guitarjon

I know this sounds really silly but I'm new to the world of megasquirt. Have recently purchased one of reverents DIYPNP kits from the group buy. Hopefully going to take it someone from a uk forum to help fit it and show me the basics of tuning. I have read a fair bit but struggling to take it all in...

Fuelling doesn't look too hard. VE tables slighlty more complicated but I know I will pick it up much better been shown rather than just reading.

Anyway the car will need a basic tune to get it moving. The only problem I have is that my car is a daily and here in the UK its been pretty cold recently (snow). I'm dreading going to turn the car over on a cold morning and the car not been able to start.

Is it possible to tune for cold starts while the engine is still relatively warm?

I wish I had left it until the summer break when I get quite a while off which would mean I wouldn't need to worry about needing the car the next day but I have so many goodies to add but don't want to start adding and making more complicated until I've nailed the basics.

Matt Cramer

Unfortunately, the only way to tune for cold starts on a hot day is to stick the engine in the freezer. That appears to be what OEMs do, who have a large enough EFI tuning budget that a freezer the size of a moving van barely makes a dent in it.

The MS2/Extra firmware has a fairly good default cold start curve in it, but it's tough to predict just how fuel will puddle in the intake when it's cold.

guitarjon

Thanks for the reply.

Am I correct in thinking that it will start during cold starts but might overfuel? Or will it not start?

Braineack

iTrader: (62)

yes on both.

Reverant

iTrader: (10)

There's a way to do it, but it will require some patience on your part.

guitarjon

Sit in the car until its cooled down again lol.

I am patient but my tuning knowledge is very limited at the moment. Really struggling with this to be honest. I usually take things on board much better than I currently am. I think its job stress too lol.

Reverant

iTrader: (10)

Well, the way to do it would be on a weekend that's really cold.

It would be best if you had the car tuned on the MS first (up to say, 3000rpm) by warming it up on the stock ECU and then switching to the MS.

Get up in the morning, warmup the car on the stock ECU, up to ~45C. Then switch to the MS. Start the car. If it starts, let it warmup by another 5C, then switch it off. Wait for a minute then start again. Do this again until the car is fully warm (~95C). For the cells that are untuned (below 45C), just fill in the values so that the curve is almost a straight line.

The following morning, start the car with the MS while fully cold. Do the same thing as before - start and stop every 5C. You should be ok using that technique.

guitarjon

That makes sense When I've got it all up and running first I will look into doing this.