My P38 is not behaving it self

[old dirt bikes]

Hi Folks,
just when you think you fixed everything something else goes wrong. So after replacing the fuel pump again because the previous one was not holding rail pressure. The non return valve must have became stuck. So I fitted a new pump and it was a lot easier to start. I filled it with fuel a couple of days later and all was still good. Then it started running rough and stalling at the lights etc. I pulled the fuel filter expecting it to be full of water but no, it was clean. I was thinking either throttle position sensor or air flow meter. I pulled the air flow meter and it looks nice and clean in side. Then I replaced the TPS, and it has improved. Not perfect but a lot better. At least it will idle now. It was only a second hand one so I will order a new one. I will put it on a scan tool next week, but I don't think I will find much as the check engine light is not on. I think I have a spare air flow meter some where, so I will try it on the weekend.
Does anyone have any other ideas???

[prelude]

Check the idle air control thingy. Don't try and move it by hand btw. it will damage it. I had to replace mine a couple of years ago and it took the damn computer months to get the auto-learning stuff up to speed so that the car would no longer stall. I also reset the adaptive learning figures in the ECU at that time.

Also an air leak in your system will wreak havoc. I tested it by using a smoke machine and a pressure hose to see where the smoke would escape. In my case it was the o-ring that closed the butterfly valve. That was a hard one to track down!

Cheers,
-P

[PeterH]

First thing I would do is a diagnostic scan , even though the check engine light is not on, it may point you in the right direction.
My first thought is your CPS might be on the way out and causing rough running and stalling.
When they die it's a show stopper, I wouldn't drive it too far like that.
I would also check and clean the butterfly valve with carby cleaner, specially the edges, gunk can build up and cause idle problems and stalling.
Hope that is of some help.

[old dirt bikes]

Hi Prelude and Peter, thanks for your suggestions. I had to go out last night and it is worse when it is cold, so it may be temperature related. I have a new idle speed control valve so I will put that on tomorrow, and clean the throttle valve etc. I also have a new crankshaft position sensor in the car so I will try that as well. Once it gets up to normal operating temperature it runs quite well except for a slow idle. I will go to work on Monday and check it on a scan tool and see if there is anything abnormal.
Thanks Guys.

[old dirt bikes]

Hi Folks,
I have made a little progress, I replaced the idle speed control valve and wound the base idle screw out 4 turns and the idle seems a lot better. I checked for codes on the scan tool and it came up with PO131 and PO151 low voltage at the O2 sensors. I checked the fuel pressure and it was normal. But flat spots in the motor seem to be caused by a lean mixture. Increasing the fuel pressure increases idle speed and manifold vacuum. Driving the vehicle with the vacuum line disconnected from the fuel pressure regulator and the car drives a lot better. All very strange. Tomorrow I am going to go back to something my friend Tom the TAFE teacher told me. When someone brings you a vehicle with a problem, you ask 2 questions. Who was the last person to work on it and what did they do, and start looking there. So the last person to work on my vehicle was me and I changed the fuel pump. So tomorrow I am going to put the old fuel pump back in. Lucky I cut that hole in the floor. At least then I will know for sure if that new fuel pump is to blame, and if not I can move on to testing other things.
Regards,
Alan

[PeterH]

Interesting that you found low voltage at the 02 sensors and possible lean mixture, I wonder if that might be MAF related?
I'd also check the air intake is sealed properly, unmetered air can cause problems with idle and running.
I cut a hole to do my fuel pump as well, makes life so much easier.

[old dirt bikes]

Hi Peter,
well I changed fuel pumps this morning and went for a short drive. Still the same. So tomorrow I will change it back. I picked up another fuel filter today, and I will change it tomorrow as well. And I will check all the intake for air leaks. And just for the hell of it I will put some Fuel injector cleaner in the tank, as all these problems started after I filled the tank. My wife's BMW was running like a bag of s--t one day, and I was very busy so I drove it to the Holden dealer and got some of their fuel system cleaner, put it in the tank and took it for a thrash on the highway. When I started it could not get up to 80 kph. On the way back it was doing about 160kph. So worth a try for the P38. I did put new injectors in it a while back so I do have a spare set.
Regards,
Alan

[old dirt bikes]

Hi Folks,
well I changed the fuel pump back to the new one and I then went to change the fuel filter. I wanted to see exactly what came out of the filter so I cleaned all around it and had a clean container to catch all the fuel in. So I pulled the fuel filter and drained it and it was completely clean, not a speck of dirt. I was thinking I will have to keep looking. I put the original filter back on and went to throw the fuel in the container on some weeds, and I noticed the fuel looked like it had wax floating on top of it. So I bought some Liqui Moly fuel injection cleaner. Put that in the tank and went for a drive and after a few kilometers it was running a lot better so I took it up a big steep hill near home, and it just walked up to the top. So I am hoping it is fixed but I will see how it goes tomorrow morning. If it was a load of crappy fuel I will have to change service stations and carry a couple of cans of fuel injection cleaner withe me.
Regards,
Alan

[old dirt bikes]

Hi Folks,
Well I drove my P38 to work today and although it was definitely better it was not perfect. So if it was the fuel it will take a while as it has over 3/4 of a tank full. I could drain the tank but I would have to grow a lot more weeds to put the old fuel on. And the missus would complain about the smell. So I think I will take it for a long drive and then refill the fuel tank and see what happens.
Regards,
Alan

[old dirt bikes]

Hi Folks,
Well I went for a good drive and got the fuel down below 1/2 a tank, then refilled with 98 octane. I towed the boat down to the river this morning, about 3/4 hour drive of both highway and off road and it performed faultlessly. So good news all round, it looks like the problem with the motor is fixed and we caught some mud crabs. So from now on I will carrying some fuel system treatment with me and I have changed servo's where I buy my fuel. Merry Christmas everyone, and lets hope next year is better than the last couple.
Regards,
Alan

[PeterH]

That's great news Alan, glad you got that sorted!
I have not struck a bad batch of fuel for a long time, but I'm sure it can happen sometimes.
I put some Moreys upper cylinder lubricant and injector cleaner every few tanks, a bit of preventative maintenance.
All the best for Christmas, happy travels!
Pete.

[old dirt bikes]

Hi Pete,
yes that is the first time I have had bad fuel for a long time. The last time the fuel was full of dirt (fine rust) and it went into my boat. We got about 35 mile out to sea and the whole fuel system was blocked. I had to keep dismantling and cleaning the fuel system to try to get home. It took hours, but we made it home. We went down the river again this morning and the hesitation is only just noticeable when you start off cold, then it is gone. So I think will get better when I use up this fuel which is 50/50 new and old.
Regards,
Alan

[old dirt bikes]

Hi folks, well things have progressed, sort of. Just before Christmas I ordered a pair of O2 sensors, as some times it just would not run right. And they turned up on Christmas eve. When I opened the box, wrong ones. So today was my first day back at work for 13 months. After a couple of hours in the office I had enough, so I went to the workshop and put the scan tool on my P38 and went for a drive, and it started to play up, and I could see one O2 sensor was working correctly and the other one was doing nothing. And it played up on the way home as well, and I still had the scan tool on it and I could see it on the graph again. I have another one, second hand, but I think it is OK. So tomorrow I will change them over and see if that fixes the intermittent problem. On another note I went to see the doctor today and it looks like I have two more skin cancers on my right hand that I have to get cut out. I guess welding without gloves is not good for you. So I will see what tomorrow brings.
Regards,
Alan Temperley

[PeterH]

Ah, bugger about the skin cancers Alan, geez you are having a tough run there, hope they get this sorted for you and that's the end of it.

Did you get genuine 02 sensors, or after market?
I got after market O2 sensors for mine and had all sorts of problems with them.
The plugs were covered in black soot, it was even coming out of the exhaust!
Then I got genuine Bosch sensors, (mine is a 2001 Thor 4.6) and the problem was solved straight away, I just had to reset the long term fuel trims and all was good instantly.

[old dirt bikes]

Hi Peter,
yes the skin cancer is giving mea hard time. But at least there is only two. Not sixteen like last time. I ordered a set of Bosch ones, but they were not correct. they were listed for a P38 but they were for a L322. So I sent them back. I have now ordered a set from my local Land Rover specialist. So while I am waiting for them to arrive I am playing around with the second hand ones I have. If I can get it to run OK on these, I can put them in the back of the car as a set of usable spares. The spares box is overflowing.
Regards,
Alan Temperley

[prelude]

(skin) cancer sucks :( good luck with that mate!

Anyway, regarding the O2 sensors. The last time I replaced mine a got a set of cheapies from... I believe spain? They have given me some headache. Somehow OEM stuff is usually better, go figure :)

Cheers,
-P

[old dirt bikes]

Hi Prelude,
yes pretty much over the operations and pain etc. I have OEM ones ordered, might be here tomorrow, so hopefully that will fix it. But I am not ruling out a wiring fault. That was the problem with the knock sensors. I replaced the knock sensors and the problem was still there so I opened the wiring harness and the insulation on the wires had turned to dust, and all the wires were touching together, so I replaced the wires and earth shield and all was good.
Regards,
Alan Temperley

[PeterH]

Alan, do you have a way of resetting the long term fuel trims?
I have a faultmate extreme which does the job, after I fitted the new 02 sensors, resetting the long term fuel trims had it instantly running perfectly.
Once you fit the genuine 02 sensors, you will need to do that.
Hopefully that will have it sorted for you.

[old dirt bikes]

Hi Peter,
yes one of the scan tools that I have access to will reset the fuel trims, when I get that far. I finally got my new O2 sensors and fitted them on Friday. We still could not get it to run right and the scan tool said that the right side O2 sensor was shorted to earth. But the left one was working, producing a good signal. Also the scan tool said the air flow meter was not working, constantly showing idle air flow. So I replaced this and now at least that is working. So I gave up and went home, Thinking that the problem must be in the wiring harness. So this morning I dismantled the car enough to remove the wiring down the right side of the motor and cut it open all the way up to the computer, and I removed the earth shield. and tested for shorts to earth and it was still shorted. So I checked the pins on the computer and I found the left and right sensor wires are joined together. (red black wire) So then I removed the wiring to the left O2 sensor and opened up the harness. And bugger me Bob the butcher had been working in there. So I cut out all his crap wiring and tested for shorts to earth and all was good. By that time it was getting dark and the mozzies were starting to bite so I packed up and I will put it all back together tomorrow.
Regards,
Alan

[PeterH]

Wow Alan, you can now add 'P38 detective' to your list of skills!
That is excellent fault finding, I'm so glad you found the culprit.
It can be challenging enough trying to diagnose issues, without adding previous dodgy repairs on top.
Oh well, at least you know you have good 02 sensors and MAF, I hope you get it all back together ok and problem solved.
Yes the mozzies are very annoying at this time of year, when they start hanging around it's definitely pack up time.
I'll be interested to hear how you go getting it all back togther.

[old dirt bikes]

Hi Peter,
well it is all back together and running. I cleared all the faults and none have come back. I reset all the trim values and took it for a bit of a drive. The motor runs really good and was doing about 14.4 lt per 100k around town, and about 15.5 lt per 100k at 120kph. I think I will have to drive it a lot more to get the computer to finish learning the fuel trims. I floored it coming out of a corner at 60kph and I think it may have picked up the left front wheel. I am very happy. I got all this done with a bandaged up right hand. I did fit the fan that I had put more viscous fluid in, and although it is doing a lot better job of keeping the engine cool I know it will make the engine use more fuel. But all in all I am very happy. Now I have to ring the doctor to see if I have to go in for more sugary.
Regards,
Alan Temperley

[old dirt bikes]

Hi Folks,
I took the P38 for a run to the beach today, about 130klm round trip. It ran really good although I could hear the fan a bit but the engine temp stayed down. I checked the economy on the way home and it was doing about 11.7 per 100 klm. That is the good news, while I was at the beach the doctor rang, they never ring with good news, The 2 biopsy's he did on my right hand are cancer. So I am booked in for a operation on Monday. I hope nothing goes wrong with the Rangie for a while.
Regards,
Alan Temperley

[PeterH]

Sorry to hear that Alan, not a phone call anyone would want to get, specially while enjoying the beach!
I hope all goes well on Monday and you get over it quickly.
What a tease, you just get the Rangie going well and now you probably won't be driving for a few days.
Keep us posted, good luck with it all.

[old dirt bikes]

Hi Peter,
Thanks Mate. Yes I was having a good day with my wife, dog and grandson. I am a bit over the operations. But I am on a first name basis with all the nurses, if you can call that a good thing.
Thanks,
Alan

[prelude]

Alan you legend :) That's persistence. I do so hate it when people butcher the electronics of a car, I've had my fair share of "why would you do that" in my P38.

Again, sucks about the biopsy results :( I hope you may enjoy your P38 soon!

-P

[old dirt bikes]

Hi Folks,
The good news is my P38 is running better than ever. Although I haven't been driving far lately, my hand has been too sore. The doctor had to cut from the middle of my middle finger to my wrist. Quite a big cut to get it all out. Once this one heals up he will have to cut out the other one. Then maybe I can get back to some of my projects, The mezzanine floor in my shed ( 6.6mt X 9mt ). Then I will get back to building a bullbar and fitting a winch to my P38. I will then build a roof rack. Then maybe a rear bar with 2 spare wheel mounts. Then I could fit a fuel tank in the spare wheel space. I had plans of going to Cape York and Fraser Island this year. Depending on the rest of the surgery etc.
Regards,
Alan