TD5 90 Chipped... Juddering at about 70mph

Ive just acuired a TD5 90 complete with Tunit chip. It all goes fine
until it gets to about 70mph (slower if going up a hill or under
load). At this point it begins to judder as though the accelerator is
being rapidly pressed, lifted, pressed, lifted etc etc. Most
annoying.

I dont think its over-boosting as it seems to drop off the power
rather than lunge forward. I tend to think its probably over-fuelling
- or just crap programming??

Dont know if it makes any difference but its also got the Disco II Q
gears in the T/Box.

Do "chips" consider revs relative to engine speed and act accordingly
or just throw more fuel in? I notice you can get tunit chips for a
Defender or Disco, so seemingly there is a difference?


I wondered if it could be a sticking EGR valve but the problems seem
to occur in too specific a region.

Any other thoughts?


Thanks
Jon

If the tuneit is the plug in type then try unpluging it and drive without it
for a while, the tuneit only adjusts the injector pulse width, so is not
concerned with tubo boost, depending on which tunit you have you could ty to
adjust the potentiometer, to back it off a bit.
Before I bought a tuning box I considered the tuneit unit but after some
enquries of the manufacture decided against it. This was a pesonal opinion
but I got the impession that it was not as sophisticated as the dastek unit,
sure the dastek is more expensive but I have after 6 months of use had no
downside to the unit.

Hope this helps

"Jon" <[email protected]> wrote in message
news:[email protected]...
> Ive just acuired a TD5 90 complete with Tunit chip. It all goes fine
> until it gets to about 70mph (slower if going up a hill or under
> load). At this point it begins to judder as though the accelerator is
> being rapidly pressed, lifted, pressed, lifted etc etc. Most
> annoying.
>
> I dont think its over-boosting as it seems to drop off the power
> rather than lunge forward. I tend to think its probably over-fuelling
> - or just crap programming??
>
> Dont know if it makes any difference but its also got the Disco II Q
> gears in the T/Box.
>
> Do "chips" consider revs relative to engine speed and act accordingly
> or just throw more fuel in? I notice you can get tunit chips for a
> Defender or Disco, so seemingly there is a difference?
>
>
> I wondered if it could be a sticking EGR valve but the problems seem
> to occur in too specific a region.
>
> Any other thoughts?
>
>
> Thanks
> Jon

In message <[email protected]>, Jon
<[email protected]> writes
>Ive just acuired a TD5 90 complete with Tunit chip. It all goes fine
>until it gets to about 70mph (slower if going up a hill or under
>load). At this point it begins to judder as though the accelerator is
>being rapidly pressed, lifted, pressed, lifted etc etc. Most
>annoying.
>
>I dont think its over-boosting as it seems to drop off the power
>rather than lunge forward. I tend to think its probably over-fuelling
>- or just crap programming??
>
>Dont know if it makes any difference but its also got the Disco II Q
>gears in the T/Box.
>
>Do "chips" consider revs relative to engine speed and act accordingly
>or just throw more fuel in? I notice you can get tunit chips for a
>Defender or Disco, so seemingly there is a difference?
>
>
>I wondered if it could be a sticking EGR valve but the problems seem
>to occur in too specific a region.
>
>Any other thoughts?



It could be any number of things totally unrelated to you Tunit device.

Overboosting can cause this. The ECU senses and over boost and cuts the
fuel. Duff sensor or split in hose on waste gate valve.

Oil in wiring loom can cause this, as can throttle pot, air flow
meter....the list goes on.

Unplug the Tunit first and try without.
--
Marc Draper

OK, thanks for your replies so far.

I unplugged the chip and all is fine (appart from its slower!). So I
guess it's probably the chip?

I found the adjuster settings after speaking to Tunit (it was set at
the half way stage). I dropped it to the "lowest" setting and the
problem is still apparent, just at a different speed.

I then increased to the "highest" setting and again, the problem is
still present, again at about 70mph.

Moving the adjustment just seems to alter where the power comes in and
thus where it judders, when its set at its "lowest" position, the
power surge doesnt come in until later on up the rev range, when its
set to "maximum", the power band seems apparent almost from tickover.

Does this shed anymore light on the issue and a solution?

Thanks
Jon


On Tue, 18 Apr 2006 16:36:25 +0100, Jon <[email protected]> wrote:

>Ive just acuired a TD5 90 complete with Tunit chip. It all goes fine
>until it gets to about 70mph (slower if going up a hill or under
>load). At this point it begins to judder as though the accelerator is
>being rapidly pressed, lifted, pressed, lifted etc etc. Most
>annoying.
>
>I dont think its over-boosting as it seems to drop off the power
>rather than lunge forward. I tend to think its probably over-fuelling
>- or just crap programming??
>
>Dont know if it makes any difference but its also got the Disco II Q
>gears in the T/Box.
>
>Do "chips" consider revs relative to engine speed and act accordingly
>or just throw more fuel in? I notice you can get tunit chips for a
>Defender or Disco, so seemingly there is a difference?
>
>
>I wondered if it could be a sticking EGR valve but the problems seem
>to occur in too specific a region.
>
>Any other thoughts?
>
>
>Thanks
>Jon

On Wed, 19 Apr 2006 06:15:22 GMT, "Dad" <[email protected]>
scribbled the following nonsense:

>If the tuneit is the plug in type then try unpluging it and drive without it
>for a while, the tuneit only adjusts the injector pulse width, so is not
>concerned with tubo boost, depending on which tunit you have you could ty to
>adjust the potentiometer, to back it off a bit.
>Before I bought a tuning box I considered the tuneit unit but after some
>enquries of the manufacture decided against it. This was a pesonal opinion
>but I got the impession that it was not as sophisticated as the dastek unit,
>sure the dastek is more expensive but I have after 6 months of use had no
>downside to the unit.
>

dastek, h'mm vowed never to have anything to do with them when their
sales guy tried selling me chip for my 200TDi Disco at the Heritage
Run. Repeatedly told them it was a 200 TDi..... They only got the
hint when I took the vehicle to their show stand because i told them I
didn't know where to fit such a chip to my engine......
--

Simon Isaacs

Peterborough 4x4 Club Chairman, Newsletter Editor and Webmaster
Green Lane Association (GLASS) Financial Director
101 Ambi, undergoing camper conversion www.simoni.co.uk
1976 S3 LWT, Fully restored, ready for sale! Make me an offer!
Suzuki SJ410 (Wife's) 3" lift kit fitted, body shell now restored and mounted on chassis, waiting on a windscreen and MOT
Series 3 88" Rolling chassis...what to do next
1993 200 TDi Discovery
1994 200 TDi Discovery body shell, being bobbed and modded.....

>Does this shed anymore light on the issue and a solution?
>
>Thanks
>Jon

Throw the box in the bin and bring the car to me for a proper chip ;-)

--
Marc Draper

On Wed, 19 Apr 2006 18:54:24 +0100, Marc Draper
<[email protected]> wrote:

>>Does this shed anymore light on the issue and a solution?
>>
>>Thanks
>>Jon
>
>Throw the box in the bin and bring the car to me for a proper chip ;-)

Marc,

What sort of chips to you use, would I need a bigger intercooler (its
standard at the moment)? AND what sort of cash are we talking?

I guess you wont be in Yorkshire either??

Jon

>Marc,
>
>What sort of chips to you use, would I need a bigger intercooler (its
>standard at the moment)? AND what sort of cash are we talking?
>
>I guess you wont be in Yorkshire either??

No you would not need a bigger intercooler . TD5 intercooler is pretty
good.

I am based in Kent but my maps are born and bread in Yorkshire so you
are lucky there.

Mail me for more info

--
Marc Draper
www.mdeng.co.uk