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-   -   High RPM misfire (https://www.thevettebarn.com/forums/showthread.php?t=111526)

thecornerman 09-01-2017 5:07pm

High RPM misfire
 
When I normally take off at full throttle I hook up and go with no hesitation or misfire.
Today when I power braked it it would drop a cylinder, let of the brake and it went away and tore off
When I was doing a burnout the engine started to misfire just over 5500rpm

I don't believe that I have a rev limiter so maybe a bad coil?

25k on plugs and wires

itsaz 09-02-2017 8:24am

Try this:

How to Access C5 Corvette Diagnostic Codes

Sneaks 09-02-2017 9:45am

Every C5 has a rev limiter. Keeps you from grenading the motor by accident. Check the codes and let us know what comes up.

thecornerman 09-02-2017 12:07pm

No PCM codes, just thought that it was strange that it does it during a power brake event

Sneaks 09-03-2017 7:40am

Traction control off?

thecornerman 09-03-2017 8:39am

Yes sir

Y2Kvert4me 09-03-2017 9:53am

Yes, the C5 has a rev limiter. Unless the PCM programming has been modified, it will cut fuel and the engine will stutter at 6200 rpm. (6500 on the Z06)

You noted "just over 5500", but when doing a burnout, the engine is spinning relatively unloaded (as compared to doing the work of accelerating the car) and it's very easy to fluctuate the engine speed that much in a split second. Also consider the fact the tachometer in these cars has significant lag. You might have seen 5500 indicated when revving, but the engine was actually spinning faster than that.

From the description I think you simply hit the rev limit. It's not a big deal, causes no codes, just a protection mechanism doing it's job. If you had it breaking up while accelerating in a high gear where the engine is heavily loaded and climbing in RPMs slowly....Then my answer would be different. An actual misfire event will usually throw a code.


:cert:

thecornerman 09-03-2017 10:06am

I agree, a split second glance isn't a factual read.

The rest of the story, one of my front tires has a bad spot from driving it in a wheel that had a barrel bend in it from a put hole. I rotated my wheels and put it on the street to true it up, tire has 9/32 if tread left and hate to junk it.


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