getting too lean ?
Discussion
Hi folks,
I have following issue with my map.
Engine runs form MAP and has no MAF.
When releasing the throttle at higher rpms (is this called trailing ?) the engine will get too lean and then start having explosions in the exhaust (unburned fuel because mixture too lean)
I have verified that this is due to not enough fuel and increasing the fueling will fix it. However in slow traffic at close to idling I am running too rich (0,79-0,85). If I program the fueling to be around 0,95 then the unburned fuel sensation are returning.
My idea is now to change the whole column setup of the map and have more resolution in the low kpa. At the moment 20 is the lowest and 105 highest with 9 columns inbetween. My hope is that if I have a column at 5 and 15 kpa I can find a setting for both idling and trailing ?
OR is there any other method that can fix this issue or shall I just live with a rich map for idling.
I have following issue with my map.
Engine runs form MAP and has no MAF.
When releasing the throttle at higher rpms (is this called trailing ?) the engine will get too lean and then start having explosions in the exhaust (unburned fuel because mixture too lean)
I have verified that this is due to not enough fuel and increasing the fueling will fix it. However in slow traffic at close to idling I am running too rich (0,79-0,85). If I program the fueling to be around 0,95 then the unburned fuel sensation are returning.
My idea is now to change the whole column setup of the map and have more resolution in the low kpa. At the moment 20 is the lowest and 105 highest with 9 columns inbetween. My hope is that if I have a column at 5 and 15 kpa I can find a setting for both idling and trailing ?
OR is there any other method that can fix this issue or shall I just live with a rich map for idling.
spatz said:
Hi folks,
I have following issue with my map.
Engine runs form MAP and has no MAF.
When releasing the throttle at higher rpms (is this called trailing ?) the engine will get too lean and then start having explosions in the exhaust (unburned fuel because mixture too lean)
I have verified that this is due to not enough fuel and increasing the fueling will fix it. However in slow traffic at close to idling I am running too rich (0,79-0,85). If I program the fueling to be around 0,95 then the unburned fuel sensation are returning.
My idea is now to change the whole column setup of the map and have more resolution in the low kpa. At the moment 20 is the lowest and 105 highest with 9 columns inbetween. My hope is that if I have a column at 5 and 15 kpa I can find a setting for both idling and trailing ?
OR is there any other method that can fix this issue or shall I just live with a rich map for idling.
Are you running DTA S80?I have following issue with my map.
Engine runs form MAP and has no MAF.
When releasing the throttle at higher rpms (is this called trailing ?) the engine will get too lean and then start having explosions in the exhaust (unburned fuel because mixture too lean)
I have verified that this is due to not enough fuel and increasing the fueling will fix it. However in slow traffic at close to idling I am running too rich (0,79-0,85). If I program the fueling to be around 0,95 then the unburned fuel sensation are returning.
My idea is now to change the whole column setup of the map and have more resolution in the low kpa. At the moment 20 is the lowest and 105 highest with 9 columns inbetween. My hope is that if I have a column at 5 and 15 kpa I can find a setting for both idling and trailing ?
OR is there any other method that can fix this issue or shall I just live with a rich map for idling.
Hi folks
made another test drive today and here some more info. As mentioned my map starts with kpa 20 (DTA S80 ECU)
I noticed that in "trailing" mode the value drops to 2-4 kpa so my idea is to have one more column
at let us say 10 kpa since typicall idling drive is around 22 kpa. So my idea is to make a perfect mixture
for the trailing mode which seems to be always lower than 10kpa. This way I can make it richer and avoid unburned mixture getting in the exhaust ?
Obviously although the pressure is lowest there is still more air coming through the manifold than in idling mode with around 22 kpa.
I have reduced the fueling drastically which will almost cure the detonations but then in idling in the 20kpa column I am very lean (1,54 lambda.
So it seems that the initial setup of the MAP done by the engine supplier was rather not for driving around the city but on the track with more
resolution in the WOT area..........
Is my thinking right ?
made another test drive today and here some more info. As mentioned my map starts with kpa 20 (DTA S80 ECU)
I noticed that in "trailing" mode the value drops to 2-4 kpa so my idea is to have one more column
at let us say 10 kpa since typicall idling drive is around 22 kpa. So my idea is to make a perfect mixture
for the trailing mode which seems to be always lower than 10kpa. This way I can make it richer and avoid unburned mixture getting in the exhaust ?
Obviously although the pressure is lowest there is still more air coming through the manifold than in idling mode with around 22 kpa.
I have reduced the fueling drastically which will almost cure the detonations but then in idling in the 20kpa column I am very lean (1,54 lambda.
So it seems that the initial setup of the MAP done by the engine supplier was rather not for driving around the city but on the track with more
resolution in the WOT area..........
Is my thinking right ?
Typically almost any "engine map" developed on a dyno will not work as well in the car especially for part throttle and transition from idle to "pull away" WOT will nearly always be spot on as it is this where the engine is on full load and the tuner usually "wants" to get as big a number as possible.
I have spent a long time on rolling roads to try and get this "magic" driveability from idle to pull away and found it almost impossible to get a "clean" transition between the two, close but could be a shade better.
I find that the idle mixture is rich also, almost to the point of plug fouling if left idling for a long time.
I was even considering upping the idle revs to 950 as it appears to be ok at that figure.
I have spent a long time on rolling roads to try and get this "magic" driveability from idle to pull away and found it almost impossible to get a "clean" transition between the two, close but could be a shade better.
I find that the idle mixture is rich also, almost to the point of plug fouling if left idling for a long time.
I was even considering upping the idle revs to 950 as it appears to be ok at that figure.
thanks I will add this column at 5Kpa and make it rich so I have a puddle of fuel to pull away. It would also probably work to make it lean but with the consequence that there will be a short time of starvation which might be more economic but not very driveable. Will report back maybe if the wheater is ok will give it a go today. I will post the map before and after so you see what has been changed.
It is quite common, that engines with wild cams can suffer from vacuum build up around idle or light throttle. Using MAP as Load in this areas can be difficult.
To overcome this, there is a strategy called alpha-n blending, where the ECU uses alpha-n as load up to predefined rpm and then "blends" to speed-density based calculation.
Not sure if DTA has this feature...perhaps worth looking at....
Griasle Cornel
To overcome this, there is a strategy called alpha-n blending, where the ECU uses alpha-n as load up to predefined rpm and then "blends" to speed-density based calculation.
Not sure if DTA has this feature...perhaps worth looking at....
Griasle Cornel
after updating the firmware (and making a special cable) in my DTA ECU I can finally use their recently added overrun setting which should set it for good. however I am sure that the strategy with adding a very low pressure column in the map table would work as well, maybe even necessary since every gear shift will introduce the same condition as overrun. I have seen that this is typically 2-4 kpa and obviously this is only achieved when throttle is closed and rpms are higher than idle.
I am glad that you are joining this conversation, as I am only an amateur.
I am glad that you are joining this conversation, as I am only an amateur.
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