12p fuel vs coolant

[Kevspec]

finishing up tune on a vr ss manual with 12p runs fine at temp but cold start floods it am i blind or where is the table to adjust fuel vs coolant temp?

[vlad01]

what injectors are you running?

[Kevspec]

775 bosch blue tops all fuel at temp is good just cold start flooded it but car does not have a wideband all been done on the dyno

[vlad01]

Could be anything without a wideband to see what's up.

The only time I had flooding when cold is when I had large injectors and the min BPW value was larger than the cranking table values, so it always flooded at starting or soon after when cold.

Also had a minor issue like this due to the target AFR being a bit too rich for the cam overlap and normally happened when the stock settings did a rich to 14.7 back to rich transition during warm up, it was the back to rich bit that killed it sometimes, I just upped the AFR overall so it was leaner and the difference in this transition point was smaller, I haven't had it stall since but can still hear it slightly stumble when from a real cold start.

You'll need to get a WB to see and work the issues out, no point guessing, only will fuel the issue (no pun).

[Kevspec]

on the dyno I have a wideband that's fine but just trying to tune it out. All fuelling is being done via open loop as has a decent cam in a unknown built 355 it all seems health with 12.8 afr and 27 degrees made 320 rwhp 410 ft lbs but hits a wall at around 4800 rpm due to stock intake and starts to pull vac due to restriction. Could definitely take some more timing but pretty sure the owner will give a hard time so just keeping it safe but it does like a pretty flat timing graph.

Which min BPW table are you talking about?

[h4x0r]

Which min BPW table are you talking about?

There is a simple scalar (not table) for minimum crank bpw and maximum crank bpw. The minimum bpw will still be set to the factory injectors which will make your car flood with bigger injectors. You probably changed the cranking bpw tables but not the minimum crank bpw scalar.

Happened to me also.

[vlad01]

Yes it's a scalar. Default is like 7 point something mS iirc (for v6), my cranking tables were as low as 4 something, so I set the min crank BPW to 2ms to be sure, doesn't need to be that low, but as long as it's lower than the lowest cranking pulse in the 1st and 2nd stage cranking tables, it will be happy.

If it is higher than those, then it will only be able to pulse as low as that scalar, if that's too much fuel, flooding ensues.

Mind you, my injectors on that particular car were almost twice the flow as the stock at 39 lb @ 3 bar.

[Kevspec]

Awesome thank you. I also played a little with a/f ratio offset vs coolant seems to help a but too even though closed loop is turned off

[Kevspec]

Was also having issues with engine catching the stall even with everything correct only thing that seem to work was changing iac idle map threshold vs idle rpm and lowered the numbers at higher rpm other otherwise decel or holding high revs and let it drop iac would go to 0 counts and wouldn't try add steps to catch until was to late. And yes I have played around with stall saver headbands and throttle sag.

[h4x0r]

Was also having issues with engine catching the stall even with everything correct only thing that seem to work was changing iac idle map threshold vs idle rpm and lowered the numbers at higher rpm other otherwise decel or holding high revs and let it drop iac would go to 0 counts and wouldn't try add steps to catch until was to late. And yes I have played around with stall saver headbands and throttle sag.

Is the engine heavily modified? If its close to stock then I found that you don't really need to change too much to have it run reliably.

I found that setting the throttle body butterfly to the correct spot fixes all stalling issues. I followed the guide in one of those beginner tuning pdf guides.