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High compression in all four cylinders

Tiny
BRONCOBILLEK
  • MEMBER
  • 2005 MAZDA 5
  • 1.8L
  • 4 CYL
  • 2WD
  • MANUAL
  • 110,000 MILES
Hello,
My car suddenly lost power and start drinking oil (3l / 1000km) and using much fuel (13-16 l / 100 km).
Oil is not leaking.
I asked my friend-mechanic to check compression.
He said first and fourth cylinder are okay and second and third have low compression (almost 0). he did it in professional car workshop, but i could not believe on document with results which he printed for me. Cylinder one -35 bar / 2-12 bar / 3-20 bar / 4-30 bar.
This is 1.8 Bensin motor so compression should be apx. til 14 bar (new car).
So i did test again using your instruction:
https://www.2carpros.com/articles/how-to-test-engine-compression
and the results are:
1st - 18 bar
2nd- 18.5 bar
3rd - 18.5 bar
4th - 18 bar
Spark plugs were very black and also check engine light, but it is gone after plugs change.
After connection till V-checker V402 found something like this -> see picture.
On each cylinder Max. Value is -1 (after erase DTC it comes back) and on fourth cylinder test value value grows.
There was also error code 0304, but after erasing it was not back.

I need some suggestions on what to do next. :(

PS. sorry for my English :/
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Monday, November 6th, 2017 AT 12:48 PM

11 Replies

Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
  • 1,853 POSTS
At first you said, "second and third have low compression (almost 0) " then you say, "second- 18.5 bar
third - 18.5 bar". So which is it?
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Monday, November 6th, 2017 AT 1:50 PM
Tiny
PATENTED_REPAIR_PRO
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Plus is there any way you can use the psi, etc on that?
I see 1000 km is 621 miles and three liters is about 3.1 quarts.
18.5 bar = 261 psi.
That is really high. That tells me there is fluid in those cylinders, possibly motor oil.
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Monday, November 6th, 2017 AT 1:55 PM
Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
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The P0304 was a misfire on cylinder number four.
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Monday, November 6th, 2017 AT 1:56 PM
Tiny
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Is this the turbo-charged MX-5?
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Monday, November 6th, 2017 AT 1:57 PM
Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
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I have the minimum as 146 psi, maximum at 197 psi.
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Monday, November 6th, 2017 AT 2:10 PM
Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
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I see now the difference between what he said and what you read.
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Monday, November 6th, 2017 AT 2:12 PM
Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
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It motor oil is obviously going out the tailpipe. Is there a lot of blue or even black smoke out the tailpipe?
All of your compression readings look okay, but keep in mind that does not tell you if the piston oil control rings are stuck or not and usually when a engine uses a lot of motor oil, it is the oil control rings being clogged up with gunk that causes the motor oil to blow-by the compression piston rings and burn and thus the loss of motor oil and blue smoke out the tailpipe if it is bad enough.
You can try to free up those oil control piston rings by following the instructions on Gunk motor flush and running that in the motor oil for five to ten minutes, than drain it out.
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Monday, November 6th, 2017 AT 2:20 PM
Tiny
BRONCOBILLEK
  • MEMBER
  • 3 POSTS
"At first you said, "second and third have low compression (almost 0) " then you say, "second- 18.5 bar
third - 18.5 bar". So which is it?"
Real compression is 18-18.5 bar (261 psi). (My "great" friend print me results from different car - diesel car)

"Is this the turbo-charged MX-5?"
No. It's 115 hp basic engine.

"18.5 bar = 261 psi.
That is really high. That tells me there is fluid in those cylinders, possibly motor oil."
Should I not see this oil during the compression test?
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Monday, November 6th, 2017 AT 2:25 PM
Tiny
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Diesel? That makes sense.
You would not see any motor oil during a compression test. Where were you expecting to see it, out the tailpipe? Not simply cranking the engine, but does it blow blue or black smoke out the tailpipe when the engine is running?
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Monday, November 6th, 2017 AT 2:51 PM
Tiny
BRONCOBILLEK
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I have not observed blue or black smoke from tailpipe. But that does not mean it is not there, because I did not think about it. I will look at it today, after work.
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Monday, November 6th, 2017 AT 11:20 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,579 POSTS
1.8L would be a gas engine. The description sounds like a lot of carbon build up in the engine. Stuck or damaged oil control rings or oil leakage through the PCV system could easily cause that.
There are a couple of ways to clean it out, one involves using a water mist, the water goes into the intake, when it hits the carbon deposits it gets absorbed a bit, when the engine fires the water turns to steam and that causes fractures in the carbon and it breaks up. A newer method involves using a hydrogen generator to do basically the same thing but in this case it is the hydrogen that explodes and sends shock waves through the carbon. Another method uses fine walnut shells to sandblast the carbon loose.

An easy way to see if it is carbon build up would be to use a bore-scope to look into the cylinder.
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Monday, November 6th, 2017 AT 11:54 PM

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