Disco 300Tdi misfire under load

[The Kop]

Hi I am a new member to the forum and hoping for some help.
I have a 1997 ES 2.5 300TDI Auto with 94,000 miles on the clock.
One persistent problem I have is a misfire on kickdown or when climbing with a full load.
My local Disco agent (although I get the feeling that they are not really interested in 'old' models) have checked the fuel supply and re calibrated the computer settings but there is no improvement.
The symptoms are as follows. On kickdown the engine revs increase to 2600rpm then the engine falters for 1sec increases for 3secs to 2900rpm and falters for 1sec, increases to 3200 and so on. Locking down a gear makes no difference and the maximum revs that I can get out of the engine is 4400rpm.
Is there any bright mechanic out there that has experienced and cured this fault.
Waiting in anticipation
Reply With Quote

 

[joey]

Sounds to me like a fuel issue... I don't know much about the Tdi's, but from what yoru saying I would put my bet on fuel pump or filter, or a bad injector.

 

[Chongo]

Disco 300Tdi misfire under load

Hi I am a new member to the forum and hoping for some help.
I have a 1997 ES 2.5 300TDI Auto with 94,000 miles on the clock.
One persistent problem I have is a misfire on kickdown or when climbing with a full load.
My local Disco agent (although I get the feeling that they are not really interested in 'old' models) have checked the fuel supply and re calibrated the computer settings but there is no improvement.
The symptoms are as follows. On kickdown the engine revs increase to 2600rpm then the engine falters for 1sec increases for 3secs to 2900rpm and falters for 1sec, increases to 3200 and so on. Locking down a gear makes no difference and the maximum revs that I can get out of the engine is 4400rpm.
Is there any bright mechanic out there that has experienced and cured this fault.
Waiting in anticipation
Reply With Quote


Is the miss consistent under load? Does it smoke when missing or not ? ( Are the injectors fired by electric coils, or camshaft rockers ? There will be wires leading to the injectors if it is electrical, I’m sorry, But I don’t remember What year off hand Land Rover changed this). This usually means a faulty injector. With this many miles on a Land Rover Diesel injection system I would strongly recommend replacing all injectors . The pumps on these Land rovers are similar to the Cummings and international engines of today. On 99 year models these pumps do not time the engines, like the old Roosamaster and Cav. systems of yesterday ( poppet style. ). The pump is just a high pressure fuel supply to all the injectors, and cannot create a single cylinder miss. Something’s wrong with an injector, or cylinder, if one cylinder is missing. If all are missing it would be related to a fuel pump.
There’s a tool available By Raytek:

http://www.raytek.com/google?gclid=CMKP8tW91pACFRa4YAodeTuwOg

On a cold engine under load, in drive with the brakes and parking brakes on, at whatever rpm it misses, check to see which cylinder heats up last, by exhaust temp at manifold adjacent to the head. This will be the cylinder that is missing. You have to be quick, the cylinders will all heat up in under a minute. Old timers, ( like me ), use to use our hands to perform this tasks.
Usually a missing Cylinder will take twice as long if not longer, if ever to heat up. On a warm engine the missing cylinder will be the coldest one and this test cannot be performed by hand, and the Raytek tool has to be used, for obvious reasons.

Hope this helps, Feel free to ask any questions…. It would be helpful if you can tell me if your system is processor controlled or not, ( I can’t remember the year they changed ), This can be done by observing electrical wires leading into the valve cover.
Chongo

 

[The Kop]

Thanks Chongo
There is no exhaust smoke when it misfires. When I say that it misfires, the engine just goes slugish or looses power for just 1 sec then picks up for about 3 secs and dies again for 1sec and so on. I am not to sure of the technical questions you asked but I will look into it.

Many thanks