And my 140k VE did very well I think. Did this a few months ago while changing the OE plugs(which were still gapped to spec) to fresh OE plugs, replaced PCV valve, and added a wix 300ZX fuel filter just for fun.

All 6 cylinders tested within 188-190 psi I presume this is an excellent result?

For those who don't know, FSM says:

Standard - 183 psi
Minimum - 142 psi
Difference limit between cylinders - 14 psi

Thing is, I did the test with the engine being pretty cold, and now I read in many places including the FSM that the engine should be warmed first. Some say it's not required. But warming the engine would just bring the readings even higher, right? Aren't my results high enough? Are my readings okay?
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Heres a pic of the OE plugs I pulled. They seem fairly new, and combined with the results of the compression test, it seems my motor has been taken care of very well by the previose(and only) owner. The coils look very new as well. Not a single crack.



And here I gave the VE face a quick clean up. Used some brake cleaner...

 

you can do a seperate test by adding 3 squirts of oil into the cumbustion chamber, this allows the rings to seat giving a higher pressure. This helps determine if your rings are worn, or the cylinder walls are bad.

 

With 188-190 psi on each cylinder on a cold engine, I don't think this test would really tell me anything new.

Edit: If I tested low on the other hand, that would be the next best thing.

 

when i did mine i got around 125 to 130 psi. and i have around 201K miles on it and 195 when i did the test on it.

 

i also got about 125 on all my cylanders .. i ave 176k miles on the engine , considering thats lower then the fsm recomended,, is that really bad?!?!

 

well i dont really care about it since i have a new VE waiting for me to swap hehe. i think as long as u dont see some blue smoke u should be good. unless u want power also.

 

Well what can I say.. You guys getting the low readings are definatly not getting everything the VE has to offer.

For low readings, there are a few steps you can take...

- What kcidmil said.. Add a small amount of oil through the spark plug holes and retest compression. If the pressure goes up, piston rings or cylinder walls may be worn.

- If the pressure stays low, you may have a sticking valve or the valve is not sealing right.

- If compression is low in two adjacent cylinders, and adding oil doesn't help compression, there is a leakage past the gasket surface. If so, replace head gasket.

(Got this info right from the VE section in the FSM)

 

Your presumption is correct. This was mine over a year ago and I have absolutely NO reason not to believe if I did the test today I wouldn't have similar numbers. I'm currently pushing 153K and have been using synthetic and premium gas since 30K. On a side note you definately could have reused your old plugs, but what the heck, why not.



BTW

 

Yep, I even think we used the same tester from Sears. Definatly coulda reused the plugs, but what the heck

BTW, you think it's awright that I ran the test on a cold engine?

 

I think so, I did mine with a warm motor but it shouldn't make that much of a difference. The only thing I suggest is to have the throttle wide open when doing the test.

 

Tested mine last night. All were 180-183.

 

you guys are making me want to check my new one.

 

Having it warmed up would most likely get a higher reading though, right? I wonder why my reading is much higher then what the FSM says. Im guessing if I warm it up, it would be close to 200 psi?

I wouldn't expect much from such a beauty

 

so with my 125 in all does that mean all my cylenders are worn >.<

 

Or piston rings.. Are you sure you did it right? Warmed engine? WOT while cranking for about 5 sec each time and recording highest reading in psi?

 

My VG got 150-160 a few months ago. It wasnt completely warmed up.

 

Not necessarally so, it depends on how your engine is running. Doing a compression test is just a starting point to see how are the cylinder internals doing. If I had a lower than normal reading, first thing I would do is put a few drops of oil in the cylinder and re-do the test. If that doesn't make a difference then I'll ask myself "how does the engine feel while I'm driving, does it feel strong" If I'm still not sure then I'll do a chassis dyno. Dyno numbers don't lie. If the dyno numbers are good then I'll disregard whatever compression readings I was getting, instead use them as a benchmark for future compression testing.

 

so many cranks do you do?

 

What would you think in my case?

Dyno'd at 180 hp and 185 ft lbs of tq

Yet a compression test yields one cylinder to be 30-40 psi lower than the others (IIRC they were all in the 180's with one in the 140's)

 

Your compression and dyno numbers have always been on my mind since the first time you posted them (maybe 2yrs ago) You've always said your car feels good on power and idles smooth, so your situation is a mystery. But I still say the dyno numbers don't lie and your numbers are within most other VE's. If I was interested in solving your mystery I would do a leak down test and see what happens

 

hey , your a NC 3rd genner, anyother NC 3rd gen??

 

You probably had some mods at the time no? Isn't a stock VE in good condition dyno'd at like 173 hp or something?

Just wanna make sure.. So what exactly does the compression test tell you? How strong your engine is running basically, right? Im confused how James has 140 on 1 cylinder and dynos at 185hp.

 

To begin with, there's way too many of these smilies in the past couple post, myself included

Most auto VE with mods dyno 170-175, and most 5spd VE with similar mods dyno 180-185. I have no idea what a stock VE dyno's, auto or 5spd

IMO doing a compression test is like doing a chassis dyno. It's like getting a baseline number so you know where you began incase you want to run the test again several months later. Some dyno's will have different numbers due to elevation, types of dyno and software and I assume some compression guages will have different numbers due to calibrations and elevation.

But to have one cylinder considerabily lower than the others and still put down good dyno numbers I have no answers. Maybe the other 5 cyl are making excellent power to compensate for that 6th cylinder. I think I remember reading that James did the compression test over and over to varify his readings. Another thing I would do is pull all 6 plugs and read their conditions. If all 6 plugs looks the same, blame the lower compression reading on a glitch in the matrix. If the spark plug in the lower comp cylinder looks different than the others, he definately got a issue in that cylinder and would require futher testing to figure out what's causing it. But with good dyno numbers and no obvious driveability problems why bother going futher in the diagnosis. Unless he has future hard core plans for the motor.

 

I see, thanks.. ""

James probably had one of those rare cases where something was causing the readings to come low on that one cylinder, even though there was probably nothing wrong with the cylinder itself. Maybe where you screw the compression tester in, the hole was weirdly shaped in a way where the readings would test low.. Probably some stupid issue like that. Who knows.

 

On my way into work tonight I was thinking about this thread and have a possible idea on the situation. How can someone have good compression readings on some cylinders but low on another cylinder, yet have no driveablity problems and decent dyno numbers.

Could it be because that cylinder has sticky valves which is not sealing the combustion chamber 100%

During a compression test you only have compression pressure in the cylinder which could cause a sticky valve not to seal completely, but once you add fuel/spark and create a much higher combustion pressure it could seal a half ase sticking valve.

Now back to your regular schedule program

 

Hey I want to test my compression...whats that thing called? dont make fun but could it by any chance be called a "compression meter"? isnt my innocence on things cute?

 

If I would have to go with a theory, I would definatly go with that one. Not bad.. Im surprised James never looked into it more though.

Or "compression tester". And yeah, I would recommend doing it. Make sure you know why your doing it first Mr.Innocent

 

why am I testing compression lol...is compression leaking through my exhaust studs making my car idle funny?

 

stfu noob!

~Alex

 

Need to do an engine compression test. Rented a compression tester from Auto Zone but cannot connect it to the deep spark plug hole. Can someone recommend a compression tester that is suited for the VE engine. Thanks in advance.

 

I bought a cheap one from the local parts store- don't rememebr what store or brand, but they have a long rubber hose on it. just stuck that down in the hole and it worked just fine.

 

^^^+1^^^

 

Ah, how I wish I could travel back in time to when I created this thread