Cranking and Startup

[Higgs Boson]

Ok so now that I have gotten through most of my tune, I am turning to startup.

I have a 408 with green tops and stock tables for

Cranking VE, Cranking Fuel, Afterstart Enrichment, etc.

Watching my AFR when starting, the key on, not running WB reads 17.1

Crank, fires right up, shows 10.5 and quickly drops to max rich 9.79 for a few seconds then starts getting stoiched.

When it is so rich the car stumbles and if I do not wait about 15 seconds, if I give it a quick little rev it will come back down and die I guess from being pig rich. Also if I start it in the driveway and pull into the garage it will die and coast in as soon as I clutch out and then in (to pull in) with a bit of throttle.

Is being this rich right? I have no idea which table to alter. I tried halving and doubling most of them with no noticeable affect.

[kamikazematt]

one place to start is to copy the matching rows/columns from your pri ve table to your cranking ve table and smooth inbetween there. i had a slight problem with it wanting to start out pig rich and then move to stoich quickly. another thing u might wanna try is the o/l f/a ratio modifier in the cells that you are hitting. start a scan before starting the car and watch what all cells you hit on the f/a table and either richen or lean it from there.

[Higgs Boson]

Well, I lowered the Cranking VE quite a bit and I also zero'd out the whole Afterstart Initial Adder vs ECT table and made sure my OLFA was 1.0....still starts up at 10.4, goes below 9.7 for a good 5 seconds and then kicks up to stoich. My commanded AFR during this is 13.4 and I don't know why.

[MNR-0]

After start is commanded open loop. If you are commanding 13.4 then that is the sum total of all adders, most likely coming from the OLFA table. With a Gen3 you need to lean off the VE map - log that and see where you are sitting. Subtle changes in VE at idle can cause big swings in measured AFR

Are you running a stock calibration or have you modified it with a SD enhanced upgrade? If so, check you VE multiplier table is all set to 1

[Higgs Boson]

SD OS. If I lean out my OLFA table it runs like chit in open loop before CL enables. VEMult is all 1.0.

VE map is tuned for normal op temp.
OLFA is tuned to run good before OL. If I switch to OL at 93 degrees it's too lean when cold driving.

I fixed the startup airflow with Friction Initial increases so it starts good even through a commanded AFR of 9.75 (from where I don't know).... it starts going to actual commanded after a few seconds (13.2 or whatever from OLFA). I don't know where it's getting 9.75 commanded for the first 2 or 3 seconds after startup....

Either way, it's not really a functional issue anymore.

[Higgs Boson]

Here is a log. What do you think?

[MNR-0]

You are not logging commanded AFR, only what is read by the wideband. You need to log commanded to see what is going on. In reality, you do not know what your ECU is commanding on cold startup without it

How have you plugged the wideband up? Via the ciggy socket? If so, on startup, it could well be resetting the power to the O2 and the sensor is re-initialising. Funny that it is almost exactly 10 seconds after startup

Does it read the same after stratup when hot?

[Higgs Boson]

Yes I am logging Commanded. If you can't see it I don't know why. I am logging it right above the Wideband reading.

The wideband is hardwired permanently to the car. It does the same thing hot or cold but Commanded is different, obviously.

Maybe it is just a power issue to the WB....? I don't think so actually because it is super rich like that in OL based on Commanded. Then it switches to 14.22 and starts reading CL AFR numbers....

[MNR-0]

OK I can see it

Well the commanded AFR is the sum total of all your adders. So you need to find which adder is dumping the fuel

[Higgs Boson]

OK I can see it

Well the commanded AFR is the sum total of all your adders. So you need to find which adder is dumping the fuel

Yeah, but it's not commanding 9.5....

[MNR-0]

From your log I can see the commanded AFR is 10.4 from cold start

[Higgs Boson]

From your log I can see the commanded AFR is 10.4 from cold start

Yes briefly but that is still not 9.5 or even richer (9.5 is the richest I can read).....so I don't really know how rich it gets.

[MNR-0]

I bet if you worked the adders to command 11.5 at start it would lean off on start

[robbyredneck]

have you set up your raf table? mine did the opposite until i set up raf.