e38 cranking help

[swingtan]

Hi Ringram,

I was talking to someone about this sort of thing last week.

Have a look at B8062 and "REDUCE" the % value for the cranking. I haven't put a lot of thought into why this works, but it seems to help a lot with larger cams. I think the guy I was talking to tried values around 75% to start with, and then jumped to 50%.

The other table would be B5119. For some reason, GM decided to put some weired steps in the spark map for cranking. I removed the -VE values, added some timing as the RPM rose and smoothed the lot out.

Hopefully this helps a bit.

Simon

[GMPX]

The other table would be B5119. For some reason, GM decided to put some weired steps in the spark map for cranking. I removed the -VE values, added some timing as the RPM rose and smoothed the lot out.

People have told me that when that table (B5119) has those values removed the engine knocks at start up just as it fires. It looks dumb but it does seem to serve a purpose.
Richard, sorry but I can't offer any practical advice on your problem, maybe I need a 440 for R&D?

Cheers,
Ross

[ringram]

Have a look at B8062 and "REDUCE" the % value for the cranking.

Good man, 50 bonus points.

My last attempt to use that table failed, (I set it at 75%) probably due to issues in other area's. I have tried to return most of the tune to stock when I have gone too far away from "normal" values to save myself getting lost in the forrest.

I have added 10% more timing to cranking timing, ~30% air to cranking air (27% more displacement) and set the cranking ve to ~70% plus added a similar ~30% air to min idle airflow. Now things are working nicely, or at least it cranks, fires and maintains idle now anyway. I reset open loop IVT table to stock as it was too rich.

Its not fun stalling in multi story car parks and needing to reflash with people stuck behind you

[swingtan]

Excellent! I've been on the side of the road flashing a tune and had every car that passed me hit the brakes thinking I was a speed camera.... Was very funny

[calais-346]

Hi Ringram,

I was talking to someone about this sort of thing last week.

Have a look at B8062 and "REDUCE" the % value for the cranking. I haven't put a lot of thought into why this works, but it seems to help a lot with larger cams. I think the guy I was talking to tried values around 75% to start with, and then jumped to 50%.

The other table would be B5119. For some reason, GM decided to put some weired steps in the spark map for cranking. I removed the -VE values, added some timing as the RPM rose and smoothed the lot out.

Hopefully this helps a bit.

Simon

After going around and round in circles changing cranking idle air and timing, i tried this, i reduced B8062 cranking ve to 75% and now have perfect starting!

Safe to say i'm a very happy man now, i was getting sick of putting my foot on the throttle to start the car