Today while I was driving down the highway @ 80mph, I noticed my rpms were at 4000. Whoa, way off. I pushed in the clutch and coasted for a hundred feet or so, and the idle was showing as 1500, which is a little high too. When I put it back in 5th, still at about 80, the needle bounced back up to 4500, then bounced between 4500 and 3500 before settling at 4000.

I pulled over and checked under the hood for anything visual but didnt notice anything...I didnt even know where to start looking.

I had to get to school so I continued on my way, and the idle fixed itself, but my a/f gauge (not wideband) was reading really lean. I know its not accurate, but ever since i've had the car it read around 14.5 cruising and 10.0 on boost. Now it was reading 15-16 cruising and when I tried to boost, the car felt like a dog. I let off because I didnt want to mess with it too much until I figured out what was wrong.

Anyone have any ideas, or things to check? Is it safe to drive my car like this (1 hour trip home)?

 

Is there a place I can tap into to check to see if my RPM gauge is getting proper readings? Everything else seems to be fine, maybe it was all just in my head, but the tach is still freaky.

 

No one? Maybe I didnt do a good job of explaining it.

What is happening is this....My tach needle is going crazy. Sometimes when I accelerate off a light normally, the needle is climbing so quickly that I almost redline it, when it should only read 3000-4000rpm. On the highway it will be normal, then all of the sudden it will just jump up another 1000rpm, no change in speed.

I think its a bad connection to the tach, but my question is: could this effect the way my car drives? My A/F gauge is reading waay higher than normal, the lowest it would read was 13.5 on boost.

No one experience anything like this before?

 

nm, i found the right search terms.

https://www.rx7club.com/showthread.p...ht=bad+tach%2A

https://www.rx7club.com/showthread.p...ht=bad+tach%2A

https://www.rx7club.com/showthread.p...ht=bad+tach%2A

 

I posted in a few of those threads, but I'll help out here too. Don't bother trying to fix the tach, I don't know anyone that it worked for. Just find a used one from someone parting out a car. Replacing it is easy.

 

Thanks, I'll probably mess with it anyways until I can find a replacement. Thanks for the advice