tach reads wrong
Thread Starter
Instructor
Joined: Oct 2005
Posts: 143
Likes: 0
From: Lincolnshire,ENGLAND
tach reads wrong
Is there any way to re-calibrate the tach
Car is an '91 L98 6 speed, Idle reads aound 1200 rpm on tach (checked with scanner, shows around 750 rpm)
When driving in 4th gear it red-lines at 95 mph!
Make me wonder what rpms im really shifting at when flooring it and shifting at the red line?
Whats causing this? any way to rectify it?
Car is an '91 L98 6 speed, Idle reads aound 1200 rpm on tach (checked with scanner, shows around 750 rpm)
When driving in 4th gear it red-lines at 95 mph!
Make me wonder what rpms im really shifting at when flooring it and shifting at the red line?
Whats causing this? any way to rectify it?
Le Mans Master
Joined: Aug 2005
Posts: 5,002
Likes: 5
From: No Opti Here Tn
St. Jude Donor '06
Not sure but I think the service manual addresses this very thing
If I remember correctly it said something about a filter on the tach
I hate to be one to say Check the FSM but
Check the FSM
If I remember correctly it said something about a filter on the tach
I hate to be one to say Check the FSM but
Check the FSM
Pro
Joined: Sep 2006
Posts: 702
Likes: 2
From: Conyers Ga
This will also happen with certain aftermarket ignition coils. I installed an MSD coil and my tach went nuts. The more gas I gave it, the lower the tach went. I went back with the OEM and all is well now..........
Thread Starter
Instructor
Joined: Oct 2005
Posts: 143
Likes: 0
From: Lincolnshire,ENGLAND
Originally Posted by nyernga1
This will also happen with certain aftermarket ignition coils. I installed an MSD coil and my tach went nuts. The more gas I gave it, the lower the tach went. I went back with the OEM and all is well now..........
Had a bad tach filter on a C3,and it didnt behave like this.
Ill go back to a delco cap/coil,see if it helps.
THANKS
Pro
Joined: Sep 2006
Posts: 702
Likes: 2
From: Conyers Ga
Originally Posted by 77vetteuk
AH, that'll be it then-DUI cap and coil installed since i bought the car.
Had a bad tach filter on a C3,and it didnt behave like this.
Ill go back to a delco cap/coil,see if it helps.
THANKS
Had a bad tach filter on a C3,and it didnt behave like this.
Ill go back to a delco cap/coil,see if it helps.
THANKS
Even a blind squirrel finds a nut every once in a while.
Let us know if that solves it.
