Esky Cluster

[1low95GMC]

The 95 tach only goes to 5K, and the 96+ vortec tach goes to 6K, both the 95 and 96+ tach occupy the same space on the gauge cluster therefore if you install a 96+ gauge cluster in a 95 the tach will be off throughout the rpm range.

but it will work? just the tach will be off?

 

[sewlow]

8cyl gauge is made to pickup an 8-tick revolution, your 6-tick rev is making it read 25% lower(I think my calculations are correct....it would either be off by 25% or 33%) I'm brain dead at the moment though haha. Maybe install vortec 6 tach internals?

Yea, trying to calculate stuff like that is a mind-f*ck. 25% one way of calculating, or 33% the other way.
Thought about changing the internals of the cluster over too the six's, but if not this winter, then next, I'm going to do a V8 swap. I will probably have to live with this till then. This engine has 320,000 kilomtres on it, (about 200,000 miles) so it may be sooner. Probably sooner. I just thought that this may be an easy fix. The addition of a resistor, or something.

 

[Aloicious]

how far off is the tach?

there is a difference on how the tach signal is processed with the PCM (v8's had a 4x crank reluctor, v6's have 3x), there are a few things you can try, there is a way to adjust the tach readout in the PCM tune, so you could tune the PCM to correct the error. you could also try swapping the stepper motor out of the v6 cluster into the v8 cluster, it should just bolt right in, and if there is anything different in the v6's motor construction, it would possibly fix the error there.

 

[stroker52]

how far off is the tach?

there is a difference on how the tach signal is processed with the PCM (v8's had a 4x crank reluctor, v6's have 3x), there are a few things you can try, there is a way to adjust the tach readout in the PCM tune, so you could tune the PCM to correct the error. you could also try swapping the stepper motor out of the v6 cluster into the v8 cluster, it should just bolt right in, and if there is anything different in the v6's motor construction, it would possibly fix the error there.

this guy is my hero....

 

[sewlow]

how far off is the tach?

there is a difference on how the tach signal is processed with the PCM (v8's had a 4x crank reluctor, v6's have 3x), there are a few things you can try, there is a way to adjust the tach readout in the PCM tune, so you could tune the PCM to correct the error. you could also try swapping the stepper motor out of the v6 cluster into the v8 cluster, it should just bolt right in, and if there is anything different in the v6's motor construction, it would possibly fix the error there.

The tach reads 1650-1700 rpm @ 70 mph. From my calculations, it should read around 2300 rpm.
I don't have the capabilities to re-adjust the PCM. I'll check with a buddy that may be able to do this.
Thanks for the info.

 

[sewlow]

this guy is my hero....

YUP!!

 

[MOBS]

how far off is the tach?

there is a difference on how the tach signal is processed with the PCM (v8's had a 4x crank reluctor, v6's have 3x), there are a few things you can try, there is a way to adjust the tach readout in the PCM tune, so you could tune the PCM to correct the error. you could also try swapping the stepper motor out of the v6 cluster into the v8 cluster, it should just bolt right in, and if there is anything different in the v6's motor construction, it would possibly fix the error there.

Had i read down, i wouldn't have just blown my mind figuring out that the 6cyl is pulling 4 revs for every 3 revs the tach is showing. Oh crap, i just confused myself again.

Ok, after a brain reboot, I THINK that if the tach shows 1500, the engine is pulling right at 2000. So at your 1650-1700 being shown on tach, your engine is pulling 2200-2267....yes i thank God for a calculator!!!

 

[stroker52]

Had i read down, i wouldn't have just blown my mind figuring out that the 6cyl is pulling 4 revs for every 3 revs the tach is showing. Oh crap, i just confused myself again.

Ok, after a brain reboot, I THINK that if the tach sows 1500, the engine is pulling right at 2000. So at your 1650-1700 being shown on tach, your engine is pulling 2200-2267....yes i thank God for a calculator!!!

dont hurt yourself boss... lol

 

[Aloicious]

The tach reads 1650-1700 rpm @ 70 mph. From my calculations, it should read around 2300 rpm.
I don't have the capabilities to re-adjust the PCM. I'll check with a buddy that may be able to do this.
Thanks for the info.

sorry, what I meant to ask was if the error was consistent (i.e. a consistent percentage of what it should be across the board), or is it only off at specific times (like at idle, or above 2k, etc)....

a consistent error is what you sound like you're getting, something around ~25% off. so if you're idling at 600, it would be showing like 450. and when you should be at 3000, it'll show around 2250...
that would be likely due to the different crank reluctor and the signal the cluster is expecting. if you have a way to tune the computer yourself (like with EFILive or something), I can show you how to correct it, but if you're not tuned, or just using a mail order tune, then I'd try swapping the cluster stepper motors first, its highly likely that they're wound different or incorporate different internal components (resistors/capacitors/etc) to compensate for the different signals that are received. that would be the easiest and cheapest way to go about it.

if it were an intermittent error, like just at idle or something, then I'd say it was probably a gauge problem, like a mechanical or electrical failure/malfunction. but I don't think thats the issue you're seeing.

 

[MOBS]

^This reminded me of something.

but I deleted and moved to new thread....was brain dead and high jacked haha.