Tuning a boosted engine using a P8 pro.

[DiscoPotatoes]

I have a few questions relating to the final tuning of my twin turbo Tvr, I have been tuning it on the road after two disappointing rolling road sessions, and I feel it's almost there as the AFR's are about right across the RPM range including when boosted, and it pulls like a train. I just need to know I'm going in the right direction.
It is rpm vs tps with MAP compensation my first question is,
1. On the MAP compensation table below 100 kpa do I need to put in - numbers or just use the correct fuel on the main fuel map?
At 100 kpa I have added 10% and retarding the ignition by 2 degs, then 20% for 110 kpa and 4 degs and so on
2.How does the lambda target a/f mix affect the fuel map with compensation under boost, And what should I set it at? Also is this where the RPM band and throttle band for correction maps come into play?
3. ANA3 or lambda input setting, it say lambda is optimised for a 1 volt switching lambda sensor, I'm using a bosch LSU4.2 with an AEM wideband failsafe gauge/controller. So should I use ANA3?
4. When parked up after a run I get a fair bit of heat soak, so when I start up again it runs very lean with air temps in the mid 30suntill the airflow sorts itself out, how do I bring the AFRs down without adding fuel in the air temp compensation Map?
I think that's it for now,
Thanks
Disco

[stevieturbo]

1. To simplify tuning then you should almost leave the default values in there, as they are correct in theory. Then tune the main fuel map, and if any smaller adjustments are needed, alter compensatons after that.

Problem being, you never really know what's going on, as the numbers you fill in the main table, are not actual injector pulse widths, and timing you fill in is not actual timing. Very confusing. I would not tune TPS vs RPM. It may seem simple in some respects....I dont see it that way.

2. If closed loop is enabled then it will try and meet those targets you have defined, assuming all other parameters are correct. Dont have too high of an expectation of this feature. IMO, tune the thing properly and you know it's right.

3. I think you used to have to use Ana3 on early firmware/software, but later it was opened up so you could use the proper lambda input for wideband 0-5v instead. So either or really, you just need to tell the ecu which you are using, and fill in the calibration table correctly for your setup.

4. A lot will depend on the numbers in your compensation table. Theoretical numbers dont always work on real life.

[DiscoPotatoes]

1. To simplify tuning then you should almost leave the default values in there, as they are correct in theory. Then tune the main fuel map, and if any smaller adjustments are needed, alter compensatons after that.

Problem being, you never really know what's going on, as the numbers you fill in the main table, are not actual injector pulse widths, and timing you fill in is not actual timing. Very confusing. I would not tune TPS vs RPM. It may seem simple in some respects....I dont see it that way.

2. If closed loop is enabled then it will try and meet those targets you have defined, assuming all other parameters are correct. Dont have too high of an expectation of this feature. IMO, tune the thing properly and you know it's right.

3. I think you used to have to use Ana3 on early firmware/software, but later it was opened up so you could use the proper lambda input for wideband 0-5v instead. So either or really, you just need to tell the ecu which you are using, and fill in the calibration table correctly for your setup.

4. A lot will depend on the numbers in your compensation table. Theoretical numbers dont always work on real life.

Thanks Stevie,
On question 2 if I set the target AFR to 13 and I go into boost the Map compensation will add fuel to richer things up and the target afr will try and lean it out again or am I still missing the point?

One more question regarding turbo control.

On the RPM scale the kpa has been set by the mapper to 300 on all rpms upto 7500, turbo over boost is set to 210 kpa,
And the open loop control rpms are as per the attached photo, are there better settings I can use for the turbo control? At the moment the boost rises to 8 psi I'd like to take it to 1 bar.
Is it just a case of putting higher numbers into the cells earlier on in the pwm map?
Cheers
Disco

[stevieturbo]

2. What you're saying sounds right. But why would you target 13.0:1 on a boost site ?

Again...a major flaw IMO using TPS vs RPM.

I havent had DTAwin installed on a computer for several years so not overly familiar with it.. Can you post screenshots of all the settings, or upload the map ?

I dont see the rpm scale with 300kpa you are referring to ? Also curious as to why there are 6 PWM tables ? Or is that for different gears or something ?

uploading the map would probably be ebst

[Rob Stevens]

I use P8 still on a supercharged engine.

The ordinary lambda input is for 1v only, you have to use ana3 if you want the full 5v (select in the Lambda Parameters screen) resolution you get from most widebands, you have to enter the calibration of your AEM wideband but you should have that with with the AEM instructions.

Set the boost compensations to standard, It looks like you have done something very odd, don't deviate for fuel, i.e 100kpa = 0% extra fuel. 150kpa = 50% extra fuel. 50kpa = -50% fuel reduction etc. Take a look at the DTAS software to see how 'set to standard' works, this isn't available as a tick box on the P8
you may wish to reduce ignition as the boost comes up being a turbo.

The target AFR will just work all the time, try and forget about the map corrections, if you are using the AFR target map I suggest that you target more like 11.5:1 at full throttle, if you have wired the lambda switch in you will be able to generate the corrections map, but dont implement those corrections automatically, do it by hand little by little, if like me I get wild corrections like 200% that can't be right.

Are you running open or closed loop on the boost? the screen dump you show is a small tps to rpm map and the cells are the pwm signals to your boost controller/bleed valve like a NR75 valve or similar, assuming there is one. It looks like you are at 70-90% any way, try 100% at WOT and see if the boost goes up(only if you have the correct boost compensation entred as indicated above or you may blow it up) if it doesnt go up the turbo may not be capable of more boost or the wast gate spring is too light.

Not much you can do about heat soak, other than getting the lambda to help out and making sure you don't have any silly corrections entered.

PM me for my email address, send the map over and I'll have a check over and make some suggestions.

[Rob Stevens]

Also I think you should bring your over boost cut down a bit to say 180kpa or less until you are sure its all working as it should, just for engine safety.

[Jon K]

Holy heck - you're pulling 2 additional degrees between 100 kpa and 110 kpa?

[Rob Stevens]

No, he is reducing by 2 deg, I'd have thought just remove a couple of deg when the boost gets up to 150kpa + ?

[Roverdose]

you can turn the lambda off above throttle/revs. ive got my wideband targetting 14.7 but turning off at 25% tps and 3k rpm. works pretty well for me on cruise, when i get into some useable boost its off.

engine start fuelling may help the heat soak issue.

Drew

[Jon K]

No, he is reducing by 2 deg, I'd have thought just remove a couple of deg when the boost gets up to 150kpa + ?

That's what I am saying, he's pulling 2 degrees from 100 kpa to 110 kpa. Thats a lot of timing to lose.