Hey guys. I need to check the compression on my 2005 with 230K that burns significant amounts of oil. I'm curious about the procedure, and google hasn't been much help for our car specifically. I'm familiar with how to do the test, but on this car I don't know which fuse(s) to pull to disable injectors and will the throttle plate go WOT if I push the pedal all the way while cranking? Is there anything else I need to know for this test on these cars? I'm used to working on older Hondas that don't have all these fancy electronics.

 

I don't think there's any special procedure. I've done it on my 4G TL, which has the same J-V6, and all I did was pulled the electrical connectors off the coil plugs and fuel injectors. It worked fine. I got the compression numbers I expected and didn't have any trouble cranking it over. I'm sure it would have been easier finding the fuse but I just did it that way.

Otherwise, everything's the same as compression testing any other car.

 

you should do a leak down test. This will tell you if the head is the issue or the piston rings.

 

Does the TL have drive by wire/electronic throttle control also? Compression tests should be done at WOT. That's why I was wondering if it will go WOT when cranking for the test.

Anyone know which fuse to pull? In older Hondas it wasn't listed as the fuel pump or injector fuse. You had to pull the alternator fuse iirc.

 

Yes, all TL's since 2004 have drive by wire, which makes doing a compression test at WOT a bit difficult unless you opened the valve manually in the throttle body somehow. And no, I don't believe the TB is going to open unless the engine is actually running.

When I've done it, I've just compared my numbers across cylinders. I got 120 PSI almost on the dot between all 6. From what I understand, if compression is consistent among cylinders, you're usually looking good. It would either indicate that there's little wear, or that wear is uniform among piston rings.


Deepdezal is right about the leak down test with determining oil consumption. That can help determine if it's the piston rings or valves (although it's going to tell you if it's the valve guides). I believe compression testing is more to assure your compression rings and head gasket are ok. I had a bad oil control ring one time which tested fine for compression, because the compression ring was fine but the oil control ring was shot. When I did the leak down test, it showed pretty miserable results.

Also, I just purchased the cheap-o kits from Harbor Freight. They're affordable enough that you can buy them for less than a mechanic would charge to do the test. And then of course, you have them for future use. Although they're not perfectly accurate, they're pretty consistent in results, which is what you're really looking for when comparing cylinder to cylinder.

 

These Acura Job Aids provide information on how to perform an engine compression test and a cylinder leakage test on Acura V6 and L4 engines.

Always refer to the service manual for the exact specs for minimum compression pressure and maximum variation for your model, year, and trim level.

If you are not using the Honda MVCI or DST-i and HDS, then you will need to manually disable the fuel injectors and ignition system, as needed. This can be done by removing the applicable fuse(s) or relay(s).

BJA45449
Engine Compression Test and Cylinder Leakage Test - V6 Engines
http://www.urvi.net/forumfiles/SB/BJA45449.PDF
http://techinfo.honda.com/rjanisis/pubs/FF/BJA45449.PDF

BJA45450
Engine Compression Test and Cylinder Leakage Test - L4 Engines
http://www.urvi.net/forumfiles/SB/BJA45450.PDF
http://techinfo.honda.com/rjanisis/pubs/FF/BJA45450.PDF