hello everyone im new here. let me start off with a little about my setup

im running a TBI350 700r4, 3.73 gears.
mods:

vortec heads
performer rpm dual plane
COMP XE256 cam
TBI mods
headers back

thats the majority of mods

i have a 6299 ecm. similar to the 747 with expanded ve and spark tables. datalogging with winaldl and tuning with tunerpro.

heres the problem. im having trouble with a stumble from 1200-1600rpm
my ve table is almost flat from 00-1200rpm from 20-55 map, but yet my blms are at 128 at 400-800rpm at 1200rpm they go to 105. way rich. Sync-async is set to 1200rpm and 55map. should i raise it? could this cause the rich condition? thanks!!

 

Glad to see you made it over to this site Whitelightnin92 Im sure that you will find a ton of good people and info over here. Best of luck with the tuning!!

 

Async fueling will cause the fueling to vary. The average fueling will be the same, but the ECM can skip injector pulses in async fueling if the PW is too low, not to mention that the firing rate is fixed at 80 Hz.

Theres nothing wrong with disabling the manditory async fueling, if your ECM supports that feature. You can simply set the entry threshold to 6375 RPM and the engine will remain in sync. injector firings.

 

thanks everyone! i have heard and read alot of good things over here, so i decided to give it a try

 

I believe the asych also can increase the PE fueling. Is that correct Dim? I am locked "synch" currently and have 80% DC at WOT last few times I checked so I dont need it currrently. Asynch seems to cause idle issues for me.

 

after raising the rpm thresh to 1600 the rich condition moved to 1600. so im going to play with it untill i find the right spot

 

Please explain "after raising the rpm thresh to 1600". Are you suggesting you are enabling asynch over 1600 rpms? My understanding is that asynch is enabled just when required. Only time I saw asynch was then the PW needed to be reduced to meet commanded A/F. I never saw asynch fueing other than idle at <900rpms. After locking synch fueling and running OL idle I never saw it again. Are you witnessing in logs asynch occuring? I would suggest you need to modify the VE table values to get the BLMs reasonable close as < 115 it may not be able to pull the fuel to establish stoich. You may out of range of adjustment at 105.

 

my ecm was set up to go async at 1300rpm above 55map with stock settings. my blms are 115 now from 1200-1600 they have to be wrong because it acts really lean in that area. are you saying the ecm cannot get the PW low enough and thats why im rich?

 

Maybe I am misunderstanding the purpose of asynch. Wont be the first time I misunderstood. My understanding is asynch is invoked when the pulse width cannot be small enough or large enough to meet requirements set in .bin. IOW one of two injector fires at each distributor firing for synch. asynch fires every other DRP dist reference pulse if PW is too large. Effectivly redcing fueling. Locking synch allows it to go rich(idle) but fueling is consistent. At WOT or PE if requirements can not be met, instead of one inj firing each DRP they both fire to meet demands.

Why do you think the BLMs are not accurrate? Try removing 5% fuel in those cells that are fat and see if BLM increases.

Your stumble may not be BLM related. It maybe is AE related. when the butterflies open in comes the air and insufficient fueling to cover the event. Cool temps require more AE for sure.

 

There is also a conversion factor for async to sync(at least in EBL -> INJ - Async Multiplier - A table of multiplier values used to convert a synchronous PW to an equivalent asynchronous value. The table values are defined by the number of cylinders.) I think I played with this to make async meet the commanded afr. It appears that EBL goes into async for too small a sync pulse width on these parameters:

INJ - Async Transition Hi

If the sync PW is greater then this value then async mode will be exited (if in async mode).

INJ - Async Transition Lo

If the sync PW is less then this value then async mode will be entered.

EBL goes into high async mode when a rpm and map threshold is met and another set to exit. Do you know if the async mode parameters you are adjusting are for high load or idle?

I have disabled the high load asyn ~ set rpm to 6375 and map to 100 since I am not over 80% duty cycle WOT. This is what RBob had to say about high load async:

The purpose of Async mode during high load is to extend the RPM capacity of the injectors. For this mode to operate properly the async duty cycle % should be above 90%. This is to ensure an even consistent fueling to all cylinders. This functionality is really a bandaid for injectors that are a little too small. And is not recommended to be used.

I was thinking of trying to use async at idle so that the spray pattern would be better firing a single injector at a time, but I have a lot of other tuning to do prior to that.

 

Why do you think the BLMs are not accurrate? Try removing 5% fuel in those cells that are fat and see if BLM increases.

Your stumble may not be BLM related. It maybe is AE related. when the butterflies open in comes the air and insufficient fueling to cover the event. Cool temps require more AE for sure.[/quote]

i know the BLM data isnt accurate for two reasons.

one my ve was lower at 1200 than at 800 (definately not right.)
two i had AE close (no more lean pops) untill now. because i lowered VE so much. why would it be lean and BLMs say rich?

 

I would go back to open loop tuning (BLM locked at 128) until you get the VE tables right before worrying about anything else. I am around 100 burns and am still tuning the open loop VE tables. Make sure to tune at operating temperature. Then after that go back and retune things like choke, PE and AE.

Also make sure to set the IAC close to zero steps at idle and normal operating temp by adjusting the idle screw. Make sure this is done before any other tuning.

 

so just set min and max BLM to 128? i guess i went about it the wrong way. i set the clsd loop thresh to 255 deg C last night. it still went closed loop on me.

 

i just realized my INT is a rediculous number 140+ but blms are in line 120-128. this is whats causing my lean problem. why would INT be so high?

 

I could be wrong, but the INT is merely a symptom of the lean condition not the cause. The INT is a fast reacting, adding/ removing fuel for sudden rich/ lean conditions. Where as the BLM is slow reacting, adding/ removing fuel for long term conditions.

 

i got about an hour long datalog tonight and found some things that never showed up before for one reason or another. im getting a lean surge under load at low rpm (below 3000) that i never saw before. im glad i spent the time and $ to go out and get a nice long datalog. you are right about the INT thing. i read/searched some and found that when INT spikes ++ its a lean condition.

 

ok im really starting to get annoyed. when i think i found the problem it turns out i didnt. started out a was lean from 2000-3000...or so i thought. i would get the occasional lean pop, and it was surging bad above 70 kpa. i started raising ve in 5% increments. popping went away but still surging. i ended up adding enough ve that the engine would surge for a few seconds and then start to choke itself out unlill i let off or mashed the go pedal. im lost as hell now. any suggestions? other than get and EBL and a wideband? LOL. that has to wait awhile

 

maybe pull some timing?

 

If the BLM/INT is within the parametors for CL fueling you will not be lean nor rich. Keep in mind when CL fuel trim is functional you WILL BE at stoich of 14.7/1 for reg fuel. when you see 115 BLM all that means is that ECU from 02 sensor feedback is placing A/F at stoich and pulling fuel. Same story at 145 BLM it is adding fuel to maintain stoich 115 or 145 BLM is not rich nor lean. It is stoich and CL is doing its job. By adjusting the VE tables by datalogging you are allowing the ECU to respond more efficiently. I used CL fueling successfully when I first tuned my engine a few years back. I depended upon my functional NB02 sensor to get VE reasonably close. No EBL back then. Issues I had were AE related. General drivability issues. Getting VE in line through use of CL allowed commanded 12.3/1 for PE to show on dyno. Not luck, as if VE on, the
PE should be on. Or pretty close. If you lock fueling to OL you will need a WB02 to tune VE.

I have never personally witnessed a max INT of 145. If so it adding fuel and resetting as BLM drops. I would think once BLM gets within its limits it should show more reasonable changes of 128-136.

Granted surging is an indicator of lean but I wonder if surging could be a fuel delivery issue(TPI pump?). How big are your injerctors at what fuel pressure? Maybe the engine will like an increase of FP?

Yes pull some SA. Vortec heads do not require as much timing. Not sure if KC will cause a surge.

 

i looked at my SA table. in that area it has stock settings, should i still pull some?. im running 24psi on 61lb/hr injectors. thanks!!

EDIT: KC? can you define that please?

 

There is a Vortec spark table posted somewhere. I believe it may be truck however. Just asa test I would highlight your current entire table and pull 7%(.93 multipier) SA.

 

i found a problem with my xdf when i went to change the SA table. im going to fix that first and see what happens