part throttle hesitation

Message
Author
gazwad
New member
Posts: 25
Joined: Sun Mar 10, 2019 5:21 pm

Re: part throttle hesitation

#21 Post by gazwad » Thu Mar 21, 2019 8:10 pm

I'm working on accessing the obd side but it's tricky as its and older obd2a ecu so my normal bluetooth code reader won't access it, will be borrowing a professional scanner soon so hopefully that will be able to read it

Brian_H
Intermediate Member
Posts: 1348
Joined: Mon Jan 23, 2012 12:21 pm
Location: Milton Keynes

Re: part throttle hesitation

#22 Post by Brian_H » Thu Mar 21, 2019 8:16 pm

Yeah, thats what I'd suspect to be the case, some pre 2001 stuff does work, but a lot doesn't. No idea with Honda what your best bet is, I've known Fords to work, but only if the adapter or unit your using supports the j1850 PWM protocol, which not all of them do (and a few that say they do actually don't as well). It may need something like that, or may be a case of specific software on a laptop with the right lead.

Gilbertd
Advanced Member
Posts: 8126
Joined: Wed Apr 09, 2008 10:00 am
Location: Peterborough

Re: part throttle hesitation

#23 Post by Gilbertd » Thu Mar 21, 2019 11:35 pm

Is it an import? My daughter had a 2000 Toyota MRS (Jap imported MR2) that used JOBD so only scanners that can read Japanese OBD would work on it. I bought a CReader but it looks like this one is the best deal at the moment https://www.ebay.co.uk/itm/JOBD-OBD2-Ca ... 2762730602
'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

Proud to be a member of the YCHJCYA2PDTHFH club.

LPGC
Installer
Posts: 3502
Joined: Wed Sep 29, 2010 6:01 pm
Location: Yorkshire
Contact:

Re: part throttle hesitation

#24 Post by LPGC » Fri Mar 22, 2019 11:36 am

Look in Parameters, Advanced Settings, 'Other' section. If there's an 'Auto Adaption' heading click 'Config' and untick any check boxes beside OBD / ISA3.

Seems you have too much pressure and besides that your map shape can't be right.
With the engine running on gas and while watching the gas pressure reading on screen turn pressure down (physically at the reducer) until gas pressure is around 1.4.
Parameters, Gas Controller Settings and change Operation Pressure to 1.4.

Then you've got to adjust the multiplier(Maps, Multiplier)... the height all those yellow dots, until calibration is correct which is the most difficult part of this. But the 'shape' of your map is currently definitely wrong, usually the shape of the map (the way in which the line drawn between the yellow dots curves as it goes across the screen) should peak at around 4ms, come down quite quickly towards 6ms and then come down more and more gradually toward across the screen toward 25ms. There's usually also a bit of a rise up toward the peak (that peak at around 4ms) from 0ms to 4ms. Trying to describe a picture in words here! What I've said about the shape of the map is only a rule of thumb and only fully relevant when the engine runs manifold pressure referenced petrol pressure (mechanical fuel pressure regulator with vacuum pipe to inlet manifold - which is the normal/usual type setup) and I seem to remember there's an unusual aspect to these Honda engine's petrol pressure referencing... but even so there should never be a trough in the map like your map has at around the 5ms mark.

Even without a code reader you should get good results. If you click on the green cross in Multiplier screen the green line will disappear, then when you drive on gas the green line will be re-plotted and calibration should be pretty close if you get the green line overlaying the blue line. You can also clear the blue line which is plotted when running on petrol. Best to clear both lines and drive the car at the same rpm on both petrol and on LPG before checking the lines overlay. They should overlay when gathered at all rpms.

Obviously you'll never get good results if there's a hardware problem. There may be a problem internally with your reducer because pressure is 2.8 bar when no gas is being drawn off.. this could be due to a problem with the internal needle valve not fully closing so allowing liquid gas past it to the vapour side even when the diaphram assembly (that controls the needle valve) is holding the needle valve shut (when pressure has reached the set pressure). 2.8 Is a high reading and could point to a problem but that would depend on a few circumstances and even if there is a problem with a bit of gas leaking past a closed needle valve it might not be a problem in practice when the engine is running, would have to see how quickly pressure rised when no gas was being drawn off to ascertain that.

If petrol pressure isn't referenced to manifold pressure it becomes a bit more problematic as few ECUs allow for correction of fuelling for the differences inherrent when petrol pressure is none manifold pressure referenced and LPG pressure is manifold pressure referenced and Stag ECU's don't feature anything that can compensate for that. Nevertheless many of these engines were converted when no ECUs were available that could compensate for that and good results can still be had... but then you really do need to check fuel trims and the compare green and blue lines method won't work very accurately at all.

Simon
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

gazwad
New member
Posts: 25
Joined: Sun Mar 10, 2019 5:21 pm

Re: part throttle hesitation

#25 Post by gazwad » Fri Mar 22, 2019 3:49 pm

great thanks, loads to look at there then, shame you are so far away or i'd just get you to sort it! but i'll have a look at all of that and see how I get on. there is a fuel pressure regulator connected to a vacuum on the manifold. just as a side note, I've been getting around 18mpg on lpg (normally around 28-30mpg on petrol) so I'm guessing the high gas pressure and poor map will be affecting that.

LPGC
Installer
Posts: 3502
Joined: Wed Sep 29, 2010 6:01 pm
Location: Yorkshire
Contact:

Re: part throttle hesitation

#26 Post by LPGC » Fri Mar 22, 2019 6:38 pm

Yeh I'd sort it hehe ;-)
1.8 bar(ish) pressure wouldn't necessarily be a problem but with your spec injectors probably is, they're already not so fast and that sort of pressure will slow them even more or even prevent them opening properly. Your spec injectors won't like working at short pulse duration anyway so pressure needs to come down to get duration a bit higher at idle.
Good that your engine has a vac referenced petrol pressure regulator, means that you could just calibrate using the match the green and blue lines method and get it pretty close to correct.
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

gazwad
New member
Posts: 25
Joined: Sun Mar 10, 2019 5:21 pm

Re: part throttle hesitation

#27 Post by gazwad » Sat Mar 23, 2019 9:04 am

I reduced the pressure to 1.4 bar, also cleared the blue and green lined on the multiplier map. Will drive it on petrol for a few miles to allow it to re-plot the line then switch to gas. Does the laptop need to be connected to the ecu for it to plot the map or will it just do it anyway?

gazwad
New member
Posts: 25
Joined: Sun Mar 10, 2019 5:21 pm

Re: part throttle hesitation

#28 Post by gazwad » Mon Mar 25, 2019 8:27 am

so after driving on petrol then gas at 1.4 bar pressure to re-plot the lines I tweaked the map to get the lines pretty close to each other and the hesitation has completely gone, it seems to run better and power has improved on gas (it was slightly sluggish on gas before). I'll keep tweaking the map until the lines are perfectly matched but already it seems pretty good. I will monitor the lpg consumption over the next tank to see if that has improved. Also the high gas pressure when running on petrol has stopped, it remains at a constant 1.4 bar now so either it was a glitch or my theory is as the reducer is fairly small and only rated to up to around 2 bar i think it might have been over adjusted (or at least to max) so that it was struggling to operate consistently at that pressure. My feeling was that due to the bad map the previous owner must have adjusted the reducer pressure right up to try and blindly solve the hesitation issue (without success). Anyway it seems the problem is solved so a big thanks to Simon (LPGC) any everyone else who replied. cheers

gazwad
New member
Posts: 25
Joined: Sun Mar 10, 2019 5:21 pm

Re: part throttle hesitation

#29 Post by gazwad » Thu Apr 11, 2019 10:49 pm

OK so it's been running perfectly on lpg but I'm still only getting around 20mpg on lpg (usually around 28-30mpg on petrol) could reducing the pressure help with this (currently set at 1.4bar)?

gazwad
New member
Posts: 25
Joined: Sun Mar 10, 2019 5:21 pm

Re: part throttle hesitation

#30 Post by gazwad » Sat Apr 13, 2019 11:21 am

I've dropped the pressure to 1.2 bar, hopefully that will be OK and not too weak

LPGC
Installer
Posts: 3502
Joined: Wed Sep 29, 2010 6:01 pm
Location: Yorkshire
Contact:

Re: part throttle hesitation

#31 Post by LPGC » Wed Apr 17, 2019 10:44 am

You're welcome Gazwad.

No, it's unlikely dropping the pressure further would help matters.

There are other things to look at though. Getting the green/blue lines to match is only a rough setting for multiplier and only works up to a certain engine load but by seeing those lines I'd be able to guestimate multiplier for higher engine loads and maybe make some suggestions. Any pics of settings screens and map screens now?

Then there are hardware parts.. If hardware isn't well suited or is worn you won't get as good results as would be possible with better suited / better condition parts.
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

gazwad
New member
Posts: 25
Joined: Sun Mar 10, 2019 5:21 pm

Re: part throttle hesitation

#32 Post by gazwad » Sat Jun 08, 2019 6:06 pm

I've not replied for a little while as i wanted to do a couple more fill-ups to get a more accurate idea of mpg. It is still on the low side (20-23mpg on a run against 28-30 on petrol). I have changed the lambda sensor and given it a good service but no noticeable change. pressure is set to 1.2bar, there are no leaks and it runs very well, here is the map:
Imagelpgb1 by garrywadey, on Flickr
Imagelpgb2 by garrywadey, on Flickr
Imagelpgb3 by garrywadey, on Flickr
Imagelpgb4 by garrywadey, on Flickr

LPGC
Installer
Posts: 3502
Joined: Wed Sep 29, 2010 6:01 pm
Location: Yorkshire
Contact:

Re: part throttle hesitation

#33 Post by LPGC » Mon Jun 10, 2019 9:22 pm

Could do with increasing pressure a bit to maybe 1.4 bar.
See what I mean with different shapes of maps, in the first (dodgy) map the multiplier dipped at 4ms which is the opposite of what should be expected, in your last map pic multiplier starts off high and then dips after 6ms, much better but still won't be near perfect (should be an increasing lead-in ramp and then drop off after 4ms or so), glad that it runs better for you now though.... That is due to a combination of factors including pressure and mapping.
If it were me I'd add some extra calibration points at 2.5, 3.5 and 4.5ms (even if I had to delete the 7ms point), would expect multiplier to be rising from 2ms to between 3.5 and 4.5ms depending on spec of injectors and then falling, again depending on spec of injectors from 4.5 to 6ms then gradually levelling off toward peak pinj. For most engines ideally at peak pinj when the engine is on cam torque peak multiplier needs to be 1 or slightly lower (reducer pressure drop to be expected so ginj will come up to pinj but not much higher).
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

gazwad
New member
Posts: 25
Joined: Sun Mar 10, 2019 5:21 pm

Re: part throttle hesitation

#34 Post by gazwad » Tue Jun 11, 2019 1:18 pm

thanks, i will give that a try. I have since advanced the ignition timing slighly (easy to do on the honda b series engine) as i believe the lpg likes a bit more advance in the low to mid range and it's not the sort of car that gets revved up much. Seems to have improved the mid range slightly and maintains speed up hills easier so hopefully that will improve the mpg slightly.

LPGC
Installer
Posts: 3502
Joined: Wed Sep 29, 2010 6:01 pm
Location: Yorkshire
Contact:

Re: part throttle hesitation

#35 Post by LPGC » Tue Jun 11, 2019 8:16 pm

Those injo1 injectors aren't great in terms of performance or reliability - have a listen to each injector and see if they all sound the same, using a bit of pipe as a stethoscope can help. Don't go any higher on pressure than 1.4.
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

gazwad
New member
Posts: 25
Joined: Sun Mar 10, 2019 5:21 pm

Re: part throttle hesitation

#36 Post by gazwad » Thu Jun 13, 2019 9:36 am

how does this map look now? I've upped the pressure to just under 1.4 bar:
Imagelpgc1 by garrywadey, on Flickr

Post Reply