Reading MAP and understanding whats happening

[kwhiteside]

Need a little newbie education here.

Can someone explain the Manifold pressure in relation to WOT to me please.

At WOT, is my Manifold pressure high or low, and as I move from the initial lug of the engine to Redline all at WOT, what happens to the pressure.

Then of course throw in the AFR equation. I see from my MAP below while at mid range rpm, the AFR is higher/leaner at lower MAP readings ( 25-40kph is around stoich, but 80-100 is richer around 12afr)

However when you get to redline, it works the other way. Low MAP pressures are 10-11 AFR while the 80-100 map pressures are around 12 AFR.

I can't quite figure out why this is the way it is.

[WeathermanShawn]

At WOT MAP equals atmospheric pressure. MAP is inversely proportional to vacuum.

I do not know your elevation, but at sea level atmospheric pressure is ~ 101.1 Kpa. So, at 100% throttle, your MAP would be 101.1 Kpa. Engine Vacuum would be near zero. At my elevation (5400'), WOT MAP equals ~82-84 Kpa.

The relationship between MAP and AFR is important to know. As engine load increases, (depending on gear) MAP likewise increases. Hence, you need additional fuel enrichment to protect your engine.

When you log the next time, look at your TPS% vs MAP. You will quickly see the relationship.

[mr.prick]

In the high RPM low MAP (numeric) areas you are either in PE mode or
the throttle is slammed shut while PE is on,
carrying the rich AFR from WOT into the low MAP cells.

If DFCO is on this would explain why you have lean cells in low MAP areas.

[WeathermanShawn]

It looks like you have DFCO enabled (High AFR's, low Kpa's).

The rich AFR's at high rpm's, low kpa's are probably just the injectors 'staying on' (exceeding minimum pulse width) after you hit those high MAP's. They stay rich for a few seconds after 100% throttle and your log is just picking that up.

You probably need to filter out those transitions and DFCO to get a pure understanding of MAP-load and AFR.

[kwhiteside]

:confused:

Lunch Time, let me read those comment over a few times

[kwhiteside]

As engine load increases, (depending on gear) MAP likewise increases. Hence, you need additional fuel enrichment to protect your engine.

Lets start with this.

Scenario - I'm cruising in 4'th at 2500 rpm, drop into 3rd and floor it.

RPM goes to 3500 and load is high ( Map will be in the far right 95-100 cells )

Progress to 6000 RPM before shift, Load gets Lighter towards redline ( Map cells traverse down and to the left ) if I understand what you are saying.

Most likely I don't because my dashboard chart from logfile for a 3rd gear pull like that has commanded AFR at 12.88 and does not change, see pic

BTW, I'm cycling thru AutoVE tune runs with my MAF disabled. I'm not sure what mode you guys call that, please let me know.

[joecar]

The throttle blade is the "restriction" or the "dam"...

As throttle is opened more, MAP (manifold absolute pressure) tries to equal barometric pressure, but the throttle blade is restricting/controlling the air flowrate...

At WOT, MAP reaches BARO... and as RPM increases (still at WOT) the air flowrate increases... and you may find that at WOT as RPM increases the MAP actually decreases a few kPa (from say 99kPa downto 96kPa)... this is because the MAF and/or throttle body is physically limiting flow and the engine is trying to pull in more air (by virtue of spinning at higher RPM)... the reduction in MAP is showing there is a pressure differential which means the air flow is being limited.

[kwhiteside]

Ok, so MAP doesn't change enough due to load to move a cell. If your full throttle, in GA, I'll be hitting the 95 or 100 cells and just changing RPM cells.

So that has me wondering how my commanded is 12.88. Seems all the cells at 95 or 100 are much lower/richer than 12.88.

And then the next question represented in the pic. 3rd gear FT, then 4'th gear FT. Both commanded at 12.84 AFR as seen. However, when in third gear with very high rpm's, my actual AFR is very close, but once I hit 4'th gear, my actual is almost a whole point richer than commanded? Many things confusing here. In 3rd gear, the RPM was 1500 rpm higher and yet the commanded is exactly the same. The tables change over a 1500 rpm variance, why doesn't the commanded change? Why would I follow commanded in 3rd gear high rpm, then be rich in 4th gear?

[WeathermanShawn]

Would have to see more of your tune & log.

I assume you are running MAF-closed loop?

OP, what does your B3605 look like? Under PE, fueling should be the richer of B3605 or B3618.

[kwhiteside]

Everything you asked for is attached.

Thanks in advance for education me. I'm learning fast as I can. Again im cycling thru AutoVE tutorial with MAF still disabled. I am getting the p0103 dtc so I know that I'm MAF less.

However, I don't understand what PE COTP or even Closed Loop really mean :help2:

Would love to know what they all mean, please share.

The two tables you question ( I just learned they exist because of you :doh2:) both seem to indicate there may be about a point adjustment going on due to either RPM or the HotAtlanta air, if they are indeed being hit????? How do you tell?

[WeathermanShawn]

COTP is B0701. Catalytic Converter Protection. Yours is what it should be..Disabled. If you had it to enable, the PCM would richen up the AFR to ~11.9 at WOT to 'protect' the catalytic converters.

Closed-loop means you are utilizing the O2 sensors, and the car will trim to ~14.63 AFR at idle and part throttle. Looking at your tune, even though your MAF is disabled, I think you are still running closed-loop. Thats why you still have Trims (LTFT's) showing.

It looks like if you are essentially running closed-loop speed density (no MAF), and you are rich at WOT, then your values in the VE Table are not accurate. It is overestimating your airflow, and thus over fueling.

[joecar]

Ken, in tunetool goto Edit-Properties->Display and set fueling units to AFR or EQ and not Lambda...

That pic of B3605 looks like you might be using Lambda units.

[kwhiteside]

Made those changes. I don't have Cats, so I'll try to remember to never enable that COTP.

[kwhiteside]

question for you guys. My car barely is starting now. It cranks hard but doesn't want to start. Is that entirely due to the MAF being disabled.

[mr.prick]

How did you disable it?
DO NOT DISABLE DTC PROCESSING ENABLERS RELATED TO THE MAF.

[kwhiteside]

How did you disable it?
DO NOT DISABLE DTC PROCESSING ENABLERS RELATED TO THE MAF.

If I understand what you are asking it like the post above said

COTP is B0701. Catalytic Converter Protection. Yours is what it should be..Disabled.

I didn't do it. I'll guess that when Vengeance Racing pulled my cats off my car they disabled it for me.

I don't see how that is related to the MAF though. If you're asking how I disabled the MAF, I just followed the AutoVE Tutorial. I'm still running in that mode. I would like to do a couple more logs in that mode to get my VE table right, but I'm really struggling to get the car started.

Any help with the starting problem would be appreciated.

[joecar]

Post your tune file.

Undo each change one-at-a-time until you can start the engine.

Questions:
- in post #10: what units is B3605 displaying...?
- in post #13: what changed that now B3605 shows AFR...?
- have you ever adjusted B3605 while lambda units were being displayed...?

[mr.prick]

If I understand what you are asking it like the post above said

COTP is B0701. Catalytic Converter Protection. Yours is what it should be..Disabled.

I didn't do it. I'll guess that when Vengeance Racing pulled my cats off my car they disabled it for me.

I don't see how that is related to the MAF though. If you're asking how I disabled the MAF, I just followed the AutoVE Tutorial. I'm still running in that mode. I would like to do a couple more logs in that mode to get my VE table right, but I'm really struggling to get the car started.

Any help with the starting problem would be appreciated.

What I referred to is in the Engine Diagnostics folder.
Setting P0101, P0102, P0103 to X: Not Reported will cause big problems.

[kwhiteside]

Joe,

tune was posted earlier today in previous post.

I had it set at Lambda and changed it to AFR per your post #12

I have never changed anything in B3605. The only changes I'm making are to the VE table and what is specified in the AutoVE tutorial. I do see that page 6 of the tutorial has the values in the rectangle changing for that table. I'm sure when I did it, I had it set to either Eq or AFR. I'm having to switch computers constantly because I still cannot get me notebook to read the logs properly. I had a big post earlier about it wiping out the PID's. I finally just gave up on it, but I have to use it to flash the car. I do have all the sequence of tunes, original, .000, .001 if you need me to compare them.

[kwhiteside]

What I referred to is in the Engine Diagnostics folder.
Setting P0101, P0102, P0103 to X: Not Reported will cause big problems.

Per the tutorial

1. Start the EFILive Tuning Tool software and open the Original Tune.tun file.
2. Open calibration {C2901} “MAF High Frequency Fail 1" Set it to 1 Hz.
3. Open calibration {C2902} “MAF High Frequency Fail 2" Set it to 1 Hz. If calibration {C2902} is not available in the operating system that you are using, then ignore this step.
4. Open calibration {C2903} “MAF High Frequency Fail Limit" Set it to 1.
5. Open calibration {C6002} " Engine DTC MIL Enablers" Set P0101, P0102, and P0103 to No MIL.
6. Select menu option File->Load alternate calibration for comparison and select SDAutoVE_0000.tun.

[kwhiteside]

I did a log on the way home and have piped it into the Interpolation spreadsheet. I'm a little concerned with the left most cells always wanting me to double them. I've been excluding them in the previous paste. Should I go ahead and raise those left cells way up like it wants me to, or keep excluding them?

See attachment

[WeathermanShawn]

It looks like you still have DFCO (B3313) enabled.

So those cells are unusually lean because DFCO..Deceleration Fuel Cut Off is still enabled. While a useful function, while tuning the VE Table it will not give you a true airflow & AFR for those cells.

[kwhiteside]

It looks like you still have DFCO (B3313) enabled.

So those cells are unusually lean because DFCO..Deceleration Fuel Cut Off is still enabled. While a useful function, while tuning the VE Table it will not give you a true airflow & AFR for those cells.

I am probably missing something here, but maybe the other members can figure it out. I do not think your VE Table is accurate.

..WeathermanShawn..

Sounds reasonable what you say.

The tutorial has you shut it off by raising the temp to 122C (252F). But later in the tutorial, you switch back to your original tune and lose that setting. Perhaps I didn't read and follow the instructions properly. After re-reading them, it appears I'm following the instructions. I'll disclaim that I don't know enough to argue one way or the other, but I'm sure you already know that :help2:

So my Maps are wanting to raise the low RPM idle cells leaner because of all the deceleration factoring into that area. Correct me if I'm wrong, but leaning those out like it wants will adversely affect real idle and accelleration from those low rpm ranges. Seems that I should either keep filtering those higher values out of my Ben Map, or put the high temp back into DFCO. I like the latter. Somebody experienced please tell me what to do here.

What about the starting problem?

[WeathermanShawn]

I would 'disable' DFCO until I was totally finished with the VE Table. I would also keep Trims disabled (keeping it in open-loop by raising the B4205 to its max).

Are you going to re-enable the MAF? And are you going to keep it closed-loop..B4205 at 'stock' temperatures (using your O2 sensors to trim)?

The tutorials are great, but like everything else in life one wrong move or turn will greatly affect the outcome. So, it all depends on how you are going to be running this car tune-wise. If you can spell out your end point, then the answers you are seeking will be a lot easier to determine.

If you are non-boosted, I can assure you that a MAF-based tune with closed-loop is very forgiving. It is nice to have a system trim you to stoich, and if your VE or MAF is off at a cell or two, you will know it when you start logging your STFT's & LTFT's.

[WeathermanShawn]

Your base spark B5932 looks very low. 16 degrees of spark is pretty low. I would just copy the high-octane spark B5913 to B5932.

You can also raise B4343 start-up Airflow by 1.5-2 g/s across the board.

More spark, more air.

Startup and Idle are covered very well in the tutorials.

[kwhiteside]

My goal would be to tune for the track so it has ample power, and is running with a safe mixture so as to last.

I've recently added catless headers, vararam, FAST92, LS2 90mm TB. So after making it breathe, I set out to get a tune. The local tuner threw his hands up because AFr wasn't following commanded. I took it to road atlanta and logged a 30 minutes session with lots of 140mph speeds and the EFI guys found lots of things wrong. AFR wasn't following commanded (much richer) LFTRM was pegged. They suggested cleaning the maf, make sure no leaks, and going thru the tutorial for a baseline tune. I intend on using MAF just like factory planned. I now have AFR getting close to Commanded. LFTRM's are way down. Of course this is with spirited around town and freeway stuff up to 90 maybe 100mph. I don't do 140 until at the tracks.

Strong, Safe tune that will get me to the 144mph redline in fourth gear without knocking or blowing anything up.

Ken . . .

[kwhiteside]

I do not want this to be a 'one-man show', but on the starting problem.

Your base spark B5932 looks very low. 16 degrees of spark is pretty low.
I would just copy the high-octane spark B5913 to B5932..

You can also raise B4343 start-up Airflow by 1.5-2 g/s across the board.

More spark, more air.

Startup and Idle are covered very well in the tutorials. I actually did that portion before VE tuning. No fun to not have your car start.

..WeathermanShawn..

My tuner did tell me he set the spark at a safe level. Keep in mind when I track the car making it like an inferno running at redline. Like a space shuttle entering orbit, as fast as it will go. My oil temp gets to 290, water temp 250, and I bounce off the rev limiter in fourth gear on the straights. Nobody wants to blow an engine.

I like your idea until I see those 40 degree cells instead of the 25 degree cells. This table is only used when foot is off the pedal? As in for starting only? Sorry if these are dumb questions. It seems I'm seeing new tables and settings everytime I put up a post :shock:

[WeathermanShawn]

Well I guess if you have a tuner, you should use him (her). They know your goals better than we do.

As far as making a post and always getting a new Table to look at..we have all went through it. It is like chess in a way. Each new move relies on the previous one. If it is all new to you, I would just go back to step 1. Every question is answered in that Idle Tutorial. If you're goals are different, ask your tuner to work with you.

Base spark is only used when you're foot is off the throttle. It has nothing to do with spark at throttle. Base Spark controls your idle spark. My car would never start with 16 degrees.

It can be frustrating. It is good if you have a tuner to work with. They should know all of this and hopefully they will spend the time with you.

[kwhiteside]

Well I guess if you have a tuner, you should use him (her). They know your goals better than we do.

As far as making a post and always getting a new Table to look at..we have all went through it. It is like chess in a way. Each new move relies on the previous one.

If it is all new to you, I would just go back to step 1. Every question is answered in that Idle Tutorial. If you're goals are different, ask your tuner to work with you.

Base spark is only used when you're foot is off the throttle. It has nothing to do with spark at throttle. Base Spark controls your idle spark. My car would never start with 16 degrees.

It can be frustrating. It is good if you have a tuner to work with. They should know all of this and hopefully they will spend the time with you.

Best of luck..

..WeathermanShawn..

My tuner kind of threw me to the wolves once they found out I tracked the car and had efilive, they told me it would be best if I tuned it myself. I'm not really sure what all there motives were. I know they have had big legal troubles with some other track cars they have recently worked on so maybe they are just shying away. As I learn, I can see how this form of real world tuning should be better then a dyno tune. Especially if I use track data to make adjustments. So, I'm on my own here. I appreciate the help you have given and understand if you stop posting recommendations.

I've decided that unless I hear back from my other post something to stop me, I'm going to smooth my last iteration of my VE table, raise the DFCO temp so its off, raise the closed throttle spark as you suggested, and flash that tune to my car before I venture home. I'll do another spirited log on the way home and unless the Ben/Map suggests a bunch of drastic changes, I'll probably enable the MAF and start working that.

I've not seen the idle tutorial you speak of. Even in the Help/Tutorials, there is no idle tutorial.

[mr.prick]

A good shop will have you sign a disclaimer so they wouldn't need to worry about problems that may occur after modding the tune.
Idle info is in my sig.

[WeathermanShawn]

The Idle Tutorial is golden.

Mr. Prick has some great links so hope you find it.

[joecar]

I would blend/shape those edge cells, and then ignore/filter any fruther changes to them...

consider this: the VE table (a misnomer...) is a "normalized" airmass table (normalized for temperature and pressure)... airmass physically cannot suddenly change/step between two cells... this is not physically possible... i.e. the VE table will have a "relative" smoothness to it with some localized minor dips/peaks/ripples (I said minor) due to such phenomenon as tube wave resonance... a correct VE table tends to mirror the engines torque curve/plane (if you could image a torque vs RPM curve at each MAP interval.).

I would push the peaks down to sort of blend with the valleys and then do another iteration.