Jumpy tachometer, any fixes (2 Viewers)

[Nickslexi]

Recently, I have notced that my tachometer jumps around erratically. Sometimes at idle it sits really low, around 400 rpm when the engine speed apears to be normal. Other times when travling steady or accelerating, the tach will bounce around by a couple of hundred RPM. Anyone have this same problem or think of any poential repairs? I am thinking that a connection may be a little loose or dirty, but don't know where to look.

Thanks,

 

[miked]

Mine does the same thing but not all the time. I can't find any correlation to temp or moister. I am also thinking it's a loose connection somewhere.

 

[BPMOU]

I too have the same issue, but only occasionally. It hasn't happened in the last two weeks, but started it doing after I ran the Redline Fuel system treatment. I'm interested in what other have to say, did you look to make sure there weren't any cracks in the intake? I didn't see any in mine. I also noticed that mine would only do this when I was getting off the highway and coming to a stop. It's idling just a bit over 600 now.

 

[miked]

On mine, I'm sure it's just a jumpy signal or connection. The actual rpm's don't jump around. I was at first concerned that maybe the ECU was seeing the same incorrect rpm and therefor setting or adjusting the timing or mixture for an rpm that the motor wasn't actually spinning at. Overall, I really don't notice or feel anything different when it happens so I've come to live with it. If I ever get one of those fancy laptop based ODBII I'll know what the ECU sees in relation to what the tach is saying.

 

[Nickslexi]

Yea, I don't think it has anything to do with actual engine operation, but merely the tach signal or someting. No matter what the tach does, the engine seems to run as normal. Even when the tach reads the engine is idleing at 400 rpm, the engine sounds exactly the same as when it reads 600 rpm.

 

[Nickslexi]

ttt for 1st page exposure.

Thanks,

 

[Riad]

After I tightened my loose throttle cable, the jumpiness went away.

https://forum.ih8mud.com/showthread.php?t=128459

 

[cruiserdan]

If the needle "lurches" suddenly that is an indication of an electrical issue, usually within the tach. Mine has done that twice that I am aware of. The fix would be to replace the tach since there are no serviced components within it. I have a backer tach in the bullpen for when mine goes completely goofey.

 

[IdahoDoug]

My 93's done this a few times I'm aware of - maybe 6 times I've noticed. Just a quick movement of the needle a few hundred RPMs with no corresponding change to the engine speed. No ill effects and I first noted it about 2 years ago.

DougM

 

[Indy Travis]

I have seen this on the Honda/Acura car's also. I have replaced the Distributor assembly. The tach gets the reading from it. I would say the Toyota's are the same way.

I'm a Acura tech if you were wondering why I would know this.

Thanks
Travis

 

[cruiserland]

my 96 does this almost always right around 2200 rpm while driving
rpm does not actually change

 

[landtank]

I had this a few years ago and then did a round of heavy maintenance and haven't see it since.

 

[Riad]

My truck some how figured out that I was posting on this thread .

This jumpy tacho has started back again today. What Dan said makes sense. IT does seem more electrical than mechanical issue.

Just curious though, is there any after market instrument panel out there that can be used or installed easily? I would be replacing it with a OEM one if I really have to. As long as this is not triggered by any kind of voltage discrepancy (alternator), I'm OK with it.

 

[Brian894X4]

Mine does the same thing too. Seems mostly at idle but very intermittently.

I know that on some of other Toyotas, the tach gets its signal from the ignitor and a jumpy tach on other Toyota can indicate a failing ignitor, but since I'm new to the Land Cruiser, I'm kind of confused on the LC ignitition system. All I see is a tiny contraption that powers the main coil wire to the distributor. Is that the ignitor/coil? Seems awful small.

 

[Bluetribal]

I have a new wrinkle to throw into the jumpy tachometer needle. My gauge issues started after an off-road trip on 1-30-11, pulling into my driveway. Once home I noticed my 'D' light went out on the dash. Then this past Friday (2-11-11) on my way home from work I noticed my tach needle jumping while at speed (65mph). And when I would let off the gas the needle wouldn't drop. But at the same time my 'D' light was lighting up again? Once on surface streets I didn't notice any issues and this week no issues and 'D' light still working.

I was going to break out my electrical manual to see if a sensor at the tranny was the culprit but the dizzy cap mentioned above could be the issue too but doesn't explain my 'D' light.

 

[dallen341]

My Chevy TBI motor will have the jumpy tach issue when the plug wires go south. Check your plug wires lately? Different motor I know but....

 

[greenseaman]

I've got the jumpy tach too!

 

[Cruisin']

I will throw in my $.02 I have the occasional jumpy tach (usually at idle, though sometimes it will be up to 400 out while on the highway). My truck is a diesel 1HD-T, so no distributor to get a signal from there. I'm thinking Dan hit it on the head that its within the tach assembly in the dash, since most likely the diesels and gassers get their signals from a different source, and the problem is the same. I haven't been able to nail down a definite pattern, though when it acts up, its usually a cool and damp day out.

 

[Layonnn]

Mine does the same thing but not all the time. I can't find any correlation to temp or moister. I am also thinking it's a loose connection somewhere.

Same here. ? Very sporadic and doesn't happen often, when it does its only for a few seconds or so.

Though, when looking at it via the scangauge the RPM stays the exact same.

 

[scrowley]

Old thread. Another random jumpy tach here.