17 replies to this topic

[Dylan720]

Hi all i have 2001 subaru liberty with a ej25 sohc. I had to replace my head gaskets in it as they were leaking externally water plus oil. After replacing them i seem to have a knock but a missfire at the same time i have 2 cyls firing and 2 not firing 1 3 firing 2 4 not firing at all ive replaced everything i can thing off spark plugs leads coil pack fuel injectors had timing belt re done 3 times by 3 difernet subaru mechanics and they all said that have never seen anything like it before and said post it on this website see if anyone else had this issue. Anyhelp would be great thanks

[duncanm]

is there spark on 2/4?

[Dylan720]

Yeah theres spark on all 4 cyls is there a way i can upload a video on here i have a video on what its doing

[El_Freddo]

Upload to youtube.

Where's this knock coming from in relation to the engine block?

If from the front cam belt area on the block it could be the cam belt tensioner gone bad. Ours did this within 15k km. replaced with a used oem unit and it came up tops without any knock issue.

As for running on two cylinders only, I can't help. Cam belt timing comes to mind, but I could be completely wrong too since so many qualified mechanics have already taken a look at it.

Cheers

Bennie

[Dylan720]

Has a brand new timing belt tensioner still does it ill upload a video to YouTube and past the link here

https://m.youtube.co...h?v=vAO4agKcJsA

[El_Freddo]

Ours was a brand new aftermarket tensioner too... But it's definitely not that.

The noise doesn't sound like a knock as such, more like a pop/cracking sound like a backfire.

Weird how it idles (seems high) then goes rough, pops and dies shortly after. Not a crossfire in the ignitor? Got a spare to swap in and see if there's a difference?

Cheers

Bennie

[Dylan720]

I havent tried that i did forget to meansion thow when running for about a min or 2 the cat glows red hot like completely glows red

[El_Freddo]

That to me indicates that there's a serious problem in the spark timing or lack of spark. The cats are getting a load of unburnt fuel which will kill them very quickly if you don't work out what's going on.

Who did the cam timing?

What are the compression specs for each cylinder?

Cheers

Bennie

[Dylan720]

3 suby mechanics have done the timing 3 times each one re done it each cyl has 150 to 155 psi

[Barbbachello]

That to me indicates that there's a serious problem in the spark timing or lack of spark. The cats are getting a load of unburnt fuel which will kill them very quickly if you don't work out what's going on.
 

This. 

Post a photo of the timing marks. Both cam and crank

[Dylan720]

Ok i couldn't work out how to upload a pic on here but i can explain the 1st cylinder is sitting in the middle of the bore like middle dead center both cam marks are st 12:00 and crank mark is 1 tooth to out to the passenger side witch seems to corrospond with mark on the block above the crank pully

[duncanm]

Definitely sounds like ign, fuel or cam timing.

 

Go old school - stick a timing light on it to check the ignition timing on the crank marks.

 

Belt should look like this:

 timing.png   108.78KB   2 downloads

 

(btw - to add images to a post, select 'more options' right side under the text input box)

[Barbbachello]

Make sure youve used the line at the back of the crank sprocket and not the triangle 

[Dylan720]

Oh then thank you guys so much ill check that out tomorrow and let you guys now how it goes

[crjohnson]

injector plugs plugged into the right cylinders?

[Dylan720]

I had a feeling that they might not have been but the qay they seem to run dont seem like they can be plug in anywhere but where they are running ad the wiring is to short

[El_Freddo]

Injector wiring shouldn't have been touched in a HG job - lift whole intake off injectors and all, and that's that.

Other thing to look at: spark plugs - it could be that te plugs have been crushed somehow. This could close the spark gap. So check that all plug gaps are correct.

I can't see the cam timing being out if three mechanics have checked it over. If it is I'll be dumb founded... And happy for you that it's a relatively easy fix if there's not been any valve damage from valve on piston action - although if it's the arrows that have been used I don't think that'd happen.

Cheers

Bennie

[Dylan720]

So ive checked the timing the back line on crank sprocket is lined up and the cams seem to line up properly to spark plugs have been replaced twice and the set thats in it now i have tried in a mates suby with no issue.