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Digifant timing

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SebRogers View Drop Down
Vanorak
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SebRogers Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 10 at 16:36
Originally posted by Beaker Beaker wrote:

probably difficult to do effectively as the signal lead is only running less than 1v and low amps and is screened to prevent interference because of that, relay would probably cause interference itself

and yes it does a system check on start up and after 30 secs, if no lambda it'll go to default map, that's why when they fail and you get the overfuelling and black smoke undriveability if you stop and turn off and disconnect lambda when you restart it's ok

Shame really, because if you could switch the lambda via a relay I would've thought you could wire it up to the fuel switch so it'd be automatic...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ..lee.. Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 10 at 18:05
seb i think you have got it the wrong way around. the lambda influences the afr according to what is already pre programed in to the fuel map in the ecu. its an add on. and not the main controll. oxygen in the exhaust gas is dependant on how complete a burn the combusion chamber produces. the oxygen content in the exhaust gasses varies very slightly even without a closed loop lambda system its just with that type of system there is no lambda correction.
if you connected a lambda probe to a non lambda system you would see it vary voltage as the oxygen left over from the burn varies.
it should do the same with gas i belive. the posts on you tube seem to confirm this.
if the afr is optimsed on the gas and the oxygen levels in the exhaust gas are correct i can see no reason why the lambda should not behave and produce a variable voltage of between 0.1v and 0.9v. if the oxygen level goes outside of the lambda`s tolerance then it will flatline. thats what will cause the fuel system to play up when you switch back over.
i dont think it should flat line on gas. "again i`m no expert but the video`s on you tube show voltage variance on gas. check it out"
 
i think if you hanen`t allready done it check the lambda readings on petrol and also as you switch over to gas and let us know what the readings were at idle and at say 2500 rpm.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SebRogers Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 10 at 18:20
Originally posted by ..lee.. ..lee.. wrote:

seb i think you have got it the wrong way around.

Quite possibly! Tongue

However, this is what happens from cold startup on petrol: the lambda output at idle is essentially steady for, I dunno, a while (Aidan reckons 30 seconds but it seemed a bit longer than that to me, though I didn't time it) until the engine starts 'listening' to the lambda and cycling the afr to keep the exhaust somewhere between just lean and just rich. At that point the lambda output suddenly changes to the curve you'd expect. 

Of course the afr will vary a bit anyway, but surely it can only cycle between 0.1 and 0.9v if the fuelling is actively being changed, whether that's because of throttle position off idle or because the ecu is varying fuelling at idle? If there isn't that constant cycling of afr then the output voltage from the lambda will be a steady 0.x v, where x varies according to throttle position and engine load.

My lambda changes output voltage with afr as you'd expect. But it only cycles when it's running on petrol. That seems right to me.

At least, that's how I understand it. But I could well be wrong LOL Will look into it some more...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ..lee.. Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 10 at 18:32
ooooooo. ive had an idea.
 
 
 
 
 
 
 
 
                                          tdiThumbs Up
 
 
 
 
 
 
.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SebRogers Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 10 at 18:58
Originally posted by ..lee.. ..lee.. wrote:

ooooooo. ive had an idea.
 
 
 
 
 
 
 
 
                                          tdiThumbs Up
 
 
 
 
 
 
.

Thanks! Thumbs Up

Nah, I like the 2.1WBX, despite its various quirks. If I wanted a cheap to run, reliable and practical van I'd buy a T4 LOL
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Baxter Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 10 at 19:56
Originally posted by ..lee.. ..lee.. wrote:

ooooooo. ive had an idea.
 
 
 
 
 
 
 
 
                                          tdiThumbs Up
 
 
 
 
 
 
.
 
The bastard, he always has the best ideas.
 
LOL
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ..lee.. Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 10 at 22:03
Embarrassed
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