1.195
2.195
3.180
4.195

this is on a 1995 gsr with 98k miles on it. i'd say thats not too bad for bone stock and good number of miles, although the 180 bugs me a little bit. doubt its anything awful though

 

that's still very much within spec, so don't worry too much about it. it's probably just a slightly worn exhaust lobe.

 

do you guys have any idea why my compression is so low? I have a 94 LS with 95k miles on it... started modding it at about 66k miles.

i was pretty much 135 in all 4 cylinders... the results (exactly) were:
133
135
130
134

My car does not burn oil... no smoke out of the exhaust.... what could be the problem? What other ways can i diagnose the problem without taking apart the motor?

thanks,
Ryan

 

first you need to specify exactly how you went about doing the test, tegasaurus. Was the engine warmed up? Was the gas pedal depressed? 5 cranks? 7 cranks?

The fact that your numbers are so close makes me suspicious? Usually if the engine is that bad there will be a wider range (always seems to be a middle cylinder too).

If nothing makes a difference, use a different comp. tester, that DOES make a difference.

d

 

The car was driven for about 35 min... sat in a drive way for about 2 min...
-then all of the plug wires removed
-ECU fuse was pulled (15a)
-All 4 plugs removed
-Screwed Compression tester into #1 cylinder until it was snug, then gave it about -a 1/6 rotation so it was nice and sealed in there
-I sat in the car and pushed the gas pedal to the floor.
-Friend monitored gauge
-Cranked motor over. About the 4th crank my friend would either tell me keep going, it's still rising, or that's good... No more than 7 cranks.

Again, no smoke of any kind out of the exhaust and im even running a 2.5" straight pipe.

Would the possibility of bent valves cause the compression to be this low? When i first got the car, i did a couple of 5-2 downshifts on accident, resulting in a couple of 8 or 8.2k redlines. but i quickly pushed the clutch in when i realized my mistake so i wasn't riding it or anything.

Help me out guys. Thanks

Ryan

 

Anyone got any ideas as to why my compression test runs like this?:

1. 260
2. 270
3. 280
4. 290

That's wht the autozone $25 compression tester...

I have higher compression than stock (10.6:1), but I still wouldn't guess my comp. test would be that high... anyone got ideas?

 

I think if you two switched gauges then all would be well.

Seriously tho, either try a different guage or try yours in a different car. Narrow it down.

d

 

well, i did a comp test a couple of weeks ago (posted it too) on my 1995 gsr, stock motor with 95k.

235
230
240
235

everything was done correctly.

 

we tried it in my friend's ls/vtec. His car has stock ls internals with a b16 head. Runs well with no major problems (other than the fact it's slow until 5200 rpm hehe) and his numbers were between 160-170 on all 4


P.S. what kind of gauge are you guys running? we were using a 29.99 one from pep boys....


[Modified by tegasaurus, 7:56 PM 12/18/2002]

 

his numbers look low too. My 200 000mile plus ls engine had solid 160 -170s across the board right before i pulled it out and junked it, and that was with my low reading tester.

the b16 head alone should add about 0.4 cr, i've been told, to the 9.2 cr of an ls engine. Just a shot in the dark, but assuming both of your engines are running right, they should each be showing about 40psi more.

d

 

for me, the car was running for max of two minutes, cranked it 5 times, and thats it. no pushing down gas pedal

 

Normal, Normal, Normal, and Normal. All those compression tests looked normal, don't trip!!! If you had problems, you'd notice one that's 15+ points off any of the others. Compression tests aren't always 100% accurate either.

 

When the compression is off by more than 40 psi on nearly the same car it shows that something IS wrong...

im just gonna boost @ 8 psi and see if that will make me rebuild my motor

 

if your comparing your car to mine being the same, you said you have LS, i have gsr. somewhat different engine i'd say