Going Lean????

Turbotungsten

forum member
Joined
Jan 26, 2008
Posts
144
Reaction score
2
At 11psi of boost AFR stays at a steady commanded 11.3 during WOT runs. When I gave my manual boost controller a twist I got 14psi of boost, but it went lean (about 12.7). I went home and adjusted the MAF Transfer function where needed and went out for another test run. It still went to 12.7 under full boost. Added more fuel (for a total of 18% in the needed areas) and still the same.

MAF counts are climbing, MAF volts are climbing, fuel pressure is staying a commanded 39, injector pulse width is climbing. I am at a loss as to why it's leaning out.

Spark blow out??? I would think this would show rich instead.

It's still pulls hard..maybe laying down just a smidge.

Any ideas???

Car is a single turbo 3v running 93 octane.
 

Turbotungsten

forum member
Joined
Jan 26, 2008
Posts
144
Reaction score
2
One of you tuning pros PLEASE PLEASE PLEASE help. This has me baffled! I did close my gap on my HT0s to from 32 to 28, but did not help. I did some more logging and this is what I found. First of all I was wrong in my initial post in reference to injector pulse width.

Commanded fuel pressure is as commanded (39 delta)

V Bat is right at 13.9

MAF Volts climb steadily

MAF Counts climbs steadily

Load climbs to 1.6 the starts to fall even as MAF Volts continue to increase (this is where I start to go lean)

Injector Pulse With Starts to decrease at the same time the load does

Why are my RPMs, and MAF Counts/Volts increasing but my load and injector pulse width decreasing?

I do have failed MAF tables increased to 1.9 in the higher two TPS voltage rows.

I would greatly appreciate some help on this. Thanks in advance
 

redfirepearlgt

forum member
Joined
Mar 19, 2011
Posts
2,497
Reaction score
263
I'd love to know more about this phenomenon as I am reading a tech manual on tuning by Greg Banish (slow but thoroughly) so I can at least speak on a more technical level with my tuner and better understand what is happening. I may end up going with the Pro Racer tuning software package down the road but have not made that decision yet. In the end I know that actual hands on tuning is an art form and something that can ultimately only be learned hands on. Like many skilled trades it can't be mastered from just reading a book and I get that as a skilled tradesman in my field.

So my first question in hoping to strike conversation and input to this thread from actual hands on tuners is this:

Was your tuning for air flow done at the lower boost level or the upper boost level? If done at the lower boost level would this not cause a lean out which could cause some really weird things at WOT open loop? It would be my guess, and correct me if I am wrong that if not done so, the air flow modeling for the MAF Transfer Function at WOT would need to be done at the higher boost level. Then when a lower boost level max is desired the HEGO's would see enrichment and trim out fuel properly to maintain targeted AFR at WOT. All of this is assuming that you aren't having any issues in closed loop with no boost while targeting Lambda 1.

Second question: Is there a limit to the amount of air flow a Ford PCM is capable of reading? Some PCM's max out at around 70lb/min and to over come this the MAF transfer function has to have scaling added. Further then that scaling has to also be added to the fuel models and VE models as well as I understand it correct? So if it is a matter of the PCM having a fixed range on air flow regardless of MAF size could scaling be the issue only with regard to the higher boost level which may be going outside PCM range without scaling being used? This is assuming at lower boost level air flow is in the PCM range and at the higher it is not.

Hopefully my input will generate some feedback from experienced tuners that will help you and correct me in my attempt to learn more about the mysteries of tuning.
 

Turbotungsten

forum member
Joined
Jan 26, 2008
Posts
144
Reaction score
2
I really appreciate your input! You may be on to something with things needing to be scaled, but I thought this was only the case when you were pegging the MAF.

As far as the the HEGO's go, they do not add or trim fuel at WOT. Unless I am mistaken.

I like Banish's book and it has been helpful
 

redfirepearlgt

forum member
Joined
Mar 19, 2011
Posts
2,497
Reaction score
263
I really appreciate your input! You may be on to something with things needing to be scaled, but I thought this was only the case when you were pegging the MAF.

As far as the the HEGO's go, they do not add or trim fuel at WOT. Unless I am mistaken.

I like Banish's book and it has been helpful

I am quoting right out of the same book on page 110. Appendix A at this point. I have not gotten that far but just flipped to it earlier. I read when its slow here at work and there are no down machines. ANY-HOO!!! Page 110 states EEC-V ECM's are limited to being able to calculate no more than 1700 Kg/hr MAF volume. Therefore if you are above that you will have to scale MAF Transfer function as well as a lot of things along with the MAF transfer function. Page 71 hits on this as well.

As for the fuel trim I am pretty obviously mistaken, but this is why I am chiming in....to learn as well as solidify what I have digested. Obviously with the ECM in open loop (hence the term - duh on me) you would have to be correct I would think.

So that said Q: Does a variable boost setup have to be tuned at the higher boost level such that when dialing the boost down only the associated data in the tables need apply to the minimized boost level or does the boost controller somehow generate an output the ECM/PCM sees that it uses to correct MAF flow as volume (and VE aka Load) obviously will change with boost.

Thanks for letting me engage. I appreciate being able to learn new tricks at middle aged. This stuff is fascinating.
 

Turbotungsten

forum member
Joined
Jan 26, 2008
Posts
144
Reaction score
2
Brother, I really appreciate your input. I think that if you tuned for say 15lbs of boost and everything was correct, you could dial your boost back to any number and be spot on. I work my way up so I don't blow my motor. I plan on having a higher boost tune and a lower boost tune but the only difference should be commanded AFR. I plan on commanding 11 for higher boost, say 11 to 16 psi and 11.5 for lower boost. Timing will be able to be the same in each tune as I will request lower timing as load increases.....so at 10lbs (maybe 150 percent load) it may be 17 degrees timing, but at 15 lbs (maybe 180 percent load) the same tune would be @ 15 degree timing. I want to stress I am no expert though, so my understanding could be wrong.
 

01yellerCobra

forum member
Joined
Apr 11, 2011
Posts
2,230
Reaction score
158
Location
San Diego, CA
Ideally you should be able to go up or down a couple PSI with no issues. As long as your MAF curved is totally dialed in that is. Some guys are able to extrapolate the higher part of the curve to get it dialed in before upping the boost.

If the newer ECU's are like the older models, the LWFM table doesn't do anything for WOT. That being said if you haven't dialed it in using the histogram you really should. Makes life so much easier.

I really wish the SCT forum didn't suck like it does. I remember someone having this exact problem and now I can't find where the solution is.
 

redfirepearlgt

forum member
Joined
Mar 19, 2011
Posts
2,497
Reaction score
263
Brother, I really appreciate your input. I think that if you tuned for say 15lbs of boost and everything was correct, you could dial your boost back to any number and be spot on. I work my way up so I don't blow my motor. I plan on having a higher boost tune and a lower boost tune but the only difference should be commanded AFR. I plan on commanding 11 for higher boost, say 11 to 16 psi and 11.5 for lower boost. Timing will be able to be the same in each tune as I will request lower timing as load increases.....so at 10lbs (maybe 150 percent load) it may be 17 degrees timing, but at 15 lbs (maybe 180 percent load) the same tune would be @ 15 degree timing. I want to stress I am no expert though, so my understanding could be wrong.

No problem. I just hope what I am reading is being digested correctly. Like I said I am a novice but was hoping with what I have been learning there may be some use........OR at least get someone else's attention who has more experience first hand and redirect both our thoughts if we are both off in left field.

TBH if I wasn't making payments on this car I would have already bought something like Pro Racer software package and learning to do my own. I rather blow up a car learning that is paid off so I can afford a rebuild than do it to one I am still making payments on and have to keep making payments as well as overhaul the engine.

FWIW I am running 18 deg timing WOT on 9.5-10 psi with a PD setup @ 151 percent load (VE). My knock sensor data stays very happy on 93 octane. Granted this is PD v Turbo so there may be some variation but your VE and boost with those timing numbers is almost directly linear to what I am running which tells me you are close. But you are being very wise in sneaking up on it. Brst of luck.
 
Last edited:

Turbotungsten

forum member
Joined
Jan 26, 2008
Posts
144
Reaction score
2
Redfire, you may be my hero! I looked at my MAF transfer function and it just so happens that where it starts to lean out is about 1700kg/hr of air.

Another thing that I noticed in my tune is that I have "0" for displacement. This is one of the areas that should be scaled as well. It should be "46" and if scaled 25% it should read 34.5.

I am going to change my current tune to read "46" in displacement and I will also write another the same as my current tune, but scaled 25% to 35% (I haven't decided yet) the MAF trans function, high and low slope, and displacement. I might also scale injector break point but I am not sure if I should. If anyone knows if this or other areas should be adjusted, please let me know. Probably will need to mess with failed MAF too.

Anyway, I will try both tunes out tomorrow and post results.

You are way ahead of the curve if you are already trying to understand tuning before you mod your car. I commend you for that!
 

redfirepearlgt

forum member
Joined
Mar 19, 2011
Posts
2,497
Reaction score
263
Redfire, you may be my hero! I looked at my MAF transfer function and it just so happens that where it starts to lean out is about 1700kg/hr of air.

Another thing that I noticed in my tune is that I have "0" for displacement. This is one of the areas that should be scaled as well. It should be "46" and if scaled 25% it should read 34.5.

I am going to change my current tune to read "46" in displacement and I will also write another the same as my current tune, but scaled 25% to 35% (I haven't decided yet) the MAF trans function, high and low slope, and displacement. I might also scale injector break point but I am not sure if I should. If anyone knows if this or other areas should be adjusted, please let me know. Probably will need to mess with failed MAF too.

Anyway, I will try both tunes out tomorrow and post results.

You are way ahead of the curve if you are already trying to understand tuning before you mod your car. I commend you for that!

No problem. But thanks are to Greg Banishes book to be honest. I just happened to read that section in his book the other day. And then was flipping through the appendix today and saw the Ford tuning section. Hope this gets it sorted out for you. Let me know. Helps me confirm that I am comprehending what I am reading. Thanks.
 
Last edited:

weather man

Persistance Is A Bitch
S197 Team Member
Joined
Mar 3, 2012
Posts
13,332
Reaction score
152
Location
MN
Just a heads up, on 91 octane, at 12 psi and 15 degrees of timing I could not add timing or boost without knock. You are on 93, be careful.
 

Turbotungsten

forum member
Joined
Jan 26, 2008
Posts
144
Reaction score
2
Thanks weather man. That's good info. I was hoping to run about 15 degrees at 15 psi, but might not be able to.
 

Turbotungsten

forum member
Joined
Jan 26, 2008
Posts
144
Reaction score
2
I scaled my tune 30%. It ran great normal driving, but went lean again under boost. I am at a loss!
 

redfirepearlgt

forum member
Joined
Mar 19, 2011
Posts
2,497
Reaction score
263
I scaled my tune 30%. It ran great normal driving, but went lean again under boost. I am at a loss!

My elementary mind leads me to think that the MAF table up high is still needing to be re-tweaked if actual L is not making targeted L and leaning. But there may be other factors that I am ignorant of at the moment being in the learning phases of this as well.

Not to make simplicity out of the situation but your fuel injectors aren't going static indicating you need more injector? You did say that DC was fine on the fuel pump side as I recall. But fuel injectors could still be too small which would cause a lean out as well.

Sorry I can't be of more help. Hopefully someone else will think of something and give us both direction in thought. Best of luck and thanks for letting me chime in.
 

Turbotungsten

forum member
Joined
Jan 26, 2008
Posts
144
Reaction score
2
I failed to mention that when I scaled my tune that I also made one additional change. This change was setting IMRC hardware present from 1 to 0 (meaning that I have removed them...which I have).

Well, my lesson to myself here is don't make too many changes at once when tuning.

I decided to just scale the tune without any other changes at it worked great.

I was able to increase boost and get to 15 psi boost while keeping commanded AFR. By then I was at 96% pump duty cycle, so I had to call it quits. I am thinking 15psi boost is plenty on 93 octane pump gas.

I will post my results and other issues from my trip to the drag strip Friday night.
 

redfirepearlgt

forum member
Joined
Mar 19, 2011
Posts
2,497
Reaction score
263
Sounds great! DC of 96% is really running scary harry. But I'm sure you know that. 80% is the number I hear thrown about when it comes to max DC before a fuel pump upgrade.

I envy you getting the chance to do this first hand. Post your track results.
 

Support us!

Support Us - Become A Supporting Member Today!

Click Here For Details

Sponsor Links

Banner image
Back
Top