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

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Fubawu

Guest
Hey Guys

I was at the track yesterday and had a problem. Not sure what the problem is
but as I got onto the straight the car sputtered and misfired bad. I was told black smoke puffed as I misfired. In the pits the car was idling very rough (sounded like a Suby)
Pulled the plugs all very clean except one which was loaded with carbon. No arking from the plug wires etc. The injectors are stock and the car was running 0.9 bar. I am thinking the piston is shot or something is wrong with my injectors. I have a power FC in the car but I am not sure what to look for. Knock levels peaked on track around 32-33.
Any ideas??
John
 
J

jameswrx2

Member
Sounds like it could be an injector sticking. May be worth swapping that injector for another one (if you have a spare can borrow one to try)
 
F

Fubawu

Guest
Thanks for offer , I have a set of Evo injectors that I was too lazy to install before the lapping event. I will make the swap this week
John
 
F

Fubawu

Guest
Carbon Fouled: If your plug tip and side electrode are blackened, they have been running with too much fuel (or possibly too cool from a stuck-open thermostat). Other sources of the problem may include bad wiring, leaking injectors, or in some cases the vehicle has been driven at too slow a speed for extended periods of time. The combustion process is not being allowed to have its natural burning-off, or cleaning, effect.

I can rule out slow speeds. Though I find it odd that only one plug is black
If it was a thermostat wouldn't all plugs be black?? This leads me back to a
faulty Injector. Ther is hope for my motor after all. I am going to swap them tonight and also do a compression check

John
 
F

Fubawu

Guest
Ok
Did the compression test on a luke warm car (engine sounded rough turned it off)
1 150
2 151
3 150
4 149

Did the test with the throttle pumped any thoughts?
John
 
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F

Fubawu

Guest
The 149 plug was the plug with the carbon build up. Does anyone know if the power FC can go into Limp mode to protect the car?? i.e boost spike, lean or something like that?
John

I am guessing it is something with injectors
 
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P

pulsarboby

Guest
yeah the comps are fine matey! would have to agree that you have a dodgy injector, or could possibly be related to the other problem that youve just posted up.

if the engine is running up n down in revs at idle, then that is called 'hunting' this is caused mainly by air leaks somewhere in the vacuum system.
check for split pipes and get a tin of wd40 or similar and spray it all round where the inlet manifold meets the head and any inlet gaskets, if the idle speed then evens out then you know theres a prob with a gasket leak somewhere or split pipe that the spray will temporarily seal for a second or two.
 
F

Fubawu

Guest
Thanks, it is nice to know the motor is not shot. Now time to problem solve.
John
 
antgtir

antgtir

New Member
Just out of interest have you checked a different set of leads?Check the dizzy cap for build up of scum on the terminals and also check the rotor arm.

Ant.
 
F

Fubawu

Guest
I am very green when it comes to turning wrenches. I am enjoying
the challenge so far. Antgtir can you you explain what the rotor arm
is?
Thanks
John
 
antgtir

antgtir

New Member
Fubawu said:
I am very green when it comes to turning wrenches. I am enjoying
the challenge so far. Antgtir can you you explain what the rotor arm
is?
Thanks
John
Click to expand...
When you remove the distributor cap you will see a black arm with a tan coloured, flat insulated metal strip. This strip makes contact with the terminals of the distributor cap which sends the current through the leads and to the plugs firing ignition.

If there is too much scum on these terminals of the dizzy cap or the end of the rotor arm is so badly worn the current cannot jump far enough the current will not be sent through to the spark plug (or a current not strong enough for good ignition) this can lead to a carbon build up on the plug.

Just something simple that could potentially cause the problem.

Ant.
 
C

CanadianR

Member
!!!!! make absolute sure that the engine is off before you pull plug wires off. We were testing a honda's plug wires (blasphemy, yes I know:p) and the owner decided he'd check which cylinder was missing . . . by pulling off and replacing a spark plug wire one at a time. He finished one cylinder before the dizzy fried and copped out on him.
 
F

Fubawu

Guest
Well, I swapped the injectors out and it had no effect. What I did notice is the Fuel Regulator was making an extreamly load noise. Squelling (spelling?) Could that be the route of all evil??
John
 
Y

youngsyp

New Member
Fubawu said:
What I did notice is the Fuel Regulator was making an extreamly load noise. Squelling (spelling?) Could that be the route of all evil??
John
Click to expand...
You can either change it out to see or, check the fuel pressure across the fuel rail.
The later would be the best route to start with.
 
antgtir

antgtir

New Member
Check that there is a vacuum leak from the gasket between the throttle bodies and the head, this is a possibility.

Ant.
 
F

Fubawu

Guest
Any other ideas. I have not yet located a Fuel pressure Reg. I am very puzzled as to why my Car sounds like a Suby. It really sounds Identicle to a boxer very odd. Compression is good 150psi ,new injectors. Plugs are fresh wires are newish. It really sucks as I have missed two track days and could miss a third if it is not ready this weekend.
John

PS how would I check for a vucuum leak?
 
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