Hi, I have performed a compression test and all those 3 cyclinders are at 160. I have had the injectores tested again today on a test bed and obsered the spray patterns. All ok. I have mechanically tested the timing with a timing light on indivudal cyclinders against the crank. All ok The injestors are runnning multi point at the moment anyway and mixture on that bank was tested with an o2 sensor and was ok . I have removed the new plugs that have done 10 mins of operation and they are all of a normal color and all the same color. Havent really checked the blow by if any but i will do that tonight. I am running an intercooler and only 6-8 pounds of boost at the moment with hight Oct fuel. I have adjusted the valves and also removed the rocker cover and re checked and they are and where ok. Thanks for all the suggections. I will keep you posted. Cheers, Nick Posted by: "David Teitelbaum" jtrealty@xxxxxxxxxxxxx jtrealtywebspannet Date: Mon Nov 6, 2006 12:21 pm (PST) Examine the spark plugs. If they are white (or at least much lighter than the others) my guess would be that somehow those cylinders are running leaner than the others. Maybe the "O" rings are not seated properly or somehow your fuel system is undersupplying those cylinders. Also do a compression test. Maybe the head gasket is leaking. Are you getting much blow-by? I had an engine that sat for years and the rings were not sealing good on a couple of cylinders. They eventually did start to seal better after a while of driving. It can also be that those cylinders are just running hotter than the others so they are going to be the first ones to get to detonation. Limit your boost to 6# unless you either intercool or change the pistons. Use the highest octane gasoline you can get and maybe retard the timing. On the Island Turbo set-up the mechanical advance is taken out and the base timing is set back a few degrees. It probably wouldn't hurt to check the valve adjustments either. You should run synthetic motor oil and change it, the air, and the oil filters every 2,500 miles. David Teitelbaum vin 10757 To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/