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cold start help

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Hi everyone my name is Brian.

im pretty new to efi tuning and am hoping to learn all i can about it.

i have a k20a2 that iv been learning to tune on, with a haltech pro plug and play.

now that its gotten cold where i live the car will no longer start and back fires when i let off the key.

its about 20F outside and i understand that with carburetors in cold weather you choke them because the air is denser to achieve a good staring AFR. so i tryed adding more fuel and it didn't seem to fix anything.

it will not let me upload my tune so im willing to email it to anyone that ones to take a look.

thank you for your time and help looking forward to learning more.

Attached Files

Cold start performance can be a tricky one to really nail but provided you're running on pump gasoline you should be able to get good cold start performance at 20 deg F.

First of all I'd be a little mindful of your ignition trims. Personally I don't use any modifiers for ignition timing based on coolant temp but that's just my preference. What you do have though is a number of modifiers that will work together to possibly end up with a little too much timing once the engine is running (admittedly it sounds like your current problem is getting the engine to start in the first place.

I would start with your cranking injection timing as this is the primary value the ECU will use during cranking which will influence that ability of the engine to start cleanly. These values are ms based so they are dependent on your injector size. I normally start by making a coarse change to see the effect of that change quickly - For example highlight the entire table and double the values. From here you can assess whether that has shown an improvement or made things worse. You can then start making finer changes to zero in on values that give you acceptable starting. Once the engine is running you can tune the post start and warmup enrichment based off the wideband.

I did end up getting the engine to start I was at 32ms and 12 degrees of timing. That seems like a lot of fuel for an engine with 1000cc injectors

It is quite common to see large pulse widths like this during the cranking phase. You really need to just give the engine what it needs to start correctly. As soon as the engine is running you'll see the injector pulse width will be more inline with what you'd expect to see.

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