Once again took the vehicle to the local dealer where it was purchased. dealer stated that all spark plugs need to be changed (@43k miles) because of fouling do to the fact that if this engine (GM 3.5 V6) is not run on the highway every so often, carbon builds up in the intake and fouls the plugs. Paid for the service and as soon as I drove away same issue occurred. Took the car back and told no misfires possible, bad tach needle. Yet the loss of vacuum and change in brake pedal "hold" could not be explained.
Has anyone else suffered this fluctuation in RPM at or near idle.
Update from Aug 17, 2016: After doing several CRC intake valve cleaner treatments along with fuel additive treatment this is still an on going issue. doing treatment apprx. every 5k Miles.
Once again took the vehicle to the local dealer where it was purchased. dealer stated that all spark plugs need to be changed (@43k miles) because of fouling do to the fact that if this engine (GM 3.5 V6) is not run on the highway every so often, carbon builds up in the intake and fouls the plugs. Paid for the service and as soon as I drove away same issue occurred. Took the car back and told no misfires possible, bad tach needle. Yet the loss of vacuum and change in brake pedal "hold" could not be explained.
Has anyone else suffered this fluctuation in RPM at or near idle.
Update from Aug 17, 2016: After doing several CRC intake valve cleaner treatments along with fuel additive treatment this is still an on going issue. doing treatment apprx. every 5k Miles.
- franks71vw, Miami, FL, US