Misfiring bad, one dirty plug??? Help!!

[CanadianR]

you can check for a vacuum leak the same way as boost leaks.

Make a boost leak tester, as shown:http://www.gtiroc.com/forums/showthread.php?t=46585.

First, do you have a fmic? anways, fit the tester to one end of your pipe run. Pressurize the pipe run to what your max boost would be. (don't pressurize is so much that it blows out a gasket or anything, if possible).
Then, fit it on the otherside of the pipe run and repeat. Now all I think that you need to do to check for vacuum leaks is open the throttlebody linkage with your finger? I'm not sure how close to the intake valves that vacuum can get drawn from, but the tester will let you hear leaking air wherever you may have a boost/vacuum leak.

 

[Fast Guy]

I am very puzzled as to why my Car sounds like a Suby. It really sounds Identicle to a boxer very odd.

Either it's running very rich or you're running on 3 cylinders.

 

[youngsyp]

I am very puzzled as to why my Car sounds like a Suby. It really sounds Identicle to a boxer very odd.

The Impreza sounds the way it does because the exhaust runners, on the exhaust manifold, are of unequal length. So, the exhaust pulses from each bank of cylinders are reaching the tail pipe at different times. Hence the bub bub bub sound.
The sound has nothing to do with the engine layout.

With that in mind, your distributor isn't way off is it ? Maybe the distributor cap or rotor arm are damaged ?!

 

[neil240z]

i would say its running on 3, have you tried a HT lead and Plug swap? if the cylinder hs compression it can only really be fuelling and ignition, you can disconnect the lead to the injector while the engine is running to see if there is a difference in tone, then you will know if it is getting fuel, then try plug and lead.

regards

Neil

 

[youngsyp]

i would say its running on 3, have you tried a HT lead and Plug swap? if the cylinder hs compression it can only really be fuelling and ignition, you can disconnect the lead to the injector while the engine is running to see if there is a difference in tone, then you will know if it is getting fuel, then try plug and lead.

regards

Neil

All very sensible mate.

 

[neil240z]

All very sensible mate.

many thanks youngsyp, i had the same problem on a fresh rebuild engine recently and it was running on 3, couldnt work out which cylinder it was so i just disconnected the injector plug from each cylinder and spotted it no problem, fitted a new plug and it was running perfectly, also even if you have had new plugs recently one could easily be duff, (it happens) also it is much easier to do this with a front mount as the car will run much better with the boost pipes connected though i did it with top mount disconnected.

give it a whirl and let me know.

regards

Neil

 

[neil240z]

also looking back through this post and reading that the plug is dirty suggests that it is getting fuel but not combusting it which only leaves ignition, so a plug, plug lead and dizzy cap would be on my shopping list the fact its running on the other 3 suggests that the rotor arm is fine but could mean one of the contacts on the dizzy cap has failed.

 

[Fubawu]

Thanks guys I am going to keep looking. I have not touched the dizzy yet so maybe the problem lies there. What would explain the loud scream/vibrating coming from the fuel pressure regulator?
John

 

[CanadianR]

have you tested for boost leaks?

and if you unplug the HT lead from the coil or from the spark plug, make sure to turn the engine off before putting it back on, otherwise you can burn out the dizzy.

 

[Fubawu]

As I am new to this how would a boost leak create a rough idel problem? Even when the car is not on boost it has problems?
John

 

[neil240z]

a boost leak wouldnt cause it to idle any different unless a pipe had fallen off, The ECU knows how much air the turbo is flowing at idle and on boost ( it barely flows anything on idle)

get double checking for a duff plug, HT lead and dizzy cap and we can go from there.

also Im pretty sure you cannot burn the dizzy out on an R as it uses a coil (it may be possible to burn the coil out) where a Honda uses no coil and an electronic igniter instead which can burn out if the ignition is left on too long.

regards

Neil

 

[Fusion Ed]

A boost leak after the throttle body(s) will cause the engine to idle higher. This is because the manifold pressure raises slightly and more air is available. Pull the crank case breather pipe off (PCV valve side) or one of the TB plugs if you want to see it for yourself. If its a large leak after the throttle body then it will simply stall (at idle) as the airflow meter is not seeing any air passing through, and run rich under boost

 

[CanadianR]

a boost leak wouldnt cause it to idle any different unless a pipe had fallen off, The ECU knows how much air the turbo is flowing at idle and on boost ( it barely flows anything on idle)

get double checking for a duff plug, HT lead and dizzy cap and we can go from there.

also Im pretty sure you cannot burn the dizzy out on an R as it uses a coil (it may be possible to burn the coil out) where a Honda uses no coil and an electronic igniter instead which can burn out if the ignition is left on too long.

regards

Neil

ah. The car that we burned out was a honda. Good to know.

 

[youngsyp]

What would explain the loud scream/vibrating coming from the fuel pressure regulator?
John

Mine used to do that, as does others on here, even new ones. I don't think it indicates the FPR is shot ?! It's just one of those strange things that happens.

 

[antgtir]

Mine used to do that, as does others on here, even new ones. I don't think it indicates the FPR is shot ?! It's just one of those strange things that happens.

Could it not be a symptom of the FPR being blocked slightly i.e. trying to force the fuel through a smaller hole?:?

I know you tested your fuel pressure Paul but did you also do it after the FPR? maybe the fuel pressure is low the other side of the FPR?

Still not sorted my little hic up yet but i think its slightly worsening now so maybe it will show itself and stop hiding the little git :lol:

Ant.

 

[youngsyp]

Could it not be a symptom of the FPR being blocked slightly i.e. trying to force the fuel through a smaller hole?:?

I know you tested your fuel pressure Paul but did you also do it after the FPR? maybe the fuel pressure is low the other side of the FPR?

Ant.

Ant,

It's kind of a high pitched vibration, hard to explain but, I think you're not far off the mark with that ideal. I'd expect it to be the pressurised fuel vibration whatever restricts fuel flow, to control the pressure in the FPR.

As for measuring the fuel pressure after the FPR, I don't think it works that way. What you're seeing when measuring the way I did, is the pressure across the FPR, not just the pressure acting on one side of it. If you see what I mean ?!
Plus, the FPR is actually in the fuel return line, not the fuel rail feed iirc so, measuring after it would only tell you the fuel pressure going back to the tank.

Paul

 

[red_dragon]

hey guys,

im actually helping John try and solve this problem since this was my Gtir... but anyways, we're guessing its the regulator... would a r32 GTR regulator work as that would be the easiest for us to find?..since the pump and injectors are the same, im guessing it would be..

 

[antgtir]

Just get an FPR from Bob aka Pulsarbobby, now thats the easiest way and the most reliable, i would assume the R32 GTR FPR may be set to a different pressure rating.

Ant.

 

[Fubawu]

Just changed the FPR and the noise is gone! Only problem is the car still runs rough. Pulled the sparks plug wires whlie idling and found plug wire # 4 had no effect when pulled. Other 3 had a noticable effect. Does this mean bad dizzy?
John

 

[CanadianR]

could also mean bad lead I'd assume.