New Thread Misfire on Cyl #4

[Fubawu]

Before I took the car to a pro so they could look at it. This is due to the old problem stated above. The ar has been firing on 3 cyl.
I was working on the car last night (aka charging the battery) I ended up doing a comp test the engine was cold so the #'s are a little low but across the board I got 154! Pretty good so that kills my theory that # 4 is shot. I really have no idea what could be making it not fire. SO here is my question is it possible a bad relay fuse could be at fault? It did go before and was replaced with a non factory unit.
John

 

[youngsyp]

If it's still not firing on one cylinder, and the comp levels are fine, I'd suspect the distributor or one of the injectors isn't working as it should be.

Have you tested the injector for cylinder 4, and if it squirts in sequence with the others, on the correct stroke ?

Just an idea.

Paul

 

[Fubawu]

I just installed Evo injectors thinking it was the same problem. Is there something I am missing in the fuel system other then the actual injector?
Thanks
John

 

[youngsyp]

I just installed Evo injectors thinking it was the same problem. Is there something I am missing in the fuel system other then the actual injector?
Thanks
John

I guess the power feed to the injector could not be working as it should. Stick a meter across it and see if there is power at the injector in question.

Paul

 

[Fubawu]

Thanks,
makes sense. My question is would the power feed to the injctors not affect all cyl's the same? 1,2,3 run fine???
John

 

[pulsarboby]

maybe a sticky or blocked injector on that cylinder!!!

 

[youngsyp]

Thanks,
makes sense. My question is would the power feed to the injctors not affect all cyl's the same? 1,2,3 run fine???
John

Not if it's only a dodgy lead/connector to just the one injector. ;-)
The injectors are completely independent of each other and they all fire at different times (1 and 4 together and 2 and 3 together iirc?!). Again though, that's not because the injectors themselves are linked but, just the way the engine is designed to work.

Paul

 

[pulsarboby]

sorry paul but wrong (dont you just hate me lol)
1 & 4 dont fire together, they fire individually ie 1,3,4,2 as with engine firing order (sequential injection)
its possible that theres a dodgy connection on one solenoid (but unlikely) as im sure he would have checked connections already.
the ecu controls the injector firing sequences and as fubaru has said its highly unlikely that one injector harness has broke down from ecu as all 4 would generally be problematic or not work at all.

 

[youngsyp]

sorry paul but wrong (dont you just hate me lol)
1 & 4 dont fire together, they fire individually ie 1,3,4,2 as with engine firing order (sequential injection)
its possible that theres a dodgy connection on one solenoid (but unlikely) as im sure he would have checked connections already.
the ecu controls the injector firing sequences and as fubaru has said its highly unlikely that one injector harness has broke down from ecu as all 4 would generally be problematic or not work at all.

Don't the cylinders reach firing position in pairs though ? I only say that, from what I can remeber of the crank design !

And it could be that the cable between the ecu/loom and the injector is damaged, not necessarily the connection itself. As you've said, the GTiR uses sequential fuel injection so, each injector has an independent feed from the loom.

I'm just clutching at straws really but, it seems perfectly possible.

Paul

 

[pulsarboby]

Don't the cylinders reach firing position in pairs though ? I only say that, from what I can remeber of the crank design !

Paul

no!
1 & 4 are both at tdc at the same time but only no1 cyliner will be on compression / firing stroke ie 4 stroke. so only 1 injector will be squirting at one particular time
the same applies to no's 2 & 3 cylinders when there @ tdc

thats where induction, compression, ignition & exhaust comes in (each cylinder is on a different stroke at any given moment in the cycle)

 

[youngsyp]

no!
1 & 4 are both at tdc at the same time but only no1 cyliner will be on compression ie firing stroke ie 4 stroke. so only 1 injector will be squirting at one particular time
the same applies to no's 2& 3 cylinders when there @ tdc

thats where induction, ignition, compression & exhaust comes in (each cylinder is on a different stroke at any given moment in the cycle)

Of course, sorry. ;-)

Paul

 

[antgtir]

So has the rocker arm not broke then? or have i missed something here?

Ant.

 

[B1Ad3]

Might seem a bit silly but my cars prety noisy and when/if i take out a lead to the plugs i find it hard to hear or notice a difference in the running of the car.

Is there a sure tell way of knowing that the car is running on all 4's other than running rough because mines always rough.

Cheers.

 

[antgtir]

Depends on what you mean by rough as some R's have quite wild cams and as such do sound lumpy on idle etc but run obviously on all 4 cylinders and as they should.

If your r is not running correctly, then one way would be to run it for a couple of mins at the most and then stop, remove all the plugs and see if any of them are wet with fuel.

If there is a lead or plug braking down or an injector isn't working then as you rev the car the miss should be noticeably more prominent.

Ant.

 

[B1Ad3]

Depends on what you mean by rough as some R's have quite wild cams and as such do sound lumpy on idle etc but run obviously on all 4 cylinders and as they should.

If your r is not running correctly, then one way would be to run it for a couple of mins at the most and then stop, remove all the plugs and see if any of them are wet with fuel.

If there is a lead or plug braking down or an injector isn't working then as you rev the car the miss should be noticeably more prominent.

Ant.

Are the stock cams lumpy, because mine is.

 

[pulsarboby]

stock cams wont be irratic idle, uneven) unless they have vernier sprockets fitted (which i doubt yours has)
if its not running on all 4 cylinders, then you can tell by the note of the engine after pulling each plug lead off in turn (easier if you have a kv meter)
if the note of the engine stays the same with lead removed then put an old spark plug in the end of the lead and put that to earth to see whether theres a spark on that particular cylinder!
if not then its more than likely the lead thats breaking down or your distributor cap.
if there is a spark at the plug then its more than likely the plug in engine breaking down.
but if you change the plugs and probs still there then its either an injector or worse still! a mechanical problem.







there you go fubawu ive edited my description just for you!!!!!

 

[Fubawu]

B1a3d

What do you mean by lumpy? Is it pulsing or is it a true lumpy idel?
I have a friend coming this weekend with a little more knowledge then myself. I will
keep it posted

John

 

[B1Ad3]

There's like a murmer in idle and it feels rough overall.

It will be a smooth note and then you will get murmers in the note like a miss fire or something.

When cold it sounds like a rotor.

 

[Fubawu]

Thanks Pulsarboy,
I am guessing it is Mechanical as the dizzy rotor arm, injectors and leads were checked.
I keep hearing rocker arm mentioned I guess that is the next step!
John

 

[antgtir]

If you are certain you have checked everything you can, all you can do is whip the rocker cover off and discount the rocker arm as a possibility. It doesn't take much to identify tbh so may be worth just for piece of mind.

Ant.