Recently my newish VMC has developed a tachometer flutter:
* Sometimes, the tach does not begin to work until around 5 minutes of drive time.
* Tach drops/dips at any given RPM, and doesn't really rise about 4k rpms
The videos give a small glimpse of the issue.
Videos: https://imgur.com/a/sxDcIoF
Is this a wiring issue or battery issue?
Just a note: this is a gauge issue only, the car runs/revs normally.
Anything I can easily remedy?
Thanks in advance for any help.
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Ok, so the simplest thing to try is to open the engine cover and find the ignition coil. There should be several wires connected to it and may be secured either by nuts or by 1/4” fast-on tab connections.
Make sure all of the coil connections are tight. Sometimes those fast-on tabs loosen up (or were loose when installed) and can be a problem. Gently squeeze them with a pair of flat pliers to make the connection tighter.
Try looking up under the dash and make sure the connections on the back of the tach are tight, too.
If that doesn’t change things it may be the gauge unit itself. I am NOT familiar with those newer gauges but it may have DIP switches on the back to select the number of cylinders. If it does, sometimes the DIP switches need to be cleaned by flipping them both ways a few times and then re-setting them to the original positions. If it has acted like this from day of delivery, the DIP switches may be set to something other than a 4-cylinder, which could make it read lower.
If that doesn’t apply (i.e. no DIP switches) then call Greg, the builder, for his input. (Or start with Greg in the first place!)
could be Chinese crap...my last car from Kirk he sent me 3 differnt tachs,all junk,,he finally had 1 rebuilt at N. Hollywood and it worked perfect,,he paid for it..
@Gordon Nichols Thank you for that information. I'm as green as it gets when it comes to these things, so I'll check the 1/4" fast tabs and under-dash wiring this weekend. Already texted Greg, and he usually replies quickly. Just wanted to check if any other owners had a snappy fix to a problem that is really "cosmetic" in a sense, as the car drives/revs perfectly.
Your gauges are our new(er) version VDO and although Greg does not buy them from me, I am familiar with them. We have had very few tach issues and the majority of the ones we've had were related to other loose wiring at the back of the gauge, loose wiring at the coil or a failing distributor/coil. That isn't to say the tachs are infallible, I just haven't experienced it over many years of use.
I assume from your comment the tach worked well previously? A positive answer here would eliminate the dip switches being in the wrong position.
What distributor/coil do you have?
He has a CB magna spark. I already sent him a text we need to adjust the gap in the module in the distributor.
