DaveFJ
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| posted on 29/9/08 at 07:42 PM |
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stalling when cold
OK.. need some more advice.... yes I know - yet again!
I have the car running reasonably now once warmed up BUT whencold it wont idle 
If I open the throttle stop then it runs fine and idles at about 900 rpm when cold BUT idles at about 2000rpm once wrmed up
If I back up the throttle stop so I have 1000 rpm warm then the cold idle drops back to where I am now...
basically It will start with a little left foot but until it hits about 70 degrees it will stall a few seconds afetr i lift off the pedal ....
Any ideas what i should be looking at ?
I have tried switching on the coolant related ignition advance and bcked off the warmup enrichment but doesnt seem to help....
have attached my latest .msq file just in case someone fancies a peek!
Dave
"In Support of Help the Heroes" - Always
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ravingfool
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| posted on 29/9/08 at 07:57 PM |
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more choke required!
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DaveFJ
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| posted on 29/9/08 at 08:02 PM |
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hmmm....
more choke with throttle body injection??
there is a secondary stop on the gsxr bodies which could be rigged for this but surely i dont need to use that????
Dave
"In Support of Help the Heroes" - Always
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coozer
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| posted on 29/9/08 at 08:31 PM |
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You need to get the ecu to overfuel slightly at low rpm with it detecting low engine temp. It should lean the injectors back as it warms giving you an
automatic choke.
1972 V8 Jago
1980 Z750
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Paul TigerB6
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| posted on 29/9/08 at 09:15 PM |
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As Coozer says. Shouldn't you be increasing the warm up enrichment rather than backing it off in order to do this??
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DaveFJ
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| posted on 29/9/08 at 09:30 PM |
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my reasoningbehind backing off the warm up enrichment was that i have to open the throttle slightly to keep it running which allows more air in
therefore leaning the mix slightly...
also I am seeing and idle AFR of 11 to 12 which is way too rich surely?
Dave
"In Support of Help the Heroes" - Always
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BenB
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| posted on 29/9/08 at 10:02 PM |
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The problem may well be the lack of an idle air bleed valve. Most car TB setups use one to bleed extra air when the engine is cold (essentially an
automatic choke). On motorbikes this isn't usually fitted. Hence you'll need to keep the revs up until it warms. Exactly the same thing
happens on my tintop ('96 micra) cos the valve went south about 5 years ago. Nothing a bit of heel+toe action for the first few minutes
doesn't sort out.....
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omega 24 v6
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| posted on 29/9/08 at 10:18 PM |
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I'm having the exact same problems mate. I thought it would be possible to run it up with a richer mix as well but it does look more and more
like extra air is required as well as a faster tickover. Looks like choke type of cable or an idle valve may be the only answer.
If it looks wrong it probably is wrong.
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blakep82
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| posted on 29/9/08 at 11:27 PM |
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opening the throttle does let more air in, but also pulls more fuel too. the choke on a car restrics the air, making the mix more rich doesn't
it?
i think you need to richen up a bit
________________________
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daviep
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| posted on 30/9/08 at 04:47 AM |
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Classic case of over complicating things here. Back to basics thinking is what is required.
Choke = richer mixture
As Coozer said, more fuel required. It doesn't matter whether it is a carb or TB the engine needs a richer mixture.
[Edited on 30/9/08 by daviep]
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DaveFJ
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| posted on 30/9/08 at 05:25 AM |
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you really think richer? when I have it running @ an AFR of 11 already? 
Its running so rich that all i can smell is fuel......
Dave
"In Support of Help the Heroes" - Always
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omega 24 v6
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| posted on 30/9/08 at 11:31 AM |
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Seems to me some of you are getting confused. Throttle bodies DO NOT draw more fuel by choking them (unlike carbs). The injectors squirt a SET AMOUNT
of fuel as controlled by the ecu. Usually most of the work in an efi system is taken care of by the air idle valve. It is true however IMHO that a
higher idle speed may be needed in this case and mine to keep the cold engine running.
If it looks wrong it probably is wrong.
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DaveFJ
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| posted on 30/9/08 at 12:10 PM |
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quote:
Originally posted by omega 24 v6
Seems to me some of you are getting confused. Throttle bodies DO NOT draw more fuel by choking them (unlike carbs). The injectors squirt a SET AMOUNT
of fuel as controlled by the ecu. Usually most of the work in an efi system is taken care of by the air idle valve. It is true however IMHO that a
higher idle speed may be needed in this case and mine to keep the cold engine running.
That was kinda what i was getting at... the fuel is set and i can decrease the richness by opening the throttle a fraction....
hence my assumption that i am running too rich at idle...... plus the petrol smell and silly AFR
Dave
"In Support of Help the Heroes" - Always
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daviep
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| posted on 30/9/08 at 01:09 PM |
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I am well aware that fuel injection does not rely on vacuum, the clue is in the name. When I used the tem choke I was refering to a "simple
application".
The reason a cold engine does not want to run is because the mixture is weak.
Why is the mixture weak?
The mixture is weak because there is no heat in the inlet manifold to aid the atomisation of the fuel. By richening the mixture we are pouring in lots
of fuel in the hope that enough of it will atomise to give us a mixture that will burn.
The reason your AFR is so high is because the cold engine doesn't atomise a lot of the fuel so it doesn't burn properly.
As a test make your mixture even richer and see what happens.
Keep us posted
Davie
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DaveFJ
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| posted on 4/10/08 at 07:19 PM |
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Ok
finally got another chance to do some fiddling...
if i make the mixture just 2 points richer at the idle position it stalls immediately!
basically it is running so rich already that the slightest tweak kills it
I have tried fiddling with the warm up enrichments again (reduced right down so i am at about 110 at 16 degrees) and it starts and sustains an idle -
just
think maybe i need to look at that secondary throttle stop solution because with the normal stop where it is i am looking at an idle of 1400 when
warm....
Dave
"In Support of Help the Heroes" - Always
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omega 24 v6
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| posted on 4/10/08 at 07:46 PM |
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I think you could be right dave. I've resigned myself to the same solution although I did not get any done today cause it's PIss*d down
here all day and only 5 degrees Still got some other jobs done though.
If it looks wrong it probably is wrong.
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