2G Misfire, limp mode, and and tach showing half of actual RPM

too_genecide · Jan 26, 2015

I'm stumped. Ive been a member for a while but my answers are normally answered by searching.
So, my 95 GSX is throwing a random misfire code at random times after I let off the throttle. The problem is starting to happen more often and I noticed that the tach has stopped reading right and is showing about half of the actual RPM. The car then gets stuck in "closed loop drive" mode (according to my scan tool) and if I turn the key off and restart the engine the engine returns to normal but the code stays until I erase it.
My scan tool shows the actual RPM reading throughout the hole ordeal. I have replaced the Crank position sensor recently and the Cam position sensor has around 10,000 miles on it. I am wondering if the Ignition Transistor would cause this but I am unsure how to check it. Please any help will be appreciated

synthetek · Jan 26, 2015

A bad transistor pack or bad/loose connector on the transistor pack could cause that.

too_genecide · Jan 26, 2015

Thank you , I have been leaning toward that but the limp mode made me hesitant to throw parts at it. Do you know of a way to test the power transistor by any chance?

synthetek · Jan 26, 2015

http://www.dsmtuners.com/threads/how-to-test-the-power-transistors.229419/ I wouldn't go out and buy a new one just to see if works but its easy enough to swap if you know someone that would let you barrow one for a few min. I always try to keep a few extra around.

luv2rallye · Jan 27, 2015

Note that my PT test link above tests the PT function of driving the coils but not the tach signal output (which the PT also has).

too_genecide · Jan 28, 2015

Awesome, that was it.
Thank you sir!

Tanro · Mar 20, 2017

luv2rallye said:
Note that my PT test link above tests the PT function of driving the coils but not the tach signal output (which the PT also has).

How would one Test the Tachometer functions?

luv2rallye · Mar 20, 2017

Assuming you have a 2g, connect a tach (like from an engine tester) to the PT white wire pin 4 (or ECU pin 58).

Tanro · Mar 21, 2017

luv2rallye said:
Assuming you have a 2g, connect a tach (like from an engine tester) to the PT white wire pin 4 (or ECU pin 58).

Thanks. Will have to see what I can find out. My car is currently having some tach related issues.

Runs way better than it did though, so maybe once I figure out why my tach is not functioning properly, the underlying cause is probably related to the last of my running issues.

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2G Misfire, limp mode, and and tach showing half of actual RPM

too_genecide

synthetek

too_genecide

synthetek

luv2rallye

too_genecide

Tanro

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Tanro

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