DFI, Batch Fire, and other myths

[Shannen Durphey]

Geoff Richards wrote:
> 
> ----------
> <snip>
> > According to a service bulletin, the 3.8l engine suffers from carbon
> > accumulation on the back of the intake valve which significantly
> > reduces performance.
> 
> How to remove this carbon ?
> Possible with the myriad of 'carbon blast' type of miracle cures,
> you know the cans of cleaners etc,run 'em through the engine
> while running or pull the heads?
> Geoff
Apparently, walnut shell blasting.  GM claims that no chemical works,
but I would be interested in seeing the results from properly applied
Top Engine Cleaner.  A mechanic I worked with left some in a cylinder
on night while the head was out for reconditioning, and the piston
wiped clean like new in the morning.

Shannen