My RPM gauge bouncing around. Any thoughts or suggestions?
 

I recently bought a 1990 honda accord for the winter. And for some strange reason when the car hit 72 mph or higher, the RPM needle starts going crazy. When under 72mph, the RPM needle will stay steady between the 2 and half and 3 mark. But as soon as I start going like 73 to 80 mph, my needle RPM will start bouncing around back and fourth while climing all the way up to 4 and half and even 5 on the RPM gauge. It looks to be reving the engine too high and it is not normal. I think usually if it is workign correctly, even at 80mph, the RPM should be around 3 or 3 and half or so on the RPM and not bouncing around back and fourth and climb as high as that.

It kind of sound like maybe the timing is off on the timing belt or something to me but I am not sure. Not sure when the last time the timing belt was changed. The car has about 197 thousand miles on the engine. Anyone have any thoughts or inputs?

Thanks....:)

1990 Honda Accord LX
(2.2L, 4 cyl), Cpe 4 door, FWD
Manual transmission
197540 miles on engine
Uknown when timing belt was last changed
Everything is stock

is the engine revving all over the place or just the needle bouncing around?

Engine seems to sound normal I think. I don't hear it reving high when the needle is starting to bounce back and forth and start creeping up high. Needle just smoves when the speed starts to increase.

might just be a bad gauge.

on another note, you are braver than me for taking a 17 year old used car with almost 200k miles on the clock to speeds past 70mph. ;)

pfft, I take my '91 Lincoln up to 120 when there's nobody else on the road and I have a half mile of visibility. Only 96k miles, but it still holds the road tight.

My pappy said, "Son, you're gonna' drive me to drinkin'
If you don't stop drivin' that Hot Rod Lincoln" :lol:


It sounds like a bad gauge. I had an '87 Honda Civic that did it all the time, had it checked out and nothing was wrong with the car it's self, besides being crusty old.

Good luck!

how long have you had that '91 Lincoln? you do all the upkeep on it?

I had that happen to my 1994 Ford Escort. Take it to your mechanic. It's a simple electrical system fix and shouldn't put you back much.

This is a Honda we're talking about. Those cars were bulletproof back then. I had 200K on my CRX. I would ride it hard, put it away wet and that thing would come back begging for more.

The highest probable cause of tach needle bouncing is the ignition coil. The tachometer gets its input from the primary side of the coil. Every time the coil primary collapses, it fires the coil. Then, based on the engine cylinder numbers programmed into the tachometer, the gauge will register rpms. If the coil has a building high resistance in the primary side, or there is a poor connection, then the gauge gets an incorrect reading and will "bounce" all around, even if the engine is running normally. This condition is more prominent when the engine is warm, or the rpms are higher than 2500-3000.

Change the air filter. That fixed it for me.

Thanks guys. Will try a few of the things mentioned above and see if it fixes the problem. I hope it does. Don't want to shed out anymore money on a winter beater only.