tach problem

billy6351

Original poster
Member
Apr 1, 2012
3
I have an 03 trailblazer and I had a code for the therstat but the truck would buck and the tach needle would jump when the it hit 1800 to 2100 rpms but the speed do would be ok. the only code was for the thermostat which I replaced and alos replaced the fuel filter, blet and put in ac delco plugs code was cleared themp ok but still have the same problem when at 1800 rpm , stepping on the gas pushes thru the problem but whne the tach hits the same area it bucks.

I was thinking of chamging the vss but doesnt that only work to tell the tranny to shift, my last resort to to have the cylinders checked for leaks, I was told it could be the valve seats could be wearing that meand a new head and motor work.

Please advise with any help
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Checking compression is always a good thing, but more importantly if you're getting misfires. No codes? No flashing SES light? How many miles? Check for vacuum leaks, and an oily CPAS unit. Valve timing could be messed up by a bad CPAS, which may or may not throw a code.

I don't think it has anything to do with the VSS.
 

billy6351

Original poster
Member
Apr 1, 2012
3
the roadie said:
Checking compression is always a good thing, but more importantly if you're getting misfires. No codes? No flashing SES light? How many miles? Check for vacuum leaks, and an oily CPAS unit. Valve timing could be messed up by a bad CPAS, which may or may not throw a code.

I don't think it has anything to do with the VSS.

ok the truck has 109,000 miles run strong but I do notice that three out of the six plugs had oil on them when I change them, where is the cpas located soI can change it
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
Sorry if I'm miss-reading, but, is there an actual miss? Or is the tach just jumping?

Is there oil on the tip of the plugs? Or just the threads?

If it's just the threads, it's probably just a leaking valve cover gasket.
 

billy6351

Original poster
Member
Apr 1, 2012
3
the truck bucks and feels like it losing power but when its given gas problem goes away, I did see oil on the threads and I cant be sure it was on the tip could have been
 

Forum Statistics

Threads
23,330
Posts
637,982
Members
18,531
Latest member
MEHMET ONUR

Members Online