Eratic tach

WONKABOY · 10-11-06, 06:16 PM

I hope i can get some feedback on this one before i have to take my Vette to the shop , here it goes , it seems for the past couple of days when i start her up there's no choke and i have to keep my foot on the gas , then about a couple of minutes the choke comes on with a high idle and after a good warm up i'm able to kick it down , is the chock an automatic with the heat riser or is it a electric? Second problem, when i start her up from a cold start and drive along even a highway speeds i see the tach jumping up and down and of coarse i can feel hesitation in the motor, this last for about maybe a good 10 miles then all is well ? i thought it would be bad gas but i noticed i have to drive it for awhile as stated and it goes away? Would it be the choke not fully out? I just had a tuneup , plugs, wires, cap but that was like 2 months ago and it was fine , so i'm guessing it's the carb , i would not think it be the coil because like i said you have to drive it for a while and all is well? Please help with suggestion's!!! I was thinking i should spray the carb with cleaner too.

Thanks Rick

hdkeno · 10-11-06, 06:56 PM

Rick,you may,or may have not seen my earlier posts,on this,which seems very simalar to the problem that i had early on with my 81.

In my case the car all of of sudden would run rough,and tach would go crazy. I too thought bad gas,changed filter,cap rotor,and ignition module.
(the cap and rotor were original with 41k andd 25 years so they were due to be changed anyway.

Turned out to be a bad TPS throttle position sensor,which is in the carb.

I also had to change the ecm as from day one i never got a "check engine"
light.

Ever since then runs,idles perfect.

Hope this helps, Ken

WONKABOY · 10-11-06, 07:07 PM

Quote:

Originally Posted by hdkeno

Rick,you may,or may have not seen my earlier posts,on this,which seems very simalar to the problem that i had early on with my 81.

In my case the car all of of sudden would run rough,and tach would go crazy. I too thought bad gas,changed filter,cap rotor,and ignition module.
(the cap and rotor were original with 41k andd 25 years so they were due to be changed anyway.

Turned out to be a bad TPS throttle position sensor,which is in the carb.

I also had to change the ecm as from day one i never got a "check engine"
light.

Ever since then runs,idles perfect.

Hope this helps, Ken

Thanks ken , i hope this is what it is , as you know i live in Connecticut too , so where did you bring your vette to have this problem dio-noticed ( bad spelling ) and fixed and what was the charge$ Yes my check engine light comes on when sitting idle in drive or park but never while driving...

hdkeno · 10-12-06, 03:57 PM

Rick, the guy that found and fixed the problem owns Spring Street Auto in Windsor locks.

Back in the day (late 70's to mid 80's) he worked quite a bit on corvettes at a Chevy dealership, very familar with the c3 and c4 vettes.

That is about an hour ride from you tops traffic permitting. But you may want to consider him if nothing else works.(his name is Clark) phone #860-627-7495

later ken

WONKABOY · 10-12-06, 04:57 PM

Quote:

Originally Posted by hdkeno

Rick, the guy that found and fixed the problem owns Spring Street Auto in Windsor locks.

Back in the day (late 70's to mid 80's) he worked quite a bit on corvettes at a Chevy dealership, very familar with the c3 and c4 vettes.

That is about an hour ride from you tops traffic permitting. But you may want to consider him if nothing else works.(his name is Clark) phone #860-627-7495

later ken

Ok ken thanks so much, i will give him a call very soon