TD5 Delayed Acceleration at low engine speeds

Thought I would dig this thread back up as this issue has been on an off for me for years.

Went for a drive tonight with the Hawkeye connected while watching the IAT sensor values.
Every time the IAT recorded 119 deg C the car lost all power below 1900 RPM. It was intermittent. Not sure if it is the sensor or some broken wires.

The manual says the MAP and IAT (same sensor) share the 5v input. A 5v output from the IAT causes the 119 deg C. It might be the sensor or there could be a wiring issue in the loom whereby the IAT output is getting 5v from somewhere else.

Will advise after some more troubleshooting.

Simon.

P.S. This has been ****ting me for years. I was just about to register the car and couldn’t make it to the inspection garage. Oh the shame.

I'm 99% sure that it's the sensor at fault, i've seen this symptom few times with exactly the same behaviour and new sensor cured it

Had exactly the same symptoms with my D2 some years ago. I logged the IAT with Nanocom & whenever it spiked, power vanished. New sensor cured the problem. Wasn't an expensive fix either.

Quote:

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Originally Posted by crt560

Hi,

I have an annoying problem with my TD5 Auto which I thought I would post to see if anyone else has had the same problem and fixed it. Overall, vehicle performs really well, pulls like a train at 100kph, but...

Symptoms:

2) Pulling away at a roundabout or junction, there is about a 2 second delay before anything happens, then all hell breaks lose when rpm gets above 2000. This delay is reduced if I turn off the A/C system.

3) The lag is more than classical turbo lag, it appears to be some form of fuel reduction.


Thanks.

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Since I got mine it has been dangerous with the delayed throttle from cold. Noticeable difference when aircon turned off, the previous owner did mention if no throttle response to turn off aircon but I was only half listening as I expected it to have some issues.

Today I received a replacement MAP sensor (all of $16) and put it in.

Now I have a vehicle that actually moves when I put the foot down and can now dart into traffic, only to promptly lose midrange revs.

However this is enough to tell me that yes the sluggy disco is not a live with it issue (none of the stuff I have read makes sense and I don't know why people put up with what I believe is a faulty car not a characteristic) and that my MAP sensor is a dodgy cheapy as it cured one part of my issue but introduced another.

So because I am a cheap ***** I have now ordered a Tridon TMP110 for $40 as I am trying to avoid the $150 Bosch bill.

I already did the clean everything with sensor grade spray and the throttle voltage to MAF input on the ecu.

Unplugging MAF and AAP (separately) did nothing (no improvement or loss) and unplugging MAP put it into a 10 km/h limp mode.

With previous MAP it did jack till it slowly got to 2000 then shot off like a rocket, however ran out of puff at 3000 and hills/slopes knocked it back to 90 km/h

I consider this progress.

I do have a cheapy MAF on order as well for substitute testing and a fuel pressure block gasket set, as it is dripping out of the regulator.

Have been doing a lot of reading (and emailing sellers) re diagnostic tools and seems the nanocom is the go for this vehicle.

Seeing the fault is worse with A/C on have you had the aircon checked for pressures?

I can remember once in my RRC when the aircon fans died in Kununurra the starter would not turn the engine with the aircon on as the system pressure had increased due to the condenser not working. Could maybe be a blocked receiver drier.
Also simply check the Viscous Fan bearing and the idlers for free movement.
Regards PhilipA

Quote:

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Originally Posted by PhilipA

Seeing the fault is worse with A/C on have you had the aircon checked for pressures?

Regards PhilipA

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With the new MAP sensor the aircon on or off does not affect the driveability anymore. I have gone around the block a few times accelerating from a standing start (which is an outstanding difference with this MAP sensor) and all good on takeoff and no change in loss of midrange with aircon in or out.

Later today I will play around a bit more but the stark difference between the 2 MAP sensors has made me keen to get this engine running sweet, the take off I have now, combined with the mid range I had before I changed sensors is telling me this car can boogie even in stock trim once I have it sorted.

I was swapping between a 2 litre automatic Econovan loaded with tools, a 3.6 litre auto VE sedan and a 5.7 litre auto VT sedan (infringement notice magnet) throughout the week before I cleared the stable and got this as my one and only daily. So plenty of range in power levels to compare with.

Also have a replacement Delphi brand Crankshaft position sensor but it has been purchased as a spare only. The car starts instantly once glow plug light goes off and idles like a clock on 760 rpm , no cutting out or misfiring when driving.

So I now know the original laggy dead throttle issue is a faulty MAP sensor, which I have replaced with a new, no brand out of spec faulty cheap crap sensor, which is to now be replaced with another new, also cheap but known brand name (Tridon) MAP sensor.

No oil anywhere in loom from where injector wiring plug is in front of head to ecu sockets.

Also with laptop plugged in to OBD port I can read engine rpm and throttle percentage (changes in proportion to movement) and a reading saying 8% load at idle (which I am not familiar with) and nothing else but surprised I got that even, as I thought the disco Td5 shows nothing with standard OBD instruments.

Without a diagnostic tool as an aid it is a sensor swapping, wiring checking, grey matter excersize.

So I now know I know nothing, and that cheapie MAP sensor put egg on my face.

It did make an 'improvement' but I think I got too excited because my throttle response was so crap to start with that anything was an improvement.

Anyway the Tridon MAP sensor was cancelled as seller had no stock (or realized everyone was selling them for $110 and their price was $40 so not doing themselves any favours)

I got a Bosch MAP sensor from Supercheap Auto but car performed the same .

I also swapped out MAF sensor no difference, left Crankshaft sensor alone because it starts fine and no cut out or missing when running (I did purchase a new one for spares regardless)

Did the throttle voltage to MAF input on ecu trick no change, also MAP voltage to MAF input as suggested in another thread somewhere and no change

And finally bit the bullet and ordered a nanocom at full price coz none of you people loves me enough except Brucie to join a group buy

So thanks to Nano and matey mate SD card I actually managed to graph the take off delay while watching 2 lanes of traffic bearing down at me as I crossed them moving at a crawl foot through the floorboard.

I am now a legend in my tiny little mind as far as getting a grip on understanding the fueling recordings the nano makes and have decided by process of elimination and new found knowledge that my sensors are all working fine and the one thing not measured by nano (fuel pressure) needs to be checked.

A cheapie 80 buck pump and a fuel pressure test kit from ebay should be here by Friday to add to my arsenal of bits.

I also found I have a TRS chipped MSB101340 ecu (I took lid off and it is socketed) and thought to maybe buy an unmolested spare for comparison, however when I turned up at the guys place it was another TRS stickered MSB unit with a big green 'performance tuned' sticker on it. It has been fitted but no change in the throttle lag, but at 120 bucks and I now have the original as a spare I can't complain.

So it is a long process of elimination and I wish I had a nanocom before I started buying sensors as it would have been much easier getting an insight into the way this engine works and saved a lot of probing with the multimeter.

For those who haven't got one and are diy types stop thinking about it, just get one, life is a lot easier when you can log the sensors and the three tracks on the throttle pot doing their thing instead of farting around doing continuity and voltage checks manually.

I saved 150 straight up by clearing the flashing odo and bought a 315mhz key on ebay for 30 bucks and synced it then went and paid another 10 to get it cut. So spare key for 40 bucks or would have been 220 at locksmiths and much more at dealers. Not to mention being able to grab another ecu at 6pm and have it in the vehicle and test driving half hour later all synced up with bcu at home thanks to mr nanocom

I will win in the end even if I cheat and buy another disco and go 'aha that fixed it !! '

I've had the same problem since my autobox rebuild. So far I've replaced the MAF, MAP/IAT and CPS all with genuine parts without change. The issue is still intermittent though - yesterday when it was cold it played up but this morning it didn't. It's almost like the D2 doesn't like me on some days...:-)

Seeing as the problem became obvious only after the gearbox rebuild I've come to the conclusion that it's either gearbox related or the faulty gearbox masked it.

It seems almost as if the lockup clutch is somehow engaged until about 2000 rpm when it plays up. I'll start recording the gearbox stuff in the nanocom and see if that turns anything up. My hopes are not high though.

If anyone on this thread with performance issues has a Nanocom, do a log recording from the td5 instruments screen, post it here and I'll have a look.

Cheers
James

Attachment 169897

I condensed this down to show what my foot is doing to what the car did if it is of interest to anyone

As you can see the throttle pot works fine, the engine sorta went to respond then stayed at 1000 for a few seconds as the car slowly moved forward across the 2 lanes, then it starts to move quickly and I back off the pedal to not speed.

The MAP MAF readings and other stuff follows along as I would expect from info on here and reading RAVE when my brain can take it in.

It is not trying to take off in a high gear as it does change up once driving and there is no changedown that I can discern before it takes off after the delay.

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