Why does my idle surge after switching to full sequential?
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Why does my idle surge after switching to full sequential?
I'm having trouble with my new turbo setup at low speed/idle. I recently switched to full sequential fuel. The engine still hunted at idle on batch fire and got a lot better on semi sequential, but now I'm back to a very bad idle. It swings about 3-400 rpm. When I look at the fuel/timing calcs, I've got everything locked down.
3.5l bmw M30 engine
ID1000 inj's
E85
S300x turbo
custom cam
9lb flywheel/twin disk clutch
MS3x 1.4.0
3.5l bmw M30 engine
ID1000 inj's
E85
S300x turbo
custom cam
9lb flywheel/twin disk clutch
MS3x 1.4.0
Re: Why does my idle surge after switching to full sequentia
there is a big jump in ve between 46kpa and 50kpa in your table, i would flatten you ve table on the 50 & 58kpa rows
1990 bmw 320i daily driver with m20b25 ms3 sequential fuel, 380cc injectors, d585 coil near plug, home made cam sync, launch control, fan control, vss, homebrew egt logging what's next????
Re: Why does my idle surge after switching to full sequentia
Does my VE table still effect my IDLE VE table when that is active?
Re: Why does my idle surge after switching to full sequentia
thats a good point ve and timing are locked solid through idle advance and idle ve so it should be fairly steady but your pw is still changing some what with the swing in rpm / map
1990 bmw 320i daily driver with m20b25 ms3 sequential fuel, 380cc injectors, d585 coil near plug, home made cam sync, launch control, fan control, vss, homebrew egt logging what's next????
Re: Why does my idle surge after switching to full sequentia
One thing I've done to have consistent idle is manipulate the timing table by having it advanced a couple degrees in the cells below your desired idle rpm and the same or a couple degrees retarded in the cell above it.
420" Gen III Hemi MS3 Gold box
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Re: Why does my idle surge after switching to full sequentia
This.BlueBlur wrote:One thing I've done to have consistent idle is manipulate the timing table by having it advanced a couple degrees in the cells below your desired idle rpm and the same or a couple degrees retarded in the cell above it.
Box your idle with spark and fuel. Engines need it anyway.
Then try idle ve and idle advance options perhaps.
If it has happened with sequential then I wonder about your injector timing and it may just be running stronger with better injection timing and moving into new part of map.
Re: Why does my idle surge after switching to full sequentia
If I have any other timing numbers than all the same in the idle advance table, it only amplifies the fluctuation.
I turned off IDLE VE and set all the VE table cells around idle to 56.5. All the cells from 100kpa down and 1000-1600rpm are all the same.
Idle PW still swings seemingly out of nowhere. What else is acting on the pulsewidth? It would be nice to have an IDLE VE table that was just what you wanted the injector to be open to without any other interaction from the MS algorithm. It also seems like the closer the load gets to 100kpa, the more fuel is injected, even though the VE cells are set to the same number.
I turned off IDLE VE and set all the VE table cells around idle to 56.5. All the cells from 100kpa down and 1000-1600rpm are all the same.
Idle PW still swings seemingly out of nowhere. What else is acting on the pulsewidth? It would be nice to have an IDLE VE table that was just what you wanted the injector to be open to without any other interaction from the MS algorithm. It also seems like the closer the load gets to 100kpa, the more fuel is injected, even though the VE cells are set to the same number.
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Re: Why does my idle surge after switching to full sequentia
It's normal for the PW to vary with the MAP because MAP is multiplied in the fueling equation. You need to stabilize RPM/MAP. To do it, add a 500 RPM column into your ignition table. Lower your idle timing to around 12°. In the 500 RPM column, set it to something like 15°. In your 1200 RPM column, set it at 10-11°.
Do the same with the VE table. More fuel at lower RPM than idle, less fuel at higher RPM than idle.
Your engine wants to go high in RPM because you are giving him too much timing (too much torque). Also, do not bother with idle VE and idle Timing tables until both main VE and main timing table are tuned to something that gives you a good rough starting point. These are for fine tuning.
Sam
Do the same with the VE table. More fuel at lower RPM than idle, less fuel at higher RPM than idle.
Your engine wants to go high in RPM because you are giving him too much timing (too much torque). Also, do not bother with idle VE and idle Timing tables until both main VE and main timing table are tuned to something that gives you a good rough starting point. These are for fine tuning.
Sam