95_Civic_4dr

D16Z6
First I have searched, most threads I found related to this either died before it was solved or suggested repairs I've already done.

It doesn't happen continually, but if I had to put a number on it I'd say 75% of the time my RPM gauge while accelerating will jump from 6k RPM to 7k RPM, hold for a split second, then drop back down to 6k. The engine doesn't jump with the gauge so I know for sure the reading is wrong, but I also can't tell if the engine is still accelerating or if it is just holding at 6k.

I've replaced:
Cap & Rotor
Spark Plug Wires
Spark Plugs
Ignition Coil
Ignition Switch (Actually was faulty - this one wasn't a guess)
Battery + Alternator tested at Autozone - both were good

Also went over all the engine and transmission grounds, cleaned, tightened them up and made sure they had a good connection.
On a side note: I also had a blown cylinder head gasket about a month ago so the gasket is new as well. Timing and compression are good.


So far only the ignition coil has showed any help, before I replaced that it would jump up randomly 800-1k rpm anytime past 4k RPM when accelerating (engine continued on normally though). After the coil was replaced it completely stopped and now 2 months later here it goes again except only at 6k rpm.

I can't be the ignition coil going out again already can it?

my99ekcoupe

Have you checked the actual speedometer?

wellwell

last time u had a full tune up

95_Civic_4dr

The speedo no, cause it's a tachometer issue. I'm actually not sure how I'd go about testing the gauge other than swapping in a different cluster and seeing if it continues Anyone know how I could test it or should I just go pull one from a junkyard and hope for the best?

Really hasn't been a need to since a lot of the parts are new like the ones listed above. Compression has been fine, did a leak down test - all is good. All the filters are new or almost new, cooling system is all in check - took care of that when I did the head gasket along with timing belt. Battery and alternator are maybe 2 1/2 years old, distributor is only 3.

Maybe it's a sensor causing it...idk...I'm stumped. Other than this issue, I know the injector for #4 cylinder is cracked at the tip - but I don't think it'll cause this, I mean, it runs perfectly fine I just can't figure out this jumping tach

BryanM.

iTrader: (1)

You have replaced many things that have nothing to do with tach signal.

Do you have a CEL? Would you happen to have CEL code 4?


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95_Civic_4dr

Yeah I know, some were due for a change anyway - 60k miles plus whatever the owner before me put on the parts. And the jumping seemed to cease when I replaced the ignition coil so I did the entire ignition system only to have it come back 2 months later.

Nope, no CELs. Although that does make me wonder if there's a ckp issue.

Former User

The tach signal for your engine comes from the igniter unit inside the distributor. Have it tested at an auto parts store. Also make sure the blue wire (tach) attached to the igniter unit is clean and tight.

AGENT_47

Try another tach and see what happens, you've already thrown enough parts at the problem.

Do you have a friend with the same type of car you could try and borrow his or would a junker loan you one? That way you wouldn't be throwing more money at the problem

My speedo on my 93 sol crapped out at only 30k orig miles, the dealership couldn't even figure out the problem so they put in a new one.


Hopefully it's just the connection as Ron suggested

jdmkha

It could be your speedo sensor conection wiggled off. Or maybe the sensor died on you man. C heck the sensor its located on your tranny. looking down into the engine bay it would be on the top left hand corner of your tranny. ** (SOME PEOPLE FILL THEIR TRANNY WITH FLUID HERE GIVE IT A CHECK.)

jdmkha

CHECK IT NOW!!!! LOL

95_Civic_4dr

Alright, I'll check that wire today and see if there may be a connection issue. See if I can get a store to test it over the weekend - I didn't even know they could lol.

Yeah, what I'm gonna do is check out the connection Ron suggested and if that doesn't work I have a buddy who will let me swap his cluster in over the weekend and I'll get the igniter tested.

Connections nice and snug, all the bolts are secure. But the VSS has been working fine so I don't suspect a problem with that yet - unless it does have some kind of connection in both the tachometer and speedometer?

Former User

The VSS has no connection with the tachometer.

igniter unit--->blue wire--->tachometer

teamfdudb7

on the igniter unit, pull out the wire 1 by 1 and put grease and crimp them back on. it should work fine after that.

95_Civic_4dr

Swapped the cluster, same issue.
Tried cleaning the connection RonJ suggested, worked for 2 weeks but now the problems back worse than ever.

I give up, I guess it's just time for a new dizzy.

95_Civic_4dr

Also, at the end of the ignition coil, what's the purpose of the small spring between the coil and cap? It just to help with contact?
Just wondering.

Deetz

jumping tach is a common issue of the ignitor on it's way out

95_Civic_4dr

If the ignitor was dieing wouldn't it also cause misfires and loss of power? Cause I feel no power loss, engine is revving normally, Tach just has a mind of its own.

Deetz

NO! I drove my crx with a jumping tach 2000 miles on a big hiway trip....right till it suddenly died!!!

Good thing i brought an extra with me for my trip....10 min replacement, and fixed...no jumping and car never ran better

95_Civic_4dr

Huh...I'll have to give replacing the igniter a shot then. I always thought it came with a lot more issues before the usual no-start symptom.

KLiK

Do you mean the IGM or Coil is the problem?! :/

94eg!

iTrader: (2)

If you search honda-tech for "bouncing tach", the #1 suggestion should be to replace the igniter. At least it always was back in the day.

tony_2018

Igniter