DISI Compression Results

[Lex]

We have seen quite a few people with low compression numbers and blowby. Is this cylinder wear? Is it bent rods?

Go and grab a test of your motor, post up the results along with mileage and mods. Let's see if we can find something useful out.

[superskaterxes]

just a note u can rent a compression gauge from autozone for free. im gona do mine soon so ill post up when im ready.

[aaronc7]

just pull spark plug one at a time and crank over motor a few times?

[superskaterxes]

yah make sure the motor is warmed up and pull the [inj relay] bottom left most in blue (on MS6)

if you find your low on one cylinder then pour a teaspoon of oil into it and repeat test. if the number comes back normal you have a problem in that cylinder.

[Lex]

Originally Posted by aaronc7 just pull spark plug one at a time and crank over motor a few times?

Warm up engine. Pull all spark plugs. Pull fuel inj fuse. Step on clutch and gas at the same time. Crank for 5-7 seconds. Repeat for all cylinders.

[djuosnteisn]

I'm going to retest with above suggestions right now.

More results to come.

Oh, and it's best to pull all plugs at once, it makes it easier for the engine to crank. And you may want to put a trickle charger on your battery while you test.

[superskaterxes]

is stepping on the gas just to open the throttle plate?

and does all the charge piping need to be connected when doing this?

[djuosnteisn]

charge piping is pointless w/out boost. Doesn't need to be connected imo. Only thing i didn't do is warm engine up. So i guess we'll get a cold vs. warm comparison, lol.

[2007speed3]

Holding the gas pedal down when cranking stops spark from being generated right? or is it fuel getting sent into cylinders? i know it does something..

[djuosnteisn]

cars warming up. brb in like 15 mins with results.

[m4tic]

holding the gas keeps the injectors from firing....

[djuosnteisn]

Sigh of relief...

Let me stress the importance of warming the car up first, lol otherwise you'll think your ship is tanked.

23k miles.

3071 for 5kish
int, tbe, wmi, ap, bsd, etc (except for exh mani) for 10kish
dnp exh mani with ewg for like 30 miles, lol.
fuel pressure scalar (DJ CKT) for 20 miles

Here's cylinder 1:

MOV06490.flv video by djuosnteisn - Photobucket

MOV06490.flv video by djuosnteisn - Photobucket

Here's cylinder 2:

MOV06491.flv video by djuosnteisn - Photobucket

MOV06491.flv video by djuosnteisn - Photobucket

Here's cylinder 3:

MOV06493.flv video by djuosnteisn - Photobucket

MOV06493.flv video by djuosnteisn - Photobucket

gf accidentally hit pause between cranks.
and of course the one cylinder most suspect is blurry lol, but it's obviously on par with the others.

MOV06494.flv video by djuosnteisn - Photobucket

MOV06494.flv video by djuosnteisn - Photobucket

Here's cylinder 4:

MOV06495.flv video by djuosnteisn - Photobucket

MOV06495.flv video by djuosnteisn - Photobucket

So i retract my previous compression data in the fuel ckt thread, and now feel much more comfortable about my motor. Though now that i said that, the god's have been tempted lol.

[Lex]

Lol good stuff Dustin! The warmup is indeed important!

Nice nails btw

[glocK23]

Yeah Lex, those are some nice nails indeed!!!!

[bykeryder4life]

you guys should also post what the first "puff" puts the gauge to. It should get right up around 100psi or more on the first puff of a healthy cylinder. If you do end up doing a wet test as well the readings will be higher with the oil in there, they need to be considerably higher to know your compression isnt holding in that cyl.

[silversurfer3]

I got 0's all across ?? What does that mean????

[socks]

doh, i was gonna test mine, but i cant warm up the engine. i have no exhaust on the car...

I am running 8.8:1 compression, so im looking for 155-160 per cylinder to match your 170's

[2007speed3]

good job home boy, thanks for posting this up...

[wassup61]

Uhh... here is the procedure for comp test.

1. beat shit out of car to warm up
2. come home and pull plugs
3. depress clutch AND gas all the way to the floor and crank 5-8 times (will keep injectors from firing and open throttle plate).
4. Measure compression per cyl.
5 charge battery.

I have 8.8:1 arias, after beating on it and getting it hot i comp tested 183,182,184,187, which is high for a low comp. motor.

[djuosnteisn]

Very high! Your at sea level?

[wassup61]

720 ASL

[superskaterxes]

so after fighting with the POS compression gauge i rented from auto zone i ended up testing 180's across the board. might have been +/- 2 but w/e still good nonetheless. what a sigh of relief.

[djuosnteisn]

Might as well post your mileage, mods, and altitude.

Basically, 30psi on a re-worked, and not scared to catch a lil air now and then lol.

[Deadman]

we should test mine on sat anthony. We will actually..

if my car is about to blow im parting out and taking to dealer. SOLD

[superskaterxes]

Originally Posted by djuosnteisn Might as well post your mileage, mods, and altitude. Basically, 30psi on a re-worked, and not scared to catch a lil air now and then lol.

damm straight thats how i roll haha

like 75' ASL 38k

PTP SST ~ TXS BOV ~ CPE Xcel CAI w/Injen Hydroshield ~ AP PROtuned by me @26psi ~ Grimmspeed EBCS ~ Custom Side-to-Side FMIC ~ Corksport Downpipe (Heat Wrapped) ~ DNP Mani w/Tial 38mm MV-S EWG VTA'd~ Custom Turbo Inlet Pipe ~ TWM Stage 1 Short Shifter ~ CPE RMM ~ TTFMM ~ CPE RDM ~ BC CO's slammed ~ SPC BJ's ~ EBC Red's ~ Stoptech's ~ Technafit SS Lines ~ Autometer Boost & STRI EGT in Custom Built Vent Pod ~ 20% Tint ~ LED Tails ~ Denso ITV-24's ~ Xtra Shorty Antenna ~ Dashhawk ~ Magnaflow Catback ~ TXS Test Pipe ~ Custom Strut tower bar ~ Whiteline RSB ~ PnP'd IM ~ CDFP Internals ~ labonte meth kit ~ VC tapped OCC ~ 290WHP/337WTQ on a MD ~ 12.9 @ 107 1.8 60' ~ fastest stock turbo trap speed in the USA

[socks]

Originally Posted by socks doh, i was gonna test mine, but i cant warm up the engine. i have no exhaust on the car... I am running 8.8:1 compression, so im looking for 155-160 per cylinder to match your 170's

Ok, so I finally got around to testing mine.

Spec is 175. on a 9.5:1 compression ratio.

175 / 9.5 = 18.421

18.421 x 8.8 = 162.1

This is what i was looking for when i tested mine.

My results

1........162
2........165
3........165
4........162

Im pretty stoked. Those numbers are in line with eachother, and in line with what i expected. Im 800' ASL, have 11,000 miles on my motor, with a 3071 @ 20+ psi.

[darth vader]

I just yanked out my leakdown gear a couple days back...cuz I can. I tested all four and found they all read low for leakdown. I could hear some air escaping into the crankcase but, obviously not alot. Turbo motors need fairly loose tolerances anyway. All four were pretty equal in terms of leakdown so, it looks like I haven't killed anything with my fail stock CD fuel pump and in and out mods.

The modestly tricky bit was actually getting the cylinders to exact TDC. This became much easier to see when the leakdown fitting jammed in the 3 plug hole and I had to pull the cam cover.

Here's a little cool thing: The cam cover bolts are captured so you don't have to remove them and drop them into the engine bay, ne'er to be seen again. The also act as spacers so, tighten down til it stops and you're torqued.

Plus, the bolt on the end of the crank for turning the engine over is standing proud of the pulley and is easily reached with a simple undoing of two 10mm bolts and push pin from the plastic shroud.

I love little examples of practical engineering excellence. This car is stuffed with them and, I appreciate it.

[jwdp54]

i got mine checked on sat. not sure what to think about the results..

1-145
2-145
3-140
4-145

[gsrtype1]

Originally Posted by jwdp54 i got mine checked on sat. not sure what to think about the results.. 1-145 2-145 3-140 4-145

What are your miles? Im gonna do this soon as well.

[SSinstaller]

Originally Posted by jwdp54 i got mine checked on sat. not sure what to think about the results.. 1-145 2-145 3-140 4-145

The actual numbers are less important than the consistency of the numbers. I would keep an eye on #3, but wouldn't be overly worried..

[jwdp54]

they were actually closer in numbers. he said cyl 3 was dead on 140 which he tested 3 times and same results. the other cylinders read between 140-145. car has no problems with 22k of hard driving, fully bolted, very minimal kr and stock ecu. runnin like a champ

[wassup61]

Originally Posted by jwdp54 they were actually closer in numbers. he said cyl 3 was dead on 140 which he tested 3 times and same results. the other cylinders read between 140-145. car has no problems with 22k of hard driving, fully bolted, very minimal kr and stock ecu. runnin like a champ

Your numbers are borderline replace motor...

[djuosnteisn]

did you warm the car up before testing?

[socks]

129psi is the minimum according to the FSM, and there should be no more than 28.5psi variance in the cylinders.

[jwdp54]

Originally Posted by djuosnteisn did you warm the car up before testing?

i don't know if he did. i meant to ask him. i'll call him tomorrow.

he said borderline is 129 which does have me worried but i've been looking for a new toy if i do run into problems.

[darth vader]

When you get #s that concern you on a comp test...#1, redo the test, making sure it was done properly with a strong battery, throttle open and engine warmed up well.

If you get the same results you don't like, time to do a leakdown test and determine actual engine condition. These motors should leak a fair bit over an NA engine, as is, being turbo engines and thus having fairly loose bore tolerances. However, if you're seeing over 20%, that cylinder is tired out. Listen for where the leak is going and that'll tell you what's worn. Hear it out of the oil fill? Rings. Hear it out of the exhaust? Exhaust valve. Hear it out of the intake? You get the idea.

I just pulled out my gear and did this on my own car a couple days back. It's really easy on this car, I have to say, due to the manufacturer's foresight in design.

[jwdp54]

lol i hate troubleshooting on this car cuz of all the noises in the engine bay. i always think my cars knocking yet it's just my fp ticking and all the rattling from motor mounts.

i didn't get a chance to call him today. hopefully i can tomorrow so i can figure this shit out.

[evidence]

1000ft ASL, 18k miles. Heated the coolant to 190, and started on the right, ~6 cranks each.

left to right from the front of the car:

175
175
175
178

BTW, just pulled the blue fuse near the top right that says 'injector', but also depressed clutch and gas just to be safe. Figure the later is enough to keep the cylinders dry though.

[802MS3]

I just wanted to come in here to bump an old thread to piss off the mods.

kidding!

Just did mine tonight-- 180ish across the board. Think I got one of the good motors. Tranny is smooth as glass too. Now for some more mods...

[Fullmetal]

sorry but may i point out all compression and tdc and valve clearance measures should be taking at cold and heated to get true comparisons. cold engines will show true wear cause as metal heats it expands. that is basic metallurgy, cause you might have great starting compression when warm. this may not be true for cold engines and i have seen many cold engine running problems! if you have cold engine running problems this will effect you warm engine closed loop operation. since the computer learns how to get the engine hot it thinks once the engines hot i can start pulling timing and allow for more emission control. this causes lean conditions which will raise the leaning out of engines to increase proper burn and near zero emissions thank you to the federal gov't. And now one key thing to remember is that taking non running compression will not give you true compression number. your compression may drop once you induce fuel into the cylinders, from the fact that most liquid takes more to compress and if you have any type of bend in the rod or cylinder leakage do to higher dynamic compression you can not tell this at @ 700-800 rpm cranking compression test. this test is mainly used to find blown or warped heads. running compression will net you more info. plus you must compare your cold vs hot reading to tell of true cylinder problems. also you need to check your valve lash to see if your running problems are not to to improper valve seating. high cylinder temps can cause valve seats and stem seals to morph allowing more cylinder problems not able to be told by a cranking compression test. load will always affect cylinder pressure along with engine temp. this is why the ecu has complex fuel and load tables based on a very complex algorithm of up to 8- 10 different sensor readings. and it uses an average of cold verse hot to tell which is the most economical and efficient way to use the engine. just my two cents. years of diagnosing all engine types and running problems i will follow what i have learned based on what i read.
Always do cylinder leak down test.