Hi All,
I have a VH45DE in a Z32, using an 8bit early ECU using the 66U15 base rom board from memory. Engine is relatively standard apart from valve springs and cams. Cams are 274 advertised / 222 at 50 thou. Everything is pretty well dialed in.
Have left the factory after-start table as it is up until now, and only adjusted the main fuel table, cranking and warm-up tables.
However...the After-Start table has never highlighted when active like all the other parameters, but after recently zeroing out is definitely scanned after the engine has cranked and started. I have now found my engine only needs maybe 65% of the after-start v's factory numbers and is a good improvement from what it was so keen to get there, or thereabouts without the guess-work.
My question is: How long does the ECU look-up the after start enrichment table before moving to the cold-start enrich tables? I am guessing around a minute from the engines behaviour but keen to know if there is a fixed time as the engine's quite lumpy at idle.
Cheers,
Lincoln.
VH45DE After Start Enrichment event timed?
Moderator: Matt
Re: VH45DE After Start Enrichment event timed?
The highlighting done in the software is done by looking at the various ECU inputs (start switch, temperature etc).
For this after start table, based on the limited information we have (derived from RB30 service manual), the after start table is used for a very short period of time (say about 5 seconds) after crank and decays rapidly. So there is no highlight added to this table, but as you noted it is used
Maybe this ECU holds it for longer. The best way to notice is how the engine runs with it set to 0 as opposed to where it is currently. Normally it is not necessary to adjust such tables but with cams I can see how this might help, but I would also be more looking at the temp enrich table, or increasing your latency a little (which will affect the entire temperature range)
For this after start table, based on the limited information we have (derived from RB30 service manual), the after start table is used for a very short period of time (say about 5 seconds) after crank and decays rapidly. So there is no highlight added to this table, but as you noted it is used
Maybe this ECU holds it for longer. The best way to notice is how the engine runs with it set to 0 as opposed to where it is currently. Normally it is not necessary to adjust such tables but with cams I can see how this might help, but I would also be more looking at the temp enrich table, or increasing your latency a little (which will affect the entire temperature range)
Re: VH45DE After Start Enrichment event timed?
Cheers for the speedy response Matt. I should post more questions 
I near-zeroed the after-start today and yes, it only stumbled for maybe 5-10 secs, so my bad for not spending more time looking into this. Quite satisfying making a reasonably lumpy motor start and run almost like a factory one under all conditions.
I originally played with the latency (lowering it) to achieve a better idle when warm but found the fuel-trims kept attempting to trim back to stoich. With the lumpy unburnt fuel/air giving a false 'lean' reading (extra unburnt fuel & O2 causing this at a guess), I found it seemed to be happiest around the mid to high 15's to 1 at idle. Something else I tried to tame was an un-smooth cammy 'bucking' while light cruising at around 1500-1800rpm (yeah not asking much am I ). Found an afr of around 13:8-14:0 (with relaxed vacuum advance at this rpm) really smoothed things out. Because of these reasons I have disabled the O2 sensor trimming function, by just increasing the O2 temperature setpoint right up. I don't know if this is the best solution, but seems to drive well everywhere now while going off my wideband.
Next job is to revisit the dyno again. I was there a while back, but got side-tracked setting up the VTC points that I forgot to see what ign timing the engine wanted at high rpms. Steady-stated to around 4500rpm at 22deg advance, and left it set there to redline since I forgot to ramp-run the higher rpms. Still managed 335hp atw on Auckland's lowest reading dyno on std 95 pump gas (as it's a daily and I'm tight) so pretty happy. Not that I trust most dyno numbers, but the owner was surprised a near factory 4.5NA managed that. Should be a good test for the old girl when we head back.
Anyway, enjoy using your product Matt. Thanks.
I near-zeroed the after-start today and yes, it only stumbled for maybe 5-10 secs, so my bad for not spending more time looking into this. Quite satisfying making a reasonably lumpy motor start and run almost like a factory one under all conditions.
I originally played with the latency (lowering it) to achieve a better idle when warm but found the fuel-trims kept attempting to trim back to stoich. With the lumpy unburnt fuel/air giving a false 'lean' reading (extra unburnt fuel & O2 causing this at a guess), I found it seemed to be happiest around the mid to high 15's to 1 at idle. Something else I tried to tame was an un-smooth cammy 'bucking' while light cruising at around 1500-1800rpm (yeah not asking much am I
). Found an afr of around 13:8-14:0 (with relaxed vacuum advance at this rpm) really smoothed things out. Because of these reasons I have disabled the O2 sensor trimming function, by just increasing the O2 temperature setpoint right up. I don't know if this is the best solution, but seems to drive well everywhere now while going off my wideband.Next job is to revisit the dyno again. I was there a while back, but got side-tracked setting up the VTC points that I forgot to see what ign timing the engine wanted at high rpms. Steady-stated to around 4500rpm at 22deg advance, and left it set there to redline since I forgot to ramp-run the higher rpms. Still managed 335hp atw on Auckland's lowest reading dyno on std 95 pump gas (as it's a daily and I'm tight) so pretty happy. Not that I trust most dyno numbers, but the owner was surprised a near factory 4.5NA managed that. Should be a good test for the old girl when we head back.
Anyway, enjoy using your product Matt. Thanks.
Re: VH45DE After Start Enrichment event timed?
Good stuff!
With the O2 feedback you can try disabling the O2 flag at the bottom of the fuel map, and increase the bottom load point of the closed loop scale and see how that goes (normally we adjust the top end)
With the O2 feedback you can try disabling the O2 flag at the bottom of the fuel map, and increase the bottom load point of the closed loop scale and see how that goes (normally we adjust the top end)