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Two words - STAY AWAY!

Get a proper remap. £89 is not going to look cheap when the motor goes bang. All these boxes do is overfuel the engine by increasing common fuel rail pressure. Spells disaster for the injectors, cat convertor and in the long run everything else.
 

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The biggest problem with this type of tuning is, as as been pointed out, that they just over fuel the engine, so you get extra smoke. In the good old days that wasn't a problem. But if you have a diesel particulate filter fitted it will clog it extra quick.

Don't!
 
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crossj said:
Hmm - so what you are suggesting is that this is a bad idea? ;)

Remap it is then!
if your going to use one of these tuning boxes go for DTUK i got one for a vauxhall insignia 2ltr diesel and i must say i was very pleased with it and in fact still have it minus the car now.the thing i liked about it ( unlike remaps) it is literally 'plug and play' and there is no way that it would be picked up by a garage if its removed unlike a remap which would be detected.
performance wise approx 5-10 miles more per litre, sharper throttle response and fully adjustable to your own needs.

link for you just in case
http://www.diesel-performance.co.uk/
 

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None of the tuning boxes - even one of the better ones from DTUK can do anything but pretend to be a sensor and fool the ECU into making adjustments to it's outputs. And that adjustment output can really only be one thing - more diesel, which leads you back to the DPF clogging issue. Even a remap will cause more DPF issues because eventually they all run out of air to mix in with the fuel it's adding. At that point you need a bigger turbo, so then you can add more fuel, at which point you need bigger injectors.

As for being undetectable, even a tuning box will cause the ECU to throw errors because it will always be seeing "infeasible' values" and it will store the errors and high demands for later.

Plus, as was pointed out to me years ago, a bunch of hand-print marks in the engine bay just where the MAF sensor plugs in is a bit of a giveaway that something's been done recently, and the most likely thing is you've unplugged a tuning box. Also, generally the loom for these boxes is tie-wrapped to other cabling and they generally give you a Velcro pad to stick it securely in the engine bay. So if you know what you're looking for, it's pretty obvious.

And if you have an accident then it's very unlikely you'll be able to remove it before the loss adjuster see the car, and he'll know what to look for to.

People aren't stupid. Everything is detectable if someone wants to look for it.
 

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tter said:
if your going to use one of these tuning boxes go for DTUK i got one for a vauxhall insignia 2ltr diesel and i must say i was very pleased with it and in fact still have it
I don't know if you're aware but there is a decent market in those boxes used because they will sell you a new loom and map for a fraction of the price of a new box.
 

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...and not all remaps are good either. Revo pulled their PD170 remap for example, and very few have had robust success with it.

But, it depends on how long your going to keep your car whether a reputable remap is a more cost effective solution than a reputable tuning box.

Dan at Tunit (01257 274100) was telling me of his friend with a TT TDI CR177 Black Edition who ran their box successfully and without DPF issues, and getting over 55 MPG. They have several variables that can be tweaked and are reprogrammable.

I had one on a Touareg and reprogrammed it when I sold it to a friend for his Navara. Just needed a new loom which I got for him second hand off Dan who has P/X stuff and great support. I still have the software and cable!
 
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wja96 said:
None of the tuning boxes - even one of the better ones from DTUK can do anything but pretend to be a sensor and fool the ECU into making adjustments to it's outputs. And that adjustment output can really only be one thing - more diesel, which leads you back to the DPF clogging issue. Even a remap will cause more DPF issues because eventually they all run out of air to mix in with the fuel it's adding. At that point you need a bigger turbo, so then you can add more fuel, at which point you need bigger injectors.

As for being undetectable, even a tuning box will cause the ECU to throw errors because it will always be seeing "infeasible' values" and it will store the errors and high demands for later.

Plus, as was pointed out to me years ago, a bunch of hand-print marks in the engine bay just where the MAF sensor plugs in is a bit of a giveaway that something's been done recently, and the most likely thing is you've unplugged a tuning box. Also, generally the loom for these boxes is tie-wrapped to other cabling and they generally give you a Velcro pad to stick it securely in the engine bay. So if you know what you're looking for, it's pretty obvious.

And if you have an accident then it's very unlikely you'll be able to remove it before the loss adjuster see the car, and he'll know what to look for to.

People aren't stupid. Everything is detectable if someone wants to look for it.
have to disagree had mine on my insignia for over 2 years absolutely no problems also how can it be 'more diesel' when it returns more MPG than without, doesn't make sense.the one i have is fully adjustable and you just adjust it for the best setting i.e throttle response and mpg.
this unit plugs into the fuel rail electric supply with the provided loom and so when it is unconnected and the original loom is plugged back into the fuel rail there is no sign.the unit goes into a bag which has a long velcro strap and you attach it to anything you like whithin the engine bay so once again when it is removed no signs, fingerprints or anything.so tbh wouldn't be that obvious even to a trained eye.
 

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It is just more fuel because that's all it can adjust. The loom only connects at the MAF sensor so it knows how much airflow the MAF sensor is telling the ECU it it getting and it artificially increases that so the car throws more diesel in to match it.

The clever bit about the better tuning boxes is they have a profile rather than just the resistor which adds fuel in excess linearly. It adds lots of fuel at the top (power) and bottom (toprque) of the rev range which is why a non-DPF car will smoke if you put your foot down hard in a high gear at low revs or at high revs in any gear.

As well as making more power, you also make more torque and it's the torque that gives the improvement in fuel economy, just so long as you don't boot it all the time.

I'm possibly simplifying it a bit too much, but that's the nub of it. A tuning box can only ever adjust the amount of fuel to air ratio whereas a remap can also actively change other things like boost and camshaft timing if that adjustment is available (like on the CR170).
 

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ScooTTer said:
Dan at Tunit (01257 274100) was telling me of his friend with a TT TDI CR177 Black Edition who ran their box successfully and without DPF issues, and getting over 55 MPG. They have several variables that can be tweaked and are reprogrammable.
Could you get him to list those variables please? Better yet, a rolling road printout from a TT showing the before and after power and torque curves would be good.

Tuning boxes are only able to feed faked sensor data into the ECU, so the most the ECU will ever do is work to whatever the maximum output values are stored in it. A remap will allow you access to every variable using the genuine sensor data.

As an example, the CR170 (there isn't a CR177 in the TT, it's a new engine which is only in a few of the new cars (facelift A4, facelift A5, new A6) and the TT won't get it until the Mk III) has a torque limiter in it, and unless you open up the ECU and remove the torque limiter, you'll never make more than 380Nm of torque, so by claiming 400Nm on his website he's being a bit economical with the actualite.

I have a rolling road printout of my car before and after the remap. Before the remap it made 179bhp and 380Nm torque. You can't make any more than 380Nm on a CBBB engine because the ECU has a built-in torque limiter. After the remap, same day, same rollers it did the figures in my signature.

And I'm not getting 55MPG - I'm getting 60MPG+

Sorry, but no tuning box, even one of the better ones like Tunit or DPT can only ever alter the fuel:air ratio, and even then they can only ever alter it to whatever the ECU will allow as it's maximum legitimate values.
 

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Come on Walt! Your MPG is without a DPF.

Just as there are turkeys, M&S turkeys and the footballers' favourite - the ALDI three bird roast, there's an option for everyone. You're happy to void elements of your warranty, but others aren't. Tun it get repeat customers who are clearly happy, so what's the problem? Remaps are better - period. But there are valid reasons for not wanting one too.

You might have some entertaining sparring if you ring Dan to ask him the questions I can't answer!
 

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ScooTTer said:
Come on Walt! Your MPG is without a DPF.

Just as there are turkeys, M&S turkeys and the footballers' favourite - the ALDI three bird roast, there's an option for everyone. You're happy to void elements of your warranty, but others aren't. Tun it get repeat customers who are clearly happy, so what's the problem? Remaps are better - period. But there are valid reasons for not wanting one too.

You might have some entertaining sparring if you ring Dan to ask him the questions I can't answer!
I don't have a problem with Tunit etc. and their box is light years on from a resistor mod. I ran a DPT box on a PD140 Passat for 3 years and it was great, but if you're spending that sort of money, I agree a remap is a better bet.
 
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wja96 said:
ScooTTer said:
Come on Walt! Your MPG is without a DPF.

Just as there are turkeys, M&S turkeys and the footballers' favourite - the ALDI three bird roast, there's an option for everyone. You're happy to void elements of your warranty, but others aren't. Tun it get repeat customers who are clearly happy, so what's the problem? Remaps are better - period. But there are valid reasons for not wanting one too.

You might have some entertaining sparring if you ring Dan to ask him the questions I can't answer!
I don't have a problem with Tunit etc. and their box is light years on from a resistor mod. I ran a DPT box on a PD140 Passat for 3 years and it was great, but if you're spending that sort of money, I agree a remap is a better bet.
tuning boxes are far cheaper than maps and easier to remove if necessary.
if its improved fuel econonmy with a touch of improved throttle response cost wise its just got to be a tuning box over removing, cracking open the ecu, bench flashing it,then refitting, which is whats involved with the newer ecu's.
having had both a map and a tuning box i would go for the tuning box if i needed to improve economy/ performance.
 

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Discussion Starter · #18 ·
Hmm - interesting comments. [smiley=book2.gif]

To tell the truth I was after improved MPG, without effecting DPF etc.

You have to ask yourself if its worth risking a 20k+ car for a small black box with promises of a few more MPG! :?
 

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I think the whole point about risking an expensive car for the sake of anything is completely valid.

I actually started off with an MTM piggyback ECU but switched to a Shark remap for the DPF control.

It's really worth speaking to the folks who will be doing the remap, even asking whether you can be present while they do the remap. It can be a fairly scary thing watching someone lever the cover off the ECU although no more frightening than watching someone pull the engine to change the clutch.

You also need to be aware of warranty issues. I've worked for some time on the basis that if you can't afford to buy a new one, don't modify it!
 

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To resurrect this topic

What is the best engine mod to boost the BHP and if possible improve the MPG a bit at cruising speeds?

I see a few TDI owners have engine mods/chips/tuning on here.

If you could take a moment to state the make of your chip, approx cost and the effect its had on your TT that would be superb.

Thanks
 
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