berendd
Europe
why do I need 3 keys for one car?
Posts: 1,449
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My 1997 E420 Mercedes w210 E-class runs on LPG, the map is setup with help of the factory narrowband lambda that controls the injector timing.
By reading the timing and adjusting the map to that we got it running quite well, but not perfect.
The ideal mixture for LPG is slightly different than the ideal mixture for LPG, will this fool the engine ECU?
Does this affect the narrowband reading of the engine ECU, that in turn provides the piggyback LPG ecu with injector timing?
As I have the idea that the engine runs better after a reset of the maps in the engine ECU (self learning).
Besides the above I have an idle issue when the weather is (suddenly) warm, where the engine cuts out at idle (slowing down). I want to check if this is due to an under or an oversupply of fuel, to trace the fault, therefore I want to install a wideband lambda. Code reading does not give any faults, also live monitoring does not give any info on the cutting out.
The exhaust allready has a spare lambda bung installed, so basically it i buying and installing a kit.
What lambda controller can I best use to verify the engine, mind you it runs on LPG?
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the AEM kit is the best one I've seen so far, no messing about with calibration as they're pre calibrated, controller is self contained in the display.
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berendd
Europe
why do I need 3 keys for one car?
Posts: 1,449
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May 29, 2017 20:04:07 GMT
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Is it compatible with lpg, or are they all compatible?c
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Last Edit: May 29, 2017 20:04:34 GMT by berendd
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May 29, 2017 20:28:19 GMT
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yes they work fine with lpg or cng, even ethanol and methanol, these give different output voltages for a given afr.
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froggy
Posted a lot
Posts: 1,099
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May 29, 2017 20:47:53 GMT
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Does it do the same thing on petrol ? I'm no expert but the lpg stuff I have dealt with takes a major input from injector duty cycle . Mass air flow issues rarely give trouble codes but could give you some idle issues assuming it's an auto
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berendd
Europe
why do I need 3 keys for one car?
Posts: 1,449
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On petrol it doesn't cut out, where on LPG it does. It is a bit unstable though on petrol, lpg exaggerates this and cuts out.
Besides the tracking of this problem i want to get some information about the mixture anyway as it sometimes feels a lot faster than other days.
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ChasR
RR Helper
motivation
Posts: 10,192
Club RR Member Number: 170
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If you get the ideal map for LPG it will upset the engine ECU. This is why many LPG cars have an EML light ; they need to run 'richer' on LPG unless the stock car's ECU is 'tricked'. Almost all of the LPG setups I have seen piggyback off the car's petrol injector values. Alot of people get the cars to run right by using the car's petrol injector duty cycles as a target for the LPG items ; if there is an problem with the equipment on either side that can't happen.
What LPG setup is in running on? Does the car run right on petrol or does it have issues?
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Last Edit: Jun 4, 2017 19:15:53 GMT by ChasR
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berendd
Europe
why do I need 3 keys for one car?
Posts: 1,449
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Runs fine on petrol, LPG ECU has been setup the way you describe and runs allright.
Only major issue is the cutting out it does sometimes.
It only does it in warm weather
and the engine is idling unstable when it does it, on petrol as well as on LPG so it is not an LPG problem only, running on LPG makes it a lot worse though.
When i sit in traffic in hot weather I usually switch back to petrol to counter the issue.
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Where does the air inlet point is it drawing in very hot air from around the engine whilst idling? Is the fan running when it cuts out could it be pushing extra air into the inlet? Stoiciometric on lpg is 15.something not the 14.7 it is on petrol by the way according to lpg forum knowledge.
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berendd
Europe
why do I need 3 keys for one car?
Posts: 1,449
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The inlet pipe work is pretty curse word, so that could be a problem
is the inlet temp sensor not adjusting fast enough in that case?
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Jun 12, 2017 17:32:07 GMT
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I doubt if the LPG is taking a signal from it anyway, but if it's causing issues on petrol then yes it's possibly an issue.
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berendd
Europe
why do I need 3 keys for one car?
Posts: 1,449
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Jun 15, 2017 11:28:21 GMT
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On petrol it has a slighlt unstability idling in the same situation, but this is probably exaggerated on LPG. However I am not entirely sure if this is the case, hence the lambda control. It would help knowing if it is running too lean or too rich. on another not would an air filter box of an SL fit my engine? this model: www.ebay.de/itm/SL-500-Bj-91-326-ps-R129-Luftfilterkasten-1190940002-Filtereinsatz-0030944604-/222226671342As due to all the LPG piping the Original airbox takes up valuable space and is not easy to get sealed right
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My old 7 series LPG kit after a few years got lumpy on both petrol and LPG and stally on LPG, this was down in the end to tired LPG injectors that responded to slowly to short duration opening times, new set of injectors sorted it.
Although I would focus on getting the petrol running 100% first, even a slight issue on petrol will likely be 2 times worse (or more) on LPG.
Are you able to check the live petrol fuel trims with an OBD reader as this clearly showed my issue on the 7 series, the fuel trims were increasing to fix the idle on LPG this then showed unstable idle on petrol as the fuel trims were then too rich? If they are way out see if they can be reset and use just petrol for a while and see if the idle is ok.
Some pictures of the installation may be helpful if you can.
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berendd
Europe
why do I need 3 keys for one car?
Posts: 1,449
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The stally bit has been since installation, injectors were brand new back then.
injector timing can be read from the LPG ecu and seems fine
Will first look into the cold air piping as when the fan kicks in it is really bad... so could be onto something there..
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What's the make of the gas kit? In my time spent fitting/working on gas systems I found that some were a great deal better than others, with the quality of the hardware varying quite a bit, even when they were all using the same basic AEB electronics.
There's lots of things it could potentially be, but as noted by several others above, if there's an issue on petrol it's not likely to be related to the gas system, but will certainly be exaggerated by it.
There is also possibility that the way the system was installed has left it with a few underlying issues, however, it's hard to tell things like that without actually seeing the thing.
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berendd
Europe
why do I need 3 keys for one car?
Posts: 1,449
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It's a Vogels VGI system
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