Hi Ya'll,

Need some help.
1999 Chevy Blazer 4x4 v-6 vortec 140,000

At idle, engine feels and runs like there is a miss, but more like the engine is out of balance. As you increase idle it smooths out, but when you release the throttle pedal, it feels/sounds like the engine is out of balance, almost like a bad wheel bearing as it slows down or a bad tire, but it's in the engine when your in park. Is the Torque Convertor or flex-plate an issue on these that it would only be noticeable at idle or lower RPM's??? Don't know the history on it since I just bought it, but how would I go about checking the engine, T.C. or flex plate??? Have a good diagnostic scanner. Any help would be appreciated.

ESKYMOPACK

P.S. We did notice a coolant leak on the backside of the motor, but I've had intake leaks B4 and noticed that it would act more like a miss, than a balance issue.

 

Have you inspected the motor mounts?

 

Sure sounds like ignition miss to me. Cap, rotor, plugs, wires and fuel filter. Buy AC DELCO spark plugs.

 

An engine should not just become unbalanced. I agree, sounds like a miss on deceleration.

 

Motor mounts are fine, and we used a diagnostic scanner to shut off gas flow at each injector, with no change. It really feels/sounds like something is out of balance. Idle rough, raise RPM to smooth out, and let go of pedal fast and RPM's wind down and engine feels like the crank or something is out of balance.

 

Take a look at the balancer. I have seen some of them lose the rubber isolator between the inner and outer halves. Again though, in my experience, this has been a gradual degradation of balance.

 

Thanks Kyle,

Got underneath and inspected H. balancer and can see the thin layer of rubber in between, no noticeable problems. Wondering if there is a way to inspect the flex-plate of T.C. w/o having to drop tranny???

 

Flex plates typically break and make a noticeable noise and really do not throw off the balance of the engine when they do break (I have broken a few in the past). But there is no good way to inspect it with the full bell housing that is on your truck.

 

How about an unbalanced Convertor??? I'm sorry I wrote "flex-plate fo the T.C.", I meant to write the flex-plate OR the Torque Convertor. Is it a good possibility that it could lose it's balance weight or be bad???

 

Again, IMO, things like this do not just happen.