Hey guys,

I asked this question a while ago but I never really got an answer I understood. My question is this...I've got my combo tuned pretty decent...except for when I put it into gear it will stall out and I get a code 33.

When I datalog it will idle at 65 map..900 rpm 14.7 afr. The second I put it into gear it will IMMEDIATELY jump to 10.2 afr. I can literally go from park / rev or neutral / drive and watch the AFR toggle in and out from 14.7 to 10.2 each time it's put into a gear. It's weird. It does this cl and ol.

If I drive and stay above 3 mph I dont have the problem...just as long as I stay above 3 mph. I have to shift into neutral at a stop light or it will stall in about 8 seconds.. it always starts right up though. I can almost bump start it.

I'm using tunercat with the E6 or 6E I cant remember but it's the 16168625 ecm 93 TBI 4l60 trans.

Any suggestions what setting I need to change to eliminate this problem? Other than that it runs incredible!

 

Sounds like you need to tune your fuel/VE parameters at that rpm/map value. Your running rich when in gear so you should adjust that part of the Ve table and see what happens. Just my thoughts

 

65 Kpa at idle is too high. Have you adjusted timing at all? How's your idle quality?

 

I really dont have much of a choice on the idle KPA due to the camshaft profile. This combo is putting out nearly 500 hp. It idles at 11" of vacume or about 65 map. The idle is great and timing is spot on. Pulling it in and out of gear and having the AFR toggle in and out from 10.2 to 14.7 is not a fuel table or spark table issue. Theres a "setting" somewhere that needs to be changed (probably referencing AFR vs. map vs. gear selection) but within the program there isn't anthing i can find.

 

If not mistaken the code 33 is there becuase you have insufficient vacuum for idle conditions, usually sets right before or during the stall. Kept happening to me while I was trying to tune idle tables at low rpms & too much VE/fuel. The 3 mph is interesting as the idle spark/ fuel tables have 3-4 mph limits while anything above has seperate tables. Maybe that is where the problem lies.

 

So what did you eventually end up doing? It sounds like you leaned out your ve table and the problem went away? I'm not using a wb to actually monitor the afr at idle, but going by smell and how stable it idles i'm quesing it's running right where it should. But your on the right track with the comment on vaccume though...The second it goes into gear It idles down...creating less vacume...causing the code 33...then the stall. The part i cant figure out is the commanded afr change when selecting a gear.

 

Code 33 is triggering fail safe mode and the PCM is generating a fake MAP signal based off of the Alpha N code and the TPS/IAC position. The stock Alpha N numbers will be way off and cause some weird fueling problems. The simple thing to do is change the Code 33 trigger point to a higher value. On my 312 that idled at about 10 in/hg of vacuum (8 in/hg with A/C on), I had to push the numbers up around 80 KPA.

 

Ended up changing injectors due to high rpm fuel issues, wich interestingly enough fixed that problem but created different ones. Fast is right about the code 33,and when mine would set I coudn't clear the code with the scanner but had to disconnect the batt & power down the pcm.