basics of tuning delco non $12p

[krusty]

At 8:16 if you check road speed, WB AFR, TPS, knock retard and commanded spark advance something happens. AFR goes out to 18.4 commanded AFR due to lean cruise. This is obviously too lean for your set up with actual fuelling being commanded. At 18.4 you will also notice that commanded spark is 23deg, TPS is 17%,, engine rpm 1840, roadspeed is 71km/h.

Due to the cam and cooler the air flow is greater at those throttle / engine rpm/ load points so either bring back the commanded AFR in lean cruise and or add fuel. The on board NB sensors are abit unreliable in these kind of areas with AFR so the wideband will help alot there.

For the mean time if you aren't confident with adjusting fuelling it may be a good idea to disable lean cruise by adjusting it's temp enable value to 151deg.

A safe and easy way to adjust the fuelling is to just richen the lean cruise AFRs though. Something like 17:1 to start with.

I've only had a quick look at the log but it looks like the spark bouncing thing you are worried about is indeed deceleration enleanment. at 7:16min it is apparent. View eng rpm, tps, commanded AFR and commanded spark to get an idea of this. You can see the engine rpm bouncing...........this is the boomy noise you can hear in the exhaust at low throttle opening especially in 3rd during a down hill roll at around 70-90km/h.

Hope that's a start

[sprattzvx]

At 8:16 if you check road speed, WB AFR, TPS, knock retard and commanded spark advance something happens. AFR goes out to 18.4 commanded AFR due to lean cruise. This is obviously too lean for your set up with actual fuelling being commanded. At 18.4 you will also notice that commanded spark is 23deg, TPS is 17%,, engine rpm 1840, roadspeed is 71km/h.

Due to the cam and cooler the air flow is greater at those throttle / engine rpm/ load points so either bring back the commanded AFR in lean cruise and or add fuel. The on board NB sensors are abit unreliable in these kind of areas with AFR so the wideband will help alot there.

For the mean time if you aren't confident with adjusting fuelling it may be a good idea to disable lean cruise by adjusting it's temp enable value to 151deg.

A safe and easy way to adjust the fuelling is to just richen the lean cruise AFRs though. Something like 17:1 to start with.

I've only had a quick look at the log but it looks like the spark bouncing thing you are worried about is indeed deceleration enleanment. at 7:16min it is apparent. View eng rpm, tps, commanded AFR and commanded spark to get an idea of this. You can see the engine rpm bouncing...........this is the boomy noise you can hear in the exhaust at low throttle opening especially in 3rd during a down hill roll at around 70-90km/h.

Hope that's a start

thats great info mate, but i cant see temp enable for lean cruise. if im understanding correctly, if a adjust all values in lean cruise correction versus mc cyl to value of zero, same result yea? or even better, minus 1.0 from the correction values in this table should see lean cruise a/f drop by a corresponding amount, provided this table has no associattions with other tables, which it looks like it doesnt.

[krusty]

You can disable lean cruise in flags. I just checked the new bin and I set the Lean cruise to a max of 16:1 AFRS. Which tune you running on that log?

[sprattzvx]

im running the second one ddrh revised you sent. the cruise correction around the 350-400 mgc area is set around 3-3.4 at around , so works out to around the 18 mark when in lean cruise at 1200-1600 rpm.
if i untick the set box in flags for lean/c, that will disable it?

[krusty]

im running the second one ddrh revised you sent. the cruise correction around the 350-400 mgc area is set around 3-3.4 at around , so works out to around the 18 mark when in lean cruise at 1200-1600 rpm.
if i untick the set box in flags for lean/c, that will disable it?

I haven't actually disabled lean cruise in TP before so in theory, yes if the box is unticked then lean cruise should disable. Just confirm the change has occured with the WB

[sprattzvx]

yep andrew no lean cruise now. im not happy with doing it this way, ill trim the lean cruise correction back until i see no knock and hopefully retain some fuel economy at cruise, but was def the prob as the associated k/r is gone
ive managed to clean up any occasional k/r i was getting on tip into pe/medium throttle now also with some fine tuning of tables pe tps and pe grams/cyl. think it was loading up abit much while still in open loop, now drops to safer 12.3 no kr and any power loss from richness will hope fully be off-set by not having timing pulled. where before was 13.5 ish and seeing kr.
its good the endless reading logging etc is sort off paying off now.


if i reset my fuel trims (battery disconnect), and drive for afew hours trying not to enter pe, is this a good way for the pcm to calculate the trims?
ive installed a 4inch intake and k&n pod thinking should start fresh.

[darcy]

I wouldn't go anywhere near that lean in lean cruse.

In my stock N/A VY going much leaner than 16.6:1 results in a lean flat spot.

[Holden202T]

yeah i had similar results .... also too lean makes more heat and hense probably causing the issues your seeing.

apparently the best way to tune lean cruise is that if you feel it apply then its too lean.

[krusty]

Agree with the last couple of posts. Just to point out though, stock VY L67 LCC on the DLTK tune is actually commanded to 18:1 AFR. Mine used to go there happile when on the stock cam but with an aftermarket performance cam it wasn't so happy. I guess due to the lower efficiency of the larger duration off boost but it's been fixed with a tad more fuel to make it run at 18:1 as commanded now.

But yeah Ken, almost as easy to chip a piston under lean cruise as it is at WOT. Common denominator being mega lean = BANG lol

[sprattzvx]

Agree with the last couple of posts. Just to point out though, stock VY L67 LCC on the DLTK tune is actually commanded to 18:1 AFR. Mine used to go there happile when on the stock cam but with an aftermarket performance cam it wasn't so happy. I guess due to the lower efficiency of the larger duration off boost but it's been fixed with a tad more fuel to make it run at 18:1 as commanded now.

But yeah Ken, almost as easy to chip a piston under lean cruise as it is at WOT. Common denominator being mega lean = BANG lol

big bang eh well im glad thats fixed. Think i might just stay on the side of caution and settle for around 15.5 ish in preference to turning l/c off.