So I recently switched from E85 to 91. I made sure the gas light came on and drove a couple extra miles.
After filling with a full tank of gas the car ran rough for a bit, eventually smoothed out.

My AFR readings at idle and cruise are where they should be. While taking off in 1st gear my AEM wideband goes full lean '---' and the car is completely gutless until the afr's sweep back to 14.7. Every other gear while cruising and idle feels perfect.

During this short time while the car is fully leaned out it feels like it has no power and I can hear the turbo whine more than usual, like its working but not going anywhere. This lasts about a second or two
Any ideas?

 

How many gallons on 91 did you pump in?

 

I pumped in about 12 gallons of 91

 

are you on a flex fuel system?
or just swapping maps.?

 

It's likely not your fuel switching. Something else is wrong.

 

What are your mods?

 

I am not on a flex fuel system. I was just swapping maps

 

Any ideas on what might cause this? Ive swapped maps before with no problem. Nothing else was done to the car beside swapping maps.

here is my mod list:
Stock block and Head(Stock cams)
FP 84mm 71hta w/ 18psi wga
FP 84mm intake pipe
3" TBE
Muse 02 dump
3 port bcs
Synapse DV
Vrsf 3.5" intercooler
Muse licp
Walbro 255
RC 1200cc injectors

 

Are you still on MAF? Catch cans? No vacuum leaks? DV coupler to uicp not leaking? DV diaphram not leaking?

I'll add others as they pop in my head.

 

Maybe do a boost leak test next?

 

Have you run this map before ,without any problems?

 

I have ran this 91 map a couple times before with no problem at all

Still running MAF and not running a catch can. Have not performed boost leak test after this problem occurred. Will perform boost leak test and see what I find.

 

If it ran find before, then fine on e85, then now lean after only swapping maps. And nothing has changed between the last time it ran right and now? The battery is okay? Alternator? No voltage problems at all?
You are in closed loop when taking off from a stop, so it could be sensor related. A vacuum leak would kinda make sense because you are drawing in more air than the MAF is seeing. You say you have checked all possible areas, so it's quite the mystery...

 

Try to swap in a good MAF and see if it's better. But before that, check your MAF and clean it to see if that fixes the problem. Where in California are you?

 

Going to perform boost/vacuum leak test sometime this week and see what I find.
What do you recommend cleaning the MAF with? Just regular CRC MAF cleaner? Can says not to use on mitsubishis