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Discussion Starter · #1 ·
OK. New code (for me at least). Came on last Sunday while on the expressway. I thought it was the evap code that I'd been getting for a little while now. However, when I checked it the evap came up as well as these as "Pending" according to my code scanner (Toptak TP-100). Reads as random misfire and misfire on cylinders 1, 2, 3, & 4.

History: No problems post turbo installation. Idle was a little rich (due to idling problems when MAFS was positioned pre-turbo. Moved MAFS post-turbo but before BOV and idle problem fixed itself), but everything worked fine. Installed Energy Suspesion Motor Mount Inserts before Memorial Day and wanted to see if we could take some fuel out of idle

Sunday: I pull the #1 plug. some soot on the seat, but nothing on the electrode or the tip. Pretty much clean as a whistle (No soot or sparkle). I reset the code and wait to see if it comes up again.

Monday: Stop by the shop. We notice very rough idle (450-500 RPM) when the cooling fan starts up or A/C running. Add Water Wetter to bring down engine temps and possibly reduce the amount of time the fan is on.

Wednesday: Code comes up Tuesday night. I search here the next morning to find any possible fixes. I clean the MAFS as suggested before (non-residue brake cleaner method) and clear the code.

Thursday: Code shows again. I stop by my shop to see what he suggests. He says, next time it idles rough, pull the vaccuum line on the BOV and pinch it closed. Theory is that air is escaping from the BOV causing the engine to idle rough which leads to a misfire. Did that last night and the car still didn't idle correctly.

Here is where I need suggestions. It might be that one of my coil packs is somehow faulty. I can get 4 used ones to try out this weekend. However, I'm thinking that if it was a coil pack, then the car would idle rough all the time, not intermittently.

I was also told that the added vibration from the stiffer engine mounts may be falsely triggering the knock sensor and the ECU is interpreting that as a misfire. Happened to my friend's EVO when he blew a Stage 3 Clutch and was getting a lot of clutch chatter as a result.
 

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Discussion Starter · #3 ·
Thanks Jesse. Found the vacuum leak causing all the issues. Replaced the line, retuned the idle and everything seems to be working fine now. :thumbup:
 
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