Changing Cranking Air Fuel Table help

[JordanSBC427]

Hello,

I'm having the issue of having to push down on the gas pedal when starting my truck. Being fuel injected, one would think you should be able to tune your way out of this issue. I am trying to stay away from having to drill any holes in my throttle plate or adjust it open with the screw. I wanted to try and take some of the fuel out of it while cranking because it seems a bit rich. Do you guys think I should do some data logging with some PID's first and gather some info....something I want to do anyway. Does anyone have a good PID table set up to view some cranking values and some values after I start it by giving it a little gas. I don't have my program in front of me but I believe there is a open loop or cranking VE table correct? that you can adjust your air/fuel while cranking?

Any help is appreciated

Thank you,

Jordan.

[joecar]

Have the VE and MAF tables been corrected (i.e. off-idle, driveability, part throttle, WOT)...?

After VE and MAF have been corrected, you would have to perform idle tuning (i.e. the RAFIG process), see here for more info:



Idle Tuning
showthread.php?4661-Idle-Tuning-Helpful-Info-Inside (http://forum.efilive.com/showthread.php?4661-Idle-Tuning-Helpful-Info-Inside)
showthread.php?14439-Idle-Tips-amp-Tricks (http://forum.efilive.com/showthread.php?14439-Idle-Tips-amp-Tricks)
showthread.php?5866-Auto-VE-questions (http://forum.efilive.com/showthread.php?5866-Auto-VE-questions)
showthread.php?14153-scan-tool-wont-log-rafig-or-rafpn (http://forum.efilive.com/showthread.php?14153-scan-tool-wont-log-rafig-or-rafpn)
showthread.php?14435-Need-help-Can-Start-Car-but-dies-when-I-give-it-any-throttle-before-going-to-CL (http://forum.efilive.com/showthread.php?14435-Need-help-Can-Start-Car-but-dies-when-I-give-it-any-throttle-before-going-to-CL&p=129519&viewfull=1#post129519)
showthread.php?7011-ETC-cars-and-IAC-parameters (http://forum.efilive.com/showthread.php?7011-ETC-cars-and-IAC-parameters&p=61455&viewfull=1#post61455)
showthread.php?14544-Working-on-my-idle-tune (http://forum.efilive.com/showthread.php?14544-Working-on-my-idle-tune)
showthread.php?14794-Help-with-open-loop-%28cold-start%29-tuning (http://forum.efilive.com/showthread.php?14794-Help-with-open-loop-%28cold-start%29-tuning&p=133446#post133446)
showthread.php?149-Idle-%28Transition%29-Tuning (http://forum.efilive.com/showthread.php?149-Idle-%28Transition%29-Tuning)
Stumble-3-seconds-after-cold-start&p=178921#post178921 (http://forum.efilive.com/showthread.php?14144-Stumble-3-seconds-after-cold-start&p=178921#post178921)
Idle-Tips-amp-Tricks:post#46 (http://forum.efilive.com/showthread.php?14439-Idle-Tips-amp-Tricks&p=193144&viewfull=1#post193144)

More Idle Tuning
showthread.php?t=149 (http://forum.efilive.com/showthread.php?t=149)
showthread.php?t=5866 (http://forum.efilive.com/showthread.php?t=5866&highlight=RAFIG)
showthread.php?p=86553 (http://forum.efilive.com/showthread.php?p=86553) post #17
showthread.php?t=2630 (http://forum.efilive.com/showthread.php?t=2630)
showthread.php?t=473 (http://forum.efilive.com/showthread.php?t=473)

Throttle Cracker/Follower
showthread.php?t=3568 (http://forum.efilive.com/showthread.php?t=3568)
showthread.php?t=4081 (http://forum.efilive.com/showthread.php?t=4081)
showthread.php?t=5406 (http://forum.efilive.com/showthread.php?t=5406)
showthread.php?t=5940 (http://forum.efilive.com/showthread.php?t=5940)


Idle tuning is fairly involved as there are many more variables at play.

[JordanSBC427]

Thank you for the reply,

As far as I know they have been corrected. This engine has been tuned on the engine dyno, and we have done WOT pulls with it. My father and I told the programmer what we were going to be running for a transmission and rear end and everything else that is required. Just was never really able to start from scratch without touching the throttle.

Is there a good link that you can refer me to with regards to correcting VE and MAF tables? We are using a MAP sensor currently, but we have the wiring for MAF if we want to add the sensor.

[joecar]

So you are running MAF-less...? If so are you seeing an immediate MAF DTC (important)(without the MAF DTC the PCM is still using the MAF table)...?

The Calc.MAFT procedure corrects the VE table (and calculates a MAF table from the correced VE table)(if you're MAF-less you can ignore the portion that calculates a MAF table): Calc-MAFT-correcting-VE-and-calculating-MAF-(in-single-log)-->-reverse-of-Calc-VET (http://forum.efilive.com/showthread.php?16413-Calc-MAFT-correcting-VE-and-calculating-MAF-(in-single-log)-gt-reverse-of-Calc-VET)

Calc.MAFT is the same procedure as AutoVE, but with an added step (to calculate MAF table) and using a better correction pid (WO2BEN).

More info: see post #29 for the relationship between Calc.MAF and AutoVE: Summary-Notes (http://forum.efilive.com/showthread.php?14188-Summary-Notes)


If you run with MAF, then Calc.VET is easier to do the Calc.VET procedure (the reverse of Calc.MAFT): Calc-VET-correcting-MAF-and-calculating-VE-(in-single-log) (http://forum.efilive.com/showthread.php?15236-Calc-VET-correcting-MAF-and-calculating-VE-(in-single-log))


If you had the engine dyno tuned, do you have logs showing the fueling now following the fueling tables...?

Most important: do you have a wideband O2 sensor connected up to your vehicle and are you reading it with your FlashScan...?

( do you have FlashScan V2 or V1...? )

[JordanSBC427]

Yes we are only using the MAP sensor to run this engine at the moment. I do see a MAF DTC saying low circuit voltage I believe.

I will do some reading about AutoVE and how to manipulate the table, I don't quiet understand this step yet.

I don't have any of the fueling logs or any info from the dyno except what I pulled from uploading the tune off my ECM. I am hoping to hear back from my dyno guy and see if he can send me some info from the dyno/tune.

The 02 sensors are stock GM ones, and I can grab the part number off the box and check but I highly doubt they are wideband sensors.

I have Flashscan V2.

I will attach my DTC log as well.

16280

[joecar]

Wideband sensor does not replace the narrowband sensors... it is used in addition as a tuning tool, seen only by your FlashScan V2 and not by the PCM.


Calc.MAFT/AutoVE basic steps:
- disable MAF (trigger MAF DTC)(i.e. so airmass is coming from VE only),
- disable LTFT/STFT/CL (i.e. so PCM is not correcting fueling),
- make sure OL fueling table and PE table are safe for load/WOT,
- make sure IFR is correct (based on measured rail pressure and whether FPR is referenced or not),
- log the correction factor (CALC.WO2BEN),
- create a VE-like map of the correction factor,
- apply the transient filter (to remove any data where throttle/airflow rate is changing more than some rate),
- multiply the map into the VE table,
- repeat (with each iteration the correction factor converges on 1.00).

Calc.MAFT has the additional step of calculating a new MAF table from the corrected VE table.

[JordanSBC427]

I currently do not have a WB02 sensor, is this something that I will be needing for sure? Should the gentlemen that did the tune for the dyno have got things close enough that I will not need a WB02 or is it still a good idea to have one to watch everything?

Also, I'm going to have to do some more studying. Even the basic steps seem a bit overwhelming at this moment. Are there any good AutoVE videos or walk throughs that are available?

Thank you.

[joecar]

If you're intending to edit VE and/or MAF tables in other-than-CL then you will need a wideband.

If you're not editing VE or MAF, a wideband is still a good idea so you can watch fueling when not in CL.

[joecar]

Your dyno tuner should have gotten the VE table better than close.

[joecar]

Ok, let's take a step back...

if you can drive the car take a log showing LTFT, STFT, HO2Sx1 (and other things like MAP, RPM, ECT, IAT, DYNCYLAIR).

Lets assume that the VE table is good... when you drive the car, the LTFT's should be close to zero (plus/minus a few percent)... if this is the case, then you will have to address the idle desired air (i.e. the RAFIG/RAFPN process in the first link quoted in post #2 above).

[JordanSBC427]

Ok Joe that sounds good, I will only be able to work on the CL tuning and idling at the moment, as its winter and the truck is not quite ready for highway speeds.

What WB02 Sensor would you recommend getting for logging and tuning?

I will run some CL data logging this weekend and let you know how things go.

I appreciate the help.

[joecar]

wideband: depends on your budget and other people's experience with various widebands...

I have an old LC-1 which functions great, and I also have a newer LC-1 which functions poorly.

[JordanSBC427]

When using the wideband, I will only require 1 wideband sensor correct? but I should probably add a bung in each collector, so I can check both sides if I wanted, correct?


Where is the best placement when using the wideband sensor as far as where to put it in the exhaust system? (I'm not using Cats in this system at all)

[joecar]

Yes, having the ability to swap your wideband between banks can help to troubleshoot problems and to generally compare banks.

Some people run two widebands, and either use the data from the leaner bank (more usual), or use an average between the banks (less usual).

If you have headers, best place is at the end of the collector (so it sees gasses from each primary)... you don't want to go too much further back than this since exhaust gasses will start to cool down as they travel further (altho, some people place it in the y-merge, but the gasses have already lost a lot of heat by now).