Megasquirt Cold Start Issues

[AceOfHearts]

I have got the car running really well on the MS2 fuel and ignition, but am still having trouble with cold starts. It catches then dies almost instantly After 3 or 4 tries i can catch it on the throttle and after a few seconds it will settle down and idle fine. I have tried quite a few different combinations of ASE and stepper cranking settings but still don't seem to be getting anywhere. Anyone care to post up their tables to see where i might be going wrong?

Hot and warm starts are perfect

[sgrimshaw]

If you tell me where to look / exactly what you want I'm happy to share mine.

[AceOfHearts]

Thanks

Under the 'Startup / Idle' tab

-After start enrichment
-After start enrichment taper
-Warm up enrichment
-Idle control
-Idle cranking duty / steps

If you could screenshot that lot that would be fantastic. I know each car will be different but at least it will stick me in the right ballpark

[977]

I can do the same when I get in tonight. Posting so I can find it again easily.

[AceOfHearts]

Cheers guys

[sgrimshaw]

Here you go:

[977]

[AceOfHearts]

Cheers guys looks like i have the stepper too far open and not enough fuel. Got some promising results today but will crack on again tomorrow when the engine is cold

[977]

I would say mine is pretty rich when first started, but no where near as bad as the 14CUX was (I can at least drive off straight away normally without flooding and stalling the thing).

At some point I'll probably lean it out by 2% or something but it is for such a short period in actually driving the car, one where I'm always pretty gentle with it anyway... motivation is low! Rather be driving it than tuning it.

[Belle427]

Just stumbled across this thread and am too trying to dial in my cold start.
I’m getting there but could you possibly post up your priming pulse and cranking pulse, both under the start up/idle tab.
Thanks in advance.

[ChimpOnGas]

In my opinion there's a fundamental issue of fuel vaporisation at play here that you'll always be fighting with, I know this for a fact because tuning my cold start on LPG is way easier than it is on petrol.

This is because LPG being a gas mixes with air far better than petrol and becomes really really obvious during cold start, petrol being an evaporating liquid condenses on the walls of the inlet manifold where it collects, this just isn't an issue with LPG in its gaseous state.

I also firmly believe all us after market ECU guys can learn from what the Lucas engineers did to achieve a good cold start on the 14CUX working with those short lived disc type injectors, but of course given what they were working with there remains a lot of room for improvement.

Step away from the laptop for a minute and look at your hardware, now consider fitting a set of more modern four port pintel injectors and increasing your fuel pressure by fitting a FPR that ensures these better injectors see the 10psi higher fuel pressure they're designed to run at.

Suddenly fuel vaporisation is way better and your cold start tuning becomes much much easier

Edited by ChimpOnGas on Monday 23 September 20:46

[angus337]

here's mine.

Was starting perfectly on the key with the stock pressure regulator, but now needs a touch of throttle, since increasing the fuel pressure to 3 bar, Injectors are 30lb Bosh EV1 4 hole. I've fixed the VE table for the higher pressure, just need to tweak the cranking settings.

Edited by angus337 on Monday 23 September 21:45

[angus337]

base settings for comparison with above

[Belle427]

Thanks that's a big help.

[Belle427]

I see 977 is using closed loop idle control and doing some reading it suggests this is a good method for controlling the idle speeds.
Has anyone else tried it ?

[Dougal9887]

Yes, I'm using closed loop idle but with a Bosch idle valve in place of the stepper. Closed loop idle also had the advantage for idling along in traffic, uphill etc.
Dougal.

[Belle427]

Do you have any details on the valve, I'm thinking of switching to it from the standard 4 wire stepper.

[angus337]

i'm also looking at trying closed loop idle.

David (997) would you be able to share your closed loop settings.

Mine currently looks like this, think these are the default settings, but haven't tested it yet.

Edited by angus337 on Friday 27th September 00:33