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View Full Version : Tach is 800-1000 RPM higher than actual engine speed

S13squirrel
10-03-2005, 02:44 PM
Okay so I started my car this morning, and it made some sort of clunky-squeaky noise. It did it twice, and now my tach is showing RPM's that are significantly higher than normal. The car drives fine, shifts fine, and accelerates normally. I wouldn't even know there was a problem if I didn't look at my tach. Basically, the tach indicates higher numbers than what the crank is actually spinning. I normally shift at 3000 RPM, and now it's like 3800 RPM. It idles at 1500 rpm, and I took it past 8000 RPM without hitting the limiter. I did some searching, and this sounds like I may have a bad cluster or a wiring problem. Should I try disconnecting the battery to reset things? This problem doesn't bother me so much, but I am in the process of selling the car and the new owner won't exactly be happy with a crazy tach... but he is doing an SR20det swap soon, so this may not be an issue for him. Please help... advice needed desperately.
S13squirrel
10-03-2005, 02:46 PM
forgot to mention, it's a 1991 SE, ka24de with a 5-speed manual.
SHIFT_control
10-03-2005, 03:26 PM
HUD, digital dash? Sounds like an input signal error.
S13squirrel
10-03-2005, 04:24 PM
no, analog dash. It also feels like the higher the RPM, the more "off" it actually is.
aznpoopy
10-03-2005, 04:29 PM
never heard of this one before

i would check the TPS first

make sure its plugged in etc, then start checking with a multimeter

edit: on second thought i don't know if my advice makes any sense at all. please disregard. lol
ledzeppelin240
10-03-2005, 06:49 PM
The TPS has nothign really to do with the tach signal. It is most likely a signal problem, I can't remember if there is a voltage regulator or not in our cars, but if that dies gauges read higher...I'll check about the voltage regulator later.
S13squirrel
10-03-2005, 08:00 PM
Tonite I ran my broken tach needle all the way around to the clock button... that's like 8500 RPM, and I was only at 60mph in 2nd gear. It normally redlines at 62 mph. Would the voltage regulator make a noise while breaking or ceasing its function? Because I did hear a noise this morning... (see first post)
projectRDM
10-03-2005, 08:47 PM
The TPS has nothign really to do with the tach signal. It is most likely a signal problem, I can't remember if there is a voltage regulator or not in our cars, but if that dies gauges read higher...I'll check about the voltage regulator later.


All cars have a voltage regulator. The Schassis' is inside the alternator. If that was the case you'd be having other symptoms as well.
ledzeppelin240
10-03-2005, 11:35 PM
Im talking about the gauge cluster. The voltage regulator keeps everything below 5volts and the electronics are very sensitive to that voltage, that isnt the case here...
NismoDan
10-04-2005, 12:48 AM
Mine does this all the time, but only when it's hot.

I think it's funny shifting out of 2nd at like 30 mph but hitting the redline. :p