Well I know mine goes full rich and then full lean. When the idle drops like that the power output from the alt drops with it which means everything gets less power. For whatever reason the battery doesn't pick up the slack. N it's not because the battery is small, I have a full sized truck battery. Can't remember the exact output but it's right around 950-1000 amps, was most powerful one I could find at the store haha.

 

Hate to revive this but I'm having the same issues. I have replaced everything from the throttle body (fully rebuilt and pressure tested), iacv, tps, injectors and seals. I'm at a complete loss right now and my tuner is in the same boat. He's made adjustments with the base idle and has it sitting at 1000rpms. However my idle drops down when coming to a stop, the afr reads full rich then spikes full lean. Sometimes the car catches itself othertimes it doesnt. I removed and blocked the egr which helped with some sputtering issues but now I'm onto the idle dip. I have done the boost leak and smoke test with no leaks. Not sure what other steps to take, I am going to swap out the upstream o2 sensor next thinking it might be faulty (120k miles, stock turbo with boltons and 264 cams) or the sensor might be lagging?
thoughts?
thanks in advance!
-Jason

 

Check your PCV valve? Had similar issues and found my pcv valve transitioned slowly from open to close. Changed my setup to a bored out PCV valve with a one way check valve and solved the idle dip.

 

I had the exact same issue and had another adjustment during tuning when taking it back and it fixed the problem.

 

Guys what kind of BOV are you running? My HKS BOV on my Z did this exact same thing.(reason why I don't have it on my Evo.) the MAF Misreads the A/F because of the BOV causing the idle to bog coming to a stop. Let me know if that helps out

 

I'm running a Synapse DV with port a/b. Recirculated of course.

I already put the evo away for the winter so I didn't get a chance to change the PCV, but I will give it a shot hopefully when I'm back from my business trip. Hopefully it won't be covered in too much snow!
Thanks for the help guys!
-Jason

 

bumping this - i adjusted my LICP, not sure if there is a small leak now but the idle dip is severe

 

Remedy in this order:
BLT
BISS adjust
ISCV table adjust
Add a few degrees of timing and a bit of extra fuel in the areas where idle recovery becomes difficult.

The battery voltage plays a huge role in idle dip but it can still be stable with a mini battery.

 

I'm a new evo owner that just started having an issue with idle dip and or stalling while rolling up to stoplights. When I got the car the idle was set at 1000rpm. I was prepping my car for emissions and lowered the idle via ecuflash to 850 rpm. Thats when the issue started. (I had previously failed in my dsm for having an idle above 1000rpm). My evo has a mini battery, synapse dv and a hard intake pipe w/ k&n filter. I will try adjusting the timing as the idle timing cells are set at 5* but it seems that the idle rpm was most likely set to 1000rpm by the previous owner to correct this issue.

 

mine did it with the oem 9 bov, i changed it to a non-diaphragm type and now i cant even make it happen.

 

Changed to the stock rubber intake pipe and it fixed my iddle drop issue.