boost pressure is not controlled by the ecu on a defender, it is on the discovery, using a modulator. Defender relies soley on the pressure in the metal turbo pipe to open the wastegate. It's not uncommon for wastegates to sieze, you'll then get an overboost fault logged in the ecu.
Air flow meters also cause problems and can give symtoms of overboosting as well as lack of power at full throttle
 
RottenRich thanks for that info, 12 is the standard setting (from looking at new ones) so yours is OK on that point anyway. (there should be a paint seal on it)
Will try that turbo pipe, it is easy to get at anyway. Had similar problem with my Renault 5 Turbo, collapsing turbo pipe that only happened under load so you could not tell by looking at it! Took a while to find out why it would lose power under hard acceleration.
 
If you have a pooter you don't need a boost gauge, cos it shows ambient and manifold pressure. You should get your engine on a pooter cos it is possible that your ambient pressure switch has failed. Come to think of it that won't make much difference to you in the UK for the ECU then defaults to 1 atm which is sea level. It can make a difference here at 5000 ft.

AFAIK the ECU knows what the boost pressure is, so that it can adjust the fuelling to suit. But there is no electronic connection to the waste gate on the TD5, that is all mechanical.
 
I would like to connect it to a diagnostic unit but the dealer won't do it as they say there is no fault. The thing is I am like RottenRich in the fact that I don't really drive fast in the Defender so am not prepared to keep on arguing with the dealer about it.
My wife drives it more than me (7000 miles since last July) and has not noticed anything amiss...even after I explained the "fault" to her she said that she "did not notice" anything wrong while driving it.
Personally I think it is an ECU anomily, I drove an '06 XS the other day and that also defaulted into a different mode after full throttle was used...
I am going to get the chip reprogrammed but it won't be for a while yet as I just spent all my cash on a bike! Also I want to get the Defender Waxoyled (or similar).
I will report on my experience with chip upgrade after I get it done, maybe that will remove the "fault" as I believe it allows for higher boost etc.
 
Your article still struggling with my TD5 I have identical problem with mine been back to the dealer 5 times, only bought in Feb 07. 21,000 miles on clock
Misses broke down going across a busy two lane carriageway shut right down no response to thottle. When I got there I had to stop and start again Ok for 1 mile approx went into shutdown mode ran on tick over. No response to throttle. Had to be recovered to dealer who cannot find a fault. Thinking of giving the bugger back stick with my old Series III, has never let us down always got us home.
 
Hmmmm, I was cadging a lift off someone in their 2dr classic Rangey to Robin Hoods Bay trial(volunteered to Marshall) and he had a lot of problems. First off, the dizzy was loose (irrelevant to a doozul motor), but the main problem was vapour lock. It went like a train for about 2 miles then died. Turned out the tank breather pipe was blocked, opened fuel filler, (took in a LARGE amount of air) rodded out breather and has been right as ninepence since.

Just my 2 pen'orth ;)
 
buy a manual boost controller they solve all them problems buy bypassing the ecu . it works by a little black box just under the turbo take the two pipes off and fit a boost controller there.. but leave the wire that comes from the ecu attached . its a plug...
 
I took some advice from a genius on Land Rover electronics. He suggested to get the dealer to change the accelerator pedal as this, when wet, ruins the electronics in the pedal.

When he told me this I remebered when we saw the Land Rover foir the first time the dealer had cleaned it inside the cab and it was wet. He said it was that there was a leak.

Since the accelerator pedal has been changed the LAnd Rover has been totally reliable.

Thanks for all your help

icon12.gif

Steve Miles
 
i had identical troubles on a 2001 td5, looked at all sorts to fix it, hoses, waste gate stuck, wrong boost setting on waste gate rod, wiring harness contamination...the list went on, but i was due to fit an egr removal / blanking kit. from "td5 alive2 circa £46 i believe. check out his website for its description. anyway this fixed mine fully, and its upto full power and feels stronger too. i still cant say for certain what fixed it, but the egr removal does involve removing an item that has two vacuum controllers on, i was left assuming these were the culprits in some way. mine was a looked after 71k mile defender, with all those symptoms you say. i posted on here before about it, do a search on my posts. people gave me all sorts of reasons, but its best to start at the cheapest options and work your way up. good luck.
 
clutchdust said:
boost pressure is not controlled by the ecu on a defender, it is on the discovery, using a modulator. Defender relies soley on the pressure in the metal turbo pipe to open the wastegate. It's not uncommon for wastegates to sieze, you'll then get an overboost fault logged in the ecu.
Air flow meters also cause problems and can give symtoms of overboosting as well as lack of power at full throttle
Click to expand...

Beg to differ there dust. to quote :

"The ECM controls the amount of boost pressure the engine receives by way of the turbocharger. When full boost is reached a control signal is sent to the waste gate modulator, and a vacuum is applied to the wastegate valve. The wastegate valve opens, bypassing some of the exhaust gasses away from the turbine to be output to the exhaust system."

the way i figured out a way to overcome this problem was to have a puter connected to the landy and then go on the road and see at what boost pressure the ECM tells the wastegate to open, and then watch the actual manifold pressure to see if it stays there. if someone has fiddled with the wastegate adjuster, u will see it immediately. then, u got 2 options...play with the wastegate adjustor until you get it right [it must open and hold the boost pressure - from memory there is a value that the boost pressure must not pass, at which point the ECM reduces max boost to 1 bar or 14.5psi.] which i seem to recall as being around 20 to 21 psi [can anybody verify this?] or alternately, see wot your max boost is, and then have the max boost pressure value changed to slightly above this [not recommended tho]. mine was doing exactly the same thing, and i chose the fiddling route.
a third route is to chip it. i think all of these values are upped in the chip to increase performance.
 
from wot i can gather, when you switch on the ignition and apply full throttle, you are basically forcing the ECM into a reduced performance mode. why u would want to do this, i wouldn't know, but sum bright spark must o thought it was a good idea.
 
charlesy
Can you help. I have a disco with a td5 engine. I have just purchased a boost gauge. Can you tell me where you connected you boost gauge hose as the td5 vacume hose is computer controlled. This would be a great help as i have the same problem as lightning with the waste gate settings.
Cheers steve
 
Clutchdust is on the money with the Defender TD5.
There is no waste gate modulator controlled by the ECU.
If the turbo overboosts it logs in the ECU and engine performance is reduced to prevent overheat problems. ECU resets on startup until next overboost event.
Only symptoms are: a slight cough as overboost is logged and then throttle response reduced where last third of pedal travel apears to do nothing.
Standard max boost is set at 15psi in the ECU. Any more than this logs an error code. It can be altered but you need to know your stuff.
Fitting a turbo boost gauge is easy but you have to know how to interpret what it is telling you.
Most fit it to the tube between the wastegate acctuator. This does not always read actual boost pressure as it fluctuates with the wastegate.
Fit the pressure take off to the inlet manifold which is much more stable and reads actual pressure. This allows for pressure loss in intercooler and hoses etc. This is why they fit the ECU pressure sensor to the inlet manifold.

You might be surprised to know that modern turbochargers can easily boost to well over 30psi if unregulated or the wastegate is seized. This is extremely dangerous where diesel engines are concerned as cylinder pressures are much higher and hence why the ECU goes into safety mode.
 
thanks shifty I will look for the ECU pressure sensor. I understand about the over pressurising of the engine as i have had to rebuild an engine after a turbo blew all the seals out.
I have tried connecting the gauge to the waste gate hose and have got notheing. My waste gate vacume holse does go through an electric valve which in turn has an electrical connection to the ECU.

Thanks for the comments will try and look tonight when i get home.
 
steve911 said:
thanks shifty I will look for the ECU pressure sensor. I understand about the over pressurising of the engine as i have had to rebuild an engine after a turbo blew all the seals out.
I have tried connecting the gauge to the waste gate hose and have got notheing. My waste gate vacume holse does go through an electric valve which in turn has an electrical connection to the ECU.

Thanks for the comments will try and look tonight when i get home.
Click to expand...

Hi Steve,

that will probably be the over charge solenoid mate, we have them on the VAG stuff.

If you are getting over charging sometimes it's worth checking the operation of the actuator/vanes.

It will have a variable geometry turbo on the TD5 which is operated usually by vacuum and if the actuator is faulty or worse the vanes in the turbo are stuck then this will cause over charging.

I think what Shifty is talking about is the MAP sensor

Something else to check maybe

Good Luck
 
Hello pussyeater not quite understanding the over charge solenoid will look this up. I know the waste gate setting on the turbo is wrong because the actuator arm came off and I put it back on again. I need to attach the boost gauge so that I can set the waste gate up properly. I was just wondering where to connect it as the TD5 is different to the other diesels I have worked on.

The turbo fins are working fine and the pressure to the engine is ok but most probably too high. This is my concern as shifty said this could cause major damage to the engine.

Cheers
 
forget all the computor controlled jiggery pokery,you cant beat a 2.5td 90,20 years old and will keep up with my mates 2 year old td5 offroad(not on road) and i have loads more fun than him
 
Hello Wiltshire landyman
I will totally agree with you. I have had a few old diesels and have loved working on them. The engineering is easier to understand and work on. All this computer interference just makes it harder and more expensive to fix. Not mentioning the poor reliability of it. An old diesel is well know for there reliability. Unluckily for me I have bought this computer car and now am stuck with it.
If I could buy again I would buy the older model
 
Been out to the car tonight had about half hour to work on it. (Kids to put to bed). Disconnected the inlet hose to see the electrical solenoid for the waste gate pressure. There I found the pipe coming from the bottom of the solenoid to the pressurised side of the turbo pipe. Finally I can see were to connect my boost gauge pipe. Connected the gauge fired up the engine and at 2500 revs I get a reading.

Not what I was expecting as it only read 7 to 8 psi. This is with the waste gate fully wound shut. Know this could be the pipes are not tight enough to the gauge or the waste gate on the exhaust side id not shutting properly. (Not wanting to go down this line as it would involve disconnecting the exhaust) worst still the turbo is not delivering enough pressure. If so it’s looking expensive. The car pull fine and I can hear the turbo so expect it to be ok.

Will have to leave it till Saturday when I have more time to work on it longer. Car will have to stay of the road till then.

Any ideas on why the low pressure will be nice to know.
 
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