RangeRovers.net Forum banner

41 - 60 of 104 Posts

·
Premium Member
Joined
·
2,565 Posts
Were they already there or the're cleared and come back? just wondering how old they could be, not that it probably makes any difference. It will take a long time given the mileage your doing to have any real effect certainly on long term fuel trim.
Don't know what a dealer would charge for adaptive reset, perhaps worth a chat their not monsters, there's no real alternative until you can get a testbook et al...on it.

You could check the O2's are doing their job as best they can, either with a multimeter or on OBDII you can watch them flip floping (should be) every second or so, also watch how fast both banks enter Closed Loop from cold, should be fairly quick and at similar times, shows the heaters are working too. All really to get a sense there healthy or if there's anything that stands out between the 2 banks.
 

·
LEGACY VENDOR
1995-2002 Range Rover P38A
Joined
·
4,174 Posts
Discussion Starter #42
Hey Larry,

I'm not sure how old the codes were to be honest. I'm having a play with Torque now, and will try and get it set up to show me everything. Will pop back out to the RR once I've done it and have a quick play. I'll clear the fault codes and see if they reappear at all. I worked out what 11g/s is and its about 39.5kg/hr on MAF, which seems a bit high, but having said that, it is still idling a little bit high.

Yes, I agree about the LR dealers.. I think I'll give the local one a call when I'm back from London and see if they can have a quick look for me and reset the values.

When it had an emissions test awhile ago (mechanic mate wanted to check them to rule out any major internal engine issues) the HC's were a tiny bit high... would this be consistent with rich running? (It makes sense in my mind, but just wanted other thoughts)

Thanks as always,
Marty
 

·
LEGACY VENDOR
1995-2002 Range Rover P38A
Joined
·
4,174 Posts
Discussion Starter #43
OK, an update...

I've been out and connected it back up to the OBD reader, and to Torque on my tablet.

I've cleared the fault codes that were in the ECU, started her up and logged the data that came back. Ran it for 3 minutes, by which time it was nearly up to temp, and it was getting dark - so left it at that for the moment...

I've attached a spreadsheet of the data, for anyone who's interested in taking a peek...

To my (very) untrained eye - sensor 2 on the O2's looks to be all over the place compared to sensor 1 - but then again, it wasn't at full running temp, so will see how things are tomorrow.

Still planning on giving the main dealer a call next week and will see what they say...

Marty

View attachment OBD Data.pdf
 

·
Registered
Joined
·
517 Posts
I'm not sure about the O2 readings. On the time scale is it in seconds? If it is it will be difficult to interpret those figures. When looking at the O2 sensors I prefer to use a graph that just shows the 2 O2 sensors so you can see how quickly they are changing and if at a similar speed. To do this you really need a sample rate higher than once/second.
In terms of the MAF the suppliers are talking through their **** when they advise against them for LPG. The MAF does not directly connect to the LPG. The reason they may be saying this is a historic one that doesn't apply to your system. The old single point system if poorly set up could cause a back fire through the airbox - potentially destroying the MAF and airbox. The sequential systems do not suffer this. I would always stick with a recognised name for a MAF - Bosch for yours. I don't rate Bearmach much and often find them more expensive than the dealers - had a drag link from them - ball joints failed in 18 months and 10k miles.
With regards the MAF figures it does seem a little high, but possibly more important and accurate is the 3000 rpm figure.
I did note the one O2 sensor seemed to start switching sooner. If you find the O2 sensors not working well - do not be tempted by cheap generic ones, they will not work. I had to throw a pair away and replaced with genuine for a reasonable price.

As to lpg software and leads. As you have said a lot of the ECUs are made by AEB and so use very similar software and connection leads.

source of software - http://www.autotanks.com/downloadsgis.html

a usefull website with advice on setting up a system - http://autogashelp.co.uk/default.aspx

interface kits - http://www.lpg-kits.com/interfaces.htm
 

·
LEGACY VENDOR
1995-2002 Range Rover P38A
Joined
·
4,174 Posts
Discussion Starter #45
Thanks for the reply :)

I sat down and had a look through the data over a couple of alcoholic beverages (what else is there to do on a wet British evening after dark and tinkering time is over...)

I did a fair bit of reading (I think I found your O2 sensor thread regarding the aftermarket ones that didn't work properly) and I agree that the 1 sec time intervals logged are not fast enough to determine whether the O2's are working properly. It *looks* to me like the bank 1 O2 sensor IS switching between 0 and 0.8v (I can't remember if RAVE had those values, but I know I saw them posted by allyv8 in one thread) and I think it's a case of that the software can't keep up with the switching rate.

The Bank 2 O2 sensor also looks like it is switching... sort of... as you say, it starts switching later than the other one.

I'll have a look into the LPG software and interface kits - many thanks for the links!

I'll give the Indy a call on Wednesday when I return, and see if their diagnostics are back from repair yet... If so, I'll see about getting them to reset the adaptive values for me, as I still think that would be useful, since I've changed 3 sensors on the engine... If they don't have diagnostics back, then I will give the main dealer a ring and see how much they want to put it on the computer, reset the adaptives and have a poke around for me...

If I need a new O2 sensor, then is it worth replacing both at the same time, or just the defective one? I will definitely go for a genuine Bosch one, as it looks like aftermarket ones are just a nightmare (as you found out!)

The MAF sensor... I thought Bearmach were ok (well, better than Britpart and Allmakes?) I understand about the LPG side of things from the single point systems blowing air boxes off and destroying MAF's - but also didn't want to have an issue with one, call up to send it back and get asked the question "do you run LPG"... because to me that would be an easy out for them if I said yes... the answer would be "well, it DOES say not to use it with LPG systems". Maybe I'm just being too cynical over how companies work and the customer service (or sadly lack thereof in a lot of cases these days) they provide!!

I still have the original MAF sensor, so if it turns out to be that this one is a bit ****e, and the problem lies with an O2 sensor, or the likes - then I'll send it back and put the original back in after a decent clean... and then save the pennies for a proper Bosch one...

I just hope now that I don't have too many issues on the trip!

Does anyone know of any decent Indy's around North London (as I'll be there Monday/Tuesday) who have diagnostics kit, and won't charge an arm and a leg for an adaptive reset and a quick squizz?

Cheers,
Marty
 
D

·
Guest
Joined
·
0 Posts
A-ha, Marty - Fault Codes (at last !).... and showing rich on both banks. Assuming that these are reset, and both do return, this may thus not be the Hegos of course.

-Now, are you monitoring the 'Short Term Fuel trims' for both petrol and LPG, and are they substantially different ?

[Yes, I know it is hard to tell as the voltage oscillates around 'Lambda', hence the significance of monitoring both Hegos simultaneously and making comparisons etc, but it makes we wonder how (if ?) the LPG installers check such things out when 'fine tuning', too...]

The main point here of asking all this is that the Long Term Fuel Trims (and accordingly the stored Adaptive Values) are effectively a log based on numerous Short Term Trim values of course... This brings us back to your question 'if running mainly on one fuel affects the Trims on the other fuel if this is (briefly) selected'. {Presumably 'Yes' !}

Thus, if you run for 'a while' on LPG only this must bias the trims towards that fuel, surely ? Similarly I am not sure if the Trim values from LPG are within the 'expected' specs. for the ECU (petrol) MAP.. and if not then may ultimately show up as a 'matching pair' of DTCs, ie. on both banks {?}... as you have found ?

Anyway, lots of good ideas above, particularly swapping out the MAF and seeing what effect that has.... and keep us posted after your run !
 

·
LEGACY VENDOR
1995-2002 Range Rover P38A
Joined
·
4,174 Posts
Discussion Starter #47
Hi Dave,

Thanks for the thoughts!

The pdf I attached above has data in it from the fuel trims.

Bank 1 Sensor 1
Bank 2 Sensor 1 (I presume these are the short term trims)
Bank 1 Sensor 2
Bank 2 Sensor 2 (I presume these are the long term trims?)

Both Banks on sensor 2 show 99.22% which I presume again that these mean they are out of range from what the ECU can change?

Bank 1 and Bank 2 Sensor 1 values are differing greatly, but once again - I'm not 100% sure if that's due to the engine not having reached full operating temp

I will try and do the first part of the trip today on petrol, and if possible capture some data once it's properly up to temp and cruising.

I'll report back any findings!

Cheers,
Marty
 

·
Premium Member
Joined
·
2,565 Posts
hey Marty, yeah its quite hard to get a sense of whats going on from the chart, the ECM will just react to what it see's at the O2's it knows nothing about the fact your using a different fuel, it know nothing that this fuel has a slightly different lambda for example.
The lpg ecu you have (and the setup/installation) hopefully will account for all this, but the ECM is still blind to it all. The long term fuel trims could be at their limit for reasons nothing to do with lpg, old sensors, inlet leaks (unmetered air), exhaust leaks upstream of the O2's, its just that with lpg its more likely and probably faster to happen.
 

·
LEGACY VENDOR
1995-2002 Range Rover P38A
Joined
·
4,174 Posts
Discussion Starter #49
Hi Larry, and anyone else still following this...

Well, I made it to London on what ended up being a quite a wet and horrible Saturday night!

The drive to Leamington Spa went pretty well. Managed to get all of my tyre pressures up to spec, and the difference was felt! A lot smoother. I still seem to have a bit of a vibration from 65mph upwards, so not sure what to look at for that... its felt through the whole vehicle, so after searching a bit, I think the U joints are on my short list of things to do next!

Regarding the engine performance...

Ran the first part of the trip on petrol only, and it seemed to cope pretty well. Had a couple of steel hills and the engine seemed to surge a bit, like power was pulsing with foot evenly on the throttle. To be fair they were white steep hills, and I'd say she was under a fair bit of engine load. Other thank that, ran pretty well. Didn't have my OBD scanner connected though.

Ran the trip to London on gas, also ran fine.

Hooked up the scanner this morning whilst I was putting parking permits in, and the 2 previous fault codes are back: P0175 and P0172.

Got the 87 mile run home tonight, which will be on gas again for part of the way at least but I'm going to attempt to hook the scanner up and see if I can log the whole journey home. Will see if that gives any other insight.

Think that I'll definitely try an get the adaptive values reset when I'm back, and will also look at the links that AMcK posted regarding the LPG tuning cables and software...

Will let you know what I find out...

Marty
 
D

·
Guest
Joined
·
0 Posts
Interesting, I wonder if those Fault Codes would have returned if you just ran on petrol for 'a while' though ? Sorry, Marty, as you will have noted in my other related post above I just have it in my head now that the LR ECU is optimised for petrol and so running for 'a while' on LPG will -probably- produce such DTCs..... !!

I also expect that 'long-term adaptive values' will differ between the two fuels, too... Do diagnostics show different (short term trim) results for different fuels ?

Has to be some reason that AMcK suggested the LPG ECU software: Maybe you can adjust the settings so the LPG does not trigger the Faults (if it actually is causing these !)
 

·
LEGACY VENDOR
1995-2002 Range Rover P38A
Joined
·
4,174 Posts
Discussion Starter #51
Oops... the 'steel hills' should have been 'steep hills'... bloody auto correct on my tablet!

I agree that the petrol ECU is definitely set up for petrol only - it was probably never even thought of back when the system was designed that a second fuel would have been an option...

I'm thinking that as the codes have come back for both banks, then the O2 sensors are probably working as they should at the moment. I think that due to me not getting it fully up to temp before, is why the data didn't match up. Also the fact that the scan rate isn't fast enough to keep up with the switching of the sensors.

I think that an overall good tune up if both the petrol and LPG systems is probably in order, to bring any differences in fuelling values back into some form of equilibrium.. as mentioned earlier, from what I can gather from previous tax discs, and the cost thereof, I think that the vehicle has been on LPG for at least 4 years, and also from the lack of service history above about 54k miles, and the issues I've found with the vehicle so far regarding things I would consider preventative maintenance, I think that at least the previous owner, and maybe even the owner before him have used the vehicle as more of a 'look at me, I drive a range rover ' status symbol, and not actually looking after the vehicle properly.

Maybe she's just after a bit more TLC! After the long drive though, it did bring back all the memories of past P38's I've had and reminded me of the reasons I love them!

Marty
 

·
LEGACY VENDOR
1995-2002 Range Rover P38A
Joined
·
4,174 Posts
Discussion Starter #53
Cheers allyv8!
 
D

·
Guest
Joined
·
0 Posts
Forgot to suggest Marty that you monitor the short-term trims, switch fuels and then see how the values change: Tricky I know as the values go up and down but there may be some different/discernible trends ?

Similarly, but with a dual-trace scope (slow scan), monitor the Hego outputs with both fuels in turn ... ??

Overall such monitoring might produce some useful results as far as Adaptive Values (and associated re-sets) are concerned ?
 

·
LEGACY VENDOR
1995-2002 Range Rover P38A
Joined
·
4,174 Posts
Discussion Starter #55
Hi Dave,

I was attempting.to capture a data log of my whole journey back from London... But found out after logging 2 hours of data that the settings in Torque for what parameters are logged seem to revert to default every time... So I have 2 hours of GPS data and that it... Wasn't impressed!

I did check the DOC's whilst in London and the P0172 and P0175 codes are back...

Got it booked in to see Jon on the 15th, so will see what the verdict is and report back...

Marty
 
D

·
Guest
Joined
·
0 Posts
Do you have a talking GPS Marty - and if so does it say 're-Set the Adaptive Values - now' !? (ah, a man can dream... an inexpensive in-car GPS/Testbook combo... if only). By now I would probably have been driving around with a storage 'scope riding shotgun too, hooked up to the Hegos......

Anyhow, good plan to involve an LPG pro. Hope he has some Zavoli S/W to tweak the LPG ECU too - it may even just need a subtle modification of the LPG injectors' duty cycles/pulse length to resolve this (Hopefully !). I look forward to reading your update in ~10 days !
 

·
LEGACY VENDOR
1995-2002 Range Rover P38A
Joined
·
4,174 Posts
Discussion Starter #57
Haha, I wish it was that simple!

He does have Lpg software for a lot of the systems, but I'm not sure if Zavoli is one of them... I might hunt out the software on ebay or something etc, and see... could be worth having!

I will report back!
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
112 Posts
Marty, i also run LPG and have done for six years, i've also had dodgy tickover and racing tickover, it was an air leak. Yes, there are complications between the petrol and the LPG because petrol runs at 13 to 1 air fuel ratio and LPG is 17 to 1, it messes with the sensors and the software but it won't give the issues you have. An air leak will. Mine was the joint face on the plenum chamber but i think i have another. I'm going to look for it over the next week or so, i'll also take some vacuum readings. Remember, if the motor is drawing air from a leak then the air is not passing through the MAFF and will screw the software up. Obviously, this will only effect airflow at very slight throttle but that's where your issue is. Jon is something of a legend and i'm sure he'll sort it, it'll be interesting to see what he finds. Good luck.
 

·
LEGACY VENDOR
1995-2002 Range Rover P38A
Joined
·
4,174 Posts
Discussion Starter #59
Hi arudge,

Cheers for your thoughts!

I have been considering the possibility of a vac leak, but can't for the life of me figure out where I may have one... all air connections from MAF to throttle body are secure. I cleaned the butterfly and replaced the throttle body gasket, when the plenum was off to do the rocker gaskets, and HT leads.

A new inlet manifold gasket was used too... vac lines/rocker breathers seem ok. I replaced the oil separator doofer the other day... IACV pipes are clear and properly connected.. I've got a couple of vac lines for something to do with the LPG system, and they're firmly seated... *scratches head*

My tick over seems to be a bit better lately... not perfect, but better.. I spoke to Jon and he said that I'd probably be lucky to get it running fully right with the after market MAF... I've kept the original, but I purchased after market as that was the only only that didn't have 'NOT for LPG systems'

I know they say that because the older single point ones had a habit of blowing the air box off and killing the MAF, but I didn't want to end up with a faulty one and then get asked "do you have an lpg system" when I try to return it...

Hopefully Jon can work some magic for me! After taking the RR out on the road for my mini road trip, I've got back into loving these things!

Going to order me some U-joints to hopefully help with my 65mph + vibration...

Marty
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
112 Posts
I spoke to Jon and he said that I'd probably be lucky to get it running fully right with the after market MAF...
Marty[/QUOTE]

Marty, I've just fired up my motor, from cold, and let it run up to temp with the MAF unit on my bench, i did this because i wanted to observe the throttle plate movement and work out how the induction system works. It fired up at approx 800rpm, duly settled to about 650rpm. I then drove about five miles without the MAF unit and it drove fine. Good tickover, good gearchanges, no issues. I also flitted from petrol to LPG a couple of times without any ill affect.

I'm not entirely sure that faulty MAF units give the issues people think they do.:?:

I connected my mercury manometer to measure the plenum vacuum but it went off the scale , so that was the end of that idea.:sad:

What i did find were dirty joint faces and a loose bolt. IMG_1989.jpg

The bolt i'm pointing at was loose, not even slightly nipped up. This was the LPG guy, he simply forgot but it's not helping!

IMG_1990.jpg This joint face had something trapped in it and wasn't sealing properly.

IMG_1991.jpg I think this image speaks for itself, if the gaps are big enough for the clag to get in, then air will get in easy, and one of these bolts wasn't done up at all.


What i've learned is that the throttle plate, the one connected to your right foot, is slammed shut until you open it. Air is drawn through the plenum via the left rocker cover, through the engine, through the right rocker cover, to the throttle valve body on the atmospheric side, that's the one you can see next to the throttle plate. They've done this to create a partial vacuum in the engine to burn off blow-by and reduce oil leaks. More air is dosed in via the Air Idle Control (IAC valve) to make up enough air to idle.

My point is, what if you have a leak? What if the IAC is already shut because there is too much air and it can close no further?, there is no other way to reduce the air flow, the throttle plate is always closed until you open it with your foot. If air is leaking in through dodgy joints and the IAC has closed as far as it can go then you end up with high tickover because you have too much air. Plus the fact that you can't control an air leak and it can fluctuate. The IAC can't compensate because it's closed already.

I know this flys in the face of what others have to say but i think it's a valid argument and one worth looking into.

Good Luck
Andy.
 
41 - 60 of 104 Posts
Top