Hunting throttle D2a TD5

[Jazzman]

The throttle on my TD5 appears to not want to hold a constant acceleration. It keeps dropping about 200rpm and reaccelerating. It can do it up to 5 times before I reach 100km/h.


What do you think will be causing the issue? No I don't have a Nanocom I need one before June, so if you want to off load one feel free to PM me.

[Jazzman]

This bloke seems to have a similar if not the same issue on a Defender.


http://www.aulro.com/afvb/showthread.php?p=2300733#post2300733

[Disco W.A]

clean the earth terminal for the ECU, I had a simular fault and it turned out to be a corroded earth connection.

[Jazzman]

clean the earth terminal for the ECU, I had a simular fault and it turned out to be a corroded earth connection.



Is this connection one of the 3 body earths behind the battery?

[sierrafery]

Is this connection one of the 3 body earths behind the battery?
Yes, under the battery cover near the jack compartment, though IMO a bad earth there would cause more serious trouble,

if you have cruise controll you can rule out the TPS by using cruise controll to accelerate and if the symptom is still there the TPS is fine if you see what i mean

[Jazzman]

Yes, under the battery cover near the jack compartment, though IMO a bad earth there would cause more serious trouble,

if you have cruise controll you can rule out the TPS by using cruise controll to accelerate and if the symptom is still there the TPS is fine if you see what i mean



I'm pretty sure the acceleration using the cruise control still works fine. I'll test it shortly. I've cleaned the earths anyway as it was not a big job.

[sierrafery]

Hmmm...then the TPS becomes suspect cos if it was some fueling or other issue it would have gave you that symptom with cruise controll too IMO

[Jazzman]

Cleaning the earths did not achieve anything different.


It only does it under load from about 3rd gear onwards. I first notice it at full throttle, but does it at less then full throttle too.

The cruise control works. I can accelerate using the steering wheel controls.


It seems to be getting more aggressive or the pause in acceleration might be getting longer.

[Jazzman]

Hmmm...then the TPS becomes suspect cos if it was some fueling or other issue it would have gave you that symptom with cruise controll too IMO



I only accelerated from 90 to 100km/h using the steering wheel control. I'll accelerate from a slower speed tomorrow using these controls.

[Roverlord off road spares]

Shane, it could be fuel delivery, a fuel pump momentarily stopping supply when needed.
Cheers,
Mario

[discorevy]

Boost controller?, try to bypass and see if your symptoms are still there

[discolaw]

Boost controller?, try to bypass and see if your symptoms are still there






Agree boost controller could be the cause. When mine started to go, it began to momentarily cut fuel supply. Fairly cheap to buy and easy to replace. Good tute and info for this on Urban Panzers website

[Jazzman]

Are you talking about some genuine boost controller? Because I don't have an aftermarket one fitted.


I hope it isn't the fuel pump, it was replaced not that long ago. The boost controller makes a bit of sense because it has shut the turbo off on 2 occasions since I started this thread.

The last time that happened was when I turned the boost up on the waste gate. I've turned it back since then, about 3 months ago.

[bronson]

Im def eager to hear how you go on this one, mine has a really similar problem around 1800-2000rpm.

[discorevy]

OK , to at least see if boost controller is the problem , you can bypass
to diagnose , to do this you need enough vacuum line to go from the take off point which is on the metal pipe between turbo and intercooler about half way along , remove vacuum line from there and the turbo modulator and fit new line between these two points , but before you do , check to see if existing lines haven't split as this could also be your problem , jazzman you do have a boost controller , only the defenders don't, follow the line up from the metal pipe and you will find it . it has three lines . let us know how you get on cheers

[Jazzman]

OK , to at least see if boost controller is the problem , you can bypass
to diagnose , to do this you need enough vacuum line to go from the take off point which is on the metal pipe between turbo and intercooler about half way along , remove vacuum line from there and the turbo modulator and fit new line between these two points , but before you do , check to see if existing lines haven't split as this could also be your problem , jazzman you do have a boost controller , only the defenders don't, follow the line up from the metal pipe and you will find it . it has three lines . let us know how you get on cheers

I"ll have a shot. Cheers for the help. I'm going to China for 2 weeks leaving Friday night. Might not get back to you until i'm back in Aus.

[Jazzman]

Just got my car back today after having some pannel work done to it.

Today I disconnected the MAF just to isolate it. The problem became worse and more aggressive. I've since plugged the MAF back in and the problem is the same as it always was.

I'm going to have a look at what discorevy has suggested this weekend at the latest. Cheers for your input.

[Jazzman]

OK so that didn't take long. I have bypassed what i'm pretty sure is the boost modulator. It is a little black cylinder shaped thing the that resembles an old camera film canister. It had 3 vacuum hoses. two on the top, one on the bottom.

1: off the bottom to the metal pipe between the turbo and the intercooler.
2: off the top to the vacuum diaphragm on the turbo waste gate.
3: off the top to the intake piping behind the MAF.

I disconnected 1 and 2 from the boost modulator and connected them together. (Hopefully bypassing the modulator) 3 I did not touch.

The result - Symptom of hunting throttle gone. So I guess this means I need a new boost modulator?

Just as a side note. Once this symptom had gone I also disconnect the MAF to see if there was any change. There was a minute increase in performance. To be specific i'd put it down to the pause between gear change 1 to 2, it was much shorter and in turn the engine revved up smoother. I don't think it is an issue but thought i'd mention it anyway.

[bronson]

What rpm range does it do it? Mine at around 2k mark, still not sure what the go is with mine????? just waiting to get someone to have a look at the driving data ive got on my nanocom.
let me know

cheers

bronson

[discorevy]

Jazzman , you can try removing it and cleaning with brakecleaner and compressed air , sometimes works , otherwise , new ones are only around $50 or so , 2 x8 mm bolts and wiring plug plus tubes to remove and replace, part number pmk 100130 , the correct name is wastegate control unit, re: maf do you have access to nanocom or equivalent, this is the easiest way to diagnose
Cheers

bronson , have you checked your wastegate and modulator to see if it is free ? , have you shortened the rod before the symptoms started?

[bronson]

Hi discoverey,

My car doesn't run via the wastegate modulator, the turbo just runs via the intercooler pipe and bypasses the modulator. The wastegate rod has also been shortened to raise the boost. Is there some connection there do you think?

Cheers
Bronson

[discorevy]

What are your boost pressures when it happens?

[bronson]

Only low pressure at 2k, Max's out to about 220

[discorevy]

When you next drive it , have a look at your airflow readings when the problem occurs , could be anything from delaminated intercooler hoses to dirty map sensor , to badly oiled up intercooler, as it seems to be when the turbo is spooling up from what you are saying. Is it a miss or more of a stutter? . are there any logged faults?

[Jazzman]

Problem rectified by replacing the boost modulator, very easy fix. Thanks for your advice.