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2.5RS misfire 3&4 only


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6 replies to this topic

#1 steve landay

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Posted 08 October 2012 - 07:49 PM

I think i'm posting in correct forum.

On my 05 2.5RS, any thoughts on why i get misfire CELs on 3 and 4 but not 1 or 2??? The main problem though is retarded timing and lack of power under medium to heavy throttle in any gear/rpm range which THEN causes the CELs. Problem immediately goes away when I decrease throttle. Starting from a stop , throttle is much more sensitive to the threshold between running fine and than bucking and retarded timing.

But under lower torque/throttle settings the engine accelerated smooth and fine and I can operate up to 90mph, although at that speed the threshold between normal and retard is much lower and more easily crossed.

-s

#2 davebugs

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Posted 08 October 2012 - 08:06 PM

Welcome to the USMB

Search here - often asked question. Infact a thread or two about this last week.

I have no experience with anything that new.

But on Subaru's and their "wasted spark" ignition system that simply means it's an electrical problem. Plug(s), wire(s), or coil pack. Both those cylinders use the same part of the coil(3&4 are in the back).

#3 torxxx

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Posted 08 October 2012 - 08:17 PM

spark plug wires that are bad generally act up the most under a load. I'd start with visually inspecting your wires and check them with an OHMS meter.

Also check the coil pack and make sure there isnt a ton of corrosion under the plug wire boots.

Oh and next time give us a lil more info than a 2.5RS. Year helps sometimes because there is year specific issues with every type of car

#4 cal_look_zero

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Posted 08 October 2012 - 09:55 PM

3&4 misfire is commonly attributed to the camshaft sensor.

#5 davebugs

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Posted 09 October 2012 - 06:58 AM

3&4 misfire is commonly attributed to the camshaft sensor.


I've never seen this. Hope the OP lets us know what the solution is.

Timing cold always be off a tooth or so but often you get cam/crank errors since the ECU can't actually tell you the timing belt is off and can't match up the signals. It'll occasionally throw a crank or cam sensor error - but not often a lot of the time. I've seen this on the DOHC's and imagine it could also happen on SOHC's.

#6 torxxx

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Posted 09 October 2012 - 01:59 PM

I honestly cant see the cam sensor only throwing codes for 3/4. They use the same type of magnet on each spot on the cam sensor. The only thing I could see causing that is metal stuck to the magnet on the back of the pulley causing interference between the cam sensor and the pulley itself.

But yea, please let us know what you find out

#7 Fairtax4me

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Posted 09 October 2012 - 05:12 PM

How many miles on the car?
Misfires under load are almost always spark plug related. When were the plugs and wires changed last? What brands were used?
How long since the last tune up?
Does engine temperature have any effect?




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