Desperate for some Help With Microsquirt, Beyond Frustrated Options

[Mblizzard]

I have been trying to get my conversion done in time for Okteenerfest. I have run up against a brick wall and just cant seem to figure out what i am doing wrong.

If anyone can help me by looking at my tune files or providing insight it will be very much appreciated.

I can get th car to idle but nothing beyond that. Any use of the throttle is less than impressive and almost useless. Meaning it bogs down and does not accelerate at all.

I have no clue what i am missing.

2056 with new low impeadance injectors. Bosch Wideband O2 sensor.

Really need some suggestions. Not sure if i can post the tune files here. But will try.

[JamesM]

I told myself I wasn't going to get involved in another Megasquirt troubleshooting sessions on the board, the amount of crazy uneducated bat:stromberg: advice i have seen around here over the years has really turned me off to discussing it.

That being said I have been having to much fun with it again lately so here we go...

First things first, dont make changes based on suggestions from anyone that isnt looking at 100% of your configuration, it will most likely mess you up more than you already are. This is a very complex system and its a lot more involved than turning a screw to lean it out, in reality there about about 1000 adjustable values here that interact with each other. There should be ZERO guesswork here as every variable is defined and should be set appropriately.

ok done with the rant and on to business:


1. First order of business, is the MSQ file you posted still current or have you fixed some things there? I see a few fundamental problems with the basic settings.

2. As Mark Henry stated earlier we really need full build details. The one detail I am most concerned with at the moment is are you controlling fuel and ignition or just fuel? If you are control spark you need to fix your advance table based on known advance curves for a type 4 you are way over advanced (assuming the physical timing is set correctly).

3. Your req_Fuel value needs to be set CORRECTLY. Yes technically you can set this to just about anything and then tweak your map around until the car runs but doing so will then render the values in your VE table meaningless. (seriously people tweaking the req_Fuel value around to "fix" a problem may be my #1 megasquirt pet peve) req_fuel is a constant that is set based on your injector setup NOT A TUNING VALUE. Specifically the number is a constant that represents a fuel pulse width at 100% VE based on your engine displacement and injector flow rate. Set this correctly and the numbers in your VE table will actually represent the volumetric efficiency for your engine at the given RPM/load bins. This then makes it a lot easier to roughly predict what those values should be. SCIENCE!!! NEAT! Given you had your injectors flow benched you are ahead of the game in that you know exactly what they flow (270cc/min@43psi) so the only question left is what fuel pressure are you running them at? The current req_fuel value you have set of 17.3 would only be correct if you were running at 24psi which i suspect is not the case. If you are running stock 914 fuel pressure 29psi those injectors calculate out at flowing ~220cc/min so your req fuel value would be 15.7 This is a calculated value, there is only one right answer so we need to know what your fuel pressure actually is. Lowering this value is going to lean out everything across the board so IF you have trouble starting after this change you will need to add fuel back by increasing values in the VE table.

Fix these things first and get it idling and then ill go over tuning fundamentals/workflow


looking at your VE and advance tables its easy to see why it is running the way you say it is

[Mblizzard]

I told myself I wasn't going to get involved in another Megasquirt troubleshooting sessions on the board, the amount of crazy uneducated bat:stromberg: advice i have seen around here over the years has really turned me off to discussing it.

That being said I have been having to much fun with it again lately so here we go...

First things first, dont make changes based on suggestions from anyone that isnt looking at 100% of your configuration, it will most likely mess you up more than you already are. This is a very complex system and its a lot more involved than turning a screw to lean it out, in reality there about about 1000 adjustable values here that interact with each other. There should be ZERO guesswork here as every variable is defined and should be set appropriately.

ok done with the rant and on to business:


1. First order of business, is the MSQ file you posted still current or have you fixed some things there? I see a few fundamental problems with the basic settings.

2. As Mark Henry stated earlier we really need full build details. The one detail I am most concerned with at the moment is are you controlling fuel and ignition or just fuel? If you are control spark you need to fix your advance table based on known advance curves for a type 4 you are way over advanced (assuming the physical timing is set correctly).

3. Your req_Fuel value needs to be set CORRECTLY. Yes technically you can set this to just about anything and then tweak your map around until the car runs but doing so will then render the values in your VE table meaningless. (seriously people tweaking the req_Fuel value around to "fix" a problem may be my #1 megasquirt pet peve) req_fuel is a constant that is set based on your injector setup NOT A TUNING VALUE. Specifically the number is a constant that represents a fuel pulse width at 100% VE based on your engine displacement and injector flow rate. Set this correctly and the numbers in your VE table will actually represent the volumetric efficiency for your engine at the given RPM/load bins. This then makes it a lot easier to roughly predict what those values should be. SCIENCE!!! NEAT! Given you had your injectors flow benched you are ahead of the game in that you know exactly what they flow (270cc/min@43psi) so the only question left is what fuel pressure are you running them at? The current req_fuel value you have set of 17.3 would only be correct if you were running at 24psi which i suspect is not the case. If you are running stock 914 fuel pressure 29psi those injectors calculate out at flowing ~220cc/min so your req fuel value would be 15.7 This is a calculated value, there is only one right answer so we need to know what your fuel pressure actually is. Lowering this value is going to lean out everything across the board so IF you have trouble starting after this change you will need to add fuel back by increasing values in the VE table.

Fix these things first and get it idling and then ill go over tuning fundamentals/workflow


looking at your VE and advance tables its easy to see why it is running the way you say it is

Thanks for the help> It is a huge learning curve!

I am running right at 49lbs of fuel pressure which should put me right in the range of the rated injector flow. But what I wondered is if the max flow rate should be used or the 50% duty cycle? I changed to the 50% and as you said a number of adjustments to the VE table were required. If I should use the max flow it is an easy fix for the VE table if you look at the math!