I've been struggling to combat a problem I've been having for a while now, and everywhere I look I can't find an answer, maybe someone on here had the same problems as me.
Got a boosted b16 EG with uberdata and 450's the car runs great most of the time. Lately I've been having a problem with the tachometer "jumping" around. It seems that the jumping of the tach is a misfire or something, because it only does this when it's in boost. The jumping is a rapid movement of the tach accompanied by loss of power.
Here's the situation.
When I'm driving, if i build boost say at like 3-4k rpms, it will start to jump and it seems like it's misfiring, but then with VTEC it just takes off, and the tach jumps much less when it's in VTEC.
At first the problem cause was thought to be the battery, because after a long trip I turned the car off and when I went to turn it back on it didn't crank. So I checked the battery terminals, which were a bit loose, and tightened them. Then the problem disappeared. For a little that is.
Now it's back.
I don't drive the car during the week, but when I try and start it after a week of sitting it is dead everytime. I have to jump it everyweek I use it. After it is jumped and I run it for like 20 mins, then it is ok and will start up fine the next day.
This leads me to believe it is the battery, because the problem seemed to go away when I tightened the terminals. Now the terminals are real tight but it still does it a little bit... Gotta be the battery right?
Anyone else ever have this problem?
Info on jumping tachs online poinits to a problem with the ignition coil... This could be the problem too, because the coil is not honda it is from pep-boys, i think it's borg warner coil, could this be the problem?
I checked the plugs, and they LOOK fine...
Maybe the engine is being fed too much fuel?

Also, I have a 93 EX all stock, and it has had the same problem a couple of times even though it is not being boosted, wtf?

 

My friend has a 99 Prelude here in the office. Its doing the same thing. The car is completely stock and no one can find anything wrong with it. Coil, distributor, computer, all come out legit time after time. How did you fix your random freeway tach and rev issues?

Thanks,

Ty

 

After about a month of pulling my hair out trying to find the cause of this elusive problem, my brother was working on it with me one night and while I was starting the car, he noticed a spark under the battery tray...

Turns out it was a loose/bad ground connection. We took it off, sanded the metal and put it back on. Prob hasn't come back since...

Good luck!

 

if your tach is doing this ad throwing a MIL. Pull the code up and see what it is, usually the TPS sensor malfunctioning can cause these symptoms. But glad you discovered the problem.

 

Check to see if something is grounding out.