Hey guys,
Recently bought a used 2004 A/T RX8.
Previous owner changed the coils and spark plugs about 2months prior to me buying. I later discovered (today) that he used RX7 plugs - NGK BUR-7EQ leading and BUR-9EQ trailing but he didn't shim the trailing plugs.

Car worked fine for about 1 month then I started having hard start issues- i.e
Car starts perfectly fine on first/cold start ups and starts again easily after the engine warms or after a run if I switch off then immediately start.
However If I switch off and leave for a few minutes , I have to crank several times to get it started.

My question is -could the longer RX7 Trailing plug have deformed my housing and be causing low compression thus hard starts?

If I shim the Trailing plugs or change to OEM plugs ,will the problem go away?
Or has my engine been permanently damaged?

Thanks

 

From what I read, the BUR-9EQ has to be used with a 2mm shim in the trailing position. If they weren't shimmed you might have damaged you apex seals, not your housing.

 

common complaint around here unrelated to the plug/shim issue . BTW - I don't run shims with the BUR9EQPs either but it is a good idea to at least put an extra crush washer on them .
check this thread .....
https://www.rx8club.com/series-i-trouble-shooting-95/hard-starting-suspect-your-starter-motor-check-out-207244/

 

I bet the plugs didn't hurt anything.

 

Thanks Guys,
Hope They didn't do any permanent damage myself..but will shim them anyways just to be safe. Read that the BUR-9EQ are 3mm longer than the oem plugs

some dealers sell them already shimmed as in the pic below.
Oh I upgraded the starter to the N3Z2 model (Brand new) already so I know that can't be part of the problem.
BTW I'm from Trinidad West Indies -not too many mechanics with rotary experience here so I'll be depending on you guys alot.