bouncing tachometer
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 950
Likes: 172
From: Westminster, CO
bouncing tachometer
I have had an unusual problem with my S2s tachometer since not long after I purchased the car September of last year. When shifting, the tachometer needle will bounce as much as 750 RPM back and forth 2-3 time before settling in. From then on it increases and decreases normally until the next time I shift. If I shift harder and am on the gas it may only bounce once in a range of about 250 RPM. All my other gauges seem to work fine, and I do not here the engine revs bouncing so I am fairly certain it is an instrument issue. I have had my cluster out a couple of times this spring, but as I had the issue beforehand I don't believe I caused it. Any ideas on a cause? Where to troubleshoot?
Thanks
Thanks
Racer
Joined: Sep 2005
Posts: 451
Likes: 0
From: OC, Ca & Phx, Az
hey Karl,
I've seen this topic up a couple times over the last few years. Check all your grounds under the dash for starters. I'd also speed sensor on the bell housing, check to make sure it's connected at the plug and still screwed in.
First things that come to mind, you might find more results using the search. Or even check clarks-garage.
I've seen this topic up a couple times over the last few years. Check all your grounds under the dash for starters. I'd also speed sensor on the bell housing, check to make sure it's connected at the plug and still screwed in.
First things that come to mind, you might find more results using the search. Or even check clarks-garage.
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 950
Likes: 172
From: Westminster, CO
Grounds under the dash looked good last month when I checked them to troubleshoot the fact my fuel level doesn't go above 3/4ths full. I didn't find much regarding a similar issue when searching, but I'll look up more info on the speed and reference sensors. Thanks for the input.
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 950
Likes: 172
From: Westminster, CO
To add a bit more information, the amount of bounce varies quite a bit depending on my shift. If I rev match well and am consistent with my application of power it only bounces a little bit. If I perform a harder shift or I am hardly on the gas it can bounce over 1000RPM.
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Rennlist Member
Joined: Sep 2010
Posts: 61
Likes: 0
From: Northern New Mexico
Any solution to this? Search gives a bunch of threads with tachs that don't work or stick at certain RPM, but not this problem... My S2 has done this since I got it a few months ago. Not a deal breaker obviously, but annoying. Is this specific to the S2?
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Burning Brakes
Joined: Apr 2005
Posts: 1,229
Likes: 1
From: cleveland ohio
my '87 S doesn't do it, so it's not a 16V thing. my 89 951 doesn't do it, so it's not an '89 thing.
I watched my tach really carefully on the way to work and back yesterday to be sure, but it doesn't do anything like you're describing. weird!
I watched my tach really carefully on the way to work and back yesterday to be sure, but it doesn't do anything like you're describing. weird!
Instructor
Joined: Apr 2010
Posts: 118
Likes: 0
From: The frozen white wasteland of the north
Grounds under the dash looked good last month when I checked them to troubleshoot the fact my fuel level doesn't go above 3/4ths full. I didn't find much regarding a similar issue when searching, but I'll look up more info on the speed and reference sensors. Thanks for the input.
