Hello,

Now that it's starting to warm up I'm going to try and troubleshoot a small issue with my flashed IX. I have a Jester flash, TBE, fuel pump, and intake. When throttle is barely applied the engine seems to stumble, buck, or almost backfire through what seems to sound like the cone filter. It is more pronounced in the cold and only started to do it when I put the above mods on. I haven't emailed Jester yet and wanted to start here. One comment is that I didn't see any increase the the MPG after the above mods... And "Yes" I still drive the car the same (like a little old lady). Any ideas / suggestions would greatly be appriciated.

Thanks,
Charlie

 

does it stop after the car warms up?

 

one thing to definitely check is the gap on your spark plugs

 

No. It does not go away after the car warms up.

Thanks,
Charlie

 

i have the same issue on my 05 evo 8...it does not go away either when warmed up.. i tried running a some techron and that did not help

 

I put all the mods on the car at around 5k miles. Car now has around 15K. Problem introduced itself after mods and has been constant ever since.

Thanks,
Charlie

 

same problem here..... give a little gas say bout 2000 rpm and you can here it miss or backfire/ whatever uw anna call it, but during normal driving it is fine...

 

are you guys getting any cel? when is the last time you have changed your spark plugs?

 

This is a common problem. I have had it on both my Evo VIII and Evo IX but only after exhaust and intercooler mods with flashes in both cases. This occurs when slowly lifting the throttle following acelleration like when keeping up with traffic on the freeway. It is not turbo surging because you are not in the boost. In fact it occurs when in vacuum. I noticed quite a reduction in this problem when I switched from a connical filter back to the OEM airbox. The suggestion that plug gap could be an issue would be attractive if the mixture was going very lean. However, when you close the throttle plate you richen the mixture.

I would suggest having Jestr log the car while you make the stumble happen and see what finds. Then tell all the rest of us what he finds so we can get ours fixed too.

 

Clean your MAF with some electrical parts cleaner (sell it at Autozone, Murrays).

The oil from your cone filter probably gunked up the sensor. It did mutiple times on my car.

 

Those metal intake pipes and conical filters are known to do this. The conical filter can mess up the air flowing across your MAS, making the MAS miscalculate. Second (even though you aren't talking about experiencing this), the metal pipe causes echoes when your compressor bypass valve opens and diverts air back into the turbo inlet pipe. These echos are picked up as noise by the MAS and once again miscalculated. This is the reason people notice stumbling or possibly stalling when they go from cruising to hard braking for a stop without downshifting.