Engine compression test How to

[AresROC]

Hi everyone! I am still a TN newbie with a 93' Paseo & 5E-FE, 170k miles and high hydrocarbon (HC) at idle. It fails the Vegas emissions tests. I suspected burned valves or bad head gasket, so I purchased a compression test tool and performed some tests on it. Here is how I did it:

• warm up engine
  • remove spark plugs
  • remove fuel injector relay
• Test1: 2 crank revolutions
• Test2: 5 cranks
• Test3: 10 cranks

Cranks.....1.....2.....3.....4..Cylinder
-------+---------------------------------
...2......65....67....67....69...PSI
...5.....100...100...100...110...PSI
..10.....160...156...156...160...PSI

Seems pretty consistent! Is this safe to assume I don't need to open up the head and cut the valve seat, install head gasket, or install new piston rings!?

[96paseo]

Those are some pretty even readings and your closer to or at 160 psi so thats good. That also falls within the 10% rule. Wouldn't worry about pulling the head so long as oil and coolant are clean. How's your maintenance coming along? Did you fix the exhaust leak? How far have you gotten with tune-up related items?

[AresROC]

Hi! Thanks, glad to hear the 160 psi is good. It took 10 cranks to get it, and I didn't try any more cranks. The readings are consistent with the oil burn and white ash deposits I found on original spark plugs from cylinders 2 & 3.

Just did some O2 sensor test tonight! I will start another thread for the O2 sensor as the quest continues! Sorry for not following up on the exhaust leak yet, I did some patch-up job and wanted to verify if it worked well or not first. As far as tune up goes, I do see a purchase of a timing light in the very near future... The DIY to fix high hydrocarbon at idle continues...

[Tercel GTS]

I can tell you a larger exhaust system makes the engine run richer. Thus a leak would also. Fix that known issue first then proceed. 96Paseo gives really good tuning advice. Listen to his suggestions and your car will be back up to par quick.

[AresROC]

Thanks for the advice and encouragements! After my highly optimistic 2nd smog test failed, I was down for a while. Now that I may have avoided some major work on the engine, the hope rises again!

I prefer the DIY route because of the knowledge you gain on the car and the sense of accomplishments are priceless! Instead of paying someone $$$ to do it, I get to spend that money on tools I can use later. This forum and many regulars like 96paseo have been most helpful to me! Thanks!!!

[96paseo]

Originally Posted by AresROC

Thanks for the advice and encouragements! After my highly optimistic 2nd smog test failed, I was down for a while. Now that I may have avoided some major work on the engine, the hope rises again!

I prefer the DIY route because of the knowledge you gain on the car and the sense of accomplishments are priceless! Instead of paying someone $$$ to do it, I get to spend that money on tools I can use later. This forum and many regulars like 96paseo have been most helpful to me! Thanks!!!

If being a DIY mechanic is your goal, then you've got the right attitude. Just remeber simple stuff first. You'd be suprised how poorly a car can run with just a bad rotor or cap. And worn out ignition system parts will affect your emissions. What grade of oil are you currently using?

[AresROC]

I am using 20-40w, plus one little bottle of stp oil treatment. I have too much oil in it right now, about 3.5 qts I think. Didn't expect it to fill up with only 3 qts..

[WilliamRobert]

20w-40??? holy cow, that's really thick. That's what we use in the diesels up here. I use 5w30 in my Tercel, but it is much hotter where you are. Still, 10w-30 is what we used in the (gas)rentals in the Afghanistan, can't see Vegas getting as hot as that crap hole.

BillyBob

[Tercel GTS]

Agreed 10w30 and no stp will get better economy.

[AresROC]

Yep 20w40 for now. It's thick so I can be more or less sure about the engine not burning oil (high hydrocarbon), vs burning fuel rich and get hydrocarbon. I would probably change it to 10w30 or 10w40 latter on. Warm mornings here so no problems starting in winter. The 40 weight just makes the engine a little quieter, especially in 110f heat with A/C on full blast. It was even quieter when I had slick 50 in it! Have you guys heard about people dumping banana's in the oil? That's pretty scary if it is true! The exhaust would probably smell like fried banana's LOL.

Fuel mileage wise I would probably lose a little with it's current 30mpg average...