question on going lean on start up

[WS6FirebirdTA00]

well on a cold start i command 9-14.0:1 and hover around 14.7:1. on a warm start i command somewhere between 11-14:1 and it goes way lean, about 17:1 or so. i have read some posts on this but nothing real definative on why this happens. can anyone explain? or know somewhat of a fix for it?

[jimmyblue]

AIR pump could be active, there's a minimum temp
to run it?

[WS6FirebirdTA00]

air pump has been off my car for about 2 years lol

[jimmyblue]

So you have roughly a 4-point difference between
commanded and actual, in both cases, but the
commanded-stoich one is bothersome?

Is this -only- at idle, open loop? If so do you really
trust what you've done with that part of the VE
table?

[WS6FirebirdTA00]

on a cold start, when it warms up, commanded=actual. so after about 10 min of starting or once the multiplier goes to 1.0, all is good. except for warm starts, warms starts it will just take about 5-10 min. before getting to be normal. but aftera long drive at idle i hover around 14.6 or so

[jimmyblue]

So how much trimming is showing at hot closed loop
idle? Anything on the order of this startup error?

All of the environmental adders / multipliers should be
rolled up in your logged fuel air multiplier. How does
the final logged value of FAM agree with the value you
expect? That should tell you if it's a command problem
or a prediction/feedback problem. And open loop has
no feedback so if you see commanded and wideband
jacked apart then it has to be airflow or fueling (or
some error air source hitting the wideband but that
is off the table).

[WS6FirebirdTA00]

my o2s went way + on me when they went into closed loop and the longer the car ran the lower they got. i have been reading a bunch of posts with people having similar problems, i wonder if its just from car to car it does this or what? only thing effected is start up. oterwise i can command whatever i want and get it once the car has been on for a while

[S2H]

here the basic low down of what I think is going on....
you have tuned your vehicle and set OLFA to 1.0....
now its lean anytime its in open loop...
so you nned to tune OLFA...I have a writeup ....99% complete...it works dam well...I just need to get my wideband back(a guys car fried it cause he kept blowing fuses and we didnt have any available and couldnt find one cause of time of day...blah blah blah...had to drive 3 miles with no power to sensor...fried sensor...he's buying a new one for me..waiting for it to show up...)what I need to verify is teh data matches for driving in open loop...make sure its all correct before it goes into HPT user writeups and posted everywhere...
pm me and I'll shoot you the basics....

the part of them going lean in closed loop sounds like your cam is geting in the way of idle trims....no easy way around that....its going to trim way positive because of cam overlap

I remember seeing a table in another program called Maximum speed and max TPS for Idle LTFT learning
and also I remember seeing something called LTFT and STFT correction values for Idle...or something to that effect and an STFT idle enable disable...I dont see them in HPT...but it made it to where you could disable trimming at idle conditions...

perhaps these are things maybe to be asked about being added to HPT as they would be useful for your issue and helkp determine what the real culprit is by disableing a few things to see if it changes or not...basic troubleshooting..

[WS6FirebirdTA00]

yeah i remember talking to you about it. the cold start is fine for me, the afr is where i want it. it is just the warm starts, after the car sits for a little bit that bothers me. i dont plan on going back to closed loop due to the oscillation in the o2s were causing some odd issues, but now the car runs great, there is no bucking so i like it in open loop. once i get a log of it i could prob show it a lot better. the thing is i have a 180*f start up that shows lean but once the car is on for a while it is ok. and if i adjsut that in the olfa im screwed for when it gets ok, ill go really rich. there has to be something associated with some sort of timer in there, cause if the car sits for xx min it will happen. i remember we talked about the bias factor maybe contributing to some of this but i tried to shift it over to the left and that made no difference.

[S2H]

how long does it take it to go from lean to normal??
20 seconds?? a minute?? 5 minutes??

just curious....have some ideas....just need tyo know some details

[S2H]

also what ECT... and what cylinder volume are you in at idle...what map are you in at idle....

[WS6FirebirdTA00]

On a cold start, the AFR stays at 14.7:1 everywhere, but i command from 9.0:1 and it gradually goes to 14.7:1. On a warm start after sitting for maybe 30 min or more, I start up, any ECT, and it is around 16.0-17.0:1. After about 5-10 minutes it goes back to being normal after driving it, I have never just let it idle to see how long it takes to go back. I idle at about 46-48 kPa and have around 0.16 g/cyl (I will have to double check that though as I am not 100% sure but I know it is between 0.15-0.18).

[WS6FirebirdTA00]

ok well on live they have this same issue so i am apparently not theonly one

http://efiforum.iqd.co.nz/showthread.php?t=1683&page=12

I posted on there to see if they found anything out. I command 10.0 on start up and see about 14.5 or so on the WB. If I start warm it does this as well. I wonder if there is a table in there that controls fueling for when the motor is just started. I just went out and did the VE in OL and am staying OL and still see the problem. I can add enrichment on start up to get it to be safe but on hot starts it would make me run rich at operating temp, so I am kinda stumped right now

[NTIMID8]

Your not alone..and one of the reasons I do not recommend Speed density tuning yet.

I would like to see some direct support from HP on this.

Every speed density tune car I have messed with seems to do the same thing.

My personal car does it as well, its as if there is a bug in the enrichment routine on cold and hot restart. instead of adding fuel it subtracts it in the actual pusle width delivery.

It seems to mirror the fuel enrichment routines for hot and cold start in terms of time to get to the commanded airfuel.

Phil

[NTIMID8]

Oh, also the cars with MAF/closed loop start and run flawlessly

Phil

[WS6FirebirdTA00]

my car runs so mcuh better OLSD once its warm, i just fudge some of the numbers for start up to get the desired a/f, i would like to get it right though so it sees what it commands.

[MNR-0]

At warm startup, how long before the commanded OL value moves to 1.0 from cranking? What is it commanding OL wise immediately after and before cranking - measured via the scanner, not what you think it is in the VCM.

[WS6FirebirdTA00]

i have log posted in the help section on this if you want to check them out, its the section for bugs/issues.