Tach on instrument cluster problem
 

So me and my frien rewired my LT10S about a month or 2 ago and i have a slight problem with the tach on the instrument cluster.

I have a S4 TII block in a S5 GXL shell and the last time everything we had installed which was 6 months ago it worked fine with no problems at all. Since it was stripped for a complete ressurection on body and paint we decided to redo the microtech install.

So what happens is when we start the car there isn't any response from the tach at all. Only when we have drive the car for ohh 20-25 mins does it only sort of work. By that i mean it bounces around and never reads the coorect value of engine speed, kinda like it lags by like 4 secs or more from the actuall reading. Also when it first starts working it just jumps around from 0 to the actuall RPM of the motor.


If it's any help i can try to post some video of the problem, but i figured i would start here first.

That tach is driven by the trailing coil. Make sure that the trailing coil connector is in good shape and check the condition of the yellow/blue wire in the front body harness.

You can also get this strange behavior if the trailing is misfiring.

what could cause the trailing coil to misfire? Being that it could be junk and i need a new one?

Bad plugs, bad wires, bad ignitor, bad coils.

Or it could just be that the AF ratio is far too rich.

Found that problem with the tach, blue wire came loose. fixed that.

Now i do have a very rich idle when i cold start around 10.2 - 10.8. What can i change to bump the A/F ratio up?

550's up front, stock coils, BUR9EQP's all around, Racing beat wires.

I can PM or post my current map too.

First you need to tune your map. I suggest switching to Matrix mode as it offers far more resolution then Normal mode.

Then, with your TPS adjusted properly so the ECU knows the engine is supposed to be at idle, just pull a bit of fuel in the bin that is highlighted while the car idles, and pull a little from the bins to the left and right as well.

Until you get your main map tuned, messing with the warmup corrections isn't going to help.

Okay so im updating this thread. I have checked and re-checked all connections. Even the back of the instrument cluster and still not tach response. Only time it somewhat works is when the engine gets up to about 7K.

Suggestions

Problem is finally fixed. For some reason i can't close the thread. So if someone with the rights to do so could, i would appreciate it