Tuning a Diesel Engine with a plug in box

fivetide

lfc321 wrote: »

(genuine question this): why is it possible to retune engines to make them both more economical and more powerful, as per Alx33277's example? I can understand manufacturer's sacrificing some power for efficiency, or vice versa. But why do they sell cars that can be improved both ways. Do you lose out somewhere else? Reliability??

Firstly - I wouldn't touch one of these plug in boxes at all. The likelyhood it will damage your engine is rather high IMHO. This is because a custom map, with someone who knows what they are doing will get the best from your specific engine. This might well get more power initially but if your engine doesn't actually like it, big bills could be on the way.

Secondly, to answer fc321's question, Manufacturers build an engine within certain tolerances. This gives the middle road for performance and reliability. However, not all engines are the same and it is possible to find the best balance for your specific engine rather than the one size fits all that the original ECU has.

As said, soemtimes the differences are small between engines with different power outputs but essentially the cars that benefit from things like this are turbo engined. That is because whacking the boost pressure up gives a significant performance boost. Off boost the car is the same so no difference to fuel economy until you start booting the car.

With a petrol engine at least, cars tend to run really rich to protect the cat. Decatting the car allows a mapper to lean out the fuel for the optimum ignition. This reduces both fuel use and emissions. If they then turn up the boost on the turbo you have gained power as well.

From my own experience I had a Subaru WRX go from 225bhp to near 300bhp, still pass the emissions test without a centre cat and return over 30mpg on a run. Not bad. Map did cost £500 though.

5t.

Lum

forgotmyname wrote: »

These plug in boxes usually just fool the ecu into thinking the fuel pressure is too low. So the pump works harder
and the injectors work harder.

That type is less common these days. The ones you will usually find today plug into the OBDII port and flash new software onto the ECU.

vax2002

basically the remove the emission strangling restriction on the pressure regulator.
You can do the same by swapping the regulator for a non EU model
ours are generally set at 5.5 psi and the non EU ones at 7psi
the boxes just reduce the current to the pressure regulator.
The upside is many engines were designated to run at 7pis and are strangled down to meet EU emission maximum targets.
So no they dont tune the engine, the just remove the de-tuning.
You will get more power and more mpg if you drive sensibly but also more viable smoke if you do boot it.

motorguy

I've used them on and off for years. You will definitely get a power increase, and the benefit is they can easily be unplugged.

motorguy

fivetide wrote: »

Firstly - I wouldn't touch one of these plug in boxes at all. The likelyhood it will damage your engine is rather high IMHO. This is because a custom map, with someone who knows what they are doing will get the best from your specific engine. This might well get more power initially but if your engine doesn't actually like it, big bills could be on the way.

From my own experience I had a Subaru WRX go from 225bhp to near 300bhp, still pass the emissions test without a centre cat and return over 30mpg on a run. Not bad. Map did cost £500 though.

5t.

These plug in boxes work best taking a maybe 110BHP diesel to maybe 135BHP. Theres little risk and they have a proven history.

I dont think a £90 plug in box to do that is anywhere near as risky (to the engine, to yourself and to other road users) as taking an otherwise standard 225BHP car up to 300BHP (a 35% hike)

fivetide

pgilc1 wrote: »

These plug in boxes work best taking a maybe 110BHP diesel to maybe 135BHP. Theres little risk and they have a proven history.

I dont think a £90 plug in box to do that is anywhere near as risky (to the engine, to yourself and to other road users) as taking an otherwise standard 225BHP car up to 300BHP (a 35% hike)

Well you'd be wrong but there you go.

I spent hours with the mapper, checking engine response, power, fuelling and emissions in all gears and under different loads to ensure it was 100% safe and matched to the engine.

Of course, why not take two minutes to consider none of these things and simply plug a box in and hope for the best with no idea (as is clear from the number of different 'facts' in thsi thread) what it is actually doing.

Please do explain how it makes the car more dangerous for other road users though, I'm keen the hear that one.

5t.

Hammyman

lfc321 wrote: »

(genuine question this): why is it possible to retune engines to make them both more economical and more powerful, as per Alx33277's example? I can understand manufacturer's sacrificing some power for efficiency, or vice versa. But why do they sell cars that can be improved both ways. Do you lose out somewhere else? Reliability??

Quite simply because they are factory tuned to give a good driving experience with a smooth power delivery with good economy so everything is a compromise.

When you do a rolling road tune, you are prepared to sacrifice either economy or a smooth power delivery for performance.

I've built cars at the extreme of tuning. The stock motor was a nice thing to drive. Mine went infinitely faster but you had to drive around town in 1st gear as there was next to no power below 2500RPM.

Lum

fivetide wrote: »

Please do explain how it makes the car more dangerous for other road users though, I'm keen the hear that one.

Well a major increase in power with no corresponding improvements to grip, handling and/or braking can make the car dangerous to others if driven by someone with a lead foot.

The plug in boxes are usually fairly conservative in their upgrades, and modern engines generally aren't running on the very edge of what they are capable of so it's pretty unlikely you will run into a problem.


A proper map will, of course, get you better results as the mapper can tune it more accurately to the specifics of your engine and push much closer to the limits than a generic map could ever do.

It's also worth noting that if you get a proper map done and are pushing it to the limits, it's worth getting the map updated regularly to take into account wear and tear on the engine.


What I'm trying to say is that both have their places, and the more reputable ECU based ones (Bluefin, etc.) are a lot different to the old days of piggyback systems that were often little more than a variable resistor that messes with sensor output, as described by Forgotmyname above.

You can still find crap like that on eBay however, so do your research before buying.

fivetide

Lum wrote: »

Well a major increase in power with no corresponding improvements to grip, handling and/or braking can make the car dangerous to others if driven by someone with a lead foot.

thanks but I was waiting for Paul to answer it The point being, he knew nothing about me or how I drive. Just because the car has more power does not mean I suddenly drive like a plank, far from it.

I did actually upgrade the brakes to go with it although no further upgrades were needed. I was annoyed at the implication that it was more dangerous though. It made overtaking for example, much safer. You could be past a lorry on the A1 in a very short space of time with no need to break the limit or stay 'exposed to danger' for long periods.

What I'm trying to say is that both have their places, and the more reputable ECU based ones (Bluefin, etc.) are a lot different to the old days of piggyback systems that were often little more than a variable resistor that messes with sensor output, as described by Forgotmyname above.

You can still find crap like that on eBay however, so do your research before buying.

Agree but on a basic motor, I don't see the point of actually trying to up the performance with one of these boxes. As you say, no further upgrades, potential insurance premium issues and no idea what it really is doing beyond (I suspect) upping the boost pressure on the turbo without actually finding out what condition the car/turbo is in.

If you have a decent performance car and you want to get the most from it, why would you not have a custom map done? It's spoiling the ship for h'penny o' tar and all that.

5t.

Lum

I always figured that the target market for the likes of Bluefin were for the drivers of low tax "eco" company Mondeos who want an undetectable and tax free performance upgrade that may also reduce their private mileage bill a little and who cares what state the car is in when the lease is up, just flash it back to standard and say nothing.