F-460 MISFIREING

[MAUBRI]

Hi All

I've been having this problem for some time but still havent got to the bottom of it.

1) my MPG is 7.5 which being on a 1997 (F-550) F-Super Duty Motorhome Stripped Chasis weighing in at 6500kg + is to be expected.

2) I have a EEC-IV with ODB 1 with no Cat.!

3) RV starts first time, every time but a little rough, it stays rough throughout the warming up cycle. Open the throttle it goes up through the revs but still a little rough. Pull away and it has about 3/4 power.and the rev counter pulses instead of being steady.

4) Just bought a Ford Code reader and came up with the following
KOEO--11.......OK
KOER--538....Very confusing, the Ford Book says "Invalid Cylinder Balance test due to throttle movement during test" WHICH THERE WASN'T.. tried 3 times the same result each time. HOWEVER. Chilton Workshop Manual says "Insufficient RPM change during KOER dynamic response test / Operator error.

Any ideas would be helpful.

I will say that I have already changed:- Fuel filter; Spark Plugs; Spark Leads; Coil.

Brian

[Tony Santara]

Brian
Could it be your throttle control valve ?

Duncan at Starspangledspanner will know what the codes mean

[Big Cubes]

Not wishing to be rude in anyway , but check the plug leads and make sure the firing order is right, is highly possible that somewhere along the line the leads have been removed and a couple are back to front . Sounds more like incorrect firing order to me.

Check #1 lead is in the right position on the dizzy and go from there.

Remember dizzy turns ANTI-CLOCKWISE.

[mikeburke]

Whatever the problem you need to ascertain which cylinder/s is/are not firing.
First when the engine is running you can pull off each plug lead and see if there's a difference - if there isn't that's the one(s) that isn't firing.

Assume you find a single cylinder that's not firing, try changing over a spark plug and be sure the same problem occurs. If it is the different cylinder it's a plug fault (however if you have changed all plugs it's unllikely).

If the original cylinder still misfires you need to do a compression test. No compression = no Bang ! No or Low compression will need further investigation, problems could be a simpl valve problem to more serious ring / piston / liner-cylinder problem.

However, before going any further try those things.

NB - when you take the plug leads off be sure to isolate yourself from the potential "shock", it does hurt a tad. Also, VERY IMPORTANT, check that you can do this without overloading the ign system and causing further damage. If an overload is possible the alternate way of doing the plug / cylinder test is to remove a lead, insert a spark plug into the removed plug cap (so it will still allow the discharge), and start the engine.

Takes longer, hurts a whole lot less and almost certainly will not cause damage to the ign circuits (always worth getting this confirmed first though - my experience on heavy mechanics lapsed in the early 90s).

See how you go.

[Olley]

Originally Posted by Big Cubes

Hi BC check that firing order, according to it you have nine pistons, two number six's.
Good thinking though about the firing order, simple mistake for someone to make.

Olley

[ruffingitsmoothly]

I know you say that you have changed the plug leads but try looking at the engine in the dark!

I had this problem years ago with a 1966 V4 Corsair,(Yes I am old) I like you had changed everything and still had a problem, when I looked at the engine running in the dark I spotted sparks running along the outside of the leads, so took them back and replaced them again fault cured

Just a thought!

Regards Pat

[Londy]

Just a thought as i had similar problems on a Mercedes.

Take distributer cap off and look inside see if a hairline crack in it, or carbon deposits on rotor arm or brass connectors.

Also maybe rotor arm faulty. Have you cleaned the connectors were they screw int dizzi cap.

television interference connectorrs at plug end faulty, swop one with next plug.

also check i think its called the condenser attached to points.

Just a few suggestions. Im getting on now but had all these probs in the past

Londy

[MAUBRI]

Thanks to you all with your suggestions,some I have tried some still to do. When I get to the bottom of the problem I will let you know.

I've also had some input from FORDTRUCKS.COM who I recently joined, but you have to also learn a new slang language, but I.m slowly getting there.

Timing was also put forward as a possible, I am currently waiting for delivery of a Timing Light. It seems I may also have a problem with the EGR ? vacuum.

Brian

[Olley]

EGR Exhaust Gas Recirculator, allows a proportion of the exhaust gas to go back into the inlet side, improves the emissions. I suppose if it let to much go in, that might cause a misfire?

This from www.wisegeek.com

If the EGR valve is stuck open, it will essentially cause a vacuum leak, leading to inefficient combustion, rough idling, hesitation, and sometimes stalling in extreme cases. This is because the car cannot combust on carbon dioxide from the tailpipe — it needs atmospheric oxygen. If the combustion chamber is flooded with exhaust from an open EGR valve, it will not function properly. To check and see if the EGR valve is stuck open, have someone idle a parked vehicle with the brake on while you examine the plunger shaft to see if it is stuck open.

This sort of technology came in after I left the game, so I no nowt about it, apart from what I have read.

Olley

[MAUBRI]

Originally Posted by Olley

EGR Exhaust Gas Recirculator, allows a proportion of the exhaust gas to go back into the inlet side, improves the emissions. I suppose if it let to much go in, that might cause a misfire?

This from www.wisegeek.com

If the EGR valve is stuck open, it will essentially cause a vacuum leak, leading to inefficient combustion, rough idling, hesitation, and sometimes stalling in extreme cases. This is because the car cannot combust on carbon dioxide from the tailpipe — it needs atmospheric oxygen. If the combustion chamber is flooded with exhaust from an open EGR valve, it will not function properly. To check and see if the EGR valve is stuck open, have someone idle a parked vehicle with the brake on while you examine the plunger shaft to see if it is stuck open.

This sort of technology came in after I left the game, so I no nowt about it, apart from what I have read.

Olley

I know what you mean Olley, I bought an oldie for that sole reason, but technology in the states was working faster than over here in the UK, so I to am a bit out of my depth, but I'm learning slowly.

Thanks for the info though, more things to try.

Brian