TBI injector open time
05-11-2018, 08:49 AM
#1
Supreme Member
Thread Starter
TBI injector open time
I'm wondering what people are setting their TBI injectors to for Megasquirt. PWM wise. I had issues with this and did a lot of damage previously, so it's something I want to be sure is right. I'm using PWM, but will possibly switch to resistors instead. Thanks!.
05-28-2018, 10:35 PM
#2
Supreme Member
Thread Starter
Re: TBI injector open time
Okay, so I've learned a few things. These are my settings:
-NO resistors for the injectors. This is done with a TBI adapter board and as 100% plug in with no additional hardware on the engine side.
-On the MS2 I'm using JS10 output. I tried D14 didn't have any luck. Settings may have played in to this, but I've historically used JS10 fine.
-I eliminated the diodes D1 and D2 on my V3.0 board as they were giving me issues with RPM sync. I left R12 and C12/C30 and the XG1/XG2 ground. I figured a bit of low pass filtering is a good thing to keep garbage off the input. Oddly this worked fine historically. Wonder if something changed in the newer code but that's just speculation.
On to the settings now. USE AT YOUR RISK these are probably starting points. Not a sub for the tuning guide. This was done on a TBI 4.3L. It's still really far from perfect, but a few tweaks would probably get you started up on a 305, 350 or even a 60 degree or Iron Duke TBI engine.
-PWM current lmiit 32%
-PWM Time 1.0 ms
-Injector PWM period 66
Ignition:
-Basic Trigger
-Bypass on D16 (be sure this works and your timing "unlocks" by the ECU.)
-Input capture rising edge
-Spark output going high
-Nominal Dwell 1.5mS
-Spark Duration 1.7mS (maximum)
Note Spark Duration/Dwell are VERY important. I had some heating issues until I turned that down. Things seem a lot better now.
Any input is greatly appreciated, I'm doing okay (I think.)
This is in prep for the new engine, I want my tuning to be not sucking totally on the current one before I get it in.
Some things I've noticed are I have a lot of fuel on decel and not too much on acceleration. I think that's gonna be the next spot I tweak after I get everything sorted with the basics.
-NO resistors for the injectors. This is done with a TBI adapter board and as 100% plug in with no additional hardware on the engine side.
-On the MS2 I'm using JS10 output. I tried D14 didn't have any luck. Settings may have played in to this, but I've historically used JS10 fine.
-I eliminated the diodes D1 and D2 on my V3.0 board as they were giving me issues with RPM sync. I left R12 and C12/C30 and the XG1/XG2 ground. I figured a bit of low pass filtering is a good thing to keep garbage off the input. Oddly this worked fine historically. Wonder if something changed in the newer code but that's just speculation.
On to the settings now. USE AT YOUR RISK these are probably starting points. Not a sub for the tuning guide. This was done on a TBI 4.3L. It's still really far from perfect, but a few tweaks would probably get you started up on a 305, 350 or even a 60 degree or Iron Duke TBI engine.
-PWM current lmiit 32%
-PWM Time 1.0 ms
-Injector PWM period 66
Ignition:
-Basic Trigger
-Bypass on D16 (be sure this works and your timing "unlocks" by the ECU.)
-Input capture rising edge
-Spark output going high
-Nominal Dwell 1.5mS
-Spark Duration 1.7mS (maximum)
Note Spark Duration/Dwell are VERY important. I had some heating issues until I turned that down. Things seem a lot better now.
Any input is greatly appreciated, I'm doing okay (I think.)
This is in prep for the new engine, I want my tuning to be not sucking totally on the current one before I get it in.
Some things I've noticed are I have a lot of fuel on decel and not too much on acceleration. I think that's gonna be the next spot I tweak after I get everything sorted with the basics.
Last edited by Drac0nic; 05-28-2018 at 11:28 PM.
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