Power loss on motorway

[Slartybart]

Hello everyone.
Got an issue with my ‘new’ old beast, which otherwise is a beacon of excellence. I’ve just finished a 1200 mile trip in her, plenty of time for us to get to know each other. Twice now, she’s lost power on the motorway. Trundling along happily at 70-80mph, around 2500rpms when without warning she struggles to maintain 60. When it happens the engine tone changes and rpms jump to 3000 or more. The first time it happened I’d just overtaken a lorry and then had him right behind me as I struggled to get up a hill! I’m not sure if it’s a transmission problem, or a sensor or something, but I’m guessing. I first wondered if it was to do with me putting the more expensive diesel in it. Then I wondered if the very full tank might be the issue. Today when it happened I pulled over and released the fuel cap, to a satisfying sigh, but continued on and it was the same. Each time I’ve stopped and cut and rested the car for ten minutes and the fault goes away. Today everything seemed pretty hot under there when I did stop although no sign any problems on the gauges. Oil, transmission and coolant levels all fine. I can get it to a garage to check for any errors, but it was serviced before I left so it’s got new engine oil and filters and things. Not sure about the transmission oil, to be honest though. Thanks for any thoughts or suggestions.

 

[uHu]

The only cheap reason I can think of is that this would be typical if someone checked the ATF level without the engine idling.

I suppose this is the 4 speed auto box - in which case a synthetic Dexron3 fluid would work better than a mineral atf. (But that would be a waste if there is another transmission problem)

 

[Slartybart]

Well I’ve learnt something there already and thanks for that. First thing tomorrow I’ll recheck the ATF level with the engine running….. the Haynes manual showed the two levels for hot and cold, and the level seemed right for hot, but I did have the engine off when I checked. If there’s a bigger problem with the transmission (it is rather clunky) then so be it, but if there were another issue, like a faulty oxygen sensor, for example it’d be good to know I’ve eliminated the easy things first. Thanks again!

 

[Slartybart]

Oh, and yes it is the 4 speed gear nox with the overdrive… or is that three and an overdrive, it’s hard to tell… which may in itself be a clue…….

 

[karl2000]

There was a recent surging problem on here (on a 120, not 100) that turned out to be a faulty maf sensor. Might be worth a clean, as an easy thing to try first.

 

[Shayne]

dirty pick up in the fuel tank ?

 

[BobMurphy]

If the revs suddenly jump then the box is changing down - or dropping out of Overdrive.

The overdrive 'engage/off' switch on the side of the gear shifter may be faulty, but that wouldn't cause a lack of power.

Did you have 'cruise control' engaged at the time ?? The problem sounds electrical to me and possibly linked to the Throttle Position Sensor (TPS).

Bob.

 

[Slartybart]

Thanks. Will try checking the sensors, as far as I can tell, the overdrive switch is working as far as the dashboard, and it’s certainly something I tried toggling on and off when it happened, but it made no difference. I’ll investigate further, and try and find someone to plug it in and check for error codes…. It might show up there too. Thanks again.

 

[Odin 8]

Morning Slartybart. I suspect a corroded and perforated fuel line at the rear of the diesel tank ?

Above the rear axle at the NS rear of the fuel tank, the main fuel pipe comes out of the tank then loops around to the NS inner chassis. They corrode through in this area. If you study it carefully, you may notice some damp, it also might not start up quite as sharp as normal after an overnight?

We dropped the diesel tank on mine, de-rusted the whole area and tank. Re-painted with umpteen layers of any old paint plus a final coat of black two-pack. Replaced the complete fuel pick line with a clear braded fuel pipe right up to the filter. The beauty of clear fuel pipe is that you can soon see any air in the system.

Yours sounds like a classic 'air in the fuel' when full load/power is required.

 

[BobMurphy]

Errr Odin 8, my 2001 '100', and I suspect 'Slartybart's' 2002 '100' have plastic fuel lines. I think your '100' is a '98 so may be more like my '98 '90' where the pipes rotted.

The only steel pipe on top of the tank is a breather.

The tank still rots though .

Its a pain to get at, but I would investigate the Sock Filter on the diesel pick-up - as Shayne suggested.

You could also check the Throttle Position Sensor (TPS) as I believe these 'fly by wire' systems can have faulty contacts.

Bob.

 

[Slartybart]

Thanks for all the replies…… whether it’s the right solution or not, we think we worked out that the turbo wasn’t working. The mechanic says there was a split somewhere in the pipe work and one of the gates and the turbo itself was overwhelmed in soot. He’s taken it all apart (and hopefully) putting it all back together today. He also said the ‘filter’ was completely ruined so he’s taken it out. I think he means the DPF, but as I’m relying on a Ukrainian mechanic and a technically inept translator I’m not entirely sure. Either way if he’s right I should expect a perkier beast and better fuel economy……. Question is…. Should I get him to block the erg while he in there?

 

[karl2000]

No DPF on these 120s is there?

 

[Slartybart]

It’s a 100, and you may be right…… I haven’t seen what he’s talking about, is there another filter he may have removed?

 

[karl2000]

Oh yes 100 sorry, I think the 100s predate DPF's, but the experts will tell us....

 

[Slartybart]

 

[Slartybart]

He says this is what it should look like, but I’ve no idea really.

 

[Slartybart]

Ok….. the car has been with the mechanic for three days. He’s removed and rebuilt the turbo and bench tested it. He’s blanked off the erg and rerouted everything. He’s also cleared out the ‘filter’ which I think it the dpf on the exhaust system. He showed be a bucked full of charcoal. The car is a different beast - and for the first time (since I’ve had it anyway) drives more like a car than a tractor. She changes up and down much more smoothly and the roar of the engine now relates to an increase in acceleration, to the point where you can actually feel it - even up hills. I don’t know where it leaves me in terms of emissions testing next time the MOT is due, but I now feel we’ve got a healthy working car rather than a trusty tractor.

 

[Slartybart]

P.s I won’t tell how much it cost….. but put it this way, if I’ve also gained 20% in fuel economy it’ll pay for itself in a few thousand miles.

 

[Odin 8]

Dont go to Oz or SA and refer to a Land Cruiser as a 'Car', they don't like it. Top Tip. ; )
Good to know that you have got it repaired.
It should cope with the EGR blocked off, but more modern vehicles are programmed to sense 'restricted flow in the EGR' for when they do block up with carbon. Yours didn't flash up the code so I wouldn't get concerned.