Jimster480

Recently my tach has started jumping around when I accelerate my car. Usually once I pass 7k it jumps from between 6XXX and 8XXX RPM frantically. Yet the car will still hit the rev limiter at 7500, although on the tach it could show any number at the time it hits the rev limiter since its jumping everywhere.

Anybody know what causes this or how to fix it? Its really annoying, especially when your trying to race because I cant shift at the end of my powerband (7200) when my tach is jumping everywhere.

vtechjunkie

iTrader: (2)

This happened to me, and it turned out to be the ignition control module. You can buy those at Checker/Autozone, and just replace that piece. I just bought a new dizzy.

Jimster480

I just replaced mine a few months ago :/

Matt93eg

My tach started doing something similar to that last month..just out of the blue one day while I was driving. I didn't know what was causing it, did some searching and couldn't find anything concrete. My tach needle would jump around and it got to where it wasn't reading the correct RPM. It was showing my engine was idling at like 1300 when it was actually normal at like 700RPM. Then as soon as I let the clutch out in 1st it would start climbing from 1300..there was no way that was correct. I could be accelerating and be at what the needle showed 3000 and then in a blink of an eye it would bounce up to 5000 which was BS.

I kept searching and searching for a solution and ended up pulling my cluster apart and taking the damn needle off..it was pissing me off seeing it reading incorrectly and jumping around. So now I have no tach needle and it sucks. I am in for a "concrete" answer on this as well as you Jimster.

Looks that "Ignition Control Module" thingy ma jig is roughly $115.00 bucks from Advance Auto Parts..I just got my windows tinted and I am broke.

Jimster480

Well I replaced mine a few months ago with a used one. I really hope its not that **** again. But my tach has always been off by a bit. becaues it says I redline at 7800. Even though I have a shift light at 7400 and a rev limiter at 7500. But now my tach can jump into 8k. And i know for sure that my motor doesnt go from 6800 to 8400 and back in .1 seconds especially when im accelerating smoothly :/

I'll ask my buddy to borrow his again one of these days when its not so hot (won't hold my breath for one of those days) and swap them out and see. Because if it fixes it he can always have my fkd up one, since he doesnt have a tach on his DX :X

Matt93eg

Well let me know what you come up with. Its already gotten hot here to..glad I got cold A/C in the car this year. And I don't mind not having the tach during regular driving but when I accelerate hard I get where I can't shift right at the end of the powerband just like you were saying..I either shift before or after instead of right at the sweet spot.

I just did some more searching on this matter BTW and still didn't come up with anything concrete by any means...

Jimster480

Yea I got my AC working too for the summer Now I'm just saving up for a retune to 22PSI, but I'd like to get this issue fixed first, it sucks not being able to shift at the right time

Matt93eg

on the A/C. I have had my car like 6 years now and have never had A/C. I was not going another summer without it so I sourced the parts from a wrecked 95 and swapped everything out. Now I have cold A/C..loving it so far. I can actually go somewhere and not be soaked in sweat and pissed off by the time I get there. Now I just need boost and I will be set.

Looks like I am getting a good full time job(waiting on some paperwork to come back)so then I can get myself out of the rest my debt and start saving money, then Turbo time. Being Un-Employed sucks..freakin layoffs.

EDIT: BTW Jimster, I have a spare Distributor(Ignition Coil is bad). I looked at it and the blue tach signal wire indeed goes to that Ignition Control Module that Vtechjunkie was talking about. I am gonna swap that one out with the one that's in the dizzy in my car tomorrow(if time permits), put the needle back on my tach and see if anything changes. I guess its worth a shot. I'll let you know what I find.

Jimster480

I've always had A/C until like 3 months ago when my AC belt broke. So I fixed it about a month ago. I know that the tach wire does come from the ICM, because like I said I just changed my ICM about a month ago. Btw the AC in my car is so cold if I leave it on for too long it freezes the vents :X

jayWknight

iTrader: (3)

I had the same issue with civic. What I did was to make sure all my connections to the icm and ign coil was tight. I also replaced my cap and rotor; everything return to normal.

Jimster480

@Matt93eg Well did you swap it out and did it fix it?

Matt93eg

Jimster, I didn't get a chance to mess with it last Thursday like I hoped, I got a call last Thursday morning from a guy I interviewed with the week before and he wanted me to start my new job last Friday. So I spent Thursday running around getting things in order and then worked 12 hours Friday and haven't been able to get to it this weekend either.

Hopefully I can swap it out within the next couple days and let you know something. Apologize for the delay.

MADMATT17

This happened to me . Check your grounds there tonching somethng

Jimster480

I've already done that.

black300zx

Just to toss another idea out there - Yank your gauge cluster and see if there are any broken solder joints on the board. This happens occasionally on the Z32s and will cause some of the gauges to start jumping around. If you do find a broken solder joint, reheat the joint to melt the solder and all should be good again.

Jimster480

Well I've never heard of anything like that happening on a Honda.

Matt93eg

Jimster, I sent you a PM regarding the ICM.