parish8

iTrader: (6)

i have had a problem for awhile. with the 02's all hooked up and the truck running normal(closed loop), and while crusing down the street or highway i get an odd ocasional fueling issue. it will go way rich(10.5-1 wideband), stay there for about 1-3sec, then return to normal(14.7). do this about once every minute or 3.

i am trying to run leaded fuel now and pulled the factory 02's and only run the wideband when tuning. the problem i had before is still there but worse, it will happen but not go away. it will stay rich for 1minute or more at a time, almost seem like the factory 02's could see the problem and correct for it or maybe it was running some kind of test and once it saw the o2's react it would go back to normal.

now for the big problem , when i floor it if it is in this odd fueling mode it stays in an odd fueling mode, all the way to the end of the run. big cam, speed density and boost are a bad deal when your not set up for it. when it is in one of these fueling issues it is way rich at cruse and then goes way lean when the boost kicks in, like 15-1 or leaner measuered by 2 widebands at once.

from all that i am seeing it apears to be going speed density, the vacume is low so it thinks i am under a load and runs rich at cruse, then when the map hits 103kpa it just thinks i am at WOT but doesn't see the boost so then it heads lean. i have loged the maf flow and frequency and the numbers hold steady while all this goes on.

so, am i thinking corectly, sound like it is going into speed density? why would it do this and how can i fix it? i am not quite ready to get an after market pcm but maybe thats what i should do.

jimmyblue

iTrader: (11)

Maybe the COT function is seeing your boosted
normal operation's higher MAP as "high load" and
kicking in? Have you disabled COT or at least
knocked down the max enrichment? If you played
with max COT enrichment and saw the wideband
respond appropriately that would pin the tail on it.

I was fighting a similar-sounding deal on my car but
I think that was a transmission abuse mode deal,
I think I made it go away but haven't gotten the
road time in to know for absolutely sure and don't
have a wideband yet (the heinous bog could have
been either gross enrichment or spark pull, but
it's been hiding from the logger every time I tried to
capture it).

parish8

iTrader: (6)

cot is off, it goes lean FAST, as soon as the boost kicks in. i just found some wideband logs, first one is what should happen does happen most of the time. i am prety rich but with the cut out open it goes up about .5 so i am right where i want to be.



now on this one you can see where it goes way rich while crusing right before i nail it and then gets lean after i nail it.

Bink

Looks like COT Overtemp doesn't it?? I thought it was. Does it seem to happen only at cruise - steady throttle? I chased this problem for months!! Probably your VE table values are out of range of the reported MAF values. If the calculated AirFlow, from the VE table, is greater than the reported AirFlow of the MAF then the PCM drops fueling from the MAF and goes strictly to the VE table - Pig Rich. You cannot drive out of this by throttle feathering ...with my car it usually would last about 12 -15 seconds ( Test Condition?). I would guess when you nail it you're forcing more air into it and it's not compensating -> lean.

My car did this as it transitioned to idle and while cruising. Very frustrating!

You can create a test condition by picking a MAP and RPM that you frequently see at cruise. Then go into the VE table at this MAP and RPM (cell) and multiply this, and the adjacent MAP -same RPM cells, by 35%.
Now when you hit this area while cruising it should "fall off" the MAF onto the VE table -> pig rich.
My fix was a new VE table......NoGo you are THE MAN

Hope this helps some.
joel

parish8

iTrader: (6)

thanks bink, you are the 2nd person to tell me to look at the VE table, i have never even looked at that table but was told how to get efilive v5 to learn the table and enter those numbers, just haven't done it yet. i hate to go adjusting things i dont really understand, looks like it is time to realy start learning how that ve works.

i didn't know it would switch back and forth but what you describe is alot like what i am seeing.

Bink

i didn't know it would switch back and forth but what you describe is alot like what i am seeing. Mine did it and it never flipped a code!!

Bink

As a quick diagnostic check you could look at the RPM range it's effected at and then decrease the VE table values by 25% in this range. If it doesn't do it I'd then try to determine exactly which MAP/RPM cells need to be adjusted. 25% lean will increase AFR about 8% - at least it does with mine (NA).
Nice FJO Setup BTW.
joel