Closed loop on ECU without full remap?
Discussion
I've got my 17% reduction pulley here for my supercharger, and I'm itching to fit it, but don't have a dyno date booked yet to get a full remap. I've got an Emerald ECU, standalone, running a closed loop map using the wide-band O2 sensor, and have the option of an 'adaptive' map which will write adjustments to the map based on the O2 sensor readings. The reduction pulley should increase the boost pressure by maybe 7-10psi (unless my calculations are way off)
I was contemplating installing the reduction pulley tomorrow (and the chaps from Emerald won't be about till Monday) but am not 100% if a closed loop/adaptive map would be okay until I can get it mapped properly, or would it be more sensible to wait till I have a remap booked and run it at the higher boost pressure for as short a time as possible before the remap (e.g. just the drive over there). Don't want to end up with it running stupidly lean and wrecking the engine before I have had time to get it mapped.
Thoughts?
I was contemplating installing the reduction pulley tomorrow (and the chaps from Emerald won't be about till Monday) but am not 100% if a closed loop/adaptive map would be okay until I can get it mapped properly, or would it be more sensible to wait till I have a remap booked and run it at the higher boost pressure for as short a time as possible before the remap (e.g. just the drive over there). Don't want to end up with it running stupidly lean and wrecking the engine before I have had time to get it mapped.
Thoughts?
SuperchargedVR6 said:
Closed loop on most budget standalones isn't fast enough to fill in the fuelling gap an extra 7-10psi will create. You need to get the base map done first. You might need bigger injectors as well, plus some ignition pull. Best to wait until Dave Walker can remap it properly.
It's been mapped at the current boost already, so not sure how much different the basemap might be, but I know the injectors are bid enough (so big it was tricky to get it to idle properly).but the point about the closed loop responding quick enough, that's a good one. I wonder if the 'adaptive' mode might help that tho, where it's continually writing incremental changes to the map as it goes.
Closed loop cannot react fast enough (when it matters) I thought like you 2K on a stand alone ECU should be clever enough to work out whats needed if it's got a decent base map, it will when you off boost and going to the shop, give it the beans Ms then bang, proper mapping far more cost effective!!!
feef said:
SuperchargedVR6 said:
Closed loop on most budget standalones isn't fast enough to fill in the fuelling gap an extra 7-10psi will create. You need to get the base map done first. You might need bigger injectors as well, plus some ignition pull. Best to wait until Dave Walker can remap it properly.
It's been mapped at the current boost already, so not sure how much different the basemap might be, but I know the injectors are bid enough (so big it was tricky to get it to idle properly).but the point about the closed loop responding quick enough, that's a good one. I wonder if the 'adaptive' mode might help that tho, where it's continually writing incremental changes to the map as it goes.
Closed loop on a standalone is at best just to trim the load sites when cruising, with say 10% adjustment authority max. Sophisticated OEM systems are probably fast enough for it, but even then they get the base map spot-on and only give the lambda control 25% adjustment.
I would never trust a standalone's lambda enrichment in boost. The lambda control of my DTA S80 was frankly, crap, and I can't imagine the Emerald's being much better, no offence. You need to get the extra boost mapped in. The 'adaptive' map is a bit of a misnomer really and again, I found that to be rubbish on my DTA. Same load site, same engine load and set to average say, 5 passes of the cell before it registers a suggested + or - adjustment, the numbers varied wildly. Such is the way with constantly moving throttle plates and ECUs that simply aren't powerful enough.
So to summarise, get it up to Mr Walker, have him map in the extra boost, then just use the lambda to tickle the fuelling like a fine tune button on a radio. Don't use it to fill in gaps!!
SuperchargedVR6 said:
You'd be surprised how much the base map will need changing for an extra 7-10psi, both in fuel and timing!
Closed loop on a standalone is at best just to trim the load sites when cruising, with say 10% adjustment authority max. Sophisticated OEM systems are probably fast enough for it, but even then they get the base map spot-on and only give the lambda control 25% adjustment.
I would never trust a standalone's lambda enrichment in boost. The lambda control of my DTA S80 was frankly, crap, and I can't imagine the Emerald's being much better, no offence. You need to get the extra boost mapped in. The 'adaptive' map is a bit of a misnomer really and again, I found that to be rubbish on my DTA. Same load site, same engine load and set to average say, 5 passes of the cell before it registers a suggested + or - adjustment, the numbers varied wildly. Such is the way with constantly moving throttle plates and ECUs that simply aren't powerful enough.
So to summarise, get it up to Mr Walker, have him map in the extra boost, then just use the lambda to tickle the fuelling like a fine tune button on a radio. Don't use it to fill in gaps!!
25% adjustment is huge, but at the same time OEM is usually only narrowband and low loads, and there are many other things going on in the background to get sensible running without it going tits up.Closed loop on a standalone is at best just to trim the load sites when cruising, with say 10% adjustment authority max. Sophisticated OEM systems are probably fast enough for it, but even then they get the base map spot-on and only give the lambda control 25% adjustment.
I would never trust a standalone's lambda enrichment in boost. The lambda control of my DTA S80 was frankly, crap, and I can't imagine the Emerald's being much better, no offence. You need to get the extra boost mapped in. The 'adaptive' map is a bit of a misnomer really and again, I found that to be rubbish on my DTA. Same load site, same engine load and set to average say, 5 passes of the cell before it registers a suggested + or - adjustment, the numbers varied wildly. Such is the way with constantly moving throttle plates and ECUs that simply aren't powerful enough.
So to summarise, get it up to Mr Walker, have him map in the extra boost, then just use the lambda to tickle the fuelling like a fine tune button on a radio. Don't use it to fill in gaps!!
As for DTA's closed loop, there certainly is a lot of room for improvement, but I'm sure a lot is down to having to use an external controller which itself adds more variables. But yes giving it a small window of control makes perfect sense, especially on the removing fuel side.
But I will also counter it after having used Syvecs, their lambda control is superb and I have no concerns whatsoever about allowing it a wide range of control under all engine operating conditions
But no form of closed loop should ever be a band aid for bad tuning. The base map must always be a good one !
It is, but it's more for failsafe than a regular adjustment range. My logs show < 2% adjustment on the long term trims channel. I've only ever seen +25% once, which was when the mechanical TFSI fuel pump couldn't keep up after a remap.
The OEM system I was referring to (MK5 Golf GTI) uses wideband pre-cat. It's only narrowband on the post cat.
Good to hear you've found some good lambda control in the aftermarket!
The OEM system I was referring to (MK5 Golf GTI) uses wideband pre-cat. It's only narrowband on the post cat.
Good to hear you've found some good lambda control in the aftermarket!
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