i just noticed a yesterday that my rpm needle would jump all over the place when i would wot in any gear ? it would go from being at 5,200 rpms down to 4,000 rpms then jump back upto where my rpms should be

 

ok. what do you want to know?

fs

 

is it normal cause its not a smooth increase just jumps up then down then back up

 

Well, no it is not normal. What can cause it is basically a mystery until you get in there and find the problem.

It could be difficult to isolate since it only happens at WOT. It could be the following, among other things:

loose or dirty connection to the tach
loose or dirty connection to the crank position sensor (CPS)
loose or dirty connection from cps or tach to the ecu
shaffed wires in any of the circuits above

It could also be that your ecu is a bit schizo

It could be simple to find for a person with some mechanical / electrical experience, but, with what you are saying, and without seeing the car, i would not even look at this problem until it would manifest itself a bit more. You may spend up to a week trying to figure this out without much luck.

fs

 

ok cool i guess ill check out all the connections first then check all the wires thanks for the help

 

Do you have overlay gauges? I had a set of white face gauges and the needle was getting caught in certain spots. This too only happened at wot. Just a thought.

 

nope, but now that i think about it i do have some guages hooked up to the cluster

 

A bad ignition coil would cause your RPM gauge to act the way you are describing.

 

i just replaced the coil, and it never did it with the old one , could it be not enought ground on the coil ?