Please note that this process was written by C5-TECH. Since there was
not a tech tip for the C5 yet and the overwhelming response to a thread I
posted regarding this issue…I thought you all could benefit from the
pictures of my decarb.
Disconnect the pcv line by the throttle body and insert a long funnel into
the vaccum source end.
SLOWLY pour 2 cans of GM top engine cleaner into the funnel while an
assistant in the car maintains idle.
When you get to the end of the 2nd can, allow the vehicle to stall,
creating a fog effect in the motor. **Note if you don\’t feel
comfortable letting your engine stall, you may simply turn off your motor
after all cleaner has been poured in**
4. Let sit for 12 hours.
5. The neighbors will love it when you start it the next day.
Hit the throttle to blow out more at higher RPMs. (Don\’t redline, just
up to half throttle is good)
drove it for about a mile afterwards and hit the throttle hard to make
sure it all got out….then did an oil change…the oil did look like it
needed it too after the decarb. (I had only 2000k miles on this oil, and
it was a very good idea to change it.)