Feature Request thread ( make sticky )

This section is dedicated to discussion of DTA engine control units such as the DTA E48 EXP, P8 Pro, DTA S40, S60, S80, and S100, as well as all things ECU related.
tryolz
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Re: Feature Request thread ( make sticky )

Post by tryolz »

Obviously if the crank trigger doesnt have any TDC reference....it would be a lot riskier to ignore the cam trigger as any tooth miscount could totally screw things up.
You are right I am so used to the 60-2 :lol: !!!!
rjwooll
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Choke

Post by rjwooll »

Given the difficulty of setting up reliable cold starting with the ECU (because it's so difficult to run repeat tests as once the engine starts it starts to get warm) could a manual choke option be introduced? The choke would be connected to a throttle pot and feed into an aux input on the ECU. The position of the throttle pot would control the % overfuelling, with a maximum of say 200% increase (=3 x normal)

Not a major problem for most on here I know, but for those of us running road cars cold winter starts can be difficult and it requires quite a lot of trial and error to set up the cold start table correctly.
stevieturbo
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Re: Feature Request thread ( make sticky )

Post by stevieturbo »

Is that a joke ?
Antral
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Re: Feature Request thread ( make sticky )

Post by Antral »

lol
Rob Stevens
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Re: Feature Request thread ( make sticky )

Post by Rob Stevens »

Just use the knobs box to make rapid changes to the fuel during start and warm up. Not so easy for the first 100 or so turns of the engine as it moves rapidly through the cells. But its not that hard to get 95% there.
Alex DTA
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Re: Feature Request thread ( make sticky )

Post by Alex DTA »

You can also adjust the number of turns on the y axis.
rjwooll
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Re: Feature Request thread ( make sticky )

Post by rjwooll »

stevieturbo wrote:Is that a joke ?
Why do you think it might be a joke? Do you have access to some higher truth? Tell me and I'll learn.
rjwooll
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Re: Feature Request thread ( make sticky )

Post by rjwooll »

Rob Stevens wrote:Just use the knobs box to make rapid changes to the fuel during start and warm up. Not so easy for the first 100 or so turns of the engine as it moves rapidly through the cells. But its not that hard to get 95% there.
Thanks for the suggestion Rob, but (a) I don't have a knobs box, and (b) I wouldn't want to leave it permanently connected as I'm often carrying passengers. I just want something simple I can use on the frequent occasions in very cold weather the car won't start.

I'd also like to clarify that the problem is getting the car to fire up in the first place. Once started, I'm pretty happy that my settings work OK. So it sounds like it would be rather difficult to use the knobs box to control the fuelling while attempting to fire up.
Last edited by rjwooll on Sat Mar 18, 2017 5:08 pm, edited 2 times in total.
rjwooll
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Re: Feature Request thread ( make sticky )

Post by rjwooll »

Alex DTA wrote:You can also adjust the number of turns on the y axis.
Thanks Alex, I know all about the cold start map and how to change the axes. The problem is getting the right values for the right temperatures.

From the research I've done on the subject, effective cold start mapping is the most difficult thing to set up when developing a production vehicle. Part of this is no doubt the difficulty of carrying out tests which can be repeated as, once started, the engine - and in particular the combustion chamber - will be warmer. Also, depending on their characteristics, some engines are more sensitive to cold start settings than others.

It seems like I'm in a minority of one here and also the subject of some mockery, so I'm looking forward to hearing reasoned approaches to cold start mapping that others have used. I've tried the various suggestions on here regarding the mapping already. I've now had 3 years where using the car in winter has been a nightmare and I'm getting a bit fed up with it.

My next attempts to tune the mapping will be as follows:

1. Correct the the startup timing on the ECU. It is set at 20 degrees advance, and should probably be taken back to 10 (from 2 teeth to 1 on my 36 tooth crank sensor) as this is close to the idle speed timing on my car.
2. I had been told that the injector start pulse parameter could be used to wet the inlet ports sufficiently. Having read Greg Banish's book on tuning fuel injection systems, I think that this parameter is only really sufficient to actually prime the system, and that I should set very high fuelling for the first 4 turns (2 fuelling cycles) to ensure the ports and valve throats are sufficiently wet.
3. Hope for some frosty weather!
Rob Stevens
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Re: Feature Request thread ( make sticky )

Post by Rob Stevens »

Are you adding any air or just expecting it to start on fuel and little air. My own car has no air valve and does require you to open the throttle a little whilst cranking when at -10 or so. I think I use something like 400% enrichment for the first few turns.

However don't forget that the injection pulse is caped at 40ms by the software, I only found this by measuring.
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