Mini Me Swap: Cyl 4 not firing/low compression

[jdmjml]

hello, Im doing a mini me swap to my 94 hatch with a b7 block and z6 head. when i crank it it starts but runs very very rough so i know that i have fuel air and spark. after a few seconds of running i felt the headers and cyl one and two were warm but three and four were cold. [Edit: Cyl 4 has low compression.] i read that it could be timing but ive tried adjusting the cam (z6 cam) four times now and just dont know what to do next. any help would be greatly appreciated.

 

[sohclubkid]

did you get it TDC on the compression stroke when you installed the head?
is the timing set to 16* advanced?
new plugs/ wires?

 

[Wax Hands]

Too much air or fule could cause a lean or rich misfire.

Pull your plugs to see whats going on.

Verify spark on the two cylinders, simple screwdriver in plug boot near a ground and crank the motor over and watch for spark to jump. If it doesn't then you don't have spark in that cylinder.

 

[jdmjml]

yes, i had no. 1 piston at tdc and i have brand new plugs wires are used tho. and what do you mean is the timing set to 16* advanced? i honestly could not tell you. and all plugs are looking pretty black. i appreciate the help.

 

[Paul2281]

I would actually like to SEE spark at the plug just to make sure there IS spark....Make sure all wires are on the right plugs/dizzy cap....Plugs might be fouled now being as black as you say they are.....While plugs are out feel for compression if you don`t have a gauge.....Then check inj. to physically see fuel flow.....

 

[jdmjml]

alrite, i dont have a gauge but i used the palm of my hand to find that cyl 4 has no compression. cyls 1,2, and 3 all have good compression as far as i can tell but 4 has none. so what did i do wrong? didnt seal the head gasket right? thank you once again.

 

[RonJ]

Any CEL codes?

Before drawing any conclusions, you must first make sure the mechanical timing is dead on, that is the cam and crank are perfectly synchronized at TDC1. See diagram below.

If the timing is perfect, next check for spark at all plugs and also whether the fuel injectors are spraying fuel into the cylinders.

If all above is fine, then compression test the cylinders.

 

[Paul2281]

alrite, i dont have a gauge but i used the palm of my hand to find that cyl 4 has no compression. cyls 1,2, and 3 all have good compression as far as i can tell but 4 has none. so what did i do wrong? didnt seal the head gasket right? thank you once again.

WOW, bummer man...Well either you put the cams in off a few teeth or more and bent a couple valves, or a valve is hanging open and letting all the compression out, or dropped a valve from a keeper popping off the valve tip....Just need to take the head back off and start over and see what damage has been done...With the head on the bench pour some gas/,water/,alchol into the intake/exh. ports to see which valves are bad/bent,ect.ect.ect....
Good luclk and keeps up updated please....
Paul...

 

[Paul2281]

Any CEL codes?

Before drawing any conclusions, you must first make sure the mechanical timing is dead on, that is the cam and crank are perfectly synchronized at TDC1. See diagram below.

If the timing is perfect, next check for spark at all plugs and also whether the fuel injectors are spraying fuel into the cylinders.

If all above is fine, then compression test the cylinders.

X2.....GOOD INFO.....

 

[jdmjml]

i know, I was being so careful too. but alrite, if I get time tomorrow ill pull the head and bench test. I thought for sure I had the timing rite tho. dang. and also why only cyl 4? shouldn't cyl 1 have this issue?

 

[RonJ]

i know, I was being so careful too. but alrite, if I get time tomorrow ill pull the head and bench test. I thought for sure I had the timing rite tho. dang. and also why only cyl 4? shouldn't cyl 1 have this issue?

No need to pull the head to check the mechanical timing -- see diagram.

 

[jdmjml]

So i just pulled the head to find that cyl 4 has a intake valve not fully closing. Does this mean bent? it makes sense too because on the compression stroke i could hear it hissing into the intake. wish this wasnt my first time or i wouldve known before continuing with the swap. Any ideas on how to go about fixing the problem? replace valve? thanks for the guidance.

And the b7 heads going back on for now, this is a daily driver so i dont have a choice. Also, would anyone reccomend forgetting the mini me and just dropping in a full z6? i already have a z6 tranny in the hatch so im thinking it would make most sense. thanks again.

 

[RonJ]

Stuck intake valve 4 explains low cyl 4 compression. Any idea why cyl 3 also apparently had low compression?

Was the mechanical timing off? If so, this could have bent the valve. Or do you have reason to believe the head was bad before it was installed?

 

[jdmjml]

Is there a way to unstick the valve without removing cams rockers etc? and cyl 3's compression was fine as far as i could tell, seemed to be same as 1&2 i made the post before the comp. test so please disregard that. Also, i do have reason to believe the head was faulty because i triple checked timing and then checked again before i ever initally started the engine and the piston and valves have no strike marks on them what so ever. The first time i manualy cranked the engine i heard the hissing from that valve leaking as well. The head costed me 50 bucks, i wondered why so cheap..

 

[RonJ]

To do it right, you need to remove and inspect the valves.

Download the 92-95 Civic service manual at the link in my signature. The chapter on cylinder head/valve train should have all the information that you need.

 

[jdmjml]

alrite, thanks. and will the z6 timing belt still work with b7 head? the inital one is in dire need of replacement so its not going back on.

 

[jdmjml]

alright, everythings put back together but i am having a heck of a time getting the mechanical timing on. I know the procedure and i put the crank and cam at tdc but what im messing up is tensioning the belt. I put the crank back to tdc after tensioning and the cam is always one half to about a tooth off. I know im not tensioning the belt correctly because i have everything dead on tdc initally so if anyone had this problem tensioning or know what im not doing right please help. Thank you.

 

[RonJ]

What was the fix for the head/valve?

ONLY turn the crank counterclockwise. Don't try to tension the belt until you have rotated the crank several revolutions counterclockwise and verified the mechanical timing is still dead on.