If the problem is caused by heat related premature failure of valve guides than an italian tune-up will only make the situation worse and gasoline additives will do absolutely nothing. The only suggestion I've seen for reducing the temperature of the exhaust valve guides is to remove the undertray.

 

The Italian tuning, Chevron gas and not lugging the engine are to prevent carbon build up from the combustion (or partial combustion) of the gasoline.
If your valve guides and seals are new or excellent, the source of carbon could be from not doing the above.
If the valve guides and/or seals are shot, then it is burned oil that is responsible for the carbon deposits.
Just my take on things.

max

 

I've seen the suggestion of OBDII reset. My understanding, though, is that the system will still record the fault and that, as a result, will still not pass smog. Can someone confirm or rebut this? I guess this thread is slowly building up into one of the many threads on this topic.

 

The OBDII scanners will reset the error code, but the "readiness flags" are also flipped off at the same time, so must also be reset before you can pass most smog tests. In another thread on this issue I posted a link to a page I've uploaded which explains the readiness cycle issue.

 

ecob993;

Please point me to the thread that talks about the readiness cycle issue.

Thanks;

Don

 

Of the many, there is a thread, "Kill the CEL for $99.00", which goes into a little more detail regarding fixes and links. One link lists the codes:

http://www.onboarddiagnostics.co.uk/obdcodes.htm

In line with Father of Three's question: I would like to know if anyone out there has slipped passed a California smog test with one of these DIY methods, and not simply at the local P garage with your mechanic doing the check but, at that pesky check at a "California Smog Check Only" garage where it must be taken on specific years.

For those of us in California and other mandatory low emissions states, this is definitely a very relevant topic which will find itself much more important as the cars age.

Thanks for any input.

 

https://rennlist.com/forums/showthre...hreadid=135229