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PostPosted: Thu Sep 01, 2016 5:05 pm 
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elm doesn't show post cat or total trim

upstream o2 sensors were renewed a year ago so hopefully still good

re drilling out inj. nozzles due to my drilling out to 3mm at least one of the jets would be too far into the sidewall to achieve any extra size - the only way would be to order more jets and be a bit more accurate when drilling out , so for that reason as well I'll try the addition of 3ms of petrol and see how that goes , just checked the page for gas/petrol and indeed I do have sequential ticked so will have a check with it unchecked

Need an assistant still so may well take a while to update how things turn out

thanks again for you time and patience - its been and still is a learning curve


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PostPosted: Fri Sep 02, 2016 6:49 am 
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What software are you using with your ELM327 interface? Some return a lot more parameters than others, and some will return every valid response for a request to read an address from the OBD bus, regardless at to whether it contains anything useful. So if the other trim parameters appear at an address requestable by the ELM327, then you might get numbers back - but the software might not know how to convert that number to a percentage.

Palmer Performance ScanXL for example is quite good for getting more information than some of the more basic programs that tend to come with the ELM modules. However it's not cheap. OBD AutoDoctor is also good. Torque on Android isn't bad, but displays nowhere near a complete set of parameters, though it's convenient being able to run it on a phone. Similarly DashCommand for iPhone only shows a subset.

Post cat O2 readings aren't usually much use for tuning/mapping as they're only really there to check the catalyst is reacting the remaining oxygen in the exhaust with the CO etc. In effect they're a simple 'if oxygen level is greater than a certain level, put on the cat malfunction warning light' device.

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PostPosted: Fri Sep 02, 2016 10:26 am 
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rich r wrote:
Post cat O2 readings aren't usually much use for tuning/mapping as they're only really there to check the catalyst is reacting the remaining oxygen in the exhaust with the CO etc. In effect they're a simple 'if oxygen level is greater than a certain level, put on the cat malfunction warning light' device.
Agreed Rich, I only mentioned post cat trims because some live data readers show B1S2 / B2S2 trims and usually we'd expect S2 on a bank to be the post cat probe, thus my post cat comment. In some cases the B1S2/B2S2 readings seem to be LTFT+STFT (the sum for each bank), so where readers show S2 trims it seems sometimes this is a misrepresentation. On only very few models of vehicle I've noted the misinterpreted B1S2 trim can be useful during setup, seeming not just to be LTFT+STFT, but seeming to be some type of base trim+LTFT+STFT. On base trims - seems some BMWs for example have a base trim for idle conditions that is set according to off-idle trims, immediately after clearing certain trouble codes on such models (resetting trim data), the usual LTFT and STFT idle trims don't read the same values as they will come to read once the vehicle has been driven long enough for the petrol ECU to have confirmed IM readiness and off idle trims to have been learned, once those trims have been learned the base trim is set and idle trims then reflect near final values (so start acting like we'd usually expect for idle trims). On other vehicles B1S2 / B2S2 trims might reflect how close the ECU is to interpreting post cat emissions problems (i.e. problems with cat), in which case the data is less useful but can reflect differences in flow rates between different injectors on the same bank (so some cylinders on the same bank running rich, some lean, so cat gets both excess air and fuel sometimes irrespective of lambda flick which could lead to different post cat readings to what an advanced ECU might expect) / can show if mixture is similarly rich on gas as on petrol on vehicles which go open loop at high loads including all those that don't have wide band pre-cat probes. RRSC's have a particularly fussy ECU that for example will pick up on slight issues such as evaporative purge system flowing too much/little fumes from the petrol tank even though EPV flow is a tiny fraction of idle airflow.

Simon

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Last edited by LPGC on Fri Sep 02, 2016 12:55 pm, edited 2 times in total.

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PostPosted: Fri Sep 02, 2016 10:58 am 
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Yes, that makes sense.

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PostPosted: Fri Sep 02, 2016 1:15 pm 
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For those interested I should probably expand on what I wrote above..

I may seem a bit dubious about good long term results from calibration done just according to fuel trims on RRSC's and do regard them as a bit of a special case. Set LPG calibration willy nilly, could even be way out, but still the LTFT's can in some cases end up close to zero (or to what they were originally, or somewhere inbetween, whatever was intended).. at least while running on LPG. Only then after switching back to petrol you might see that the LTFT's that were previously noted (maybe aimed for, again whatever was intended) are now being steered to a completely different value. Yet the values for the various LTFT's don't seem to change much if the vehicle is only run on petrol and will eventually revert back to what you originally noted if the vehicle is run for long enough on petrol. Can end up with an LPG system that seems well calibrated on LPG (yet again however was intended), just that when you switch back to petrol the STFT's might be maxed out or might steer LTFT's to a completely different value, perhaps different enough to generate codes. During calibration of RRSC's I pay particular attention to fuel pressure, trims, pinj, etc also making sure gas temp correction isn't having an adverse effect. For a given fuel pressure, LTFT+STFT, engine temp, etc, it is possible for the petrol ECU to output a different pinj due to what I reckon is a 3rd layer of trim, so even though I'm calibrating according to trims I regularly switch back to petrol to compare pinj between petrol/LPG modes while taking any difference in petrol pressure readings into consideration, and I also compare what the scanner live data interprets as S2 trims.

I know of at least one installer who thinks along similar lines to me except their take on RRSC's is that they have two petrol maps (where my take on the two maps would be the 3rd layer trim), I think I even remember him mentioning quite a few years ago now that it is possible to have the petrol ECU programmed/chipped to prevent the map switching, thus preventing many of the potential problems/implications. It probably doesn't matter much which take is more correct because either take leads to a similar approach to proper calibration. If the approach isn't used you can end up with a car that will switch seamlessly between fuels with pinj and trims hardly shifting between fuels today but go to drive the car another day and fuelling can be way out on one or both fuels.

I've only seen a few RRSCs converted elsewhere that didn't have problems and these were converted using systems where the installer was probably able just to install injectors 'I' with 'N' nozzles, set pressure to 'P' and upload calibration files C1 C2 C3, all as advised and supplied by supplier B (including C files) but it probably wouldn't be same for current B systems as the installer is usually more involved with calibration themselves with B current systems. Not saying others haven't converted RRSC's and achieved similarly good results to myself or older B systems, and that would explain why they haven't been brought to me for sorting out... but I have sorted out a lot that did have problems.

Simon

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PostPosted: Mon Sep 05, 2016 10:02 am 
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a quick update :-

car running ok most of the time with no lean/rich codes so far after changing out an injector pipe on cylinder one which had a bit of a hole in it and was giving a misfire on this cylinder

anyway - I still have the misfire between about 2500 and 3000 rpm only under certain conditions - it occurs when the engine feels it should be dropping down a gear but remains in the wrong gear as it were and then the misfire happens (hard to explain tbh)

anyway I suspect it may well be nothing to do with the calibration of the lpg map but do not have time to investigate further for a couple of weeks (it only happens on lpg , and not when on petrol) could either be the injector or maybe coil pack or plug .

I'll sort it out once back from work

current map below

Image


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PostPosted: Mon Sep 05, 2016 11:50 am 
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Try enabling 'anticipate the injection sequence' (engine has to be idling on petrol to make this change'. When the change has been done the changeover between petrol and gas might not be as smooth but it could improve drive-ability... Unlikely to have a positive effect in your case (and maybe particularly on a V6) but this often improved matters on old 4L Jeeps fitted with older LPG ECUs with similar symptoms.

Simon

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PostPosted: Sun Sep 25, 2016 12:22 pm 
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hi Simon and readers - thread update time :-

I have tried that 'anticipate etc' and it made it run v rough , so no joy there

I have swapped coil packs - no joy
I have swapped injectors - no joy still misfire cylinder 1

there are no other issues ie no lean/rich codes and for the past 2+ weeks the car hasn't missed a beat - its only when trying to cause the misfire that it actually happens ie drive it like you stole it and erratically and you can bring up the fault - day to day running its not an issue

as everything has a compromise I've decided to leave as is - if it gets worse and becomes apparent in every day use I'll sort it out
my plan would be to drill out the nozzles to 3.5mm and drop reducer pressure and take it from there - it could be where the manifold is drilled as the likely candidate maybe just not in the sweet spot for that cylinder?

anyway - not what I was expecting - I genuinely thought the coil was the culprit.

Simon I now have 8 mygas injectors here (one needs a service) they have about 8000 miles on them , if you could use them I'll gladly send them to you as a token of my appreciation of your help and patience , without your input I think this forum would grind to a halt!

cheers again


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PostPosted: Sun Sep 25, 2016 12:22 pm 
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hi Simon and readers - thread update time :-

I have tried that 'anticipate etc' and it made it run v rough , so no joy there

I have swapped coil packs - no joy
I have swapped injectors - no joy still misfire cylinder 1

there are no other issues ie no lean/rich codes and for the past 2+ weeks the car hasn't missed a beat - its only when trying to cause the misfire that it actually happens ie drive it like you stole it and erratically and you can bring up the fault - day to day running its not an issue

as everything has a compromise I've decided to leave as is - if it gets worse and becomes apparent in every day use I'll sort it out
my plan would be to drill out the nozzles to 3.5mm and drop reducer pressure and take it from there - it could be where the manifold is drilled as the likely candidate maybe just not in the sweet spot for that cylinder?

anyway - not what I was expecting - I genuinely thought the coil was the culprit.

Simon I now have 8 mygas injectors here (one needs a service) they have about 8000 miles on them , if you could use them I'll gladly send them to you as a token of my appreciation of your help and patience , without your input I think this forum would grind to a halt!

cheers again


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PostPosted: Sun Sep 25, 2016 8:12 pm 
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hitman wrote:
hi Simon and readers - thread update time :-

I have tried that 'anticipate etc' and it made it run v rough , so no joy there

I have swapped coil packs - no joy
I have swapped injectors - no joy still misfire cylinder 1

there are no other issues ie no lean/rich codes and for the past 2+ weeks the car hasn't missed a beat - its only when trying to cause the misfire that it actually happens ie drive it like you stole it and erratically and you can bring up the fault - day to day running its not an issue

as everything has a compromise I've decided to leave as is - if it gets worse and becomes apparent in every day use I'll sort it out
my plan would be to drill out the nozzles to 3.5mm and drop reducer pressure and take it from there - it could be where the manifold is drilled as the likely candidate maybe just not in the sweet spot for that cylinder?

anyway - not what I was expecting - I genuinely thought the coil was the culprit.

Simon I now have 8 mygas injectors here (one needs a service) they have about 8000 miles on them , if you could use them I'll gladly send them to you as a token of my appreciation of your help and patience , without your input I think this forum would grind to a halt!

cheers again


Where is the rpm feed being taken from if its been wired up? Is it on the feed to cylinder 1 coil pack?


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PostPosted: Mon Sep 26, 2016 11:20 am 
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Have you swapped spark plugs between cyl 1 and another cyl?
Is pipe feed to cyl 1 kinked or a different length?
Is spud for cyl 1 in a different position on the runner for cyl 1 compared to other cyls (your manifold drill position point)?
If you swap injector positions between cyl1 and another cylinder, does the misfire move with the injector? Edit - I remembered you've tried this.
Under what conditions does the misfire occur (OBD2 freeze frame data might help pinpoint)? If misfire is with increasing rpm from 3000+ with quite a lot of throttle it may be due to the jump in numbers on your map between those conditions.

Thanks for the offer of the injectors, gratefully accepted! I have boxes full of old bits, never know when they might come in handy for effecting repairs where customer prefers to use second hand bits rather than fit new (keeping costs down).

Reckon there are those who think the forum might be frequented more by other pros if I didn't write as informed and thorough replies :roll:

Simon

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PostPosted: Tue Oct 11, 2016 8:46 am 
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Hi Brian to answer your ? - feed for RPM not wired up.

Simon to answer your ?s - I swapped plugs , coil packs and injectors and the misfire still showed on cylinder one , this was one of the new pipes I fitted due to leak on old pipe from injector to manifold.

on further investigation it was apparent some muppet (that being me )had been over enthusiastic with the bonding agent when sticking the new pipe onto the nozzle in the manifold with the result that some had partially choked the nozzle - oops

so after some flushing/cleaning with acetone the nozzle was cleared and RESULT - misfire cured.

car running great

I'll post those injectors off to you today

thanks again


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PostPosted: Tue Oct 11, 2016 7:19 pm 
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hitman wrote:
Hi Brian to answer your ? - feed for RPM not wired up.

Simon to answer your ?s - I swapped plugs , coil packs and injectors and the misfire still showed on cylinder one , this was one of the new pipes I fitted due to leak on old pipe from injector to manifold.

on further investigation it was apparent some muppet (that being me )had been over enthusiastic with the bonding agent when sticking the new pipe onto the nozzle in the manifold with the result that some had partially choked the nozzle - oops

so after some flushing/cleaning with acetone the nozzle was cleared and RESULT - misfire cured.

car running great

I'll post those injectors off to you today

thanks again



Good to let everyone know - Glad its sorted.


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PostPosted: Wed Oct 12, 2016 10:44 am 
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Yeh cheers Hitman. Hope there's no partial blockage of any other pipes though!

Really don't have to send me anything but if you do, please use office address. Both addresses are same place but only the office address is a viable post address, two entrances to same yard.

Simon

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PostPosted: Wed Oct 12, 2016 11:17 am 
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Simon

already sent to 37 Northcroft Ave, South Elmsall, Pontefract WF9 2UW

hope thats the right one?


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PostPosted: Wed Oct 12, 2016 12:21 pm 
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Yes that's the one and I've received a red note from the postman which will be regards the parcel you sent.. I was out in a customer car, nobody else in, not a problem I'll call down to the post office tomorrow.. Thanks very much!

Cheers Hitman!

Simon

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http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240


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