4 mile run?

[olddog]

Originally Posted by Excaliber

As the above link points out: Shut off the engine at the end of a drag strip run, after a full throttle blast at high load and high rpm. Then tow the car back to the pitts to read the plugs. That would eliminate the problem with the Multiple Spark Discharge changing the plug coloring.

That would sure be tough to do with a typical Cobra though. How are you going to tow it, or get it back to the pitts after a 1/4 mile run?

Easy on a dyno though. AFR could be measured and known, but the heat range and detonation indication could be handy. The big problem with this is aluminum heads. I wouldn't pull the plugs hot. Hmmm.

[SoTxButler]

I had a situation very similar to yours. Mine is an EFI motor, but the popping is what is similar.

Everyone who listened to the car told me it was an exhaust leak. I even moved the Oxygen sensor forward of the slip fit headers in an effort to zero in on the air leak issue since the wide band was giving me bad numbers (rich to lean and vice versa).

Finally took out the injectors and found one on the bank that was popping with some trash in it. Changed the injector...no more popping. It fooled everyone.

Now, my thought is that you may have a fuel problem in addition to a possible exhaust leak. The stumbling upon acceleration after you have let off suggests to me that it is fuel.

Anyway, this is what happened to me. Believe me, some VERY knowledgeable people swore my problem was an exhaust leak.

Hope you can fix this problem...mine drove me crazy.

[FUNFER2]

If your interested in buying a highly polished stainless steel side pipe system that will be very less restrictive than most, send me an email.
3.5" muffler with no glass to stuff up TQ & HP. I even gained 6 HP at idle.

[Rawkkrawler]

I want everyone for their comments. As usual, the knowledge here has been priceless!

Thanks!!

Mike