Hi All. Jerwin here from the Philippines. I was pointed over to this site by another member here. I'm mostly a lurker on the other site, though I've posted a couple of queries there (and provided what little input I could).

I own a 1997 NAS 4.6 P38. Had her since September 2014. Wasn't really much of a car guy prior, and even much less a home/DIY mechanic. But you learn things. After having a couple of things (expensively) done at local independent shops, I started trying stuff out myself. Mostly the easy-ish stuff: I've rebuilt a couple of valve blocks (I have 3 now -- and STILL battling leaks...), replaced the EAS pump, replaced the brake accumulator, bled brakes, swapped height sensors, replaced the fuse box, replaced tailgate cables, and maybe a couple of other minor things. I've also had some stuff done at non-LR specialist auto shops, supervising the mechanics VERY closely, armed with printouts of how-tos I found online -- this way I've had the AC compressor disassembled and the clutch replaced, then the whole AC compressor replaced with a new one, front air springs replaced, as well as rear brake rotors and calipers.

The above stuff I've NEVER done for any other car. The extent of DIY-ing I think I've done with my Honda Civic is replacing a flat and maybe the odd headlamp bulb.

I presently am in the midst of the aforementioned EAS battle (rebuilt one of my valve blocks over the weekend and swapped it in, but front is dropping very quickly with the car off -- I suspect the solenoid plungers, or maybe the quality/fit of the o-rings I got off eBay, or maybe I screwed up (much less likely, I'd like to think)). I also have a new MAF I'm planning to swap in in the hopes of curing my 8.1mpg (!) average -- atrocious I think even for epic Manila traffic (Waze satisfaction index of 1.8 for 'density and severity of traffic' where 10 is the best score). Aside from these, there a couple of rattles and creaks I hope to finally get the chance to find and cure as well.

Looking forward to exploring the forum and maybe posting some, too!

Cheers.

Hi Jerwin and welcome ! Have to comment on the 8MPG of yours (OK, sorry, 8.1MPG..) as it is equivalent to one pint a mile
This is indeed bad, even for a 4.6 (unless you really are stationary/stopped most of the time); Have you done any diagnostics ?

Glad you finally made it Jerwin!

davew wrote:

as it is equivalent to one pint a mile

That mile must take him at least half an hour then.
On the other hand, I can do a pint in less than 5 minutes, not moving at all!

Welcome jerwin, my other half works a mile away, she manages 9.4 mpg, with clear roads, lol, re the front dropping, have/did you take a 1/16 off the end of the pipes to valve block, if they've got a scratch they will leak, I always chop a bit off and chamfer the edge, spray soapy water all over and look for bubbles.
Now your on here your become a p38 mechanic in no time..

Thanks for the welcome, all! Thanks, GeorgeB, for pointing me to this site.

@davew, no I haven't done proper (RR-specific) diagnostics. A friend's generic OBD2 scanner read 2 faults -- one (P0113) supposedly relating to the intake air temp sensor and the other (P1178) supposedly relating to the MAF and/or O2 sensors and/or related stuff. Because of P0113, I checked the IAT sensor and lo and behold, the connector wasn't seated properly. Re P1178, I actually have a new MAF which I haven't fitted yet because I've read that ideally when fitting in a new one, adaptive values must be reset. When I get a spare half hour, I'll maybe try stick in the new MAF just the same and just see if the car starts and if there's anything different (idling?).

@Ferryman, it's nowhere near a common thing here, but my record is I believe 3 hours covering 20km (12.5mi). :-)

@no10chris, thanks for the tip. As a matter of fact, I only ever did the chamfer thing on my previous block swap. I did do the soapy water test, and it seems at least that the air line-block interfaces are good, which is why I'm suspecting the solenoids. Actually, after having sat for a day, with the delay timer removed, the rears also dropped. I'll recheck the air lines when I get the chance this week.

Thanks again!

Adaptive values should be reset so it can start learning from scratch rather than having to correct from incorrect (if you follow what I mean) but as long as it will run, it'll soon adjust itself anyway.

Gilbertd wrote:

Adaptive values should be reset so it can start learning from scratch rather than having to correct from incorrect (if you follow what I mean) but as long as it will run, it'll soon adjust itself anyway.

Problem here is the time that takes, mainly because it's often difficult to get a mix of driving in, especially where I am. As an example, if I fitted a new MAF on a Monday, it'd be likely the following Sunday morning before you get anything but stop-start!

Anyway, Jerwin knows where I live and although he's not local, has a standing offer to hook up to my Nano whenever he needs to, but don't let that stop you giving him the good advice! None of us know everything, 'specially me.

aero wrote:

@Ferryman, it's nowhere near a common thing here, but my record is I believe 3 hours covering 20km (12.5mi). :-)

I think my worst was two hours to get from Meralco HQ in Ortigas to beyond La Salle Greenhills school. Distance? 2km! For the Brits, they park three abreast on a four lane road outside the school at kicking out time. There's a major flyover joining just before this as well.

A client of mine was supposed to meet me for a beer after his meeting at PNR headquarters in Tutuban. I was in my local (Adriatico in Malate), so about 6km away when, three hours late, he called to say the hell with it, he was going home. Unfortunately, it was just before the Pope's visit when they practiced closing the roads all around my place, but didn't tell anyone!

GeorgeB wrote:

I think my worst was two hours to get from Meralco HQ in Ortigas to beyond La Salle Greenhills school. Distance? 2km! For the Brits, they park three abreast on a four lane road outside the school at kicking out time. There's a major flyover joining just before this as well.

I know that area and yeah that's given me some anguish as well! Authorities were supposedly cracking down some time around the start of the school year (June), but after a couple of months I believe it was business as usual.

A client of mine was supposed to meet me for a beer after his meeting at PNR headquarters in Tutuban. I was in my local (Adriatico in Malate), so about 6km away when, three hours late, he called to say the hell with it, he was going home. Unfortunately, it was just before the Pope's visit when they practiced closing the roads all around my place, but didn't tell anyone!

Ah yes, these traffic planners seem to be of the philosophy that it's better for motorists to not know (and not complain).

Gilbertd wrote:

Adaptive values should be reset so it can start learning from scratch rather than having to correct from incorrect (if you follow what I mean) but as long as it will run, it'll soon adjust itself anyway.

GeorgeB wrote:

Gilbertd wrote:

Adaptive values should be reset so it can start learning from scratch rather than having to correct from incorrect (if you follow what I mean) but as long as it will run, it'll soon adjust itself anyway.

Problem here is the time that takes, mainly because it's often difficult to get a mix of driving in, especially where I am. As an example, if I fitted a new MAF on a Monday, it'd be likely the following Sunday morning before you get anything but stop-start!

Anyway, Jerwin knows where I live and although he's not local, has a standing offer to hook up to my Nano whenever he needs to, but don't let that stop you giving him the good advice! None of us know everything, 'specially me.

But putting in the new MAF without resetting the MAF shouldn't result in anything debilitating, would it? I mean, if I put it in now, and use it a bit, and reset once I get the chance? (Btw, @GeorgeB, thanks again for the offer, I'll get in touch with you with a week's notice or so.)

And while on the topic, while researching MAFs, I came across an ad for a MAF o-ring, even found a part number for it: NTC3354. For those of you who've changed your MAFs -- did you change this too? It seems my rig doesn't have this (wasn't any when I took out the MAF before).

No - a new MAF will not cause 'anything debilitating' but as others have indicated it takes a while for the ECU to get used to it and (eventually) effectively re-set the Adaptive Values to suit. In practice this means a range of different and representative 'Drive Cycles' (and at various speeds too - so that for instance being stationary in traffic will really slow down that process). MAFs are rather tetchy things (even on a GEMS rig like yours) and sealing with an o-ring will help indeed !

From the Nanocom documentation:
Adaptive air flow value (Kg/Hr): The Adaptive AirMass Flow Rate (AMFR) is learnt by
the system over a period of time and is added to the normal air rate to compensate for
manufacturing tolerances between airflow components. The extremes of tolerance that
GEMS allows for is + 5.5 KG/HR to -5.5 KG/HR. after which it will log a fault in its fault
code memory.

So if your existing MAF is giving slightly low readings the AMFR will have adjusted to compensate. Resetting the adaptive values will zero it so it will be re-learning from scratch but if it had gone one way and you don't reset the value, it will need to adjust to a corrected value which may be a touch the opposite way so take a bit longer.

I've often read about marque specific tools being necessary to reset adaptive values etc but I've never needed to use any of them. After fitting new parts such as AFM's, lambdas, etc, for sure sometimes the mixture doesn't automatically correct if the vehicle is just left idling and that can lead to problems but there are ways of getting around the problems.

What can happen is that short term trims immediately reach an extreme (positive or negative) to compensate for improperly learned (when bad part was fitted) long term trims and when short term trims are at an extreme they no longer effect long term trims. So, e.g., if the vehicle is fitted with new probes and just left idling, a mixture error code can be generated. Imagine Ltfts have been incorrectly learned to -25% but the engine really needs Ltft's to be +10% for correct mixture. In this case Ltft's are 35% too lean, so if Stft's max out at +25% the engine will run always run lean because -25(long) +25(short) = 0, where we need 10, so the engine will run 10% lean and this won't auto correct because with Stft's at an extreme Ltft's won't adjust (we would need Stft's to max out at at least +35% for this problem to correct itself). If this situation continues we soon get an OBD error for mixture too lean, so then the ECU may go into limp mode and just ignore the probes anyway...I can see why resetting adaptive values is suggested here and on other forums/threads where this is discussed.

But, what I find is that if new parts are fitted and then the vehicle is held at fast idle, this is usually enough for short term trims not to reach an extreme regardless of long term trim state, and with short term trims not at an extreme they do effect long term trims, so long term trims are soon steered to around correct values... and then the vehicle won't generate any error codes and will run properly in closed loop mode. I just monitor lambda voltage and short term trims after fitting new parts, and then nurse the fuel trims back to normal (usually fast idle works, or may need holding on the brakes in drive while a bit of throttle is applied, or less often a short road trip where you can place as much load on the engine as you like). In case you're monitoring lambda/trims and haven't seen lambda flick or Stft's shift from extreme for a while, pretty soon an OBD code may be logged, but a quick blip of the throttle will usually prevent that, because this gives a blip of rich mixture (due to acceleration enrichment, so lambda lean timeout is prevented) and time out on any particular set of fuel trims is prevented (because after the blip the engine will momentarily go open loop). Seems to work on just about anything, P38s and all the fussy stuff like BMWs, Jags, etc that we're supposed to need to reset adaptive values on.

Simon

That's a very interesting theory/approach LPGC/Simon ! When I have tried this (and monitored the Trims in real time) it certainly takes a long time for the Trims to settle down though - as these ECUs can be quite unco-operative ! Perhaps next time I will try it however....

Guessing you are familiar with this:

http://www.rangerovers.net/forum/12-diagnostic-equipment/20300-diagnostic-trouble-codes-gems-drive-cycles.html

I agree that with some vehicles the ECU will learn to accept new Lambdas etc with just a fast tickover for about 20 minutes

I've always considered P38 drive cycle tests to complete very quickly and trims to shift quickly. Also, they have a simple set of trims compared to many vehicles (which might have more sets of Ltfts and be quite fussy around idle).

I'm not familiar with the drive cycles you linked to but I am very familiar with the concept - Every vehicle ECU has a set of drive cycles that must be completed without any problems before the ECU will report 'IM readiness complete' (which is ECU's way of reporting all drive cycles/tests have been done and passed), each such drive cycle can be considered a test roughly aimed at checking a specific set of components under the driving conditions of that test, so for each component to be deemed as checked and found good it has to pass all tests aimed at it. But it isn't necessary to know the specifics of each test, because well before all tests are complete fuel trims (including Ltfts) will shift properly, the vehicle will drive properly, and as long as there are no other problems all the tests will eventually be successfully completed (and then IM readiness will show as completed) anyway. So, if you're starting from a point where you know only one component was at fault, and you know you've fixed it, then you know that pretty soon all tests will be passed. Tests can be guessed - they will include a warm up cycle, a cruise at low speed / higher speed, acceleration, an idle test, engine restart. Having cured the immediate problem and reset fault codes the vehicle should drive properly (may need to help steer the trims as in previous post) and no other faults should come up,. I've never needed to look up drive cycles etc either, just drive under various conditions, let the engine idle, turn it off, restart, etc. P38 tests complete relatively quickly just by normal driving but my scanner (which isn't a very expensive type at all) shows which engine components have passed IM readiness tests, so if for example scanner shows heater circuit on a particular lambda probe hasn't passed the test yet, I'll know that either the probe has an actual heater fault (but then it would usually come up with a code for open heater circuit anyway) or the ECU is waiting to see if it gets a viable lambda reading soon after engine startup (probe won't show correct reading when cold even if the sensor component in the probe is good). Of course, probe will only give a viable reading with cool engine running closed loop soon after start up if Stft isn't maxed out and if the probe heater is working properly... so it can be necessary to read between the lines (as is always the case with diagnostics) - IM readiness reporting probe heater circuit hasn't passed tests could be due to actual (maybe intermittent) lambda heater fault or could simply be due to Stfts being maxed out.

Work on a lot of different make/model cars and have never needed to look up vehicle specific drive cycles etc, not even on Valvetronic BMWs which have far more complicated ECUs, trims and drive cycles.. easier just to wing it / read between the lines. If you were to carry out all those drive cycles on a P38 it would take you over 30 mins, but I'd usually have IM readiness checks completed and passed in far less time. If you try to follow those drive cycle checks having replaced a component such as a lambda probe or MAF sensor you might be there a lot longer than half an hour, because you might never pass drive cycle A, which says start the engine up and let idle for 2 mins, because during that 2 mins of idle the ECU might come up with fuel trim error due to maxed Stfts as discussed above.

Simon

More interesting comprehensive stuff Simon, cheers ! As you indicate -and the original concern - the main issue was that the OP may not be able to perform the Drive Cycle/s in his particular location and the ECU would (or could) then just 'Open Loop' on him and thus effectively ignore a new component... In practice we know it may depend on the specific component in question (eg. the GEMS ECU may be much happier to accept a new MAF than a new Lambda) and I suspect that is why LR suggest a 'general/universal procedure' when components are changed, depending on the particular engine (?):-

http://workshop-manuals.com/landrover/p38/17_emission_control/fault_diagnosis/drive_cycles_from_99my/

http://workshop-manuals.com/landrover/p38/17_emission_control/fault_diagnosis/page_363/

Not sure why they don't say 're-set the Adaptive Values etc with the T4/TestBook' though ! (Either it couldn't... or more probably LR stealers wanted £££/hrs Road Test fees ?....) Don't know if the OPs rig being NAS makes it different either.... ie. it may take longer to clear any Fault Codes just be revving it up whilst stationary for a while (?) All our pre-full OBD beasties seem (fairly) reluctant to flag Codes and then to erase them once cleared (eg. by faulty component replacement) if just left to their own devices though, that's a fact...

Again I do like your idea of simplifying (or simulating some/most of it) whilst stationary and will try it next time.
(Like many on here I have a way to reset Adaptive Values anyway but previously considered raising all 4 wheels.
-yes all 2 tons of it- up on blocks to hasten the adaptation process...)

If it's a GEMS, make sure there's a decent amount of fuel in it as the ECU locks the trims if it thinks the fuel level is low. Apparently this is so that the trims do not react to short term variations due to fuel slosh when level is low.

Great tip, Cheers OB !

I read OP's problem about maybe not being able to complete drive cycles, didn't know if he had a way of resetting adaptive values, thought the above would be of interest anyway, hence the post..

I suppose from LR's point of view it's in their interests to identify every problem etc during one visit from a customer... and performing the drive cycles would help with that (as well as being a chargeable procedure in it's own right...). But for a fairly clued up DIYer or generic garage, it might be apparent that just one component is at fault, in which case my method of preventing further codes.... that would otherwise prevent drive cycle completion being possible... is a good way to go.

It doesn't matter to an owner if drive cycles are completed, it's of no consequence, no need to rush and perform special procedures just to get a thumbs up from an engine ECU, especially not if you're reasonably confident you've just fixed the one component you know was the underlying reason for poor performance / error codes, if you have a basic scan tool that can show you all is well as you drive even before drive cycles are completed (or don't mind looking into any further error codes that might become apparent at some later time)... my method works without Nano type equipment and without wasting any fuel, time or effort.

I believe the most fussy ECUs fitted on Landrover models with the the Rover V8 are in really late model Rover V8 Disco's, the one with EGR, which do turn on Mil lamps if there is a problem... still relatively unfussy though.

How low does the tank need to be before trims are locked OB? Quite a few LPG users run with very little petrol in the tank lol!

Simon