JimMueller

iTrader: (9)

I'm trying to track down the source of my intermittent backfiring, and during diagnostics today found that my injectors needed cleaning. The tech advised that the old condition would cause the injectors to stay open too long, and could be dumping extra fuel and causing a backfire.

With the engine off, the rail pressure started at 60psi. Using a Tech2-type tool and the engine off, the tech cycled each cylinder and it reported cylinders 1-7 were dropping to 32psi, and cylinder 8 was dropping to 22psi. After cleaning, they all dropped to 52psi. He suggested using Chevron Techron fuel additive every 500miles, but I personally think that's excessive.

On the way home, it was still misfiring, so I'm a little disappointed I didn't fix the desired problem. What sort of issues could I witness when the injectors were in the uncleaned condition?

Old Geezer

iTrader: (3)

How were they "cleaned"??

JimMueller

iTrader: (9)

He hung a container from the hood latch which looked similar to a large catch can. The container had a combination of fuel and GM Top End Cleaner in it. I think he pulled just one fuse/relay, I think for the fuel pump, then connected the container direct to the fuel rail. I think he had another tube attached to the container, don't recall where that went. He said the container was acting as my fuel tank & pump... then he let it idle until it ran out of the mixture and the engine stalled. Then he re-tested the injectors and then reconnected all the original items.

Edit: What I witnessed reflected the steps in this link, although I wasn't out by the car the entire time to see all the steps.
http://60degreev6.com/forum/showthre...l=1#post313285