Hey guys, I swapped in some new plugs last night and did a compression check at a buddy's place. His IX MR turned up 180 across the board, but mine turned up 140/140/145/140, is that odd? It's consistent at least, but we both have IX's so why would it be so different?

Also, I got a SES light on since I did the compression check and changed the plugs. I used Denso Iridium (IKH22) gapped down to .25, I'm stock, so do I just need to yank the battery cable to reset the ECU and clear that SES light or what?

TIA.

 

.25 is a big gap! maybe you mean .025?

 

Put the stock ILFR7H plugs back in.

If your numbers are within similar % of each other, its good as more boost is the replacement for compression.

Your numbers are down a bit however, hopefully not due to a worn engine/head.

 

Was your car warmed up before you did the test and was the throttle completely open?

 

Yeah the car was hot, I had driven it to my buddy's house and it say for maybe 10-15 minutes while we were yanking the plugs from both cars. Are you supposed to depress the gas pedal when doing compression check? I just pushed the clutch in and cranked it... first time I've done a compression check.

 

Yes throttle 100% open.

 

n00b mistake, my bad. Thanks guys.

Any idea why the SES light would be on still? The stock NGKs were gapped at .025, and I gapped the Densos at .025 too. I'll take it to Autozone today I guess.

 

holy crap, i never knew that

 

if you are worried still you could to a leakdown test. cant hurt and the information provided is more valuable than a compression test

 

Throttle plate open or not open..........it really does not matter it just takes a little bit longer to get a reading but the reading will still be the same.

 

Did you unplug the crank sensor? If so that is you're cell......just clear it.

 

Yah, crank sensor was pulled, after starting the car 3 times the code went away, which is what I expected.

 

Those #'s look good and don't worry if it stays that way. If it gradually gets less then worry.

The 12cyl dual-turbo Porsche 918 race car from the 70's made 1300HP. It's 7.5 compression ratio allowed longevity. One car retired with over 100,000 race miles on original engine. If your engine is healthy and came that way from the factory, it might be a blessing