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Discussion Starter · #1 ·
I have had this intake filter on for quite some time now and its very filthy. when i changed it to a brand new one then my car started running like crap during idle. It was going real rich then real lean, back and forth and sounding like crap. So i put my dirty filter back on and its fine. What can cause this? Its kinda funny but it makes no sense to me.
 

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I had that problem on my Volvo before. Its most likely because your car is used to how the old, clogged filter flows. Its probably had a long time to set its fuel maps just right. Then you change the filter and all the sudden its getting more air and the computer doesnt know what to do. Essentially, it will just have to "learn" again. Im pretty sure you can unhook your battery for a few minutes and then try driving the car normally, and it should help.
 

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Discussion Starter · #4 ·
Alright i will try that. I was thinking my ecu but my car latly has been acting weird. Also my safc2 shows knock when im at idle after a long drive and set my turbo timer. it will set about 6 knock. I dont understand the concept of knock yet but i know its not good. I think alot of problems occured when i added the coil-on-plug ignition. I still have stock injectors and sometimes my safc has a mind of its own and its not controllable.
 

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+10! That dirty filter caused the ECM to adjust the air/fuel to lean to compensate the horribly strangled and choked air intake.

True, undo the negative battery connection for a good while to reset the ECM to allow new MAP settings.
 

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I kinda doubt that a dirty vs clean filter can make that much of a difference for your a/f ratios, at worst your car just takes in less air. Its not like the maf "expects" something, it just counts how much air is passing by and adjust the fuel accordingly. Maybe check over for any leaks in your intake tract? If anything is leaking you could be sucking in unmetered air which could cause your problem.

But yeah, try resetting your ecu first and see what that does. I'll be surprised if that fixes your problem though.
 

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^ my thoughts exactly. The filter would have had to be clogged to the point of being airtight for you to have screwy maps after replacing it
 

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^Yup, the difference would be something like driving in -30degree weather at sea level versus driving in 100degree weather on top of a mountain. Your car can adjust for things like that, it just sees different amounts of air and compensates accordingly.

I would check all of the various nipples and lines going to your intake tract to make sure none of them are torn or off. Also, make sure your maf is plugged in (stupid, yes, but i've done it enough times to learn that people can be forgetfull) and check its connection.
 
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