Tach only reads half of real engine rpm?
01-31-09, 09:23 PM
#1
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Tach only reads half of real engine rpm?
I finally got an axle in the new SC400 I bought, and was driving it around today. I noticed that the engine seemed alot louder for the rpm that the tach said, and after paying attention to it while driving, noticed that the tach only showed half of the real rpm!
Is this a common problem? After research, I found out that the car has 2 coils.. so could one coil have something wrong with it where it isn't registering on the tach (thus, showing only half the real rpm) ?
Is this a common problem? After research, I found out that the car has 2 coils.. so could one coil have something wrong with it where it isn't registering on the tach (thus, showing only half the real rpm) ?
02-01-09, 05:54 AM
#2
From my experience...
Driver Coil bad + Passenger Coil good = RPM = 0 @ 2000 or less. The tach would rev up to about 2k and then drop to 0 with a bad coil.
Now... I had an SC300 gauge cluster in my car when I was getting mine redone. The RPM's are about half of what they should be. Probably about 2/3 to be exact. Has this car been modded in anyway? If the car shifts around 4k @ WOT, then this may be the case.
If its less, then its probably something to do with ignition.
Driver Coil bad + Passenger Coil good = RPM = 0 @ 2000 or less. The tach would rev up to about 2k and then drop to 0 with a bad coil.
Now... I had an SC300 gauge cluster in my car when I was getting mine redone. The RPM's are about half of what they should be. Probably about 2/3 to be exact. Has this car been modded in anyway? If the car shifts around 4k @ WOT, then this may be the case.
If its less, then its probably something to do with ignition.
02-01-09, 08:38 AM
#3
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Yeah, the car shifts at about 3500-4000 rpm. I have no history on the car, but apparently some tuner owned it because it has a suspension on it and it had TT supra wheels on it before I bought it.
03-05-09, 12:23 AM
#6
From my experience...
Driver Coil bad + Passenger Coil good = RPM = 0 @ 2000 or less. The tach would rev up to about 2k and then drop to 0 with a bad coil.
Now... I had an SC300 gauge cluster in my car when I was getting mine redone. The RPM's are about half of what they should be. Probably about 2/3 to be exact. Has this car been modded in anyway? If the car shifts around 4k @ WOT, then this may be the case.
If its less, then its probably something to do with ignition.
Driver Coil bad + Passenger Coil good = RPM = 0 @ 2000 or less. The tach would rev up to about 2k and then drop to 0 with a bad coil.
Now... I had an SC300 gauge cluster in my car when I was getting mine redone. The RPM's are about half of what they should be. Probably about 2/3 to be exact. Has this car been modded in anyway? If the car shifts around 4k @ WOT, then this may be the case.
If its less, then its probably something to do with ignition.
holy crap this is exactly what my car is doing...
so you're saying the previous owner may have swapped in a sc300 gauge cluster? that would make perfect sense because the 6cyl tach would get 2/3rds of the ign signal that the 8cyl tach wants. my engine soulds like it's revving to the moon, but the tach says it's hitting the rev limiter at 4200rpms.
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