It starts at 0 the i turn the key to ign access and it jumps to 500 RPM. I then start the car and it reads very high (2500RPM on startup). I got this problem after I removed the instrument cluster to clean under the glass and replace one of the gauges.

I have a race tomorrow and I sort of need a functioning tach.


Thank you.

 

Let's see the facts:
(1) worked fine.
(2) you took cluster apart to clean under the glass.
(3) now the tach is hosed.

Easy conclusion: you did not put something back together correctly.
Options: buy another dash or take apart and fix your mistake.

So why are you asking us when you already know this. Expecting a miracle?

 

Urgent?????

Your car runs fine. What is urgent about this situation???? Never mind telling me. I don't care.

 

if its reading 500 more thanbefore just shift 500rpm later!

 

I'm also tired of people putting 'URGENT' or 'PLEASE HELP' in their titles.

If you think this is urgent you have had a very easy life.

 

In the past 10 years of posting on car forums this is actually the 1st time I've ever put 'Urgent' in the title. Go figure!

I guess it just feels urgent to me because I am supposed to be 300 miles away prepping for a race right now. It's also kind of difficult to race with a tach that is that off.


cewrx7r1 / Adam c : Thank you for your insight, it's nice to see that kind of dedication and spirit from longtime members.




For anyone that searches I did find out how to set the tach. I pluged the cluster in (cluster only no glass or hood) and started the car up and waited until it was warmed up. Then I took the tach needle with my finger and pushed it back to the stop pin. When I let go it went right back to 'high idle' (1700 RPM), so I tried pushing it back and lifting it over the stop pin then pushing it back until I felt some resistance. When I let it go this time it was at 1000 RPM. I just repeated the process until it was at 720 RPM.

 

Here is some more helpful insight

Where in the FSM manual did you find that procedure for tach adjustment???? It obviously isn't the correct way to do it. It sounds like you may have ruined the mechanism that calibrates the rpm readings.

Oops!!! I forgot that I don't care about this "urgent" matter .

 

wow...harsh...

 

If SIP had somehow hit the tach needle while messing with it and this caused the needle to rotate on its spindle, then re-rotating the needle is the only way to fix it.


Bit since it was working then he screwd it up, there is noway anyone but him knows what happened and he needs to figure it out his error.
Analysis of what you did that caused the problem is the first step. It isn't like some god is punishing you and made it go bad at that exact time.

Personnaly I would use an O-scope to measure rpms and then move the needle to match. Or if using another ECU figure how to accurately determine rpms.

But what do I know? I am only an ex USAF micro-wave comm. and ground nav-aids tech and retired I.T. supervisor.

 

i have the same problem with my speedo mate, noone ever helped me with that, only answers i had were"buy a new cluster" bla bla bla...
my problem is that after i removed the AC my speedo reads 30mph(on idle, when my car is parked up) then when i turn ANY electrical device on (pop up the lights, turn the light on) problem disapears..

ioh and if i disconnect the airpump and start the engine -everythiung is fine - i though it might be something with grounding...

still havent sorted it - gos something really bad issues with my boost so im not bothered..