Compression test

[kdrkmstp]

Alright, I did the compression test over the weekend.
The thing is I got alright numbers, like 15-, 15-, 15-, 16-.
Can't remember the exact numbers but thats bout how they
were. The thing is I didn't get to hold down the gas as I was
cranking it. How would this effect the compression results...
Imma do it again but just wondering what this would cause.
thanks.

 

[98TsiAWD]

Not sure on the throttle thing, too tired to think about it.

But 150's are kinda low. Was the engine warmed up to operating temp or did you do it cold?

 

[1fast97gsx]

yea stock is 178 I thought? I think anything to like 140ish was serviceable. How many miles do you have? As long as all the numbers are consistant I wouldn't be too worried. Maybe a leakdown test? I never heard of the throttle thing.

 

[turbowop]

When a compression test is done the car should be at full operating temp and the throttle needs to be held wide open. Also remove the MPI fuse during the test.

 

[Zenja]

You can just use the throttle cable to go WOT. You don't need a second person to be in the car to push the pedal.

 

[KPWSerpiente]

Also remove the MPI fuse during the test.

He is a second gen, he does not have an MPI fuse.

Those numbers are low. I assume the engine was not properly warmed up. Do it again with it warmed up.

Or maybe you didn't let it crank long enough. Continue cranking until the needle on the gauge has stopped moving.

In my experience it makes no difference whether or not I do it with the throttle wide open or closed (I do it both ways every time for every cylinder) but most people suggest you crank it while open.

-T

Edit*

You can just use the throttle cable to go WOT. You don't need a second person to be in the car to push the pedal.

Is there a way of cranking it over while standing in front of the engine bay that I am not aware of?

 

[kdrkmstp]

Well, the car was shut off for about 30 mins which I assumed it would
be close to normal working temperature. The car was driven for about 6-8 miles regular driving. Should I have driven hard for couple mins before I did this??? Also, what if the numbers stay the same even after
running really hard. Would that mean that my car will continue to lower
its compression??? I did this test because, the cars been idling really rough, like i have big racing cams in it or something (which I don't).
Also was thinking that it might be a boost leak, that I haven't gotten a chance to do yet. Please let me know what my engine's condition is at if the numbers stay the same.
thanks

 

[spoolinawddsm]

Originally posted by Zenja
You can just use the throttle cable to go WOT. You don't need a second person to be in the car to push the pedal.

huh? how would he turn the car over then?
the throttle being open has to do with air getting into the engine, you will get a higher number with the tb plate open.

 

[kdrkmstp]

How much would it raise the numbers about...???
Should I do the test again or just assume that it'll be higher and
i'm good...

 

[dsmracer69]

First of all compression test not really good do a leak down test it will tell if you have a leak from the head or piston you pressurize the cyclinder and if you hear any noise coming outta the intake its ur head and if you hear it outta your exhaust its your piston rings so try that most shops don't have them or get a leak down test confused with a compression test its different though.

 

[turbowop]

Originally posted by dsmracer69
First of all compression test not really good do a leak down test it will tell if you have a leak from the head or piston you pressurize the cyclinder and if you hear any noise coming outta the intake its ur head and if you hear it outta your exhaust its your piston rings so try that most shops don't have them or get a leak down test confused with a compression test its different though.

Holy runon sentence. How about some periods 'eh?

Compression tests are a good first thing to do. If compression is low then follow it up with a leakdown test to see where the problem lies.

If you hear air coming from the exhaust during a leakdown test it isn't because your rings are worn. It is because you have a bad seal on the exhaust valves. Same goes for "hearing air coming from the intake". If that's the case you have a bad seal at the intake valves. If you hear air in the crankcase then you may have some worn rings. If while doing a leakdown test you have bubbles forming in the coolant you most likely have a hurt headgasket.

 

[dsmracer69]

ya thats what i meant 2 say got it all mixed up i was working on 1 hour of sleep so and the run on sentence is just internet type not writing an essay or anything like that

 

[turbowop]

Originally posted by dsmracer69
the run on sentence is just internet type not writing an essay or anything like that

"internet type"......(sigh)

So just because you're typing on an internet forum you think it's okay to write like a five year old?

Essay or not, it's way easier to understand somebody's post if they take the time to write it like they were educated. You did go to school didn't you? Or would you rather go through life with people thinking you're a moron. That's basically what I think of every person who writes a post like that. Mistakes can be made and that's understandable, but your post was flat out laziness. Or you just didn't pay attention in english class for every year you were in school. I'm sorry if you think this is totally directed at you, because I don't mean it to be. It just seems a lot of people are getting pretty goddamn lazy and pretty soon every post is going to look like jibberish. It's not a race to get your posts up people. Take your time so others can understand WTF you're trying to say.

 

[dsmracer69]

Originally posted by turbowop
"internet type"......(sigh)

So just because you're typing on an internet forum you think it's okay to write like a five year old?

Essay or not, it's way easier to understand somebody's post if they take the time to write it like they were educated. You did go to school didn't you? Or would you rather go through life with people thinking you're a moron. That's basically what I think of every person who writes a post like that. Mistakes can be made and that's understandable, but your post was flat out laziness. Or you just didn't pay attention in english class for every year you were in school. I'm sorry if you think this is totally directed at you, because I don't mean it to be. It just seems a lot of people are getting pretty goddamn lazy and pretty soon every post is going to look like jibberish. It's not a race to get your posts up people. Take your time so others can understand WTF you're trying to say.

So the great scholar TURBOWOP says. Sorry if that wise a$$ remark was aimed at you but im just tired of people who spend all there time on forums trying to be perfectionist.I got better shyt to do so thank you and good day to you sir. :thumbdown

 

[DSMRevolution]

Just to clarify, you want to remove the coil plug in wire and hold it to the floor. Removing the mpi fuse is more of second way to protect fuel incase the wot switch in the ecu isn't working. When you hold a car wot it will cut fuel.

Sorry if that isn't 100% accurate, I am tired

 

[turbowop]

Originally posted by dsmracer69
So the great scholar TURBOWOP says. Sorry if that wise a$$ remark was aimed at you but im just tired of people who spend all there time on forums trying to be perfectionist.I got better shyt to do so thank you and good day to you sir. :thumbdown

If you had better "shyt" to do you wouldn't have the time to reply to my post. Sooooo, since you have the time to reply it seems to me you might just have enough f*cking time to type like you're older than *5*, moron.

 

[kdrkmstp]

Man...every post i've made in past couple days, its ended in a verbal
fight between dsmers...c'mon guys.