I installed a Denali cluster last night and comparing to my predator the cluster is of by 3mph and about 2-300 RPM's. Does it need calibrated or what? Maybe the MPH is off a little in the tune due to the big rims, would this effect the rpm as well. Funny part is the old cluster was dead on in the RPM range but was off about 3mph as well.

 

i know extendocab put one in his 4.3 truck and it's off

 

Maybe the predator is faster at showing the actual speed than the guage. Is it always off by 3 miles or does it eventually catch up when you reach a constant speed? If the miles are even at a cruise then there may be something wrong.

 

Always off. I was going 50 put the cruise on and the Pred. was saying 47mph. I never paid attention to the stock cluster and Pred. Maybe it was off as well?? Just seems strange the computer is providing info to both the cluster and Pred. and they have different readings. The predator is correct. At idle the cluster says 1000rpm while the Pred. says 600 or so. I know its not idling at 1000.Maybe they get inputs from different signals and EFI live can help me fix it up. When I get it.....

 

I don't think you can adjust the cluster calibration with EFILive, only the PCM calibrations but I think what you can do to fix it is if it is off linearly (say 3 MPH at 10 and at 70) to just pull off the needles and re-index them so them match what the PCM is saying. Might take a couple of tries to get it right, but would be easier then sending the cluster off to a speedo shop to get it changed. You might physically check the odometer with actual mile markers to see if it is off, this would tell you whether or not the pcm is calibrated right.

 

they did a whole article about this in one of the auto magazines, also it would be a discrepency in the size tires or what not

 

I noticed the speedo was a little off (actually about 3mph) after my dyno tune. But the rpms were not this far off. I have since put in another tune and I think when they calibrate the tire size they just use a generic calculator. It could very well be the tire size is off. But the rpms weren't off before. I was thinking I could adjust the tire size and gear ratio specs to get it perfect. I'm not sure if the diagnostic port where I hook up the Pred. and the speedo get the info from the same input. I'm guessing the Pred is right and the speedo is reading a different signal which is off due to wrong tire size or end gear ratio. Who knows, if the tune says 4.10 gears instead of 4.11 it may make the little difference I'm having. Or if my tires are 32.575" and the tune says 32.00"...you get the idea.

 

Changing the pcm, won't change the difference between it and the cluster. If you adjust for different size tires, your PCM will change the calculations for pulses per mile for the pcm, but the signal it send to the cluster will stay the same 3 mph diff. You can make it to where the real life mph and the pcm mph will be the same but the cluster will still be off 3 mph. You have to change the cluster to match the pcm either manual by moving the needles, or by sending to to a speedo shop. Same with the tach. HTH

 

My new Denali cluster was the same. Reads 3 mph faster and the amps reads 1 1/2 lower. I call the local speedometer shop they said 35.00 to recalibrate it.

 

What all would they recalibrate? You think the tranny temp/oil pressure/fuel/ blah blah are all a little off?