Pending fault codes P1171 and P1174, tuning advice needed please

[Bone9]

Hi guys, I have a 2003 discovery 4.0 v8 with a multipoint emer lpg system fitted.

I'm having problems with 2 pending fault codes that I want rid of.
To start these codes are only on lpg. It's faultless on petrol.

It uses aeb based software for adjustments etc, I have this and the required lead.

I just did some tests this morning while stationary so not under load. Each one was recorded after 30 seconds of constant revs.

Fuel trims...

Petrol (no load)

Idle = ST1 -2.3, ST2 -0.8, LT1 -12.5, ST2 -11.7

1500 rpm = ST1 3.1, ST2 3.7, LT1 -12.5, ST2 -11.7

2500 rpm = ST1 2.3, ST2 1.6, LT1 -12.5, ST2 -11.7

LPG (no load)

Idle = ST1 3.9, ST2 1.6, LT1 -12.5, LT2 -12.6

1500 rpm = ST1 25, ST2 21.9, LT1 -12.5, LT2 -11.7

2500 rpm = ST1 25, ST2 25, LT1 -12.5, LT2 -11.7

What's your thoughts?

Thanks.

[Gilbertd]

It's running lean at higher revs. Long term trims won't change immediately, they will learn the correct setting to keep the short term trims around 0. When you give it some revs on LPG, the short term trims are going up, meaning it needs more fuel. It may have always been like that, it may be the map needs adjustment or it may be that you have a restriction so insufficient fuel is getting through. It may need nothing more than the filters replacing.

[Bone9]

It's running lean at higher revs. Long term trims won't change immediately, they will learn the correct setting to keep the short term trims around 0. When you give it some revs on LPG, the short term trims are going up, meaning it needs more fuel. It may have always been like that, it may be the map needs adjustment or it may be that you have a restriction so insufficient fuel is getting through. It may need nothing more than the filters replacing.

Thanks. It's never been mapped 100% correctly as far as I know. I've owned it since October but been busy doing other jobs on it.

The filters are new, I've stripped and cleaned the injectors. There are no faults in the lpg software. It's on 1.36 bar on gas. I've just been to someone to get it mapped but later on that day the codes appeared. He may have not mapped it correctly?

[Brian_H]

Getting the right cylinders matched up can be tricky on the Thor manifold, particularly if the spuds are in the upper manifold rather that the lower one. Should be something checked in mapping though.

[Bone9]

Getting the right cylinders matched up can be tricky on the Thor manifold, particularly if the spuds are in the upper manifold rather that the lower one. Should be something checked in mapping though.

It should be all installed correctly as it never used to throw up any codes.

[Bone9]

I've just been out and it popped up the codes but ST fuel trims were good, not sure why it bought them up.

[LPGC]

Tell us what injectors you have fitted (V34's ?) What pressure is set in calibration? What actual pressure reading are you getting? Post a pic of your map... a screenshot showing the map screen and pinj/ginj at 2500rpm would be even better....

And I'll suggest changes you should try on your map. But first save your settings as they are.

Very likely running lean at lower engine loads as opposed to higher revs. We can forget revs for the most part, they only make a small difference but engine load makes a big difference and when you're running fast idle the engine is under least load (in one 'take' on load anyway, the take that corresponds with inlet manifold pressure).

[Bone9]

Tell us what injectors you have fitted (V34's ?) What pressure is set in calibration? What actual pressure reading are you getting? Post a pic of your map... a screenshot showing the map screen and pinj/ginj at 2500rpm would be even better....

And I'll suggest changes you should try on your map. But first save your settings as they are.

Hi yes v34's. I'll get some screenshots tomorrow The running pressure is 1.36bar. Shall I get them under load or stationary? My current settings are saved and backed up.

[LPGC]

If it's an automatic you can get the engine under a bit of load without driving by holding the brakes and accelerator, but not too long as to heat the gearbox too much. Or manual go for a drive.

Engine fully warmed up, screenshots of under load and at ilde, also idle in gear if automatic. Don't have the AC on. Various loads screenshots with corresponding fuel trim info. Also don't forget to tell us the calibration/reference pressure.

[Bone9]

Don't I need to keep the revs constant for 30 seconds before taking a reading? Yes it's a auto.

My laptop battery is nackered so might not be able to get info while driving. Only fuel trims from torque pro etc. I'll try to get one sorted ASAP.

Thanks.

[Bone9]

Hi sorry for the late reply, I had an injector fail and been busy with various other things. But im back now with the screens you asked for. So any input would be great. Thanks.

These were done with AC off and all under load on the same bit of road. In drive at idle also.

Petrol Idle...



LPG Idle...



Petrol 30mph...



LPG 30mph...



Petrol 50mph...



LPG 50mph...



Petrol 67mph...



LPG 67mph...

[LPGC]

Reference pressure is the pressure set in software
Actual pressure is the reading on screen

We're seeing 1.33 bar actual pressure but what is the reference pressure (check in your software settings)? I could work this out but easier just to ask you, though I'd hazard a guess your reference pressure isn't set far from 1.6?

Your system could use more actual pressure though, can tell because at high-ish engine loads when pinj is 11.33ms ging is 17.79ms, ideally the 17.79ginj should be closer to 13ms for pinj of around 12ms (pinj would be close to 12ms if fuel trims were zero but fuel trims are -3.1 + -4,7). Not yet told us what reducer you have fitted but judging by it being an Emer system and by pressure stability would guess you have an Emer Palladio fitted (though not really much to go on re pressure stability because you never really push the engine in screenshots so it isn't drawing a lot of gas)? If so increase pressure to 1.7 bar.

That peak at 7ms shouldn't be there, copy all the boxes from the row on the 8ms row and paste the same figures into the 7ms row, and it's very likely the figures in rows for 15ms and 18ms will need to be increased a little. Though when we have answers to questions it may seem a good idea to recalibrate changing reference pressure and most of the numbers anyway.

Looks like the installer was trying to prevent an intermittent misfire during tip-in from idle rpm judging by the oddly low numbers bottom left of the map screen... It was maybe in need of the plugs changing at time of calibration lol.

Have I seen this car in the past?

[Bone9]

Reference pressure is the pressure set in software
Actual pressure is the reading on screen

We're seeing 1.33 bar actual pressure but what is the reference pressure (check in your software settings)? I could work this out but easier just to ask you, though I'd hazard a guess your reference pressure isn't set far from 1.6?

Your system could use more actual pressure though, can tell because at high-ish engine loads when pinj is 11.33ms ging is 17.79ms, ideally the 17.79ginj should be closer to 13ms for pinj of around 12ms (pinj would be close to 12ms if fuel trims were zero but fuel trims are -3.1 + -4,7). Not yet told us what reducer you have fitted but judging by it being an Emer system and by pressure stability would guess you have an Emer Palladio fitted (though not really much to go on re pressure stability because you never really push the engine in screenshots so it isn't drawing a lot of gas)? If so increase pressure to 1.7 bar.

That peak at 7ms shouldn't be there, copy all the boxes from the row on the 8ms row and paste the same figures into the 7ms row, and it's very likely the figures in rows for 15ms and 18ms will need to be increased a little. Though when we have answers to questions it may seem a good idea to recalibrate changing reference pressure and most of the numbers anyway.

Looks like the installer was trying to prevent an intermittent misfire during tip-in from idle rpm judging by the oddly low numbers bottom left of the map screen... It was maybe in need of the plugs changing at time of calibration lol.

Have I seen this car in the past?

Thanks for the reply

Is this what you need?



It's an old screenshot before any changes were made from when I first got the vehicle.

Yes my reducer is an emer palladio. Isn't the adjustable pressure on these between 1 & 1.5bar?

I wasn't pushing it no, just under load going up a long hill steady at set speeds.

I don't know if you have seen this car before, certainty not with me.

[LPGC]

The screenshot shows something is amiss at that time anyway.. pressure at 3.48 bar - although it is running on petrol at that time the high reading still shows something is amiss regards pressure, and most likely either a knacked reducer or the reducer has been run too cold and has spat liquid gas into the vapour lines. But it's old info like you say and I expect those settings are not current settings.

You can only try increasing pressure, see if you can get it to go as high as 1.7

Wondered if I'd seen it because not too many would know to get around low rpm tip-in misfires by leaning those boxes and I sometimes use a similar filename format.. I'm Simon not Mick but if your name isn't Mick there is another installer on forum called Mick and it could be him who calibrated it.

[Bone9]

Where is says reducer 1 bar in the screenshot above is that the info you're after?

Ah I see, it was me that saved the filename that. It was Mick from TinleyTech that had done the latest mapping during my ownership.

I'm Toby.

[Bone9]

I've been watching the fuel trims lately and it gets +25 on both banks when under very light load coasting down a hill around 1000- 1500rpm in closed loop. If I switch to petrol at a that point it changes back to near 0. I've adjusted the map as per the photo. What is your opinion of this please? Its quite a big adjustment.

[Bone9]

@LPGC any input on the above please?

[LPGC]

Copied and pasted my reply below from my reply on your other thread... Let's stick to this thread now mate?

It's not that I want to copy it I just want to understand how a good map is supposed to look. As in the difference in timings and the positions.

What is a good map can depend on what components are fitted and on aspects of the vehicle such as petrol injector flow rate versus cylinder size, rated power, whether or not the engine has fuel pressure relative to manifold pressure or to atmospheric pressure.

But generally speaking both maps look wrong, the peak figures are too high, they both have a dip at 10ms, the 2.5ms row is very much smaller than the 3.5ms row.

[Bone9]

So what do you suggest I do?

[LPGC]

Can you increase reducer output pressure to 1.7 bar? To try this turn the reducers allen key pressure adjuster anti-clockwise while the engine is running on LPG and while you monitor the pressure reading in software. If you can get pressure to be fairly stable at 1.7 bar while driving then adjust the reference pressure in software to 1.7 bar and then re-calibrate.