Searched but could not find what the normal range of readings should be on my IX when doing a compression test. I had 140/135/150/150. Bad? We did the add oil trick and the 135 cylinder barely increased at all. About to hit this motor with about 30psi so I need to know my motor is in decent shape. Thanks for your help.

 

It sounds like you may have possibly weak cylinder, probably want to do a leak down test to be sure.

I had a test read 125-150-150-150, did a leak down and everything was fine according to the leak down.

 

OK. I will see about getting one done but I would still like to know if I'm within normal range according to Mitsu spec's.

 

I just did comp test on my ix a week ago and got 150 across the board...

 

Not looking so good for my numbers then. Nobody knows what the test numbers should be on a healthy IX?

 

actual number can vary greatly depending on cams/overlap. really the important thing to be looking for is consistency across the cylinders

 

It also varies from gauge to gauge also, only real way to tell is to do a leakdown.

 

Good to know. I will definitely be doing a leakdown test then. Thanks

 

I checked mine last week. I had 140 across the board. This is with a fully charged battery, 5 strokes per cyl, on a hot motor, fuel pump disconnected, and with the pedal depressed (WOT) during the pull. My motor has 20k on it and is 100% healthy.

I can tell you that running the test on different motors, different gauges, different number of cranks, weak battery, or while spraying fuel into the cyl, you will see inconsistent results. Simply not having the TB open during the test with sway the results.

Make sure you perform the test properly.

 

Make sure your gauge is properly (tight) seated, otherwise your readings will be off as well ...

I had a cylinder that was low and I was very concerned...turned out my gauge was not properly seating...there was some anti-seize grease on the surrounding surface allowing air to pass...

Generally 140 across the board on a 9 is fine and a 10% variance is considered 'fine' as well....So your low (135) is probably fine....

 

Sounds like there could be many variables to account for. I will try the leakdown test. Sounds like that could give me a much more accurate idea of how healthy the motor is. If I can't find someone trustworthy enough then I will go with the compression test again and try to eliminate as many variables as possible.

I do however find it strange that there has not been anyone with some serious engine building or testing experience that has run across this thread who would know the normal values associated with the IX motor. Maybe you do cij911 and Jeff! Thanks

Thanks everyone for your input!!

 

my car has 155,155,140,155 and it seems fine

 

An EVO9 will have lower numbers than an EVO8. As mentioned above, consistancy is what you are looking for but sometimes with cams and such even that can be a hard goal.

I would say 135 is healthy especially if you did a wet test and it didn't go up. Normally if you have bad compression due to a valve you won't even be able to get 100psi. You'll know right away becauce the car will crank over MUCH faster than a cyl with good compression.

It would be interesting to see of that cyl reads that same if you started with it. Sometimes the battery charge is weaker at the end of the test than it is at the start.

 

The 135 was cyl 3. We started on 1 so the battery in retrospect was getting a little weak after 8 cranks per and the being the oem battery with the 135/140 being 3&4.

Jeff. Thanks for the valve info because I was getting worried that it might be valve related. I have done several boost leak tests now and continue to get pressure leaking from the oil fill cap. After making sure the Pcv was good I started to worry it might be valve related as well. My results starting making me think complete valve job.