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Author Topic: Lambda question  (Read 4667 times)

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tigers_gonads

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Re: Lambda question
« Reply #15 on: 31 July 2018, 12:17:22 »

Yep, the voltage probably dips to 9V when you start the car, so it is designed to cope with this at the very least.

Other things like the ABS and automatic gearbox will throw in the towel long before the engine ECU.




Oh well, there is no way on earth its going to drop below 9 volts so that is that theory well and truly out of the window  :y ;D
Well at least I can say it starts pretty much instantly when the key is turned now  ::) :y :y

Oh well, back to the drawing board when I get time ................. 
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Re: Lambda question
« Reply #16 on: 31 July 2018, 18:11:53 »

Are the LTFT's drifting away from 0% when on petrol?  Need to ascertain if there is a real issue, or poor LPG calibration (not that the Stag allows good LPG calibration, at best, "adequate").

That will help pinpoint :y
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tigers_gonads

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Re: Lambda question
« Reply #17 on: 31 July 2018, 19:06:57 »

Are the LTFT's drifting away from 0% when on petrol?  Need to ascertain if there is a real issue, or poor LPG calibration (not that the Stag allows good LPG calibration, at best, "adequate").

That will help pinpoint :y




Long Term Fuel Trims ??


I'll stick 20 quid's worth petrol in it and drive it around for a day or so  :y

If the trims wander, how long will it take to start moving ?

The blue petrol / green lpg map lines are totally merged with no conservable gap.

Don't ask me about the other readings because even after nearly 7 years of using lpg on 2 cars, i've still not worked out what they are all about  ::)
All I can say is it runs okay  ;D
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Re: Lambda question
« Reply #18 on: 31 July 2018, 19:29:19 »

Turn off LPG for the entire timeframe of this test, to check its petrol running.

Put a fault on - say unplug maf and drive it a few hundred yards. Plug it back in, then clear all engine codes (if there is a code stored, this usually resets all the BLMs, including trims).  So at least they start at 0% ;)

Then drive around (on petrol) for a couple of days (50 miles or so, or whatever), then check both LTFTs again.

If they have both drifted from 0%, then you have a problem, unrelated to LPG.  If they both drift similar amounts in same direction, look for airleaks, else suspect the MAF (2.6/3.2 MAFs do tend to degrade, unlike the more reliable 2.5/3.0 that go on forever, then die completely). If one drifts and the other doesn't much, suspect air leaks or sensor.
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tigers_gonads

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Re: Lambda question
« Reply #19 on: 31 July 2018, 22:28:43 »

Turn off LPG for the entire timeframe of this test, to check its petrol running.

Put a fault on - say unplug maf and drive it a few hundred yards. Plug it back in, then clear all engine codes (if there is a code stored, this usually resets all the BLMs, including trims).  So at least they start at 0% ;)

Then drive around (on petrol) for a couple of days (50 miles or so, or whatever), then check both LTFTs again.

If they have both drifted from 0%, then you have a problem, unrelated to LPG.  If they both drift similar amounts in same direction, look for airleaks, else suspect the MAF (2.6/3.2 MAFs do tend to degrade, unlike the more reliable 2.5/3.0 that go on forever, then die completely). If one drifts and the other doesn't much, suspect air leaks or sensor.




Brilliant  :y
Thanks TB  :)
I'll do that in morning and report back in a couple of days with my findings   :y
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Marks DTM Calib

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Re: Lambda question
« Reply #20 on: 01 August 2018, 16:23:40 »

Given how they are little more than a modifier applied to the petrol injector timings, they could be merged on drifted block learn values...hence the reset the learns and run on petrol then re-merge the LPG



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Re: Lambda question
« Reply #21 on: 01 August 2018, 17:45:22 »

Given how they are little more than a modifier applied to the petrol injector timings, they could be merged on drifted block learn values...hence the reset the learns and run on petrol then re-merge the LPG

Yes, if it's actually being used on LPG, then it only collects data on petrol running when cold and mostly open-loop, so, before making any judgements, it's worth clearing the fuel trims, clearing the collected data in the LPG ECU and collecting fresh data on both petrol and (after that) LPG.
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tigers_gonads

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Re: Lambda question
« Reply #22 on: 02 August 2018, 10:11:46 »

Given how they are little more than a modifier applied to the petrol injector timings, they could be merged on drifted block learn values...hence the reset the learns and run on petrol then re-merge the LPG

Yes, if it's actually being used on LPG, then it only collects data on petrol running when cold and mostly open-loop, so, before making any judgements, it's worth clearing the fuel trims, clearing the collected data in the LPG ECU and collecting fresh data on both petrol and (after that) LPG.






Okay, so in gonad language  ;D

Un plug the MAF.
Drive around the block on petrol.
Reset any codes which should clear the short / long term trims.
Drive on petrol only for a couple of days to let the car ecu sort out its new trims.
If long term are both zero switch to lpg, wipe gas and petrol maps.
Re record petrol map for the stag ecu then re calibrate the gas side  :y


If the LT trims have both wandered, its liable to be a air leak or MAF problem.

If one sides trims are wandering, I should be looking at the lambda's on that side  :y

Apologies for more questions but i'm the sort of bloke who needs to understand what / why i'm doing something  ::)
Not just follow blindly  :)
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tigers_gonads

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Re: Lambda question
« Reply #23 on: 02 August 2018, 18:11:32 »

Okay, a few pictures of the laptop screen
All driving on petrol

Checked the codes and non apparent but the LT trims was both -1.
Started the car then unplugged the MAF.
Drove it 4 miles then plugged the MAF back in and read the codes.
Codes was the Air temp and MAF but no eml for some reason  :-\
Cleared them but LT trims refused to reset  :-\

The first 4 screens are after I plugged the MAF back in and reset the codes ............. 






 




The last 2 was taken after the 4 mile drive home ..............








Anybody make sense of this lot ?
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TheBoy

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Re: Lambda question
« Reply #24 on: 02 August 2018, 18:28:44 »

Stop oppsing around with that piece of shit, and get a usable reader ;)
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Re: Lambda question
« Reply #25 on: 02 August 2018, 20:11:50 »

That's you told...  ::)

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tigers_gonads

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Re: Lambda question
« Reply #26 on: 03 August 2018, 00:15:17 »

Stop oppsing around with that piece of shit, and get a usable reader ;)


Yes boss  ;D
Pm us your card details and i'll get one ordered  :P ;D
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tigers_gonads

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Re: Lambda question
« Reply #28 on: 08 August 2018, 16:40:13 »

Okay, fitted those cheapo sensors and both now switching pretty much through the full 1 volt range.
Both switching between rich and lean quickly.
After indusing a fault then clearing it, the LTFT seem to be settled on -1 after a short drive and the idle is rock solid too when warmed through.

Okay, back to the LPG side.
The Stag petrol map goes all the way back to when it had a slush box fitted.
Am I best now to totally re calibrate both the stags petrol and lpg ?
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