Tuning folk out there, I need your help

Focus is re-turbo'd successfully! Zetec, gt28 and tuned by yours truly with the SCT software package. 

Tune for the most part is pretty good/spot on but I do have two issues. 

1) car leans out to 12.4 to 12.8 between 3500 and 4500 in 3rd and 4th

2) I can be I'm a given rpm and tp and the car can go up a hill and the increased load will start to build boost. So now I'm in low boost at 13.5-14.7 afr...

SCT PRP specific question, for the base fuel map, is it possible to have it be based off of load and RPM vs TP and RPM? I saw a switch for it in the adaptive fuel table but not the base fuel table. I noticed that my turbo spools very reliably to start making boost around 80% load. I figure if its possible to have the base fuel map based on load it would be easier to set my AFRs more reliably.

If not possible or if no one is familiar with the SCT stuff, whats the best way to combat this problem?

I'm pretty sure that my MAF is tuned well because my open loop tune was pretty spot on throughout the entire rev range in 1st-5th. (Set the whole base fuel table to .781 lambda to get it dialed in pretty well)

As always thanks for any help provided in advance 

Nate

Re 1 - it's actually going rich, not lean. Lean would be AFRs > stoich.

Unfortunately that's the only piece of dubious information I have to add to this thread .

Where does the turbo really start making boost? Seems like a transient fuel is off if your starting to make boost at that point.

Or you are experiencing spark blowout because of boost.

BoxheadTim said:

Re 1 - it's actually going rich, not lean. Lean would be AFRs > stoich.

Unfortunately that's the only piece of dubious information I have to add to this thread .

I never could remember, so thank you. 

So if he pops 15:1, slightly lean, 16:1 is really leaning it out, and 12.5 is really rich?

I have nothing to add, just want to know how lean is too lean, and how rich is to rich. 

That said, wouldn't you want to run a turbo car slightly rich, maybe help cool down the intake charge?

Waiting to be told what an idiot I am for pondering such questions...

This thread is now returning to its original programming.  

Going FROM 12.4 TO 12.8 is indeed lean.  Not lean enough to worry about- as that entire area is the LBT region.  But going from rich to less rich is leaning the mixture.  Going REALLY rich is 9:1, as that will cause rich misfires.

Slight boost at stoich is not a problem- I would not worry about that at all, we do that all the time.  It is going slightly rich, anyway.

I'll have to look into the SCT thing- not familiar with how those operate, but while your low end MAF is good, it appears that your high end MAF may be a little on the low side- while it may not be a problem going slightly leaner at high speeds- it's unlikely that the desired a/f is actually leaner, which would suggest that the MAF at that point is inputting low.  Same for the light boost area.

So now that I know what SCT is, sorry, I can not help.  

Well under boost I'm commanding 11.5, so while technically speaking its rich, under boost 12.5 is too lean for my liking. Relatively and context here, you wouldn't want to run an NA at car at 14.0 at WOT, too lean, even if its technically rich.

The most consistent metric that the car is at 0 psi is ~80% load, anything above that is positive pressure.

Throttle position can be as low as 300 or as high as 400 to begin making boost. (Highest tp is like 750-800 iirc)

RPM to start making boost can be 2500 to 3200, by the time it's at 3500 we're usually at a full boost.

Got a response on another forum claiming that I should set my open loop TP roughly 100 points lower because the PCM doesnt really through it into full open loop until 100 points after my command.

Ex: I set open loop at 300, it wont really go into open loop until about 400

alfadriver said:

Going FROM 12.4 TO 12.8 is indeed lean.  Not lean enough to worry about- as that entire area is the LBT region.  But going from rich to less rich is leaning the mixture.  Going REALLY rich is 9:1, as that will cause rich misfires.

Slight boost at stoich is not a problem- I would not worry about that at all, we do that all the time.  It is going slightly rich, anyway.

I'll have to look into the SCT thing- not familiar with how those operate, but while your low end MAF is good, it appears that your high end MAF may be a little on the low side- while it may not be a problem going slightly leaner at high speeds- it's unlikely that the desired a/f is actually leaner, which would suggest that the MAF at that point is inputting low.  Same for the light boost area.

Oops, should've had more context. I'm commanding 11.5 and it's usually at 11.5 but will creep up to ~12.4/12.8 at WOT in 3rd and 4th. From what I'm reading from you, sounds like I just need to data log in those gears at those RPMs and adjust my MAF?

So in part throttle cruise conditions, at say maybe 1 or 2 pounds of boost, being stoich is completely fine?

What psi/conditions do I need to worry if it's still stoich? 

SCT is like hptuners, just another tuning software, for anyone else lol

Not familiar with SCT vs other tuning software but... do you have access to what the AFR targets are where it's "leaning out?" Is it only in a certain rpm range/boost level or does it get leaner as you go? Are you out of fuel system, or could it be marginal (pump, injectors, etc) where it may be dropping fuel pressure?

I usually tune to ~stoich under 4k even at 100kpa, then richen from there, generally 12.8-13:1 afr at that load. Richer at more manifold pressure but very setup dependent what the motor may like or not like. Usually 1pt rich from best power won't effect power much but gives a margin of safety.

alfadriver said:

Going FROM 12.4 TO 12.8 is indeed lean.

That was a clear reading comprehension fail from my end. Thanks for the correction.

In reply to TurboFocus :

Well, SCT modifies something that I'm not allowed to modify- on quite a few different levels.  I'm sure you can find the help that you will need, as the actual solution isn't too hard.

Alas, the specifics, I just can't do anything about.  Maybe someday, I'll be able to add some info to projects like that.

In general, though, I would not be too concerned about being stoich with a small amount of boost- you see that pretty regularly on production cars right now.  The one part I would be worried about is if the exahust temps creep to high for the turbo.  Assuming you are not knocking, the exhaust temps are the largest concern with a/f when you are not trying to make peak power.

edit- the other generality I can say- you should be getting what you are asking for.  If you are not, you need to fix that first before trying to get more of what you are asking for.

alfadriver said:

In reply to TurboFocus :

Well, SCT modifies something that I'm not allowed to modify- on quite a few different levels.  I'm sure you can find the help that you will need, as the actual solution isn't too hard.

Alas, the specifics, I just can't do anything about.  Maybe someday, I'll be able to add some info to projects like that.

In general, though, I would not be too concerned about being stoich with a small amount of boost- you see that pretty regularly on production cars right now.  The one part I would be worried about is if the exahust temps creep to high for the turbo.  Assuming you are not knocking, the exhaust temps are the largest concern with a/f when you are not trying to make peak power.

edit- the other generality I can say- you should be getting what you are asking for.  If you are not, you need to fix that first before trying to get more of what you are asking for.

It's all good, I can figure out the specifics or work around it... and if I don't I have an ST170 motor and all the stuff to drop in LOL I appreciate the information you provide either way

Well, that solves my worry about issue #2, it goes back to my command during that RPM range at anything above 50% throttle 98% of the time.

Issue #1 sounds like I just need to datalog in open loop and dial in the MAF for those conditions again. Thought I had it good but only one way to find out.

Thanks again!

Paul_VR6 said:

Not familiar with SCT vs other tuning software but... do you have access to what the AFR targets are where it's "leaning out?" Is it only in a certain rpm range/boost level or does it get leaner as you go? Are you out of fuel system, or could it be marginal (pump, injectors, etc) where it may be dropping fuel pressure?

I usually tune to ~stoich under 4k even at 100kpa, then richen from there, generally 12.8-13:1 afr at that load. Richer at more manifold pressure but very setup dependent what the motor may like or not like. Usually 1pt rich from best power won't effect power much but gives a margin of safety.

ARF targets as in like what I'm commanding? yea, I can post a pic of the table I have in the software.

100kpa per google is 1 bar, tuning noob here but that seems like a lot of boost to be at 14 pounds. Any insight as to why so lean at boost? or is it only that lean under 100% load?

I like safe, I have no knock sensor so im balls to the wall full send tuning with my ying yang hong kong hurricane maker. (99% sure its a real GT28, so... like... I actually care about the turbo lol)

In reply to TurboFocus :

100kpa is atmospheric. (At sea level, or so.. for most people it is in the mid 90s)  Must think in absolute pressure.

In reply to Knurled. :

Ahhhhhh, gotcha lol

Makes sense thank you

Yeah sorry 100kpa = naturally aspirated, sea level, full throttle = 0psi on the boost gauge.