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The Right Spark Plugs (thanks to IA)

I bought my 85 UrQ freshly tuned up in August and have put about 8000 miles on 
it since then.  (Yes, I feel guilty about using it as a driver, but can think 
of no car I'd rather drive for a 120mi/day round trip commute in WI.)  It has a 
K24 turbo and IA stage 1 mods.  Otherwise stock.  It had always surged a bit on 
full throttle acceleration, something I had always attributed to the higher 
boost pressures.

On a trip down to Chicago this weekend (to look at two SAAB 900 convertibles 
for my wife.. both sold in the two hours it took to get there... still looking 
for an 87-94 turbo 5 speed with low miles...the Audi conv't, while much more 
attractive, is simply two slow and lacks the proper number of pedals: why not a 
quattro turbo convertible?) the UrQ started bucking sharply on any boost.  
Started and ran fine, drove fine until boost starts.  I assumed I had blown a 
hose somewhere (though they were all new) that was only leaking on pressure 
vice vacuum.

Upon getting it home and carefully checking everything over, all I could find 
was evidence of a slight valve cover leak which I had not noticed before.  I 
then checked the distributor (new wires, new cap) and pulled the plugs: Bosch 
Platinums.  (Although only a few months old, one also had a cracked insulator 
on the center electrode.)  Now I can't get these plugs to run right even in a 

I remembered seeing "tech tips" on plugs on Ned's page and rechecked it.  He 
had the bad plugs figured correctly: WR7DP.  He suggested the W7DTC with the 3 
ground electrodes. (I couldn't locally find the F5DPOR.)

What a difference!  I must have gained at least 50hp across the board, even on 
low end.  No surging; smooth power all the way to redline.  And I thought the 
UrQ was fast before...   I had never seen plugs exhibit symptoms such as these 
and wanted to pass along the hint for any troubleshooting of surging/misfiring 
under boost.   (Oh, I replaced the valve cover gasket while under the hood as 

Bill Elliott
Lake Mills, WI