Quick ? about slopes and breakpoint

[WhiteDevil]

So, i have had my stang running for a couple months now. I run the J4J1 with my 347 and i have 30# injectors. I have used the stock J4J1 breakpoint and set both slopes to 30 and i ran it through EA and now its like 29.9XX and 30.xxx after that. The car runs good. Steady 850 idle KAM's are almost right at 1.000 during acceleration. Sometimes at lower loads chuggin in gear the A/F goes to like 18:1 or so and it will buck.

here is the ? does anyone think it would be better to go to a GT Breakpoint and a 30High 36Low?

 

[final5-0]

Well John

Are you in CL when the buck/lean thing happens?

I know when I am at decell, and very light load conditions such as cruise and the like, I see lean values from the wb.

The thing you wanna be looking for is are you in CL and what are the K's doing during the happenig.

You very well could be at a condition that is pretty close to an idle condition
How do the K's look at idle?

As you know, you could work with several things for help and here are a few that quickly come to mind:
low slope
inj offsets
maf curve
tb airflow
neutral idle airflow

A lot of the time, low load bucking driving conditions can be killed by dialing back the spark a bit in the spark table load row that matches the load conditions you see in your dlogs

As for the moving t4m0 values in the j4j1 ................

I think it is good and helpful to look at the GT file for the trends
but
Sooner or later ... you are just gonna have to work with values that work best for John's 347 stroker combo.

Then again ... if you wanna try the t4m0 bp ... you always could try it and put it back with ease ... if it don't work

Hope this give you something to think about even though the info is kinda gereral in nature
and
if you need or want to get into more specific info ... fire away

Grady

 

[WhiteDevil]

Thanks for the input. No im not in closed loop when it happens. Im usually coasting at less than 1500rpm in gear when it happens. Im usually in traffic or something. Other than that it has run great. I will likely try out the GT breakpoint and GT style slopes and see how it works. I still need to use EA to set injector timing and TB air flow and neutral idle air flow.

One more question. When accelerating my k's are pretty much right at 1.000 or .998 ish they look really good. But when im coasting or in other OL conditions my Wideband doesnt seem to match my Commanded fuel. Its close but i would think it would be closer. Like lets say commanded 13.95 while coasting ill really have 14.5ish or something. Whats up with that?

 

[final5-0]

One more question. When accelerating my k's are pretty much right at 1.000 or .998 ish they look really good. But when im coasting or in other OL conditions my Wideband doesnt seem to match my Commanded fuel. Its close but i would think it would be closer. Like lets say commanded 13.95 while coasting ill really have 14.5ish or something. Whats up with that?

I have always seen a range of some what lean to very lean during decell and cruise conditons. It has never really bothered me all that much.

Some of those decell conditions have got fuel shut-offs envoked anyway so you would expect that just the same.

You mention other OL conditions

I assume you are NOT talking wot OL conditons here.

Grady

 

[WhiteDevil]

You mention other OL conditions

I assume you are NOT talking wot OL conditons here.

Grady

Yeah not WOT just coasting in gear but not to the point where fuel gets shut off. Im not to worried about it i was just wondering if this seemed normal.

 

[Stanger007]

The lean readings while coasting (low load) are normal - I've seen them on the Mustang as well as several import cars I've had a chance to mess with in the past.

The bucking wouldn't be normal though - like Grady said, start by dialing back some spark in the affected areas and go over your data logs to look for any inconsistencies.

Wes