running lean P0170

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edge
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running lean P0170

#1 Post by edge » Mon Jan 11, 2021 5:28 pm

Hi every one its a long time since I was here but once again I need the wisdom of the forum
This week my Grand Vitara threw up a generic P0170 bank 1 lean and lit up the EML .
This happened as I was pulling away from a junction and was using more rev's than normal
I plugged in my code reader and the freeze frame info showed the short term trim at 20 and the long term at 15
Going into live data and on petrol at idle the short trim dropped to -7 and the long tft stayed constant although as I understand it the long term trims are a" learned" number and will change over time and driving style if it gets stabilised
Switching to gas again at idle, the shrtft shot straight back to 20 as the ecu dumped fuel in to attempt to counteract the leanness.
I know this is a bit vague and I will clear the code run her on petrol for a while see if she throws a code if not back on gas and see what happens.
I have had a look at the pipework on the gas side and can't see any obvious holes or cracks anywhere that might be sucking air in,
And also checked the petrol intake side for cracks etc but tool judging by the scan she seems to be ok on petrol .
As you may well know by now I am clutching at straws
Good thing I don't want/can't go anywhere :D

Brian_H
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Re: running lean P0170

#2 Post by Brian_H » Mon Jan 11, 2021 5:48 pm

If your gas ECU (don't know what you've got as you haven't said) supports it, you might find some answers by switching indviual injectors between fuels and watching what happens with the trims. I'd be suspecting you have an injector not opening or flowing as well as it should do as a possibility. Depending on injectors, you may be able to swap bits around to isolate the issue to a specific part (would help to post the info on what you've got fitted?)

Running it on petrol a good idea to start with anyway, as it rules out a few possibilities. No signs of ignition issues (popping when on gas for example?). Do you see the lambda readings behaving as they should on petrol - you should see it fluctuating either side of 0.5v if its the normal type of sensor?

edge
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Re: running lean P0170

#3 Post by edge » Mon Jan 11, 2021 6:58 pm

Hi Brian thanks for the reply She is running a King Ecu with OMVL Blue? injectors
I don't think my scanner is clever enough to isolate individual plug /injectors or to read a lambda
And I don't have much of a clue either
But she seems to run fine on petrol we had a trip down to Hereford towing a 8x4 trailer last week when we could still travel! 80 mile round trip and she never missed a beat
although up Dinmore Hill is a climb!
The trouble in living out here in the marches we are a long way from any installer since Tubbs packed up

Brian_H
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Re: running lean P0170

#4 Post by Brian_H » Mon Jan 11, 2021 7:32 pm

It won't be the scanner you want to do it with, it would be the lpg lead and matching software for your ecu that you'd need. Your scanner only speaks to the petrol side of the system, the gas side is seperate. I don't have a king ECU to try it with, but the software appears to support doing it.

These ones I'd guess you mean for injectors?
OMVL Superlight injectors
Image

If so, then thats a reasonable chance you'd be able to swap bits about if you can isolate it to a single injector. But without the lead, your going to struggle to do much. You might be able to do the same sort of test by crimping the injector hoses if you can get to them and seeing if each one has the same sort of effect. It would help if you could see what sort of pressure you were seeing which the lead will tell you, though if its been mapped properly it should switch back to petrol if a supply issue was hitting the pressure anyway. Without some more detail of what your seeing I can't suggest anything more besides trying some injector cleaner if its a sticking injector (which we can't say it is or isn't just yet), but maybe others can do.

This should be the lead for your ecu I would think, though recommend that you identify the ecu and confirm with the supplier before ordering it (and locate the diagnostic plug on the lpg loom as well, typically that will be a plug with a cap on the end of it close to the ecu itself).
https://tinleytech.co.uk/shop/lpg-kits/ ... g-systems/
Software here (note link at bottom of page)
https://tinleytech.co.uk/lpg-software/

The only installers active on here are Simon (LPGC), FoxVehicles and Classicsweede. None particually close to you unfortunately of them.

edge
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Re: running lean P0170

#5 Post by edge » Mon Jan 11, 2021 8:30 pm

Thanks for that Brian , Its nice to know there are still people willing to help us Dummies whilst we flail about out of our depth in the
waters of LPG.
I will let you know how I get on

edge
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Re: running lean P0170

#6 Post by edge » Tue Jan 12, 2021 5:26 pm

So I'm back and so soon!!
Taking advantage of the sunny morning I had a rummage under the bonnet re- checking for leaks cracks etc
AND one of the injector to spud pipes fell off shock horror
the end of the pipe was perished so I cut it and stuck it back on
Plugged in the scanner and the Short term trim has dropped from + 20 to - 1 .6 then climbing as I pushed the throttle . The long term is unchanged but if the leak is fixed and the Short term stay low I would expect it to change as it is re-learned.
Still thrashing about but the water is getting shallower!!!

Brian_H
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Re: running lean P0170

#7 Post by Brian_H » Tue Jan 12, 2021 5:55 pm

Good news, you might want to replace those pipes in the near future if they are that bad though! If you do, then try to keep them the same lengths as you currently have.

Theres usually a clip to hold the pipe on, may be a spring clip or could be a crimped on type. Spring clip can be reused (might be that thats caused the pipe to spilt due to the pressure on it.

Trims should sort themselves out over a few drives as you say, I'd doubt it was running right on petrol either as one cylinder was probabbly getting excess air as well if the pipe had got to a point where it could suck air in.

edge
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Re: running lean P0170

#8 Post by edge » Tue Jan 12, 2021 8:30 pm

To be honest the pipe did not look to bad..... but it was splayed out at the end like a sea anemone fishing !
And I am not convinced the crimp /spring clip was far enough on to seal the tube onto the injector stub

Brian_H
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Re: running lean P0170

#9 Post by Brian_H » Tue Jan 12, 2021 9:16 pm

Maybe its been off a while or something, long as the pipe looks good now you should be fine. I can only guess that maybe the clip was on in such a way that its caused the deformation of the pipe your seeing. At least now you know to keep an eye on it (like the petrol feed I discovered at the end of last week on mine that the pipe had got so bad that it had cracked, and touching it was enough to finish it off, which I've been sorting earlier today with some new petrol hose)

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Re: running lean P0170

#10 Post by LPGC » Wed Jan 13, 2021 1:24 am

On some engines having a pipe disconnected from a spud won't seem to cause much apparent problem when running on petrol, though the cylinder with the pipe off will see slightly leaner mixture than other cylinders which will see reduced efficiency running on petrol (of course with gas pipe off it won't run properly on gas) and fuel trims especially at low/idle loads will be more positive.

Over time pipes do get stretched toward the size of fittings such as spuds they are connected to, spring or other type clips might prevent this from becoming a problem, but if the clip was in the wrong position and the pipe has become flaired/stretched if the pipe is in otherwise good condition it would usually be OK to cut a short section of flaired end off and refit the pipe with the clip in the correct position. If pipes are going brittle, lost a lot of flexibility, are cracked, perishing or would be too short if you have to cut a bit off then replace them.

At least this proved to be the simplest fix ;-)
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edge
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Re: running lean P0170

#11 Post by edge » Wed Jan 13, 2021 8:43 pm

Now all I need to do now is fix the air leak on my suzuki GT 380 45 year old carb rubbers don't flex much
Lock down project (again )

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