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 Post subject: Cold Start issues
PostPosted: Sun Dec 02, 2012 4:05 pm 
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Joined: Fri Nov 30, 2012 3:40 pm
Posts: 15
ECU Model: No ECU
Distributor: DTA
Firmware Version: 53
Hi

I was just after some advice on resolving a cold start issue on my 2.0L vw running jenveys.

At the moment its really hard to start when cold,

Water Temperature Compensation is this the same as a choke?

Start Temperature map

here are the 2 graphs
Image
Image


what is the correct use for the 2 maps ?
What would be a good base to start with, anything would be better than whats on there.

Thanks


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 Post subject: Re: Cold Start issues
PostPosted: Tue Dec 04, 2012 5:48 am 
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Joined: Tue Aug 02, 2011 12:08 pm
Posts: 2906
Location: Norn Iron
ECU Model: No ECU
Re Water temperature compensations, taken from the DTA manual

Quote:
This section corrects the basic map settings depending on the engine water temperature. This provides the equivalent effect of a choke. As a general guide try gradually increasing the fuel increase percentage below 40 deg. C by about 20%. If the engine does not run cleanly on start up then either give it more or less fuel as required.

At DTA we no longer use this brute force approach to start fuelling and prefer to use the temperature and turns (effectively time) approach via the Start Fuelling Map. This if done correctly will reduce to the total amount of extra fuelling required especially when the engine starts from very low temperatures.
All three columns are user settable. Move the cursor to the cell of interest and change the relevant figures.


It is pretty self explanatory. Although it seems they are suggesting primarily to use the start turns map, which does make sense as it is also temperature related.

As always, tune for good running and starting when warm, and only then let it cool and start working on any cold settings working from low values and adding fuel as required.


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 Post subject: Re: Cold Start issues
PostPosted: Tue Dec 04, 2012 3:47 pm 
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Joined: Fri Nov 30, 2012 3:40 pm
Posts: 15
ECU Model: No ECU
Distributor: DTA
Firmware Version: 53
Thanks Stevie, during the summer it would start fine but now its 5 degrees in the morning its a pain.


I saw the start map temp and the start map turns but I could not see what it was referring too.

Forgot to say mine is the e48 ecu


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 Post subject: Re: Cold Start issues
PostPosted: Tue Dec 04, 2012 5:13 pm 
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Joined: Tue Aug 02, 2011 12:08 pm
Posts: 2906
Location: Norn Iron
ECU Model: No ECU
I dont have the old DTAWin software installed anymore, so cant comment if it's the same for an E48

The columns are very self explanatory though.

Temperature along the top, and engine turns ( ie runtime ) along the side. Numbers in the table refer to a % enrichment at that time/temperature.


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 Post subject: Re: Cold Start issues
PostPosted: Tue Dec 04, 2012 5:31 pm 
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Joined: Fri Nov 30, 2012 3:40 pm
Posts: 15
ECU Model: No ECU
Distributor: DTA
Firmware Version: 53
Now you explain it like that it makes perfect sense, thanks here is a pic for others

so its
start map turns
start map temps
both used to create "start Fuel map"

easy when its explained thanks
Image


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 Post subject: Re: Cold Start issues
PostPosted: Tue Dec 04, 2012 6:25 pm 
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Joined: Tue Aug 02, 2011 12:08 pm
Posts: 2906
Location: Norn Iron
ECU Model: No ECU
Bare in mind you have no fuel added after 70 turns there. Which really isnt a long time

at 1000rpm, the engine is turning approx 16 times per second.

So if the engine started and ran at 1000rpm, you're enrichment is all gone after a little over 4 seconds.

OK for a little starting enrichment, but maybe not ok for coolant based enrichment.


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 Post subject: Re: Cold Start issues
PostPosted: Thu Dec 06, 2012 3:35 pm 
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Joined: Fri Nov 30, 2012 3:40 pm
Posts: 15
ECU Model: No ECU
Distributor: DTA
Firmware Version: 53
Would a combination of the 2 be better than?

The start fuel map for the initial start and then the water temp compensation to keep it ticking over until it gets to temp.


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 Post subject: Re: Cold Start issues
PostPosted: Fri Dec 07, 2012 1:24 am 
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Joined: Tue Aug 09, 2011 2:54 pm
Posts: 318
Location: Stevenage
ECU Model: S80 Pro
Distributor: Roverdose
ive been playing with mine for the last few weeks, as the cold weather is here its in need of some work.

ive got a mix of the 2. as i average about 8dgr water temp on start, if i jump in and drive the start turns dissapear quite quickly. i was hopeing to get close to 14.7 afr when ticking over, but for my engine thats difficalt, ive got about 12.5 ish and it holds idle when i come to a stop.

going to keep playing as i dont like throwing money down my exhaust.

Drew


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 Post subject: Re: Cold Start issues
PostPosted: Fri Dec 07, 2012 4:26 am 
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Joined: Tue Aug 02, 2011 12:08 pm
Posts: 2906
Location: Norn Iron
ECU Model: No ECU
OEM engines wont even hold 14.7 on cold start, so most people will struggle to achieve it on an aftermarket setup.


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 Post subject: Re: Cold Start issues
PostPosted: Fri Dec 07, 2012 10:31 am 
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Joined: Tue Aug 09, 2011 2:54 pm
Posts: 318
Location: Stevenage
ECU Model: S80 Pro
Distributor: Roverdose
my oem had a start fuel system much like the dta, not sure how far it went as i didnt really take a lot of notice.

still needs some playing with.

Drew


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