Thread: TD5 Auto Question

Mine is the same. I have only owned it a week. I'm not sure if I have a
problem or this is how they are

Both cars definitely have something wrong.

I have owned mine ( 2002 EU3)2-3 weeks now and the step off is really excellent on mine and slightly better than my V8 3.9 with unichip and Thor.

I am pretty amazed I have to say and mine is rock stock with EGR etc etc.
Up until now it would not rev out to 4200 , but today it fixed itself.

I cannot understand your reports on slow spool at 1500 -2000 as the TC stall is 2800RPM so the engine should shoot up to 2800 then up from there as revs rise.
I wonder if diesels are driven very slowly whether the ports around the inlets and exhaust valves get gunged up so much that the performance drops off, as a series of Italian tune ups worked for mine.
Regards Philip A

Hi Philip
That's interesting to know...

I actually agree with Jadan & Joel, the slow spool up on my '01 auto has dogged me for years (esp with the air on), and over that time has given me a few "frights" when it's been reluctant to move off the way I expected it should.

This has become particularly apparent to me since buying the manual a couple of weeks ago. I know that the manual is also chipped, though I have no information on what it is (the auto is 140kW), and it has a 3" exhaust - but the difference between the two is very noticeable. I have no hesitation darting across intersections I wouldn't contemplate in the auto.

Which begs the question, if others have a similar experience is it a turbo or fuelling issue or is it an issue with the auto. And yes, once you can get it up to 1800-2200 rpm it starts moving and keeps charging, but that space between idle and there can be black hole. What has me scratching my head is that sometimes I can put the pedal down and away it goes. Intermittent issues area nightmare!

Good luck with it Jadan!
Cheers
Mike

G'day, maybe I can add my own experiences to this issue. I have a 99 series 2 TD5 auto and the only way to get it moving quickly (especially with larger tyres, 32") is to give it a big dose of right foot. Feels a bit like a slingshot at times. I have done a bit of work to my disco such as a ecu remap, vnt, larger intercooler, different exhaust and manifold etc., so it is producing a little more power and torque than standard these days.

If I needed to get across a busy intersection or get up to speed quickly, I have to think and react a second or two ahead of time to allow for the torque converter in the auto box.This, hopefully from all accounts will be rectified when I put a lower stall converter in it in about two weeks time, fingers crossed.

The box is out at the moment as the 1st planetary gearset one way clutch is u/s. It is one of the components that was "upgraded" supposedly 3.5 years ago during a ridiculously expensive rebuild (lots of $$$), ah if only I had shopped around. Hindsight is a wonderful thing.

So, if your engine is performing properly then I would suggest that it is the torque converter high stall that you are experiencing. There are discussions and information on the web about this and how opinion is that the stall is too high and converter too small for the TD5, especially a tuned one.

Cheers,
Mikey

Thanks for you replies guys.

I'll report back once my Disco gets to Darwin and I get it registered and do a bit of driving.


Happy days.

I really doubt whether a low stall TC will help a TD5 get off the line quicker.

When pondering what could be wrong with slow pickup on the TD5 I got to wondering whether somehow a petrol TC had been substituted for the correct TC somewhere along the line eg at a transmission rebuild as the petrol TC has a lower stall than a diesel.

I mean drag cars have Hi-stall converters fitted to IMPROVE step off, and IMHO the same theory exists for the TD5. The hi stall converter is fitted to allow the TD5 to gain useful revs to get into the torque band.

Regards Philip A

We finally got time to get the nanocom onto the vehicle and record the behaviour. The file is attached. Shows as an xls to get it to upload, but is actually a csv. What I find intriguing is that the air pressure is really saw toothed, rather than squarish. The wastegate is opening when there doesn't appear to be enough boost to demand this.

I have a comparative map from my vehicle on the same run (mine has a moded map, whereas the other one is assumed and appears to be factory map) and the sawtooth behaviour is major difference. The vehicle requires foot to the floor to get it to do this, whereas mine is 1/3 to 2/3 down to the floor.

To date, MAF has been replaced (already ruled that out by temporarily replacing it with mine, which is good), air filter replaced (but was still in servicable condition), cleaned IAP sensor on inlet manifold, EGR is removed, wastegate actuator has been confirmed as operational, although wound to 10 - 11 threads. The cat is removed but still the problem is there.

Any pointers on what to else may be causing the issue would be greatly appreciated.

The obvious things look alright to me:



c11-c10 is manifold pressure - ambient pressure to give a plot of absolute boost.

The wastegate modulator is just controlling the amount of pressure that reaches the wastegate. It's designed to allow more boost at part throttle openings, but when the modulator is fully open the wastegate behaves as if it were directly connected to the turbo outlet in the same way as a Defender.

The airflow readings are basically following the boost curve which is what you'd expect to see.

There is definitely no overboost happening. You can spot this straight off by the recurrence of the 100.00 inlet pressure readings which I can't see in the recording, and you would also see a peak boost reading of around 21-22 psi. The highest in this recording is something like 16.8 psi.

The IAT reading looks very odd to me. It's seems too high and maybe a bit too static. From what I've seen I my d2 Inlet Air Temp varies quite significantly with boost levels. The reading is moving but it's in a fairly limited range.

This was from an input recording I did on the weekend:



You can see how the IAT rises when the boost pressures climb.

The MAP and IAT are used in conjunction to calculate the density of the air entering the cylinders and are one of the most important sensors for correct fuelling. It would be worth temporarily swapping in the MAP/IAT from your D2 just to see if that makes an improvement.

The other thing to consider is that the intercooler may be partially blocked which is resulting in the elevated IAT temps?

cheers
Paul

Just a follow up:



I found a section of the weekend recording that had the slower roadspeeds and stop start behaviour shown in bsperka's recording.

I understand what you mean by sawtooth. The boost and airflow are very slow to peak. I still think the sensors are probably reading OK with the possible exception of the IAT.

I'm fairly sure that the issue is in the intake tract rather than the electronics. I'd be looking for restrictions or leaks somewhere between the intake manifold and the air box.

cheers
Paul