Member Since: 17 May 2019
Location: Kerpen
Posts: 181
Limb mode without fault code is not possible!
12th Jun 2020 12:29 pm
RichardLlanfyllin
Member Since: 30 May 2019
Location: LLANFYLLIN
Posts: 17
Right! Getting to the bottom of it. There is a code stored: P0000. As soon as I heard that I realised that it related to the EGR valves - I had an EGR delete a year or so back and they said that if ever that error comes up, it will be related to the EGR system. I asked about blanking and they said it wasn't required because both EGR are stuck shut.
Roll on January this year and as I went to the tip to dump a tree and boxes, went to start the car and got the dreaded oil pump fail; I had assumed that because the belts had been done 3 times in the cars history that the pump will have been sorted but no.
End of February (insurance delay) I got the heads refurbed (all new valves in one head and the other head was fine). All skimmed, polished, new cams etc. etc. New belts and uprated oil pump got the car back and it went like a train. That evening I drove to Pwllheli and it went into limp mode 4 times; stop start and its fine. It seemed to do it when I needed more power like a hill. Took it back to the garage the next day and the only thing they found was a "low fuel raise pressure"; reset the codes and said it might be just an odd thing after the rebuild. I drove home and it seemed a little lower on power but went fine; no more limping.
I found an oil leak on the rocker and because the original garage had closed due to this stupid covid, I went to another garage who diagnose a leak in one rocker gasket and the servo pump seal so fixed both. "By the way, there were loads of things unplugged so I've plugged them in". (I now think the MAF was unplugged all the intervening time). I explained that I had an EGR delete and just left it unplugged. But the car was running like a train again. Next day, BONG and the limp mode comes back. I went back to the second garage and "Low fuel rail pressure" is back. Using various guides not least Robbies I checked the LPFP and we decided it might be the fuel filter so fitted a new one. No difference. Back to the second garage and that "low fuel rail pressure" is back suggesting an expensive HPFP. They hadn't done one before so suggested I take it to a LR specialist.
So the prospect of driving 40 miles not knowing how many times it would limp didn't fill me with confidence. Again, reading on here I unplugged the MAF sensor. Drove the 40 miles to the specialist thinking "That's it! It's the MAF sensor". Got to the LR specialist, explained the story and interestingly he said "you can only delete that low fuel rail pressure code peoperly with a LR scan tool - most say "deleted" but they haven't. So they tested everything an the HPFP was fine: 24500 pascals, injectors all in range. They put on a new MAF sensor and then said "we've not bothered with the new MAF sensor coz it reads exactly the same as yours HOWEVER, you're lacking boost pressure. Air is getting in somewhere into the system, the ECU can't resolve it so it goes into LIMP mode....you know when you delete the EGR's you must blank them off and remove the butterfly otherwise if air gets in you'll lose boost?" he said. And he suggests using a proper kit rather than hacked bits of metal as you don't want further leaks or MOT testers spotting it.
It turns out that when the EGR's were bolted onto the now rebuilt engine, the valves must have been disturbed into an open or partially open position and as the EGR's are deleted, there's no software to close them.
So that's it. Thanks to Covid, we can't get a blanking kit until thursday this ween (I live in the middle of Wales so additional delivery issues). However, I'm looking forwards to plugging the MAF in and being thrown back in my seat right away rather than a second later. But! If it happens again, I know now to just pull the MAF connector out.
12th Jun 2020 2:13 pm
white rover
Member Since: 30 Jun 2020
Location: perth
Posts: 13
2010 Disco 4 2.7D U2023 and P2290
Firstly Thanks for the Great write up !!
Im new to this Forum, so Hello everyone ! Im based in Perth Western Australia.
Recently brought a 2010 Disco 4 with 270 000kms on the clock, Ive always owned Toyotas until a couple of weeks ago!
The Disco keeps going into Limp mode with U2023 and p2290 codes coming up.
Basically codes have been popping up since day one, before servicing the car pretty much every time you plant your foot through the firewall it goes into limp mode.
I gave it a service, changed the fuel filter and replaced the Trannys filter and oil (flushed it out twice)
the box seems to be substantially smoother which is great, However it still goes into limp mode but now its alot more intermediate.
at this stage I found this Forum and this article, So the testing begun last night around 1030pm !
I found the draw on the LPFP to be 3.47amps when the ignition is on and 4.1amps when the car is idling.
(Alternator seems to be producing a voltage of between 14 and 14.1Volts at idle. )
the pressure with ignition on was about 7 or 8 PSI, At Idle it was around 4 or 5 Psi
If you rev the car up to about 2500rpm the pressure drops to around 1 psi.
I attempted the fuel flow/rate test. I ran the LPFP for 1 minute and out came only about 700ml in that minute. the test was done from the pressure release valve and with the ignition on.
I believe it should be more like 1.7 + Litres or so ?
However I used a tyre pressure gauge to do this test, I removed the line from the gauge to allow free flow.
I am going to do this test again after I purchase a valve removal tool, As I am assuming having not removed the valve needle from the release valve will slow the rate of flow down ?
So my Assumption currently Stands with the LPFP or something to do with the pickup inside the tank ? for a few reasons car has 270ks on the clock so it would be about time to clean the fuel tank out anyhow!
Secondly the car seemed to have less issues after changing the fuel filter. ( Interestingly after changing the filter the car doesn't go into limp mode with full throttle) only randomly while at cruising speeds!
All in All I Brought this car for the Missus and to do a trip up the North West Coast of WA in a few weeks. Ive done this trip 4 or 5 times in a Landcruiser, without a hiccup so I thought it would be a walk in the park for the Landy !
1st Jul 2020 12:29 am
white rover
Member Since: 30 Jun 2020
Location: perth
Posts: 13
I should add to the Previous Owner had the engine reMapped. at 50 000kms.
Also, I just drove it with the OBD2 comp plugged in and the fuel rail pressure only goes up to 185000 when under 100percent load at 3000rpm, seems a bit low maybe ?
1st Jul 2020 12:34 am
wedgev8
Member Since: 17 May 2019
Location: Kerpen
Posts: 181
The rail pressure 18500 seems a little high. Maybe this is the remapped ECU. Normally it should have 1600bars.
The best way to a solution is getting a good diagnostic tool. I have a GAP IID Tool. Whithout this tool I would have brought my Disco to the scrapyard.
1st Jul 2020 6:31 am
white rover
Member Since: 30 Jun 2020
Location: perth
Posts: 13
thanks, I may have to order one. I brought what I thought was a good unit but its very limited to the information it gives me.
just finished pulling the tank out and the LPFP seems to be working well when bench testing it she flows at around 3 Litres a minute and runs pretty smooth. the little metal mesh filter on the bottom of it was half blocked but I wouldn't say it was to dirty !
anyways im about to start putting it back together and re install the tank, Then I might get it remapped back to factory tomorrow see if that solves it! if not then off to get a new HPFP I guess.
1st Jul 2020 7:03 am
wedgev8
Member Since: 17 May 2019
Location: Kerpen
Posts: 181
Before getting a new HPFP you should test with the diagnostic tool. for example with the IID tool you can see the live values of fuel pressure and PCV and VCV in a diagramm while running. And read the chapters in the Workshop manual. This is füll of information about the complete fuel system.
Last edited by wedgev8 on 1st Jul 2020 2:35 pm. Edited 1 time in total
1st Jul 2020 8:03 am
white rover
Member Since: 30 Jun 2020
Location: perth
Posts: 13
I may need to look into getting a better OBD2 reader than, the one I brought only shows me the fuel rail pressure, and nothing else as far as fuel goes.
Got the car all back together and even changed the brake pedal switch ( someone else recommendations)
Still goes into Limp mode. its really strange!!
1st Jul 2020 1:06 pm
RichardLlanfyllin
Member Since: 30 May 2019
Location: LLANFYLLIN
Posts: 17
So the saga continues.....and the solution appears to be a HPFP.
I managed to find a posting on a forum somewhere in the world that exactly described my problem and the cause. Heavy/hard acceleration appears to have no effect and neither does gentle acceleration. My limp mode happens when you have steady cruising pressure on the pedal and usually going up a slight incline. It turns out that the pressure control valve in the HPFP sticks at this point whereas under hard gas, the valve shoots open/closed normally. Once the valve sticks, the rail pressure obviously doesn't get up that requested and the PCM assumes a fuel empty situation. And as such throws the car into limp with the usual F etc. so as to (ironically) preserve the HPFP.
There was some discussion whether low sulphur diesel is the cause of this as it doesn't give the same lubrication.
Biting the bullet and getting a new HPFP fitted next week.
1st Jul 2020 3:24 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5044
Could you not learn to live with it by feathering the throttle appropriately when needed? I know this can be a pain having to constantly make adjustments, but you'd be surprised how quickly you train yourself!!
Just ask anyone who has had to live long term with a slipping clutch
By the way, did the fault occur when you are using cruise control at set speed? The other thing I would suggest is to add 2 stroke to your diesel tank for a few weeks and see if the suspected PCV or VCV finds its mojo again!!!yµ (idµ - eAµ) ψ=mψ
1st Jul 2020 3:33 pm
RichardLlanfyllin
Member Since: 30 May 2019
Location: LLANFYLLIN
Posts: 17
Here's the problem. I live in mid wales and surrounded by hills. I can't avoid them. The other thing is that the Limp mode thing is totally unpredictable. The other day I drove about 20 miles and it went limp and continued to go limp maybe a dozen times. I drove limp for about 5 miles then pulled up to restart as there was a hill coming up that no way would it make it up in 3rd. What happened? It drove perfectly all the way home. There's no prediction as to when this will happen. You can go days thinking its cured then BANG!
If someone could pull the code off the PCM, I could probably write a work-around as the stuck valve does clear. It would be easier if the LPFP was monitored tbh.
The car drives absolutely beautifully - probably the smoothest ride I've ever owned (and my 6th disco) so as I said.....time to open the wallet and get it done
1st Jul 2020 5:12 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5044
In the meantime try some two stroke! It won't harm it and there's plenty written on here regarding same. I don't use it personally as I use a different additive, but if I thought the valve was sticking I'd be happy to give it a try.yµ (idµ - eAµ) ψ=mψ
1st Jul 2020 5:21 pm
RichardLlanfyllin
Member Since: 30 May 2019
Location: LLANFYLLIN
Posts: 17
Yeah. 2 stroke. I've tried to find some more detail on here about that as it was mentioned a few times. What's the purpose? Any downsides? How much to add?
1st Jul 2020 5:32 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5044
There are some members using it regularly for years without incident. The thinking seems to be as diesel has lost much of its lubricity due to "cleaner fuel" policies, some have added it to counter those lube losses. There is a 2 stroke thread on here which should give you the correct amount, but I wouldn't worry too much on that factor. A guess would be around 300ml to a fill tank of diesel, but you should check the threads for a more accurate ratio.yµ (idµ - eAµ) ψ=mψ
1st Jul 2020 5:47 pm
RichardLlanfyllin
Member Since: 30 May 2019
Location: LLANFYLLIN
Posts: 17
I found the thread and interesting it is indeed. All subjective really "bit quieter....maybe more MPG".
I looked for a read study and there was one "scientific" study done in South Africa. Most worryingly in the conclusions was, yes, there was a marginal increase in lubricity on some diesel fuels, but in a long term bench test, there was a drop off in performance due to zinc particles (in 2 stroke) being deposited on the injectors and that was at 1 ppm - many 2-stroke oils have 16ppm. So that's a little worrying.
But. It remains. Better to fix the actual problem rather than lube your way out of it
EDIT: A few years back I was working in the biocides industry (supplying Libya of all places with Iodine and other chemicals to disinfect various terrorists) - one guy I worked with had this additive which could go in fuel or the engine. His claim was that the long-chain molecules adhered to the metal parts of the engine and fuel system and because the two facing surfaces had the same electric charge, they would repel and therefore reduce friction. He swore by it and reckoned he could get an extra 15% on mpg. I got a few bottles but before I shoved any into my tank or engine, I did some research. There were a couple of issues: one was that the molecular chains were so long, the actually decreased the clearance between surfaces and caused more friction; but the best one was that (as he found out) one of the elements of that additive ate through copper squash washers on injectors.
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