MS3 Pro Conversion

[dap930]

John,

You said when trying to start hot engine you had to crank and crank. If the engine will not catch, then I think you need more cranking pulses for that temperature range. Or is it vapor lock from sitting? Is your fuel pressure being maintained for 20 minutes after shutdown? If it is catching but just won't take off, then ASE needs increased and ASE taper may need to be increased. WUE should be tapered down to 100 (no enrichment) at a CLT where the engine will run without stumbling from cold start, so it does not have an effect on hot starts

One thing you can do help with tuning ASE taper in Tuner Studio is to change the Y-axis from engine cycles to seconds (0.1 sec increments: i.e. 600=60sec). Note that when it is changed to seconds the graph label still says cycles.

I used increased ASE taper time to cure my engine rough running hot start issues. You can have ASE going on for longer periods of time at higher CLT temps than when the engine in cold. You can also use O2 correction at idle to keep AFR's where you want them but usually after the engine is warmed up. Of course for start up, the O2 sensor does not start reading until the controller boots up.

Another thing you can do is to run the car at normal operating temperatures then run a datalog(set O2 correction authority to 0% to not effect idle) with the car sitting, idling for a period of time to monitor the AFR as the IAT increases. IF the AFR starts to lean out, you adjust the MAT correction curve in that temperature range to keep the AFR in range. This will give you an idea of how far off the MAT correction curve is off for your installation. The MAT correction curve is supposed to follow the Ideal Gas Law. Many people running MS2 & MS3 have found it too aggressive, leaning the AFR too much with increasing temperatures. I think it varies depending on the installation. This adjustment will help with heat soaked engine starts and less ASE taper may be needed. Note that changing the MAT correction curve at temperatures seen while under boost will affect the AFR in those areas as well.

Are you using the Idle VE and Idle Advance tables to tune the engine idle?

[jpilcher]

Hi Dennis

Thanks for the response. I am still trying to find my way around TunerStudio. I have been doing a lot of reading. I have not had an opportunity to do any further tuning. I am hoping to get around to it tomorrow night. I was having a minor issue with my VR sensor. I believe it was causing the intermittent stumbling.

Car idles very well, steady at 14.7 AFR, even as temperatures climb. It's only when I have to restart that I have a problem. I will try to implement the procedures you have outlined.

Perhaps once I get more tuning completed you could have a look at my tune to see if there is anything glaring?

Thanks Again

John

[xbmwguy]

No 2 cars are the same. Even with the same builds there will be discrepancies.that being said most of the efi builds I have either had a hand in tuning or have seen tuned by " real tuners" have all had a good idle in the 13-14 afr range. Also I have a tested curve for coolant ( oil) mat correction. This has worked for me and all other 930s I've seen

[jpilcher]

Thanks Xbmwguy, I will give this a try.

[jpilcher]

Here are some of my settings. If you experienced MS guys could have a look and comment, if something looks off, I would really appreciate it. It may help the next guy.

[jpilcher]

General Settings

[jpilcher]

Mat Air Density Table

[jpilcher]

MAT/CLT Correction

[jpilcher]

AFR/EGO CONTROL

[jpilcher]

AFR Table 1

[jpilcher]

Ego Authority

[jpilcher]

Ignition Options\Wheel Decoder

[jpilcher]

[Tippy]

I see you don't have a specific toothed wheel selected? Are you 60-2 or 36-1?

AFR's around idle and low RPM up to say, 2500, IMO, should be mid-13's*. This will aid lean tip-in and make the engine run smoother.

*You're sequential, so yours will run better than batch at stoch, but using ITB's and speed density is going to make lean tip-in a PITA to get right.

[jpilcher]

[jpilcher]

[jpilcher]

[jpilcher]

[jpilcher]

[jpilcher]