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Missfire - Checking sensors with AEM


jevansio

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I have developed a missfire after driving for long periods (1 hour plus). It comes on around 2k rpm under light throttle. I can seem to put my foot down & drive through it.

 

Does this seem like a coilpack problem? I'm sure ages ago I had a simlar issue & it turned out to be a sensor (cam or crank - can't recall). Can I elliminate it being a sensor by checking the AEM logs when the problem is there? What would I be looking for exactly? Is there a cam/crank signal reading that would be dropping to zero say?

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I had this Jay, exactly the same symptoms too. I replaced all the coil packs, connectors, plugs. Everything. Problem free now.

 

Next time it happens, pull over, switch the engine off and back on again immediately. Is it still there? Mine went after doing that.

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I had this Jay, exactly the same symptoms too. I replaced all the coil packs, connectors, plugs. Everything. Problem free now.

 

Next time it happens, pull over, switch the engine off and back on again immediately. Is it still there? Mine went after doing that.

Yes, I pulled over, turned off, waited 30 secs, turned back on & it was gone. Was only 5 mins away from home so no idea how long it sorts it for, but this is the second time this has happened now.

 

My hunch was coils but I thought high load situations would be the most common time for them to show any weakness

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I have developed a missfire after driving for long periods (1 hour plus). It comes on around 2k rpm under light throttle. I can seem to put my foot down & drive through it.

 

Does this seem like a coilpack problem? I'm sure ages ago I had a simlar issue & it turned out to be a sensor (cam or crank - can't recall). Can I elliminate it being a sensor by checking the AEM logs when the problem is there? What would I be looking for exactly? Is there a cam/crank signal reading that would be dropping to zero say?

 

open AEM.

 

goto.

 

sensors.

cam/crank

advanced

parameters..

 

check stat synced stays on and check for errors.

 

you can also log your rpm trace in the onboard logging.. (nice and fast)

 

does your ignition fault occur at high load?? i.e boost misfire?

if not its perhaps unlikely that its an ignition problem.

do you have a WB02? could be a sensor on the motor giving incorrect reading and trimming fuel

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Many thanks, I will check that. I have a spare set of coils Bossco has loaned me to elliminate one at a time.

 

No, under load it's fine, that's why I suspected it may not be the coils.

 

Yip I thought of the O2 also, as it's in closed loop when off boost & goes open loop as soon as there is any boost. When the miss occurs the o2 gauge goes lean, dunno if that is the cause of the issue or a side effect.

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