cruiser

My RPM gauge has been acting up lately. Usually it shows right RPMs, but sometimes it just drops down to 0RPM (when cruising) or on Saturday at the trackday it was showing 4-5k RPM whereas I was already past that shift-"beep".

What can be causing this and can it be fixed ? Anyone experienced this before ? Car has about 80k miles on it.

RX7SpiritR

iTrader: (1)

It may be a possible loose wire, or its just a bad gauge which means your gonna need to swap out a new one I would get the FEED gauge pod........comes with the 300KM/h speedo and 10,000 RPM tach. Hope you find out what's wrong and fix it. Good luck.

saxyman990

It's possible that the gauge is bad, but most likely it is a grounding or short problem somewhere. Connect a Volt meter to the tach signal in the diagnostics port. This will give you an idication of where the problem may be located (this is assuming that it is an electrical problem).

300km/h speedo, and 10 grand tach? how worthless.. and you have to pay what? $800-1000 for it? If the gauge is indeed bad, it can be replaced with a gauge from someone parting out their car for a fraction of that price...

Just my $0.02.

Good luck,
Rob

cruiser

What should I be looking for on the voltmeter ?

I assume its the speedo also, as it usually works. If it were the gauge then it would probably consistently show bad readings, no ?

Mahjik

iTrader: (1)

You should also check the back of the gauge cluster for the solder points on the tach. I've read old threads of those solder points breaking loose and causing some strange readings on the tach.

RX7SpiritR

iTrader: (1)

It may not be worthless to me though. It is your opinion though and I respect it. But I may be able to get it for a hell of a lot cheaper than what your price range was. But we'll see.

saxyman990

very true, that is just my opinion. I came up with that price by doing a quick search on JT-Imports site (usually one of the few places where you can get odd parts like that). If you can find em cheaper, and you want em, then more power to ya. Even if I don't agree with you, I still respect your opinion.


Basically, you need to look for a correlation between what the voltmeter says and what your tach is doing. If your tach is going wacko, yet the voltage at the diagnostics terminal seems stable, then the problem most likely resides on the tachometer side (probably the solder points as Mahjik pointed out).

On the other hand, if the tach starts going wacko and the diagnostics connector also goes wacko, then its more than likely on the sending side of the system.

These aren't definate solutions, and this is by no means fool-proof. But at least it'll give you a place to start troubleshooting. Electrical problems are some of the biggest pain-in-the-*** problems that cars can have. Good luck. If you need any more help, just ask.


Rob

RX7SpiritR

iTrader: (1)

true true.

FDjunkie

This sounds a little like a problem I had starting a few weeks ago. My tach didn't drop to zero like yours, but it did begin bouncing at times with the needle swinging back and forth about 500 RPM.

I searched and found that a few others had reported similar issues that could be corrected by reordering joints inside the tach.

I never found in real set of instructions, so while I attempted this repair I took photos and did a write-up. I call it a work in process because I'm still watching it to be sure it's completely fixed. Either way I was able to make a huge improvement. I tried to post a picture showing the suspect solder joints, but couldn't get it to go.

If you would like a copy of the procedure just drop me a PM. Its in pdf format and is about 500K.

911GT2

Just wanna add my broken tach experience.

The day after I got my car back from KDR as I pulled into the parking lot at work, I looked at my tach, and it read 0. Freaked me out, cus I had the radio on, couldn't tell if the engine was on or off. But anways, it was on, tach said 0 rpm. On the way home that day, the tach didn't work until the car got up to operating temps, then it worked fine. This pattern continued for about a week.

Then the tach started working at completely random times, sometimes it'd be working, other times not.

Now, it never works, but it moves every now and then. The majority of the time it sits at 0 rpm, but today for instance, I was on the highway, in 5th gear, looked down and it was reading 5500 rpm, and climbing. PFC was claiming 3100 or so which is accurate @~80 mph.

I took my entire dash apart, took the tach out, and resoldered the connections per directions I found somewhere on this site. Twice. I'm tyring to decided if I should ignore the issue, since I have the PFC, or get a new cluster from Mazda for insane amounts of money, or try to get a used one. I've been deciding now for 3 months.

Long story short, don't bother trying to fix it, many have died, yours is dead too. Accept it, and buy a new one.

cruiser

Doh!

I'll take it out and see if I can get it fixed/fix it. Real problem with troubleshooting this is that it does this on completely random basis. Although my FD could use some new grounding. Hmm...

Is it hard to take off the gauge cluster ? Any precautions I should be aware of ?

Mahjik

iTrader: (1)

It's not a huge deal. Two bolts to drop the steering column and just a few screws for the panels. Then just pull the cluster out.

GsrSol

Mine hasn't worked for months, it'll jump/work every once in a while for a second like 911GT2's.

Anyways while one of my friends was driving my car he kept hitting the top of the cluster and the needle would jump up so I am almost positive it's in the cluster somewhere. You can try that instead of the voltmeter.

pietrino

iTrader: (1)

Any know fix procedures??
i Had it, but now i lost after a pc format.
Try to rach again and post it here
Byes

NVMYRX-7

iTrader: (24)

Same problem here, post fix

NVMYRX-7

iTrader: (24)

^

GTI337

had this problem a couple weeks ago with my tach. cleaned the 2 crank sensors with brake cleaner and it hasn't happened again

NVMYRX-7

iTrader: (24)

First time I have heard of this fix, but I'm willing to try anything before taking the dash apart. Where are the 2 crank sensors located at and do you have any pics of them?

TireSmokin7

This isn't like you to not post the link.

cruiser

Ok, this got my attention also. I'm not a mechanic, but as they say... a picture says more then a thousand words

cruiser

Alright, I think I found them

Its the two pistons behind the pulley. If I'm wrong, somebody correct me quick

EFS.O

Nope,these are the flux capacitors...

TireSmokin7

I got my new flux capacitors here.

http://kalecoauto.com/index.php?main...products_id=28

They helped my tach out for a while but then it started again.

cruiser

Ah crap, someone then please post a pic od the CAS so we can clean it

TireSmokin7

Check the link I posted...

Flux Capacitors are De Lorean parts used in the move “Back to the Feuture” for time travel.

You posted the correct parts friend, we're just messin with ya.