Lean Cold Start

[TwinScrew20v]

Hey guys,

I've been having pretty good luck with my MS build recently and I'm starting to nail down all the nit picky driveability details. The last 'performance' issue I have is related to Cold Starts (if you can call it that in Az). Regardless of the outside temp, my cold starts at idle are extremely lean (15.5-17.0) and rarely survive the throttle body opening without stalling. When it warms up, AFRs are in the 14.0-14.2 range solid. I've played with the WUE non-stop since I've had it running and I don't see any change with the WUE being as high as 250% down to 103%. It happens all through warmup, but it gets better at about 145-150 and becomes drivable at that point. Anyone have any ideas? I'm not able to keep it running consistently through cold start so I can't get a datalog until after it's warmed up, but I've attached the current .msq.

Car is a VW 12v VR6 turbo, GM DIS coil packs (same result on the VW coilpack), no ISV. Thanks for the help!

[TwinScrew20v]

I was able to keep it running well enough to get a log this morning. This was all at a dead stop. AFRs started to run to the 14:1 I programmed to around 135-140F.

[PSIG]

Didn't look at your log, but try changing your fuel table settings back to default MSnS selections.

David

[TwinScrew20v]

Perfect! Thanks that did it (while making the entire table way rich) and smoothed a lot of things out.

[PSIG]

Perfect! Thanks that did it (while making the entire table way rich) and smoothed a lot of things out.

Cool. For large map areas, you can select the area overall and knock the VE down, or if your VE numbers are running substantially higher than about 100 VE at 101 kPa then pull your Required Fuel down to keep the same VE numbers but lean everything out. In either case, if you divide your current rich AFR by your desired AFR, then multiply that number with your VE or ReqFuel to get in the ballpark and start tuning closer to where you plan to end-up. Have fun!

David

[mattsteady]

I've got a very similar problem. My WUE and ASE values are making absolutely no difference whatsoever.
My settings for the fuel table are the same as the picture you showed. I'm running alpha-n if that makes any difference.

Oh and no matter the WUE values - the WUE gauge shows 100% all the time.

It idles beautifully when warm

Any help would be very much appreciated! Tune attached.

Cheers,
Matt

[Matt Cramer]

I've got a very similar problem. My WUE and ASE values are making absolutely no difference whatsoever.
My settings for the fuel table are the same as the picture you showed. I'm running alpha-n if that makes any difference.

Oh and no matter the WUE values - the WUE gauge shows 100% all the time.

It idles beautifully when warm

Any help would be very much appreciated! Tune attached.

Cheers,
Matt

Actually, it looks as if you have a completely different problem. You've set your WUE to turn off at 54 degrees.

Also, please make sure your CLT sensor is reading correctly.

[mattsteady]

Hi,

Thanks for the reply! The CLT isn't calibrated perfectly - it is about 4-5 degrees out, but it is close enough for now.

Yes you are right - the WUE will turn off at 54 and I realise that isn't how I'd probably want it. However below that the WUE is doing nothing. For instance I can put it at 200 across the board and there will be no change, and the WUE gauge still reads 100%. For now I just need to see the WUE actually working so I can tune it - I can't tune it if isn't doing anything :/

Cheers,
Matt

[mattsteady]

I'm quite happy to believe I'm doing stupid stupid or have a fundamental mis-understanding. The picture below shows what is messing with my head - the gauge and the settings don't match up.

[Matt Cramer]

Please get a data log of this behavior and post it. This will give me more to go on.

[mattsteady]

Sorry - I should have put this in with the tune.

I started with high req_fuel so it would actually start (which it did first time albeit with slightly low revs).

Whilst the log was running I changed the bins significantly and burnt it.

WUE gauge stayed at 100% throughout.

Thanks I'm sure it is something stupid.

[mattsteady]

Of course there is a tiny possibility that it is a hardware fault in my MS1 rather than user error. It is tiny though

[Matt Cramer]

Is the CLT sensor reading displaying correctly in TunerStudio?

[mattsteady]

Yes - it starts off at 19 degrees (4-5 degrees higher than air temperature so it does need a little calibration tickle) then goes up. That gauge works.

[2swe]

I don't like the 79% Gair correction in your log.. you should edit your airdentfactor.inc file. You want 100% (100T) at your typical air temerature, and pull down 1% with every 6°C (11°F ) higher MAT, and add 1% every 6°C lower MAT. this will get you in the ball park.


I would turn Barrometric correction - Off , then set EGO step size - 1'%, EGO controller autority - 10%, AFR target - 12,8 AFR at WOT would be better than 13,6..

[mattsteady]

Thanks 2swe - that's very helpful.

I've turned off barometric correction and made the changes to the EGO settings. I don't think that or the AFR targets will be affecting this problem, but they'll both be helpful going forward.

I can certainly calibrate the IAT and coolant sensor - could that be making a difference somehow? I'd still expect the WUE gauge to show changes and amending the bins to do something even if they aren't calibrated correctly (even if not good things!).

[mattsteady]

OK got it!

Sometimes it is just the simple things - I reflashed the firmware with the latest version and Bob's your uncle the WUE is responding correctly now.

Thanks for all your input - much appreciated,
Matt