I used sea foam today.. Engine now run rough..i removed 1 sparkplug wire at at a time. Engine should mis when each wire is removed but when i remove the #2 plugwire the engine speeds up..

Sounds like i have a small knock or rattle in engine on decelaration .. Please help

i sprayed the seam foam in a fine mist with small paint gun into intake..

I would check the distributor cap for a crack or carbon trace. #2 cylinder may be igniting prematurely by the ajoining plug wire in the distributor cap. Had this happen once on my Mazda 626.

So i may have carbon in cyl or wedged in valve? Was running fine until i used sea foam... Thanks

So i may have carbon in cyl or wedged in valve? Was running fine until i used sea foam... Thanks

Not really sure it's related to the sea foam. Can't see how that would effect only one cylinder. It sounds more like an electrical arc in the distributor (or between wires if they are old) that causes #2 to fire before it should.

I think it was a piece of carbon..#2 cyl is fine now but i still have the rough idle.. i think i really screwed up by spraying the seafoam in the air flow meter...???

From all you've described here and elsewhere, it sounds like dirty/sticky valves. You might have swollen some varnish with the sea foam, causing the valves to stick worse. If you keep cleaning, the problems should eventually resolve.

thanks for the advice...will keep trying..removed one plug and found alot of carbon residue left over. thinking of running gas through the intake using vacumn hose.. any suggestions?

Pull the vacuum hose from the brake booster and pour the seafoam into that hose and run the engine. That's how I used to do it when I had my Z and 810.

update..i removed valve cover and found #2 valve was loose enough to move side to side..going to remove head tomoorow.. im thinking valve guide..any suggestions on rebuilding head or buying a rebuilt head? thanks.. and any one know the cost?

I just paid $400 at a carquest machine shop, here what I got-

2 new valves, new exhaust guides, valve and seat grinding, tipping off the valve tips to keep them the same installed height, resurfaced head. Gasket set is another $50, I used Felpro, which includes the valve seals. The book by Frank Honsoweitz on how to rebuild your nissan L-series engine is a great investment, lots of detail on the does and dont's of rebuilding. good luck

Eric

thanks.. i counted on 4 to 500...anything i can do to give more performance... just to the head?