EMS thinks lean - why?

[glenhendry]

I have in the last month replaced my MAF and O2 sensors and both exhaust manifolds as my RH one had a crack in the flex pipe (http://www.aulro.com/afvb/p38a-range-rover/150555-cracked-rh-exhaust-manifold-flex-joint.html).

I thought that it would fix my running lean condition, but it is still throwing "System too lean" faults (for both banks) via ODBII. Also, I not that the new O2 sensors are only flipping between 0.0 and 0.7 on a typical trip. So even after adaptive reset with Faultmate, the LTFTs go back to 24.9% within a few minutes.

I have checked the inlet system visually, but I can find no leaks. The car runs fine, but for some reason it thinks it is too lean. I have single point LPG, but I havent used it in many weeks, while trying to diagnose this (apparant) lean issue. The only other symptom is a minute hesitation upon take-off from lights, but its running nicely otherwise. MAF range during last drive cycle was 5.3 - 48.7.

I would like to hear your ideas, I am concerned that I have killed yet another MAF (http://www.aulro.com/afvb/p38a-range-rover/147767-2000-4-6-running-bad-petrol-good-lpg.html#post1672296), but it is returning valid looking values.

[Tikka7mm08]

Hi did you get anywhere with this fault? I have the lean bank faults too and the LTFT is showing 25%...I guess that is quite high? I cleared the fault to see if it will come back.

[Hoges]

Do you have the high LTFT showing for both banks or just one? Check for intake leaks after the MAF... for example, cracks in the hoses from the rocker covers to the throttle body, leaking inlet manifold gaskets... make sure the large hose from the MAF to throttle body is properly seated and that the hose clips holding it in place are likewise seated and firmly tightened...do not over tighten!;)
Cheers

EDIT: if u use the Aulro-specific google search function in the bottom left hand corner there's an extensive thread/posts following up on the one you quoted in yr first post. Good luck with it!

[Tikka7mm08]

Will have a look...pretty sure it was both banks reading 25% on OBD Torque.

[glenhendry]

Everything Hoges said, plus -

25% is not just high, but its as high as the Eng ECU will go before throwing a fault and moving from closed loop operation to open loop, where O2 sensors are ignored from ECU fuelling decisions. Clearing the ECU faults normally resets it back to closed loop operation, until the faults are raised again.

MAFs are often the key here. You wont always get a MAF fault, even when it is unservicable. Worse still, a MAF can be giving you valid looking values in real time but be outside the operating range. Any decent bump on them, especially an LPG inlet backfire is sure to frag it.

Aftermarket MAFs are not advised, nor for O2 sensors. If you eliminate air leaks on inlet and exhaust side, then clean the MAF with a proper MAF cleaner spray can and then consider replacing MAF and then O2 sensors.

[Tikka7mm08]

I pulled the MAF...like new but sprayed with degreaser. Truck running a little better but will test run tomorrow night and check for faults again/ltft readings... the MAF readings are in g/s...is that right? Any other readings I could post on here?

[TheTree]

These are some numbers I found

At Idle...................... 20 kg/hr (5.5 g/s) ± 3 kg\hr (8.3 g/s) (^)
At 2500 rpm............... 61 kg/hr (16/9 g/s) ± 3 kg\hr (8.3 g/s) (^)
At 3000 rpm............... 90-100 kg/hr (25-27.8 g/s) (*)

22-25kg at idle,90-100kg at 3000rpm in neutral,engine hot all loads off.

At Idle 20 ± 3 kg/hr
At 2500 rev/min 60 ± 3 kg/hr ..

Steve

[Tikka7mm08]

Thanks Steve...will post idle and 3000 figures...great to have g/s values there!

[Hoges]

Will have a look...pretty sure it was both banks reading 25% on OBD Torque.

This is a long shot...but... check the plastic threaded hose fitting on the inlet manifold to which is connected the hose from the RHS (Driver's side) rocker cover. It can crack and draw air in without being immediately obvious.

In my case, LTFTs on both banks had maxed out at 25%, all connections, hoses etc were tight... was only by luck felt some "give" in the hose and discovered the fitting had cracked with age. You can't drive the car without the inlet manifold hole being plugged somehow.

IF it is a failed fitting, a 1/4" BSP (metric) brass fitting is an exact fit for the existing hose from Rocker cover as well the thread in the inlet manifold. Available from REPCO or Supercheap (<$5NZ -I'm guessing). Wrap the thread with a couple of rounds of PTF plumbers tape before you install to prevent galling (brass/aluminium). It's a tapered thread so don't over-tighten...just enough to nip it up + a little bit!;)

[Tikka7mm08]

Will do tonight... not sure what you mean by brass fitting but might be clearer when I look tonight.

[glenhendry]

I pulled the MAF...like new but sprayed with degreaser.
Yikes, I think that makes the MAF a bin job. The MAF cleaner spray is special type of spray that dissolves crud but leaves zero residue. They are very sensitive (as I understand it).

The heated MAF element is exposed to the air flow and the temp/voltage is detected. Any residue on the element will severely affect the voltage required.

[Tikka7mm08]

D'oh. I had read brake cleaner was ok and thought degreaser would be...and I didn't hold back with the spray! Will see how it is when I pick up from the airport tonight! I read you can't go aftermarket on the MAF... 26 pounds whole part.... versus just MAF insert but bosch at 100 pounds...

[glenhendry]

I hear you with the cheap MAF, but think of this, 2 tanks of premium fuel costs AUD275. You will waste more than that over a few months running rich/lean/badly :)

My advise is get a brand new legit Bosch MAF and keep yours as a spare. Good luck. Please report back.

[Tikka7mm08]

Righto... will just get the insert as nothing wrong with the MAF body...and should keep it under customs NZD400. Will also post some figures of my OBD scanner. My fuel economy was pretty good on a long trip at 12.5L/100km. But when foot flat horrendous shudder and O2 lean bank faults...going to check connections etc as previously advised. Don't get shudder when foot flat in park so I suspect it is time for a front UJ replacement.

[glenhendry]

UJ slack is more evident with handbrake off and in Neutral, but chock the wheels first! Both front UJs can be replaced for AUD90 at home with a vice, circlip pliers, sockets to use as a press plug. And ~90 minutes. The yolk bolts are imperial too, for some reason IIRC.

[Tikka7mm08]

Righto will give it a go in neutral with some clear track ahead of me....I looked up some how to videos and could probably do it... I think each UJ has 8 bolts so would have to find the UJs (front and rear are the same aren't they?) and 16 bolts - probably off Ebay :)

[Tikka7mm08]

Bugger... just bought a Bosch F00C2G2032 instead of a F00C2G2029 MAF. Couple of places say 4% difference which the computer will adjust for.... bugger bugger bugger. Was NZD182 all up so not end of world stuff....will see how it goes. Also ordered new air filter (apparently the right one too).

[Hoges]

Will do tonight... not sure what you mean by brass fitting but might be clearer when I look tonight.

Essentially a tube with a screw thread on one end, 'barbed' 'push on' hose fitting on the other and made of brass, not plastic like the original. The original one tends to become brittle from heat stress and then crack with age. It's not obvious to start with. Replace with one made of brass as described in previous post...will outlast the life of the vehicle;)

[Tikka7mm08]

Here are the figures....very interesting. The 2 O2 sensors on 1 side are buggered as the voltage doesn't oscillate (wow listen to me). MAF looks ok?? May be a bit low...cos of O2 being out (right bank).

http://i761.photobucket.com/albums/xx251/Tikka7mm08/screenshot_zpsovvrwdi2.jpeg (http://s761.photobucket.com/user/Tikka7mm08/media/screenshot_zpsovvrwdi2.jpeg.html)

http://i761.photobucket.com/albums/xx251/Tikka7mm08/screenshot1_zpscjsbwh8r.jpeg (http://s761.photobucket.com/user/Tikka7mm08/media/screenshot1_zpscjsbwh8r.jpeg.html)

Also parked the car in neutral and revved the hell out of it...definite front vibration...little to the left maybe but sounds like prop shaft?

[TheTree]

Also parked the car in neutral and revved the hell out of it...definite front vibration...little to the left maybe but sounds like prop shaft?

Mate be careful revving the ZF Transmission

http://www.aulro.com/afvb/p38a-range-rover/200326-revving-engine-3000-zf-safety.html

Also if you weren't moving I am not sure it's the propshaft

Sounds more like something on the engine, maybe the fan ?

Steve

[Tikka7mm08]

Got told that was UJ test! Only did it twice won't again.

Plan of attack replace both rear O2 sensors? Anyone recommend a good place to buy these from?

[TheTree]

I have never heard that, the best way is to get under and see if there is any movement anywhere in the propshaft

Does your beast have before and after cat sensors?

The after cat sensors were only fitted to NAS vehicles as far as I know and they are there just make sure the cats are working correctly.

I have found that ebay out of the US seems to have the best prices for O2 sensors

Steve

[Tikka7mm08]

I hope there are rear sensors I just ordered 2 off Amazon!!

[Tikka7mm08]

"UJ slack is more evident with handbrake off and in Neutral, but chock the wheels first!"

I think I completely misunderstood :(

What a day. Going to bed.

[wayneg]

I hope there are rear sensors I just ordered 2 off Amazon!!

There are only two, 4 wire bosch type. I have used generic ones with no problem, you just need to re-use the plug. The sensors come with a crimp kit to make things easy. Mine were $16 each, try and beat that

[glenhendry]

All good info.

UJs - yep, get under and wiggle in every direction with your hand. Should be NO movement.

You will only have 2xO2 sensors. Both pre-cats. Only NAS (USA) vehicles have post-cat sensors and they only check the cat performance. I do not believe they are swappable. Also beware that GEMS have 0-5v O2 sensors and THOR has 0-1v sensors (wide band vs narrow band).

So, the 'no oscillating' you are seeing on your Torque display may be monitoring the non existent post-cat O2 sensors. Also put up the display which monitors the fuelling mode, closed loop or open loop. Its handy.

Your min MAF reading looks low to me. If your ECU thinks less air is coming in, then it will put less fuel in, then your O2 will read lean. :)

[Tikka7mm08]

To recap:

- revved car in neutral instead of wiggling UJ;
- ordered wrong MAF although this shouldn't be a great issue as usable;
- misinterpreted OBD reading and ordered REAR O2 sensors I apparently don't even have;
- even my self-deprecating sense of humour is struggling to keep up LOL. Gotta be able to laugh at yourself when you cock things up this badly...

[Tikka7mm08]

On the upside my front O2 sensors are flicking nicely between .1 and .9v so at least they are ok. This morning will look for leaks as suggested...then try the MAF replacement when it turns up.

Yes I ran thr engine loop...it is closed when accelerating and open when coasting foot off...

[Tikka7mm08]

...just note that Torque showed the rear sensors are 'active' or present and that O2 heating was fine but sensors incomplete.

[glenhendry]

It will go into open loop when you are trouncing it, or when you are overruning down a hill, but you want to see it in closed loop operation 98% of the time. If it throws faults due to it hitting the 25% LTFT limits, it may go into open loop mode.

LPG ECUs often steal a feed from the O2 sensors, sometimes I wonder if this slight change in the resitance on the O2 sensor line into the Eng ECU is enough to confuse things?

[Tikka7mm08]

Ok so mine is closed loop 98%...UJs on front shaft had less than 0.5mmm wiggle either way and did noy feel sloppy, rear O2 sensors just have bolt in their place (I am a fool)...

This hose here was a little loose so tightened:

http://i761.photobucket.com/albums/xx251/Tikka7mm08/20140905_100648_zps3rah4ug0.jpg (http://s761.photobucket.com/user/Tikka7mm08/media/20140905_100648_zps3rah4ug0.jpg.html)

Front O2 sensor:

http://i761.photobucket.com/albums/xx251/Tikka7mm08/20140905_100352_zpsswomm1zt.jpg (http://s761.photobucket.com/user/Tikka7mm08/media/20140905_100352_zpsswomm1zt.jpg.html)

Not sure why big shudder under heavy acceleration (where it feels like no power is actually going to the wheels)...perhaps it is all down to the MAF, and engine/gearbox mounts to check as they alone don't explain LTFT 25%. I pulled the MAF while truck running and that stopped it and ran when restarting without it but no great difference at least at idle.

[bee utey]

ANY movement in an universal joint is a sign of advanced wear. The rollers dig themselves little grooves and struggle to get out of them.

[Tikka7mm08]

Oh ok was expecting a bit more slop...but rechecking yes enough to get a clunking sound wiggling back and forth.

[Tikka7mm08]

Local shop... UJ $50 each, 1 hour each to (2x$78) exc GST... the front and rear UJ are both the same aren't they? I gotta be able to do this myself.

[Tikka7mm08]

Finally a win!!!

Found that the cruise control brake switch was out of place and managed to resecure it and test it to find now working as it should :)

http://i761.photobucket.com/albums/xx251/Tikka7mm08/20140905_132206_zps1ipeetgq.jpg (http://s761.photobucket.com/user/Tikka7mm08/media/20140905_132206_zps1ipeetgq.jpg.html)

[glenhendry]

Finally a win!!!

Found that the cruise control brake switch was out of place and managed to resecure it and test it to find now working as it should :)



Wow, we fixed this exact problem on my brother's P38 2 nights ago! (After removing, airbag, steering wheel, rotary coupling, CC ECU, CC inverter).

The UJs are easily doable if you have good work area and tools. And still doable if you dont. :) Call me if you get stuck. 0414 six78 888.

[Tikka7mm08]

Only required removing the two panels and a piece of heating ducting... i don't think they are held in very well at all...but easy to fix if it pops out in the future. I tested the vacuum by sucking the pipe at the actuator end and couldn't suck any air this time - put is back together and took for a test drive. Was thinking I wouldn't miss not having CC but loved having it working.

Might have a crack at the UJs...sounds like that is the vibration issue. Can get them from lrdirect.com but which one as there are a heap of makes??

Propshaft Uj Def Ds1 Ds2 Rr P38 | TVC100010 - Land Rover (http://www.lrdirect.com/Parts-by-Model/Range-Rover-P38-Parts/Propshafts/Propshaft-Front/TVC100010/)

[davidsonsm]

The Hardy Spicers are the one's. Can't go wrong I understand - unless you're talking an upgrade (double cardon shaft).

Great work so far fella. Don't get dis-heartened. Its a learning process. These aren't simple cars and there are lots of issues/solutions. I've made plenty of mistakes - but have lots more confidence now when it comes to issues (I'm no guru/grand wizard by any means).

[Tikka7mm08]

Picked up these GKM ones:

2 x UJ RTC3458 TVC100010 GKN Defender Discovery Range Rover BARRY4X4 | eBay (http://m.ebay.com/itm/321077837826'txnId=1335851700011)

[TheTree]

There is a fairly steep initial learning curve with these beasts :p

UJ's are not a hard job but read RAVE and anything you can find. Make sure you make good alignment marks to get it back in the same spot as well!

Steve

[Tikka7mm08]

Yep read a good idea to use a triangle file to mark alignment!

[davidsonsm]

GKN are a reputable brand. HS's were the OEM suppliers I understand. I could be wrong. Doubt the GKN's will see you wrong. It says they're OEM. So I'm prepared to be corrected.

[glenhendry]

These are some numbers I found

At Idle...................... 20 kg/hr (5.5 g/s) ± 3 kg\hr (8.3 g/s) (^)
At 2500 rpm............... 61 kg/hr (16/9 g/s) ± 3 kg\hr (8.3 g/s) (^)
At 3000 rpm............... 90-100 kg/hr (25-27.8 g/s) (*)

22-25kg at idle,90-100kg at 3000rpm in neutral,engine hot all loads off.

At Idle 20 ± 3 kg/hr
At 2500 rev/min 60 ± 3 kg/hr ..

Steve

These numbers have an error. Since MAF values are so important, I have corrected them here (http://www.aulro.com/afvb/p38a-range-rover/165502-thor-maf-values-how-test.html#post2283423):

At Idle...................... 20 kg/hr (5.5 grams/sec) +/- 3 kg\hr (0.8 g/s) (^)
At 2500 rpm............... 61 kg/hr (16.9 grams/sec) +/- 3 kg\hr (0.8 g/s) (^)
At 3000 rpm............... 90-100 kg/hr (25-27.8 grams/sec) (*)

Bibliography:
(^) - RAVE & MAF Values (http://www.rangerovers.net/forum/7-range-rover-mark-ii-p38/18164-maf-values.html#post161516)
(*) - P38A P38 4.0 HSE MAF SENSOR DATA Is it working? Whats wrong? Please help. - Page 2 - Land Rover Zone (http://www.landyzone.co.uk/lz/f10/p38-4-0-hse-maf-sensor-data-working-whats-wrong-please-help-194493-2.html)

[DT-P38]

Probably stuff you have already looked at, but had a couple of thoughts on a couple of the problems being mentioned...

Does your MAF have the big O ring in place? If you never had one, you might not know its missing...

Also any chance your dropping power under rev's could be related to a loose and/or damaged Crank Angle Sensor?

Probably way off the mark but some of the comments reminded me of times i had problems in the past.

[Tikka7mm08]

I Think I covered this is another thread
...good to close out here. The shudder was due to a a cracked flex plate in the trans. This completely let go and destroyed the AT pump with complete loss of all drive. Fitted replacement trans and all solved. Fitted new MAF and LTFT etc back to normal. Towed 2T boat 14 hours over hills last week with no issues...other than fuel economy shooting up to 18L/100km!

[peter51]

Bad news about the flex plate. At least we all know not to ignore the signs you mentioned.
Regarding your OBD software - is it Torque?
Are you using a bluetooth transmitter or hardwiring to the OBD port. If so which one are you using. Two bluetooth transmitters I have bought off ebay have proven to be useless.

With you second screen shot you can see that your old MAF is underreporting air mass by at least 20-25%[ the update speed on yr MAF values depends on how good the ELM chip is inside your transmitter]. Assuming it is correctly reported, the metered injector pulse width/ fuel mass will be less.
Actual air mass will be more.
BTW, the ECU knows the theoretical air massflow from the Throttle Position Sensor because the engineers have loaded air mass vs throttle position into the backup fuelling maps. If you were to cut the feedback wire from the MAF to the ECU, the ECU will default to those theoretical air mass vs TPS values for fuel metering to get you home.
In your case, your ECU is "hanging on" to the incorrectly reported air mass value. Eventually as the reported MAF value drifts further towards a non-sensicle number compared to TPS your ECU will then flag a bad MAF.
As you have observed, the result of the incorrect air mass flow report is the faithful o2 sensor reporting lean - both are at fixed low voltage in your screenshot showing a fixed lean reporting status. In closed loop the LTFT must keep the STFT close to zero and so the long term Fuel trims drive a rich command by increasing injector pulse width by 25%.
Assuming that your software is getting accurate values from your OBD interface then the symptoms of a bad MAF were there in the evidence.
Now that you have a new MAF you need to record the correct values at idle, and various constant speeds (MAF,TPS, fuel trims RPm, calculated load and O2) File this away. Can you record a data stream with your software?
In the future if you see the same fuel trim story and the MAF/ TPS values are spot on from your records,you will now know you have an intake leak or fuel pressure issue.
When your car is running well you must take a data snapshot for a few minutes at each load condition for future trouble shooting.

[Tikka7mm08]

Yes I will post what I can for comment this weekend. I am using Torque.

This is BT I purchased;

Scantool 426101 Obdlink MX Bluetooth OBD II Scan Tool Interface | eBay (http://www.ebay.com/itm/ScanTool-426101-OBDLink-MX-Bluetooth-OBD-II-Scan-Tool-Interface-/301062826662?hash=item4618be2aa6&item=301062826662&pt=Motors_Automotive_Tools&vxp=mtr)