DIY Communication cable and Mapping

[RealPace3]

The system i am using is AEB MP32, (the fuel is not LPG, albeit its CNG, however, since the systems are very very similar, i am putting this here)
So, basically, it was installed by a guy who didnt know what he is doing, and i had lots of trouble with it.
So, a couple of shops later, i finally found someone who did a decent job, and his tune was fine


however, i want to reduce fuel consumption at idle to as little as possible, as currently, the fuel trims at idle shows negative for STFT, and im tired of going around to shops

There is also the problem where at times i drive without my AC On, and when i give hard acceleration, the system switches over to petrol and beeps until i press it

after that, it blinks slowly on gas mode, until i pull the CNG ECU fuse and put it back in

so, you might ask, why not just buy a cable? , well, you see, the issue is that the cable is priced at an exorbitant rate, however, if my knowledge is right, i can put together a USB to TTl adapter, some wiring and an automotive connector and make a cable for myself (should i use PL2303 or an FT232rl adapter?)

also, any tips you can give me?

[LPGC]

Gilbertd might be along with a wiring diagram for an interface cable but they're not very expensive at around £30 ? My preferred cable for 4 pin Superseal AEB stuff these days is an Alex Optima cable that also has an AEB wired connector, I find it gives fewer connection drop outs than other AEB cables and I like the fact it's opto isolated.

What car/engine is the system fitted on?
What reducer?
What injectors?
What are the fuel trims at idle on petrol? on cng?

Having AC on or off shouldn't make much difference.
It could make a difference if the water supply for the reducer isn't plumbed in correctly (so with AC off there isn't enough supply of hot water to the reducer).
It could make a difference if the problem is related to the engine suddenly going from zero load if the AC and compressor are turned off (when having AC on would see the engine still under some load due to driving the compressor) to high load, which could point to the reducer not being able to meet the sudden increase in demand.

Negative fuel trims at idle don't necessarily mean there is scope to decrease fuel consumption at idle unless the fuel trims go full negative.

[Gilbertd]

It's here viewtopic.php?p=128807&hilit=rs232.jpg#p128807

[RealPace3]

@LPGC

The car is a 2012 Hyundai Atos Prime with an Epsilon G4HG 1.1L(1086cc) MPFI 4cyl engine

The reducer is of local make: https://www.bluautogas.com/product/cng- ... -oe-cs-01/

Injectors are valvtek injectors

Fuel trims on petrol usually hangs out around +4.5 LTFT, on CNG its wanders anywhere from +13 to +18 LTFT

I live in an area where ambient temps never go below 20 degrees celcius (thats about 68F) , so there is no coolant connection given to the reducer by the installer

No, the beeping issue does not happen during idle, this is when driving , i drove without my AC on, did an overtake during which i gave hard throttle input and soon, the alarm started beeping on the switch

when i am driving with my AC on, no such issue happens

[Gilbertd]

No matter how hot the ambient temperature is, the vaporisation temperature of Propane is -44C so I'm not surprised you have problems at high loads without the reducer being plumbed into the cooling system.

[LPGC]

A CNG reducer doesn't get as cold as an LPG reducer but will still get cold especially when you put your foot down.

If there is any moisture in the CNG tank then if the reducer internals get below freezing temp it could freeze up some of the internals and prevent normal reducer operation, which could see the reducer not output enough pressure... Or maybe could see the reducer output too much pressure, which for a CNG system could be far worse (and more dangerous) than not enough pressure considering the available pressure from the CNG tank is normally very high.

Since you've said the reducer isn't plumbed to hot water I now suspect that when the AC is on the reducer stays a bit warmer due to getting a bit of heat from the AC condenser when the AC is on, and that it is this extra bit of heat that prevents a problem with one or more of pressure / reducer temperature / vapour temperature. If this is true then the solution would be to plumb the reducer to hot water. If you have the cable and software you could check readings and/or error messages to see why the system switches back to petrol while driving and confirm or rule-out this theory.

If it were my own car I would plumb the reducer to hot water anyway. The Valtek injectors will function a lot better fed with warm gas than with cold gas even if the gas is completely clean, and components such as reducer and injectors won't get as much build up of contaminants, any oil or water that is in the cng tank will be more likely to go through the system to be burned in the engine rather than stick/stay on the inside of pipes etc. You still didn't say what make/model the gas ECU is - most ECU's compensate for gas vapour temperature (because gas vapour temp affects gas density), a lot of ECU's that do compensate for temperature over compensate so if you have a gas vapour temp of (say) 0C when the initial calibration was done at a gas vapour temp of (say) 15C the effect of the colder gas temp reading is to lean the mixture off compared to the initial calibration mixture. With some injectors the cold temperature will slow the injector opening and/or closing time having an additional effect on mixture particularly at short injector pulse duration (relatively short injector pulse durations occur when the engine is at low load such as idle).

Edit - You did say your ECU is an AEB MP32 and that you're wanting to make your own cable. AEB ECU's including the MP32 usually adjust mixture for both changes in temperature of gas vapour and changes in temperature of the reducer. The reducer temp correction isn't necessary, it's only the temperature of the vapour that directly effects the density of the vapour not the temperature of the reducer (the temperature of the reducer does indirectly affect the temperature of the vapour but there's no need to compensate mixture for reducer temp because it can read vapour temp directly). If you want to check/confirm what I said above about the system likely switching back to petrol because it detects low pressure (as though you've run out of gas) or interprets a low temperature reading as an issue (either or both due to the reducer being unheated) you'll need to make or buy the cable and download the software. But I think there's a good chance you'd fix the issue just by plumbing the reducer to the vehicle heater circuit.

[RealPace3]

@LPGC
Sorry for the delay, i have got it plumbed to the cooling system, it does not seem to make much of a difference, it does seem to idle a bit smoother, but apart from that, no noticable changes, i have ordered the items to make a cable, i'll make the cable, use it to read the data

I had to go to a normal petrol mechanic to get it done, since the Installer that has fitted my system is no longer in business, they have shut shop and is now unreachable, however, i do vaguely recall the last time i was at the installer, i took a short glance at the map, and i clearly remember seeing values over 200 on the map table and the extra injection setting on and enrichment on accleration on max , could that have an effect?


The entire setup also has a Timing advancer , which advances the ignition timing to 12 degrees BTDC when running on Gas mode

[LPGC]

On most later AEB ECU's like yours it's normal to set the enrichment on acceleration setting to maximum. Earlier AEB systems were advertised as fully sequential but really only measured the pulse length of one cylinder on a cylinder bank and all other cylinders on the same bank got the same quantity of fuel as calculated from that one cylinder. The petrol ECU might be capable of increasing pulse duration to enrich mixture for acceleration for other cylinders but running on LPG or CNG those other cylinders wouldn't get the enrichment... Except the old AEB ECU's used a workaround involving seeing the raise in manifold pressure and calculating / guestimating some acceleration enrichment based on the acceleration enrichment setting but this was a very compromised way of addressing enrichment during acceleration. On the old systems the slider in the middle would give an average amount of acceleration enrichment, slider to the left less and slider to the right more than average enrichment. Most later AEB ECU's are fully sequential, they do measure petrol injector pulse length from all cylinders and on those there is no real need for acceleration enrichment because they base individual gas injector pulse lengths on individual petrol injector pulse lengths and the petrol ECU has already calculated and added a suitable amount of enrichment (and usually a lot better than the none exacting method that the older AEB ECU's could do). On most newer AEB systems acceleration enrichment set to maximum will see the LPG system follow the petrol strategy of enrichment, it doesn't add any more enrichment than following the petrol strategy and its own mapping dictates, but moving the slider to the left of maximum is like dialling in leaning in acceleration or to cancel out some of the enrichment during acceleration the petrol ECU dictates... So it's normally best to leave the enrichment on acceleration slider all the way to the right on newer AEB systems, if the rest of the mapping is correct this will usually give best results on LPG or CNG. On newer systems the enrichment on acceleration adjustment is hardly ever adjusted away from the full right slider position and its inclusion is probably a throwback to seem similar to earlier ECU's but it doesn't quite do the same thing that it did on earlier ECU's and isn't as necessary as it was on earlier ECU's, especially if the setup and mapping are done properly.

You saw 200's in the map table but were the 200's only around the low load / idle area of the map or were they across a larger area of the map? If they're across a larger area of map it might point to the installer not setting the system up with big enough injector nozzles or at high enough reference and actual pressure.

Normally an AEB system will flash an LED on the switch if calculated gas injector pulse length is bigger than calculated window for gas injector pulse length (window being the time it takes for the engine to do rotate 720 degrees). When the LED is flashing the system has temporarily switched back to petrol to prevent lean running due to there not being enough time to inject enough gas but it will switch back to petrol (and the LED stop flashing) when window is long enough (rpms decrease) or calculated gas injector pulse length has decreased (engine load is lowered like if you come off the accelerator pedal).

If you've cured the problem with the reducer getting too cold your system might be switching back to petrol when you put your foot down because the gas pressure reading is low, so it thinks you've run out of CNG. You will need to be connected with software to confirm whether or not this is correct. You've got some big numbers in the map (200's), so the installer could've known the injectors should really have bigger nozzles or that it needed more pressure. Sometimes a bad installer will set the reference pressure in software higher than the actual pressure intentionally because they know that the ECU will compensate by increasing gas injector pulse duration... The map only allows figures up to 255 in the table, if the 255 would see mixture too lean then setting higher reference pressure could make the 255 rich enough. 255 Is the maximum so the installer might increase reference pressure so mixture is rich enough with 200's in the map, leaving themselves a bit of scope for richening mixture a bit more if necessary. For example, if the installer tried to calibrate the system at say 1 bar, so he set the reference pressure to 1 bar and set the actual pressure to 1 bar, then found he would need to dial in some big numbers in the map (>255), then he went to increase actual pressure at the reducer and found the reducer was already set to maximum pressure, then he could still see correct mixture by increasing reference pressure without increasing actual pressure but because increasing reference pressure would see the ECU compensating for the lower actual pressure than set reference pressure. Increasing reference pressure from 1 bar to 1.6 bar would have a similar effect as increasing a 200 number in the map to a 278 number in the map because the ECU would be compensating gas injector pulse duration by +39% to make up for the apparent low pressure versus reference pressure. You already seem to know that 200's in the map is a bad sign, it's probably worse than you expect, if you've got 200's in the map then the system may run out of window at rpms as low as 3000, it can also mess up temperature corrections and acceleration enrichment. When reference pressure is set the switch back to petrol is sometimes automatically set at around half that reference pressure, so if an installer intentionally sets reference pressure higher than actual pressure then when pressure drops slightly when the reducer is working hard because the engine is under load and using a lot of gas it can make it more likely to switch back to petrol. Example if the reducer were outputting 1 bar and reference pressure set to 1 bar we'd expect it to interpret a 0.5 bar pressure reading as though you'd run out of CNG, reducer pressure does fall a little when the engine is under load but it probably wouldn't fall to 0.5 bar even at full load. If we set reference pressure to 1.6 bar it would probably (by default) interpret 0.8bar as though you'd run out of LPG and if the reducer only outputs 1bar at idle loads the pressure at full engine load could maybe fall below 0.8 bar in which case the system would see you'd run out of CNG and switch back to petrol. That said, you can usually manually adjust the pressure at which the modern systems interpret a tank empty situation but it might be worth checking what it's set to on your setup.

You generally need bigger nozzles in injectors for CNG than for LPG, you said you have Valtek injectors but which model Valtek injectors and what nozzle size is fitted?
When you have the software connected - What's the reference pressure setting in software and what is the actual pressure reading when it's running on CNG? Post pictures of your map and settings screens.

[RealPace3]

@LPGC

When the LED is flashing the system has temporarily switched back to petrol to prevent lean running

Yes, this has happened before, not always, but in some situations, especially when you push the engine to the limits, or in high load+Low RPM regime , the switch beeps continously and goes back to petrol, after restarting the car, the system seem to run on gas, but the Gas light keeps blinking slowly, until i pull the fuse of the LPG/CNG ECU

You saw 200's in the map table but were the 200's only around the low load / idle area of the map or were they across a larger area of the map?

I can't clearly remember that, but i remember seeing the map table and it looked dark red all through the middle, and i asked the guy who tunes it and he said its normal

You already seem to know that 200's in the map is a bad sign

Well, the installers here is not really qualified by any means (perks of living in the 3rd world), however they love making the entire thing sound like rocket science

If my knowledge is correct, in summary, basically, the LPG/CNG ECU hijacks the injection pulses sent by the Petrol ECU, recalculate it to the lookup table use the result to fire the gas injectors(along with Temp and pressure adjustments) ,

petrol ecu still does mixture control by using the narrowband O2 sensor

Energy density difference between liquid fuel and gaseous fuel means the gas injector needs to be open a little bit more than the petrol injector,

When your Engine RPM or Load increases, the petrol injectors opening time increases naturally, the gas injectors follow that(final G.inj time=p.inj + "K" value ) , however if the "K" value is set higher than needed, when the petrol injector timing increases, it reaches a point where the petrol injection timing+K Value exceeds the gas injectors pulsing ability that at which point the Injector would have to stay fully open instead of pulsing (i dont know if i am pharasing it right, but i believe that's what happening)

You generally need bigger nozzles in injectors for CNG than for LPG, you said you have Valtek injectors but which model Valtek injectors and what nozzle size is fitted?

I will have to check and report that back

When you have the software connected - What's the reference pressure setting in software and what is the actual pressure reading when it's running on CNG? Post pictures of your map and settings screens.

I have ordered the parts to make the cable, i'll post the pictures here once i am able to connect to the LPG ECU, no point in guesstimating the values

[LPGC]

You understand what the ECU does and are thinking along the right lines about why the gas injectors needing to pulse longer than the petrol injectors. Energy density of a fuel injected in a vapour state is generally going to be lowe than that of a liquid anyway due to the massive difference in mass density. The gas injectors need to open wider than petrol injectors to allow enough mass through in a reasonable time, and you understand why this time has to be less than the time it takes for the engine to complete a 4 stroke cycle, I've called the time the engine takes to complete the 4 stroke cycle the window because it is the window of opportunity for injecting LPG before the start of the next 4 stroke cycle. The different in mass of fuels injected also has to account for the different stochiometric ratio of the fuel / how much fuel has to be put in for a burn that will convert all the fuel and all the air to CO2 and H2O etc. But we could fit gas injectors that would flow enough gas that they could pulse for a shorter period than the petrol injectors for this chemically correct burn, there would be problems with that though... The gas ECU would have to anticipate the pulse duration of the petrol injectors and that would be impossible, it cannot predict the future so we generally want LPG/CNG injectors to pulse for at least equal time and usually a bit longer than petrol injectors so we can measure the length of the petrol injector pulse and multiply it according to our map so we can close the gas injector at some point after the petrol injector would have closed. Also because gas injectors need to open wider than a petrol injector (and the internal components are bigger and heavier) they take longer to open and close than petrol injectors, which means they don't have as good a response time at pulse periods shorter than around 2/3/4/5ms depending on the make / model of the injectors and the nozzle size fitted to them. If the response time isn't good the amount of fuel they deliver for short pulse durations becomes less consistent, less linear and more difficult to predict. Other variables such as pressure and temperature can also effect response time. Response time has an increasing percentage difference to the total flow / output of a gas injector for a given pulse period as the pulse period decreases. Again some injectors are a lot more consistent than others, some are more effected by changes in pressure or temperature than others. The nozzle size effects the output of an injector at any pulse length but it can have a different effect at very short pulse lengths than at short, medium or long pulse lengths depending on how far in the design of the injectors the nozzle is from the plunger or opening/closing component inside the injector - at most pulse lengths the nozzle is the part that acts to restrict most of the flow but at very short pulse lengths with some designs of injectors the volume between the nozzle and injector might have enough time to be pressurised and any fuel that gets past the opening/closing component (plunger) is going to be fed to the engine inlet port anyway regardless of the diameter of the nozzle - We couldn't get good results for example by fitting large model injectors on a toy/model car engine even if we fitted very tiny nozzles, we'd expect it to either get no fuel at all because we tried to decrease the pulse duration of the large injectors to prevent it getting too much fuel to the point the injectors didn't open at all, in which case the toy engine would get no fuel so wouldn't run, or we'd increase the pulse duration just enough to get to the point where they might (sometimes) open but then the toy engine would get too much fuel and still not run because the mixture would be way too rich. To some extent injector / size is still relevant to car engines because they can have vastly different sized cylinders, yet a lot of installers fit the same injectors on any engine they convert without considering if they are the best option for the nozzle size they intend to fit. Some of the Valtek injectors have internal channels/areas between the opening/closing bit / plunger and the nozzles that are limited to 2.5mm, other Valteks are around 2.8mm or 3.1mm depending on model. There's also a difference in response times and pressure / temperature stability among the different models.

When the switch beeps continuously - you seem to be describing an error mode. What I meant was that if calculated gas injector pulse time exceeds window the AEB ECU's will usually flash the gas LED on the switch and will switch to running on petrol until they calculate that gas injector pulse duration wouldn't exceed window (usually a short time after you've backed off the accelerator or gone up a gear). But in this situation the system does switch back to petrol automatically, you don't need to restart the engine. There are several things that could trigger an error mode, usually sensor related such as if reducer temperature or gas vapour temp fall below or rise above a certain reading. Or a disconnected / open / short circuit component such as a sensor or injector, or if the ECU no longer reads a petrol injector pulse from any of the petrol injectors - At high engine loads and low rpm the engine is more likely to misfire, especially if mixture is incorrect. Some petrol ECUs will turn off the petrol injector on any cylinder if a misfire is detected on that cylinder. Did running the engine at high load low rpm on CNG cause a misfire? Did the engine warning light on the dashboard flash?

I know you will need to have made your cable and connected with software to get some of the answers to questions, yes in the meantime you could find out what model Valtek injectors you have and measure the nozzle size that is fitted in them.

[RealPace3]

Well, i failed to find the size of the nozzle, the injectors are buried deep in the engine bay(i did manage to figure out through the incription on the injectors that its a valtek 30hm one, however setting "Valtek 3Ohm" in the software causes it to idle funnily and cause issues , so i just let it stay at "valtek") , i did manage to make the cable, pull the data, ill attach it with this post

Change Over (the one i found)

Screenshot 2025-09-20 182447.png (73.05 KiB) Viewed 3196 times

The above given is the one that was configured, all i changed here was to check the start on gas in hot engine and change over time to 6 seconds (i also checked the pressures, the Press.Gas matched the pressure on the "Reducer" section , so did not change anything there)

Lambda settings was default (Since O2 sensor was not connected)

All i changed in the "Sensors" section was to click the gas electrovalves to open in advance (since i switch to gas early)

Screenshot 2025-09-20 182914.png (54.17 KiB) Viewed 3196 times

This was the map i found , i reduced the values across the entire map by 10 points

Gas/Petrol section was all right, (the anticipate injection sequence option was not enabled, i did not enable it )

The extra injection sensitivity was enabled (however the slider was set to far left and injection identification time at 0.4ms), enrichment of accleration was set to max

Screenshot 2025-09-18 221550.png (93.8 KiB) Viewed 3196 times

There was this error on the diagnosis section, i cleared it and unticked the enable diagnosis option

That's all , the car does seem to drive alright, no percievable power loss, diving into the throttle at any conditions does not seem to cause any beeping error issues

[LPGC]

Well done for making the cable and connecting with software.

The gas injectors B error points to gas injector B being open or short circuited at some (probably recent) point in time. When that occurs the system does switch back to petrol.

You're sure there's no misfire when running on CNG? If there were a misfire on the cylinder that gas injector B feeds (probably cylinder 2?) the first thing to check would be gas injector B. Even if there's no misfire it would be worth checking gas injector B. If the error message reoccurs you could check injector B by swapping the electrical connectors from injector B to (say) injector C (and swapping injector C plug to injector B), also swap the outlet pipes between injector B and C. If the error code were then to point to injector C you'd know there was a problem with the injector that was connected to channel B now connected to channel C.

The numbers in the map table can be though of as a percentage multiplier, so if petrol injector pulse duration (pinj) input were 3ms and the applied number from the table were 200 then (if pressure compensation and temp compensations were zero) gas injector pulse output would be 6ms. Petrol injector flow rates are normally matched to an engine so that at high rpm and engine load the injector doesn't spend much time closed, or to put it another way the petrol injector runs at maybe 90% duty cycle at high engine load, or to put it yet another way the petrol injector pulse duration is almost as long as available window for pulse duration. If your gas injectors need to open for twice as long as petrol injectors then you'll realise that the gas injectors couldn't possibly have enough window to inject enough fuel at combinations of high loads and high rpm. The numbers in your map and the fact ginj is reading around 6.3ms when the engine is idling and pinj is around 3.2ms point to the flow rate of your injectors not being high enough for the engine, the injectors should really at least have bigger nozzles fitted in them, perhaps a higher flowing model of injectors should really be fitted. You should be able to get it to run with correct mixture at low rpm or lower throttle settings but the injectors (at least with current nozzle size) won't flow enough fuel for combinations of high rpm with high throttle.

[RealPace3]

You're sure there's no misfire when running on CNG?

There are very very rare occassional misfires

The plugs, HT leads and Coil is in fairly good conditions (even put in new plugs gapped at 0.6mm a couple of months ago)

No one really knows what exactly is causing these error, i visited 2 shops, even tried swapping injectors, no avail, one guy cut and got rid of the Petrol Injector-to-gas injector couplers and connected it directly, but the error still occasionally pop up

Will disabling diagnosis stop these errors? (well, not really stop,but will it prevent the Gas ECU from throwing the beeping error?, since the car is also being driven by old people, who panic when the switch starts throwing a racket out of nowhere)

flow rate of your injectors not being high enough for the engine

Now i understand why i have trouble at high speeds, the car will wheeze its way upto 80kmph (at which point the engine is spinning at about 2900-3000 revs) without much effort, 80kmph to 100KMPH takes its own sweet time !

Well, in any case, speed limit here is 80kmph, it can maintain that relatively well , most of the time, the car is stuck in traffic, idling with the A/C on!

Any other settings that i should change?

[LPGC]

What conditions do the misfires occur under (relatively cool / hot engine, low rpm, high rpm, low load, high load, during constant conditions / during acceleration / deceleration)?

What spec plugs are OEM standard for the engine and what gap? What plugs have you got fitted? You said you'd gapped them to 0.6mm.

Is your TAP timing advance processor fitted and working properly?

Some older AEB ECU's could develop a problem after a certain age in which they'd start to report none-existent errors. On those affected I often disabled error reporting to prevent problems and the system switching back to petrol. But I don't think the MP32 ECUs are affected in the same way. Also, if it's incorrectly reporting closed/open circuit LPG injectors then disabling error reporting isn't guaranteed to prevent that.

I'm not very familiar with your engine. Why is the Valvetronic setting ticked in LPG software?

[RealPace3]

What conditions do the misfires occur under (relatively cool / hot engine, low rpm, high rpm, low load, high load, during constant conditions / during acceleration / deceleration)?

Usually during Idle, i have not noticed any misfiring under other conditions

What spec plugs are OEM standard for the engine and what gap? What plugs have you got fitted? You said you'd gapped them to 0.6mm.

OEM is 1.1mm, however the misfires mostly stopped after new plugs gapped @ 0.6mm

Is your TAP timing advance processor fitted and working properly?

Yeah, its an AEB Spider 511N model, set to 12 degrees advance, starts advancing the moment throttle is applied

I'm not very familiar with your engine. Why is the Valvetronic setting ticked in LPG software?

That one, i don't understand as well, it was enabled when i pulled the data from the ECU , the engine is a simple Naturally aspirated 12 valve SOHC Inline 4 engine with conventional multi port injection and electronically controlled ignition https://mymotorlist.com/engines/hyundai/g4hg/

[LPGC]

If it's a simple DOHC engine the Valvetronic box shouldn't be ticked.

But if/when you untick the Valvetronic setting you'll need to recalibrate the system, the numbers in the map table will need to be changed.

I read the standard gap is 1.1mm and you changed the gap to 0.6mm but what are the OEM plugs and what plugs did you fit?

[RealPace3]

If it's a simple DOHC engine the Valvetronic box shouldn't be ticked.

SOHC actually, it does not have VVT or anything, i did try to untick it, but it made it run very lumpy, i dont have a laptop. i actually connected it to my desktop via the cable and pulled the data , so i cannot drive around and tune it at the moment, gotta wait until one of my friends come back home, so i can borrow a laptop for the purpose

I read the standard gap is 1.1mm and you changed the gap to 0.6mm but what are the OEM plugs and what plugs did you fit?

It had NGK BKR6E(the gap was around 0.9mm when i measured it) in it, looked pretty knackered, replaced it with Bosch FR7DC4 gapped at 0.6mm about 2000km ago , standard copper spark plugs, not the fancy iridium plugs

[LPGC]

I don't know how compatible the FR7DC3 plugs are with BKR6E but if there are certain differences such as if one were a resistor type while the other wasn't it could make a lot of difference perhaps particularly under the higher demand conditions of running on CNG versus petrol.

Would expect it to run poorly when you first unticked the Valvetronic box because the numbers in the table will then also need changing.

Don't expect you to drive around with a desktop PC in the vehicle (though I have in the past when I wanted to use an old computer with a parallel port to connect a 'dongle' to and didn't at the time have a laptop with a parallel port lol). But in the meantime you could maybe try to get it idling properly with the Valvetronic box unticked? When idle is close to correct the other numbers could then be guesstimated based on the idle numbers. You could save the current config and always reload it if you couldn't get it idling OK.

[RealPace3]

But in the meantime you could maybe try to get it idling properly with the Valvetronic box unticked? With idle something like correct the other numbers could then be guesstimated based on the idle numbers. You could save the current config and always reload it if you couldn't get it idling OK.

I'll try that , see how it responds, i gotta order a new TTL to USB convertor, the FTDI one keeps glitching out (it connects and then disconnects a minute or two later), so i'll do that and try tweaking around with the numbers

Thanks a Lot! i really appreciate it

[RealPace3]

Hey!
A few updates:
I haven't been able to get it running properly without the valvetronik option, it keeps running lumpy, so i decided to leave that alone

i have managed to use an OBD Scanner to monitor fuel trims and adjust to the map on idle
Earlier, when i put on load on idle (AC ON, Headlights, Indicators etc), the fuel trims used to go +10 to +15, then after i switched it off, the fuel trims would go -10 to -20 and would stay like that, that issue has been fixed, now, on idle without load, it shows +/- 5 , and with load , its close to +/- 3

Screenshot 2025-09-26 081355.png (55.97 KiB) Viewed 2680 times