G8 L76/6L80 swap to 1969 Mercedes 280 sedan, stall at stop

[Coasttocoast]

First post here, thanks for all the info to those that post! Been reading for a few hours now.

Purchased a 2008 complete dropout with 106k miles. DOD delete with 218/224 .600?/.600
114 LSA +4 cam. No other mods. Car weighs 3300lbs. 3.92 rear gear with 24.9? tall tire.

I completed the swap, initial tune was by 150 tunes.com to match my car, cam, etc. Engine started up first try and drivable.

I purchased the tuning suite and 2 credits. I have successfully downloaded the software, downloaded the tune from the car into my laptop, and played around with simple changes (tire size) to make sure I understand the download and upload procedures.

If I drive a little sane/slow, with the A/C off, the engine doesn?t die at stop signs/lights. But any quick stops, or with the A/C running it feels like the torque converter doesn?t let go quick enough. Not sure if that?s what?s actually happening, but that?s what if feels like.

I would appreciate any guidance or a place to start, have?t been able to find any similar questions.

[kevin87turbot]

Just post your tune and a datalog. We can certainly give you some pointers.

[5FDP]

Buy a wideband as well, you'll need one asap if you don't.

[Coasttocoast]

Just post your tune and a datalog. We can certainly give you some poifirst read of L76 ie starting point.hptnters.

Thanks Kevin. I have attached the tune, I haven't looked at making a datalog yet.

I will read up on how to make a datalog now.first read of L76 ie starting point.hpt

[Coasttocoast]

Buy a wideband as well, you'll need one asap if you don't.

I welded in a port for a secondary O2, what should I buy and how does it connect to the MPVI2?

Thanks for your advice.

[Coasttocoast]

Here are a couple log files, hope I did this correct.

[kevin87turbot]

For some reason, the website isn't allowing me to make attachments this morning.
The IAT's are really high. Does it have an open element air filter with no enclosure?
The minimum air flow table appears to be stock. I'd start by making your min airflow numbers approx. 9 gps.
You'll likely have to add some startup airflow for hot start as well.
I'd also increase the ignition timing at idle. 20 degrees would be a good start.

[Coasttocoast]

For some reason, the website isn't allowing me to make attachments this morning.
The IAT's are really high. Does it have an open element air filter with no enclosure?
The minimum air flow table appears to be stock. I'd start by making your min airflow numbers approx. 9 gps.
You'll likely have to add some startup airflow for hot start as well.
I'd also increase the ignition timing at idle. 20 degrees would be a good start.

Thanks for the reply!

Last night was the first time I drove the car, with the computer connected, when cold. Even at startup the IAT was reading over 120 degrees, probably should have been reading 75 degrees. I used the stock G8 MAF sensor, I looked back at the details from 150tunes and I’m directed to use a different one. Ordered last night should have Wednesday.

I’ll post back after I have the correct MAF installed with data.

That aside, would that affect the trans from downshifting/dying at stop?

Thanks

[kevin87turbot]

If you'll increase the min air table, it won't die at a stop anymore.

[5FDP]

The AEM OBD2 wideband will plug right into and work with the HP Tuners. It will use the can-bus on the computer and OBD2 port to make the wideband function without any extra wiring. You can even find youtube video's for setting up the AEM wideband channels to make it log.

[Coasttocoast]

If you'll increase the min air table, it won't die at a stop anymore.

Kevin, great thanks I’ll try tomorrow

[Coasttocoast]

The AEM OBD2 wideband will plug right into and work with the HP Tuners. It will use the can-bus on the computer and OBD2 port to make the wideband function without any extra wiring. You can even find youtube video's for setting up the AEM wideband channels to make it log.

I just ordered it, should be here by Friday. Thanks for the recommendation!

[Coasttocoast]

I have been playing around with the software and getting more familiar with it. I have purchased and installed the AEM wideband and have it logging. The MAF sensor that I was supposed to use to match the tune by 150tunes came in and installed it. But I coundn't find any stock tables to double check that the right tables were installed, I know the air temp table was off. Since there is a stock G8 tune here on the forum I swapped back to the stock G8 MAF and loaded the stock tables. The air temp is reading correct now.

I have an K&N filter just proud of the MAF sensor tucked in behind the panel to the drivers side of the radiator. The temps read a little high. I'm researching now to modify to get access to cooler air.

Attached are the current tune and a log. I'm still having issues with stalling at a stop, so I shift into neutral before slowing too much, fyi.

The main concern right now is still that the engine either dies when coming to a stop or almost dies then really surges. I've had a couple close calls because the surge was so great I almost hit the car in front of me.

In the transmission settings, under torque management, under general, under stall torque management, the enable and disable RPM field are both set at 7,000. I see on the stock G8 tune they are set at 1.500 and 1,300. Could this be an issue?

I appreciate any suggestions and guidance.