Tach is 200rpm too low.

[ajfrac]

OK, been a while since i messed with my truck, but remembering when i had it hooked up to AE, and I noticed my tach reads a idle of about 480 rpm, but AE says the rpm is around 690, and when i rev the motor the gap gets up to250 rpm difference. (all at full temp)

Is this normal? if not, any experience with these issues or insight as to what might cause it?

currently only have codes for 1 glow plug being bad and a transfer case solenoid. Also have about 3 bad injectors, no codes, but by dropping them off on AE, there are 3 that dont make it stumble as much and causing no issues just a vibration on hwy when cold and no power when cold.


Thanks in advance

[ajfrac]

Anyone got something to chime in with, maybe have AE and check it on theirs?