Tuning which remap for my panda multijet

[g8rpi]

I fitted a 'tuning box' about 7 years ago, and left it set at its default of 3 (out of 10). Performance was noticeably better, and best of all economy went UP during normal driving. Original clutch lasted till 90+k, now on 141k with no engine/gearbox/clutch problems.
Brakes are vented disk front and seem perfectly adequate for the car. Standard tyres a bit skinny if you fancy cornering at speed.... !

The improvement in fuel economy shown by the trip computer when fitting a tuning box to a diesel is false. Most of theses boxes just fude the fuel pressure signal causing the fuel pressure to rise and thus injectors to flow more fuel. As the trip computer fuel calcultion is based on the calibrated fuel flow (standard pressure) it over-reads showing improved fuel consumption when the pressue is increased.


Robert G8RPI.

 

[Trimdoner]

The improvement in fuel economy shown by the trip computer when fitting a tuning box to a diesel is false. Most of theses boxes just fude the fuel pressure signal causing the fuel pressure to rise and thus injectors to flow more fuel. As the trip computer fuel calcultion is based on the calibrated fuel flow (standard pressure) it over-reads showing improved fuel consumption when the pressue is increased.


Robert G8RPI.

While your technical description may be more or less correct for some sytems, as I understand it fuel pressure is constant but injector timing is increased to give more fuel flow.
More to the point, I used to log fuel/miles precisely in the MJ's earlier years, and fuel economy brim tank/tank rose quite dramatically. (I only stopped logs about two years ago)
If you find my earliest posts, I was initially very disappointed with the MJ economy, so whether in my case the addition of the tuning box helped correct an original set-up fault may partly explain the improvement?

 

[g8rpi]

You are correct, fuel pressure is held constant and injector timing controlled by the ECU to control the engine. But, the tuning box cannot adjust the injector timing so most of them reduce the signal from the fuel pressure sensor so the ECU increases the the actual pressure to get the right indication. Tank to Tank comparision is an accurate way (subject to speedo error) to get consumption and you may have seen an improvement but this is likey to be from a change in driving habits due to changed engine characteristics especially if the car was orginally underpowered for your driving style. Increased economy directly results in reduced CO2 emissions but does not go with increased power. It's not impossible, but unlikely. I did only say that the trip economy was false with this type of tuning box.


Robert G8RPI.

 

[Trimdoner]

You are correct, fuel pressure is held constant and injector timing controlled by the ECU to control the engine. But, the tuning box cannot adjust the injector timing so most of them reduce the signal from the fuel pressure sensor so the ECU increases the the actual pressure to get the right indication. Tank to Tank comparision is an accurate way (subject to speedo error) to get consumption and you may have seen an improvement but this is likey to be from a change in driving habits due to changed engine characteristics especially if the car was orginally underpowered for your driving style. Increased economy directly results in reduced CO2 emissions but does not go with increased power. It's not impossible, but unlikely. I did only say that the trip economy was false with this type of tuning box.


Robert G8RPI.

The car computer was always optimistic by 3 - 5 mpg versus tank-to-tank calcs, which I did for a very long time (old business habits...!) Also, mpg always dropped about 5mpg over the winter months.
BTW, normal use is about 75% rural / 25% town driving, so not too much crawling about at low speeds.

From new the car originally felt underpowered unless driven hard (compared to an earlier 106 diesel), and oddly the tailgate would be covered in soot.
Dealers as usual weren't interested ... "it's not showing any error codes, guv", which led me to think something was badly set up from new which the tuning box 'adjustment' corrected in some way.
As the car is rarely driven in anger, your comments about driving style probably hit the nail on the head - it now doesn't need much throttle to keep up with normal traffic flow, whereas before it needed a heavy foot to avoid embarassment
My driving style hasn't really changed over the years (still got the same bad habits )

 

[steve w hebburn]

hi, guys. the only info everyone wants to know, is where can we buy a good plug- in tuning box, at a decent price.:worship: cheers, steve

 

[g8rpi]

Hi,
"good plug-in tuning box" is an oxymoron. All these boxes are a bodge to a greater or lesser degree and can cause damage to the car. Get a proper re-map instead if you wat to "tune" the engine, but check with your insurance company first.


Robert G8RPI

 

[koalar]

interesting you see a drop in winter


my petrol has no noticeable difference in winter.


I found by putting the heater blower only on setting 1 the car heats up within a mile or so

putting the blower on max it takes forever to warm up.

 

[koalar]

You are correct, fuel pressure is held constant and injector timing controlled by the ECU to control the engine. But, the tuning box cannot adjust the injector timing so most of them reduce the signal from the fuel pressure sensor so the ECU increases the the actual pressure to get the right indication. Tank to Tank comparision is an accurate way (subject to speedo error) to get consumption and you may have seen an improvement but this is likey to be from a change in driving habits due to changed engine characteristics especially if the car was orginally underpowered for your driving style. Increased economy directly results in reduced CO2 emissions but does not go with increased power. It's not impossible, but unlikely. I did only say that the trip economy was false with this type of tuning box.


Robert G8RPI.

As far as I know the trip computer only uses the fuel pump and abs to work out the MPG

which makes sense as going up hill after a bit of coasting you can get a reading of 141 MPG for a sort while.


don't see how increasing the pressure only could reduce the MPG


Such a lot affects MPG road surface,driving style, wind direction, sticking brakes and so on.

i am always around 62-64 but had the battery off to help another car. First trip out was 200 miles againt the wind only averaged 58.

Its now on 1225 miles and the MPG is still climbing (61.8) but its taking a long time to wipe the inital against the wind out.


A few miles isnt enough to judge the MPG. When you get to about 4k it tends to level out.

 

[DaveMcT]

A tuning box stands out like a sore thumb. A remap is all but invisible.

Why bother with a 100HP.
https://www.celtictuning.co.uk/serv...70-bhp-2005-2011-ECU-remap-chiptuning/stage-1

 

[Trimdoner]

A few miles isnt enough to judge the MPG. When you get to about 4k it tends to level out.

My 86mpg on the computer was over 2300 miles....

I found by putting the heater blower only on setting 1 the car heats up within a mile or so

Our MJ takes ages on a moderately cold day - at least 5 miles before a trace of warmth from the heater, so we just leave the blower off until the temp gauge starts to move. Add to that my wife's at that tender age when we must have the windows open all year around, and it's definitely a gloves and dutt car for me

 

[DaveMcT]

My 86mpg on the computer was over 2300 miles....
Our MJ takes ages on a moderately cold day - at least 5 miles before a trace of warmth from the heater, so we just leave the blower off until the temp gauge starts to move. Add to that my wife's at that tender age when we must have the windows open all year around, and it's definitely a gloves and dutt car for me

I had a Montego turbo diesel back in the early 1990s. It was amazingly fuel efficient but sadly much too smokey. During the cold winter around then I was never getting it warmed up after 7 miles of town commuting.

It was fine for long journeys but for winter commuting it really needed and electric preheater. Today's diesels are cleaner and do warm bit faster, but fuel efficiency means less wasted energy to get the engine warmed up. Electric preheaters are cheap and really do make sense.

 

[g8rpi]

As far as I know the trip computer only uses the fuel pump and abs to work out the MPG

which makes sense as going up hill after a bit of coasting you can get a reading of 141 MPG for a sort while.


don't see how increasing the pressure only could reduce the MPG



<SNIP>

On a modern injected car the figure used by the trip computer for fuel used by the engine is based on how long the injectors are open integrated over time. This is multiplied by the flow rate for the injectors to give the fuel used. The injector flow rate is calibrated at stndard fuel pressure (Mulijet injectors are individually calibrated and coded so you have to tell the ECU the code if you swap them). If the fuel pressure is increased (by the tuning box making the signal from the pressure sensor lower), the flow increases but the ECU still calculates the fuel low for the reported (false) pressure. This means the engine overfuels (so you back off on the throttle) but the trip computer still uses the standard fuel flow giving a false improvement in consumption.


Robert G8RPI.

 

[koalar]

On a modern injected car the figure used by the trip computer for fuel used by the engine is based on how long the injectors are open integrated over time. This is multiplied by the flow rate for the injectors to give the fuel used. The injector flow rate is calibrated at stndard fuel pressure (Mulijet injectors are individually calibrated and coded so you have to tell the ECU the code if you swap them). If the fuel pressure is increased (by the tuning box making the signal from the pressure sensor lower), the flow increases but the ECU still calculates the fuel low for the reported (false) pressure. This means the engine overfuels (so you back off on the throttle) but the trip computer still uses the standard fuel flow giving a false improvement in consumption.


Robert G8RPI.

i was under the impression the Panda Trip computer only used three signals.


engine revs via crank sensor
road speed via abs
fuel level via pump


very basic. But works well.

 

[steve w hebburn]

hi, guys. wow lots of info. so tuning boxes are a no no. it looks like a remap so how does the same engine( 1248 diesel) produce higher power in other pandas/ grande puntos etc. must be the ecu units. best regards. steve

 

[g8rpi]

Hi,
Mainly the power for a given engine is set by a different ECU map and possibly also different turbocharger and other inlet tract components.


Robert G8RPI.

 

[g8rpi]

i was under the impression the Panda Trip computer only used three signals.


engine revs via crank sensor
road speed via abs
fuel level via pump


very basic. But works well.

I'm not aware of any system that uses the fuel level in the tank for fuel consumption figures. It is far too inconsistent and not very accurate.

The Panda, like most modern Fiats has an instantaneous fuel consumption display, this clearly cannot be using the tank level for it's calculation as it does not change enough in the short term.


Robert G8RPI.

 

[koalar]

I'm not aware of any system that uses the fuel level in the tank for fuel consumption figures. It is far too inconsistent and not very accurate.

The Panda, like most modern Fiats has an instantaneous fuel consumption display, this clearly cannot be using the tank level for it's calculation as it does not change enough in the short term.


Robert G8RPI.

this is all I can find

 

[g8rpi]

Hi,
Obviously the instrument cluster need the tank level for the fuel gauge, and the trip computer needs it for range but I'm 100% certain it does not use it for trip computer fuel consumption. Td you follow the D5050 ling to engine management? I'm certain the engine ECU doees the fuel flow calculation and transmits that via CAN to the "trip computer" which is of course just a software subroutine sitting in another ECU (I'm pretty certain it' in the dashboard computer). This is confirmed by Multiecuscan (in simulation I don't have a Panda handy) showing a fuel consumption parameter in l/hr coming from the engine ECU. I think that eLearn discription is over simplified.


Robert G8RPI.

 

[dave]

A tuning box stands out like a sore thumb. A remap is all but invisible.

its not invisible if the insurance claim is so high they need to get out of paying. its best to declare what ever one you choose

 

[DaveMcT]

its not invisible if the insurance claim is so high they need to get out of paying. its best to declare what ever one you choose

It's always best to declare everything. But plenty don't bother.