Calculating acceleration enrichment on alpha-n

[se7ensport]

Just put my car back on the dyno this morning as although flat out it is amazing, in traffic the idle to low TPS% transition the car is very jumpy.

Having added a number of low down tps values to ensure a smooth transition I'm still finding it has a very rough transition from 800rpm tick over (sat in traffic) to 1300-1700rpm (letting clutch out in 1st to move off) I find I have to dip the clutch and rev the engine to 2000rpm to get it moving without stalling.  The VE table was set on a dyno holding each cell until lambda stabilised, as such I'm confident the it is correct, my acceleration enrichment is 100/40/10/0, is this appropriate for Alpha-N? or any other suggestions greatly appreciated.

This is the log file I took yesterday before taking it back to the dyno today: http://vems.hu/vemstune/sharingcenter/reports.php?cmd=view&key=EuAHqQ

Config from today's dyno session (the issue still exists, but I haven't logged it yet): http://vems.hu/vemstune/sharingcenter/reports.php?cmd=view&key=cfnWVY

Thanks

Alex

[GintsK]

Try from: dtps 3/10/33/150 with values 0/25/55/100. Give most attention to second 10vs25 point. Position of this point is the key.

Another common problems with itbs is:
-improper linkage system. It should be constructed with variable ratio over range. At small openings pedal travel must be 3...6 times less sensitive comapring to WOT region.
- play between itb axle and TPS. Seems you have this problem. TPS signal is still 0, but Lambda already goes lean.

Also try to manage lower idle advance around 5deg if possible. It will give more power at very beginning.

Gints

[gunni]

- play between itb axle and TPS. Seems you have this problem. TPS signal is still 0, but Lambda already goes lean.



Gints

If this is the case then it´s the first problem to solve without knowing TPS has moved it´ll still just fuel along for idle.

[se7ensport]

Gints, you were spot on about the TPS, I could move the axle slightly without it registering a change in position. The fault is in two places, the 1st is the TPS didn't like small movement in its position, I rotated it about 15degrees and re-calibrated, the interface between the axle and TPS also had a bit of play, this is now snug; shimmed with of baking foil.  Test drive will be tomorrow.

Thanks
Alex

[se7ensport]

New TPS fitted and calibrated, not the same scale as the old TPS so I went back to the rolling road again.  The car is significantly smoother in traffic and small movements in the throttle are reflected in TPS signal.

I've taken another log which still shows the engine going lean on acceleration: http://vems.hu/vemstune/sharingcenter/reports.php?cmd=view&key=E3pwnF

Is now an appropriate time to set dtps 3/10/33/150 with values 0/25/55/100 as per recommendation?

[GintsK]

You can try for sure.
But for me seems you have to tune VE map properly. In your log target and actual lambda never matches. And shape of VE map tells the same.

Gints

[se7ensport]

You can try for sure.
But for me seems you have to tune VE map properly. In your log target and actual lambda never matches. And shape of VE map tells the same.

Gints

I don't understand what is causing the lambda target and actual to mis-match, each cell was set on rolling road holding each one until they match yet when I log I don't get the same results.

[GintsK]

Your injector dead time is not configured. It is zero. Means your VE table matches just at specific battery voltage and multipliers (lambda, MAT). You can ascertain by slowly changing target lambda near your idling. Actual lambda should follow 1:1. If real lambda is too sensitive your dead time is to small. If following is sluggish, deadtime is too high.

What about air temperature?
I guess you use MAT sensor from Ford company? Or? Not possible to get precise readings without board modification. Resistance at 25degC is far too high.

Here is IMO best sensor in terms of reaction time and heat soak issues: BOSCH 0 280 130 085

It is wise to check all this before rolling road. God is in the details.

Gints

[se7ensport]

Gints

Correct, I'm using a ford MAT sensor, plot points were configured using boiling water cooling with a thermometer in it, will replace as recommended though (ordered, do you have the MAT sensor plot points or are they one of the standard options?).

Turns out my TPS was also breaking down as the voltage would drop off with the throttle kept at the same opening, although new it was a pattern part rather than OEM, so that will be replaced as well.

So... on to injector dead time, at the moment I have "traditional" selected, this doesn't give an option of deadtime, do you recommend switching over to "simplified"? 

I'm using Bosch injetors 0280156127 : Static Flow Rate: 42lb/hr @ 43.5PSI = 440 cc/min (+/-2%),Coil Resistance: 15.9 Ohms (+/-0.35 Ohms) / High Impedance / High-Z (No ECM driver modifications required), is there a way to find/calculate sensible starting values?:

[GintsK]

As I wrote: if you change the target, actual lambda should follow your changes. You can achieve it by both methods.
In addition you can check voltage compensation slope: actual lambda should stay settled while voltage drops/rises. Traditional method is good just for relatively narrow range. In simpyfied you can adjust dead time at various voltages or rewrite/adopt from somewhere published injector data.

For that Bosch sensor I use NTC 1900 256 patch. With BOSCH 17-point curve it gives couple degrees error what can be adjusted then.

Gints

[se7ensport]

Gints

Appreciate what you are saying about setting deadtime, I've tried both options; using simplified and the data from the source bottom of the page (converted to 43.5psi fuel) I used:

8v      2559
10v    1754
12v    1241
14v    1004
16v     820

I tested by turning main beam on at idle which caused lambda to rise from .90 to .96 as the volts dropped for 13.5 to 12.7(ish), I'm assuming the different boards and flyback resistor effects deadtime.

Although "simplified" I would end up having to try to find 5 different figures, so I moved back to traditional.

I used 200 for injector rampup as recommended within help files (is the correct figure within the data below? I couldn't spot it), and then proceeded to increase injector voltage compensation until lambda stabilised using the above test, this was 2000us, does this look feasible before I start logging and tuning again?

[GintsK]

Slope of simplified curve seems OK. Values, you are right, varies depending from flyback voltage, pressure etc.

2000 theoretically is way too much. about 400 accordant to this datasheet. 400...1000 is usual range. http://www.vemssupport.com/forum/index.php/topic,1261.msg13418.html#msg13418

Do not leave open time @13,2V zeroed. Start with 900 there. Otherwise VEMS adds just [192/1.5][email protected] - too less . By finding  open time @13,2V you can find right adder what makes multiplication results correct. By finding Injector voltage compensation - immunity to voltage drops (just small drops - in traditional case because correction is linear). Be careful - if you change current consumption you change also engine load with it.

Gints

[se7ensport]

so a year on....

I believe I have my injector slope sorted, I went back to the rolling road again about 3 months ago (this is getting expensive!) to sort out idle and top end, by torque curve has increased and it is better in traffic, yet it still isn't right.

It is booked in at the local rolling road for Friday 11th as I know that there is a some further room for improvement in the VE table following setting the balance on the throttle bodies with a Carbtune kit - this beats using a normal airflow meter for ease, speed and accuracy by a long way.

I have increased the accel enrichment to dTPS 3/10/33/150 with % 5/40/60/120, but I'm still seeing quite a swing from lean to rich on acceleration. I am also experiencing misfire under certain loads, I would really appreciate someone taking a look through my log/config and advising where I am going wrong, its getting closer, but I ran out of knowledge a long time ago and don't want to wreck the engine through a silly mistake.

https://app.box.com/s/1zgkw424tvtm3q37d7qx

For reference I am running a 2009 2.0 Ford Duratec, all standard except lightened fly wheel, tubular manifold and a set of DICE throttle bodies with 440c blue injectors, it is putting out just shy of 220bhp at 7200!

I am in Bristol, if anyone is local and is prepared to help in person I will gladly pay a good hourly rate as my local rolling roads aren't familiar with VEMS.

Thanks
Alex

[GintsK]

Throttle response is hardly dependant from injection angle. Usually 350...500 degrees gives best results. On past 1.2.0 firmwares lambda signal is fast enough to find best combo.

... a Carbtune kit - this beats using a normal airflow meter for ease, speed and accuracy by a long way.

Carbtune uses vacuum principle. But what is important to us for matched mixtures are air mass passing to cylinders. So your statement about accuracy is questionable.
At same vacuum airflow may differ. Especially on worn engines. For same reason we do not use Speed density for engines with ITBs: pressure after the throttles do not tell a lot about the actual air flow.

Gints

[se7ensport]

Gints

Appreciate the reply, but not really sure what to take from it.

I understood Injection angle can only be changed if using cam sync, otherwise the default is 720, I don't currently have cam sync; if it is worth moving to I'm happy to invest in a new cam cover with sender, will this improve the lambda consistency and reduce the misfire I am seeing?

Didn't realise my carbtune comment was potentially misleading; for me it worked and allowed me to set idle significantly smoother than using one airflow meter and moving it between cylinders  - I don't have the luxury of having four of them. 

Other than changing to cam sync is there anything else that needs to be addressed within my config?

Thanks
Alex