Compression test figures?

[danielbarton94]

I've done a compression test as my engine light keeps flashing on idle and here are the figures:


4-3-2-1

190-193-193-177

Im just wondering if theses figures seem okay? the car has a misfire cylinder 1 error so would it be that the injector isnt injecting enough fuel causing the lower psi reading on the compression test?

Many thanks!

 

[Pops52]

Figures are not as bad as they look. I was always under the impression that if their within 10% then there's nowt to worry about. Bit concerning that the misfire is on the same one though...

Fred said mine were 14 bar, which is around 200psi iirc.

 

[sven_8t4]

No1 is a bit worrying tried the old faithfull of a couple of squirts of oil down the bre and retest.... willtell you if its a valve or ring issue

 

[danielbarton94]

If the injector is dodgey on cyl 1 surely on cranking over on compression test might make a slight bit of difference on that cylinder? Eg less fuel to compress = less compression?

 

[Pops52]

Try it with the injectors unplugged to be sure. Wedge the throttle wide open too.

 

[mark123]

No. 1 looks worrying to me, especially with your other problems in that cylinder.

You're mostly compressing the air so I can't see the injector making a difference to that degree.

 

[Michael Woodford MST]

Injector will make next to no difference!

You should be doing your test with them unplugged if you were going about it the textbook way.

I wouldn't be worried about that. 170psi plus is no where near low enough to cause a misfire.

 

[MicKPM]

As above, injector seal will make no difference to engine compression levels on an F4R as they're after the valves.

Re-run the dry test and if your results are identical carry out a wet test which will, as also mentioned above, tell you if you have a ring seal or valve sealing issue.

How do you know there is a missfire on cylinder 1 specifically... diagnostics?

Mick

 

[Michael Woodford MST]

Not that I want to s**t the wind up you but this was making 165psi!

 

[Michael Woodford MST]

Doubt that's the fault with yours tho.

 

[MicKPM]

Not that I want to s**t the wind up you

Failed lol

 

[danielbarton94]

the car hasnt got a misfire really its more of a lumpy idle and the flashing engine light is on idle only but once your driving the light isnt there, the car pulls tremendously! and made a 350mile trip home from wales without a problem, i bought the car knowing it had the engine light on and the previous owner said it had been scanned and came up "Misfire cylinder 1" i have not scanned it yet as my diagnostic scanner is in the post so i cannot confirm myself what the problem is yet. And its only done 64k with fsh.

 

[danielbarton94]

anyone?

 

[Michael Woodford MST]

Injector.

 

[danielbarton94]

just scanned the car and it came up with cylinder misfire 1 error p0301

 

[jenic]

Could be coil pack or injector (or something else!)

Swap over injectors with another cylinder and see if the fault moves? If not try moving swapping leads/plugs. Then try another coil pack. That's what I'd do anyway.

 

[danielbarton94]

cheers buddy , will try it out tomorrow im starting to think its a exhaust valve now