Single Fire/Double Fire

[v6bucket]

I rebuilt a VP V6 recently for my mates Dato 1200, nothing out of the ordinary, just std internals & a SC14 blower bolted to the side. So I suggested that it be run in on a dyno & give it a tune as it's only ever been tuned on the track. After a few dramas with a vacuum leak, stuck wide open iac & brand new 2 bar map that was u/s, we started tuning.
The dyno operator isn't familiar with the delco 808 tuning so I was on my own. I had a few issues with the getting a stable afr from idle up through the rev range, it was really rich at idle, then really rich with a few revs. I noticed that the Set "Single Fire Option" was flashing on & off, can't remember exactly but Double fire was alternating as well. I could only find 2 items for single fire, so ticked the box which allowed us to get a stable a consistent afr. I got the 1 bar table pretty close, so we tried to do a power run, but kept running out of fuel, which I couldn't work out as it has run with this setup using 60lb Dekar injectors for a number of years. Only suggestion that the dyno operator could come up with was rising rate reg, or a Microtech ecu.
So we packed up after making 194hp with very little timing & not reaching 5000rpm. After doing a search for double fire on this forum I found that the Single fire option limits the injector duty to 50%, thus why I run out of fuel.
I didn't use the previous bin that had been raced with as it had a mixture of petrol & methanol figures, so I created a new bin, which I got from Holden202, then changed the parts to suit this application, but it looks like I left the single fire/double fire option. As we already have the afr pretty close with it in single fire mode, can I change the figures to 0 in the 2 scalar tables, un-check the single fire option? What will I have to do to the VE table? We hope to get it back on the rollers in a couple of weeks. Unfortunately I didn't get a log, I pushed the wrong button to save.
This is the bin, I still have to smooth a few spots in the ve table.

JP2bin.bin

(32 KiB) Downloaded 288 times

[festy]

If you un-tick "Map A:set=Single fire option", then there are two scalars that control the changeover point from single to double fire: Run A/F Param - Minimum BPW for sync double fire fuel delivery (Upper Value) and Run A/F Param - Minimum BPW for sync double fire fuel delivery (Min Value).
The upper value dictates the BPW at which double fire mode starts, and Min value is when it switches back to single fire.
If you set both to 0, double fire will be used everywhere which is usually fine unless you have huge injectors on a small engine.
From my (rather limited) experience with those values, you probably want a bigger difference between them. Mrfiat's 2L 4cyl with Deka 60s seemed to work well with Min=1.00ms, Upper=2.00ms. That let it idle nicely with single fire, but switched to double fire almost immediately off idle.

[Dylan]

VE shouldn't be affected after changing to or from single fire mode.
So long as your injector add on table was right and VE was right to start with.

[vlad01]

thats all good, but some injectors become unstable at low pulse width so no adder table will fix that as its physically mechanically unstable. That might be the case here.

[Dylan]

What injectors are you running?

[VX L67 Getrag]

Sorry to hijack, it looks like in the v112 blcf v8 stock bin the double fire option is natively set?

Does that mean it will run twice the set injector rate for crank/run if left unset?

Again sorry just trying to figure out why a car I'm tuning is fouling plugs compared to a factory $5D tuned car!

[Dylan]

Id say double fire would be default in all versions? As far as I know single fire is extra code added by VL400.
Maybe it was there but unused by Holden?

Post up these tunes you have maybe a fresh sets of eye's might help.
I've converted a few $DB tunes to 12P with pretty good success. Just the AE that needs a tweak I've found.

[VX L67 Getrag]

LOL thanks Dylan, the way it started was trying to use your tune as a base for the other mentioned I another thread with a 106* lobe seperation & caused a immediate flood?

So I thought could be a coding error with single/double fire option!

I've tried copying all previous $5d differences to $12p but don't think it will be that easy as there's a LOT of code changes too!

[Dylan]

Feel free to start a thread if you want I've done a few of these big cam tunes now.
I had double fire mode on that tune and set for blue tops 28lp injectors.
Think even start up enrichments were less than standard as I've seen these things kill plugs even after professional tunes.

Id be keen for a look over the tune I love tuning these things the big shops are scared of.

[VX L67 Getrag]

Well the tune I've attached is what another tuner charged big dollars for & ended up killing a trans (which cost the owner over the cost of the tuning fee) but it still didn't start up well & need 2 feet to keep running at idle! But although it seems to line up with ATJN it really should have been a later file & there was a slight difference in release date info so not sure if it was the original file used?

I then copied (as close as I could to the latest $12p file) & will test tomorrow.(attatched)

I'm just dubious as to how quick the other file (not mentioning names) should be close to get a start fouled the plugs & wouldn't allow even firing a start.