I have a 96 EX V6. The tach is acting very weird at times. here is what happens.

On a cold start the tach reads fine, nice and smooth throughout each gear. Then as it warms up or is pretty warm (closed loop?) the tach starts "popping" around. If i accelerate i will watch the tach and instead of steadily going up in rpm as it would and should, it spikes/jumps up like 600-1000rpm and back down. It like bounces around (usually up and then back to rpm).
??weird? Also if im sitting at idle (warm/closed loop?) it will bounce up and back down randomly. its like the tach is having a seizure at times. and then sometimes it will happen and then go away?? sometimes it wont happen at all(rare)?

Im pretty sure that the engine is NOT following/reving to this sporatic jump/bouncing of rpm on the tach.

i.e.--when warmed or up to temp, say i am driving on the highway at 3K rpm. randomly the tach will spike up real quick and bounce up to say 3700 or 4Krmp then bopunce back down to 3K where i was. it will do this sometimes for 1 minute and stop or for 10 minutes sometimes. it doesnt seem that the engine is reving with it. its a quick jump up and down. just BOUNCES around if that is easier to understand.

Anyone got any ideas?[>:]

 

Hmm. Good thin the engine isn't following it. If you're sure it isn't, then it's electrical. It could be the wire is loose for the tach signal (It's on the coil or ignitor. I forget and don't have my manual in front of me..) or a bad ground. I guess the ignitor could be causing it, but I think you'd have some engine difficulties if that were the case.

 

You could also hook into the OBD and see if there is by chance a trouble code...

 

id say one of two things....one a bad tach, two a bad wire leading to the tach (its the blue wire leading out of the distributor). there is also an outside chance that your voltage regulator is going out. so i would check that first. just take your multimeter (you should have one of these) and hook it up to your battery after its started doing what you have stated and check the voltage....it should be just over 12. if the voltage jumps to like 15 or 16 or 19 or something you know that you have a problem.

 

Dug these posts up here..looks like it may be a common problem with 96-97 V6's to have this sporatic tach problem. anyone have any more input?

https://www.hondaaccordforum.com/97_.../m_7212/tm.htm

https://www.hondaaccordforum.com/97_.../m_8775/tm.htm

 

where can i hook up an OBD connector to check for codes? how much?

 

the scanner hook-up is behind the ash-tray. The tray just pulls out of there no problem, as far as the scanner, I got one from wal-mart for 60 bucks, it is just a plain jane piece, but it pulls codes, if you want a good one, go to auto-zone etc, I think most of them go for about $110-$120. The scanner is definitely a good investment, use it twice and it's paid for itself. Sadly though, if your engine doesn't follow the tach spikes, sounds like a bad tack (it takes a pretty mean circuit board to make that needle turn)

 

What was the outcome to your problem. I have the exact same issues with my 97ex v6? What did you do to eliminate?Thanks

 

Your complaint has a running problem too, right? I wouldn't call it the exact same, if his tach is jumping with no miss. This guys problem is likely his coil, yours may be something else since it is missfiring.

 

on the rt rear of engine comp by the shock tower there is a black plug 2 wires going to it,,( blue wires ) that's for the tach test plug , hook up a manual tach to it and see what the rpm do,,,,,,,,,,,,if they flactuate the problem is from there to ,,,,coil, ignitor,wiring . chk for possible loose connections, ., ......If rpm hold good,, the problem is from there to..... gauge, wiring ..

try and post results..