parkster747

Hello I'm new on here and I have a problem with one of my 496 HO's can anyone help I'll appreciate it.

Here is the problem, at high rpms, underway the starboard motor boggs at 4000 to 4500 RPM's but it runs fine at 3300 rpms, and idle. I've changed my plugs, and wires and put it on a scope and no codes. I do notice one thing my port side motor purges and hisses while the starboard does not, could this mean something? What should I do next guys. Thank you

gttaply

I had a similar problem on my 496 HO, it turned out to be the Idle Air Control tube had come loose from the intake. It was located at the rear of the motor on the backside of the manifold. The "hissing" is the air leaking into the manifold. I resealed mine with Loctite and have not had any problems in the last 2 years.

SDFever

Not sure how loud your hissing is but if the little piece of foam is missing from the throttle body it will cause a light engine lope and on/off hissing that will be consisent with the lope itself...

Run the other engine with the scanner hooked up on plane and see what data you get when the rpm's drop back like you're saying... Could be light guardian mode compensating for one of the vitals.

BryanTuvell

I would check the fuel injectors.
Bryan