Afternoon all,

So i've been playing with MES again, but on the new stilo!

Its a 1.9 16v Multijet 16v 150, sporting model.

When i first drove the car it felt quick, it has a K&N OEM fitted kit and pulls like a train, its had cam belt kit done at 63k in 2015 and serviced regular since.

Each service has had 5w 30w silverstone oil put in.

It has been looked after and drives sweet when feathering the peddal but as soon as you tap it a little bit, all hell breaks loose and it lights up the tyres or wants to take you into the nearest curb or car, cyclist whatever.

Since this engine is the same as found in many Astras and in the same power figuers, ive drove them and this is nothing like them - its mind blowing, loves drinking the shell v power nitro diesel too, thought i was going to save on fuel but not really, only on a good run will i hit 55mpg, now im at 30mpg steady with a heavy foot loving the power, on a feather its around 45mpg.

I took some boost readings etc from MES and in third gear i hit what appears to be 40 PSI of boost...

is this normal for this car and turbo with a K&N filter... i think it may have been remapped but i want to be sure.

At idle it reads 1080mBar on manifold air pressure.
then you get this... see below, what i recorded with MES.

This is at Idle...

Engine speed
849 rpm

Boost pressure
1028 mBar

Then at full chat in 3rd

Vehicle speed
46.1 mph

Engine speed
3679 rpm

Boost pressure
2800 mBar

Desired boost pressure
2468 mBar


When converting mBar to PSI I get this:

Idle: 1080 mBar = 15.66 PSI
Full Chat: 2800 mBar = 40.61 PSI

Them figures look a bit off or way too much to me.
It has a Garrett turbo but cant see the model number... looks like Garrett **46 - the ** being unreadable.

Any ideas?

What boost is the 150 multijet supposed to produce stock.

My opinion is that your car has been remapped at some stage of its life. Boost values that you are getting (especially the desired VS actual boost difference ) should trigger Check Engine warning certainly.


Since you are not getting any warnings on the dash, and mention K and N kit etc. being installed, I guess it is remapped.


I have experience with the same engine and have been fighting with over boost for a while , have narrowed it down to dirty variable turbo mechanism.

std boost would have been around 2350-2400mbar and std boost limit in map was 2800mbar so take that as a warning(for fault code ).
the std turbo is gt1749va and safe for 2500mbar or 2600mbar long term.
remember mes is absolute so take 1000mbar off. usual std 20-21psi mapped 23-24psi
with your mes you should log just revs , desired boost, actual boost and vnt %
and log a good 4th gear say 2000rpm to 4000rpm(or as high as you can as youll be traveling pretty quick by then)
post up graph or log in excel.
you could also log revs ,actual boost, total fuel quantity,maf airflow.
there are a couple of things to check as to why boost is so high.
vnt operation of the actuator at the turbo , crawl under car with someone else keying car on and off(or you leave car idling and pull off the vac pipe from the actuator,should be a blue pipe) and observe the vnt actuator moving (see vid below how far it should move)if stuck or sticky can easily cause overboost.
swirl flaps if stuck closed could cause overboost also.
whats your thermostat like, should get up to temp and sit bang on middle,when mine went it got upto temp when on the gas but would cool down below middle when coasting or pootling round,new stat sorted out.
or could just be a bad map ?
30mpg sounds way too low. my commute is fairly quick at under 10miles and car only just gets up to temperature and i see 40mpg winter and 45mpg plus in summer.
heres my fuel economy
http://www.fuelly.com/car/fiat/stilo/2006/sussexa/24193/fuelchart
are you going by brim to brim calcs or fuel computer ?
heres my youtube vids brouse and youl find swirl flap,vnt actuators etc in there.


ooh thats not worked as i wanted
search sussexa on youtube to see others

sussexa said:

std boost would have been around 2350-2400mbar and std boost limit in map was 2800mbar so take that as a warning(for fault code ).
the std turbo is gt1749va and safe for 2500mbar or 2600mbar long term.
remember mes is absolute so take 1000mbar off. usual std 20-21psi mapped 23-24psi
with your mes you should log just revs , desired boost, actual boost and vnt %
and log a good 4th gear say 2000rpm to 4000rpm(or as high as you can as youll be traveling pretty quick by then)
post up graph or log in excel.
you could also log revs ,actual boost, total fuel quantity,maf airflow.
there are a couple of things to check as to why boost is so high.
vnt operation of the actuator at the turbo , crawl under car with someone else keying car on and off(or you leave car idling and pull off the vac pipe from the actuator,should be a blue pipe) and observe the vnt actuator moving (see vid below how far it should move)if stuck or sticky can easily cause overboost.
swirl flaps if stuck closed could cause overboost also.
whats your thermostat like, should get up to temp and sit bang on middle,when mine went it got upto temp when on the gas but would cool down below middle when coasting or pootling round,new stat sorted out.
or could just be a bad map ?
30mpg sounds way too low. my commute is fairly quick at under 10miles and car only just gets up to temperature and i see 40mpg winter and 45mpg plus in summer.
heres my fuel economy
http://www.fuelly.com/car/fiat/stilo/2006/sussexa/24193/fuelchart
are you going by brim to brim calcs or fuel computer ?
heres my youtube vids brouse and youl find swirl flap,vnt actuators etc in there.
https://www.youtube.com/watch?v=N6l3xPp0B9A
https://www.youtube.com/watch?v=WOLSdym04ZY
ooh thats not worked as i wanted
search sussexa on youtube to see others

Click to expand...

Some good points there.

I spoke to NJS Alfa Fiat Specialists that did the timing belt job... they said they may have remapped it but cant tell unless i take the car to them to read it... 180 miles away - cheaper alternative would be for a power run at RS Tuning in leeds.

I will take some more readings later when i go out.

I can get around 40 - 50mpg when driving like a grandad, changing gear before the turbo even kicks in.

However, my turbo seems to be there instantly - first gear for half a second or less and your ready for second and then before you know it - another big kick and your into third and breaking the speed limit

I will check the other things you said to mention too... as for overboost - MES wasnt recording any overboost when i checked, the car seems fine with it but i dont.

I mean, come on... whoever has mapped this has gone for shear power in my mind and driveability is somewhat lost in low gears - its an animal and going to end with me getting a speeding ticket, even when trying to drive nice and slow - its there and ready to blast.

I noticed in MES that EGR is disabled and was at 3.9% open and never budged, i read that this may indicate that EGR has been blanked and disabled, however - would of thought it said 0% open when its not activated.

Visconti said:

My opinion is that your car has been remapped at some stage of its life. Boost values that you are getting (especially the desired VS actual boost difference ) should trigger Check Engine warning certainly.


Since you are not getting any warnings on the dash, and mention K and N kit etc. being installed, I guess it is remapped.


I have experience with the same engine and have been fighting with over boost for a while , have narrowed it down to dirty variable turbo mechanism.

Click to expand...

Sorry, i forgot to ask you a question!.

What is overboost? what effects, what does it do, how does it feel, how do you know you have it, i thought i was experienced at turbo engines but apparently not lol.

I ask because my turbo sounds like an owl and on idle it you can hear it low down sounding like an owl noise....

Here is the MES file for about 4.5miles driving, managed to get 4th 2000rpm onwards...

ok its definately remapped
im seeing figures of 1680bar fuel requested pressure , the std map is 1600max and wont go over it.
the egr may well be mapped out and if blanked all the better, mes shows 4% when closed .
the closer the actual boost follows requested boost the better, when it gets 200,300 mbar over id say may be vnt problem mechanically or a map issue.
the vnt maps are very difficult to adjust when you get to more agressive mapping as yours sounds to be.
you need to log less items at a time try to stick to 4 or less as the logging speed drops so low the figures are useless as there are values lagging behind .
try to stick to just activating the log when your ready to accelerate to capture just that event. 2 or 3 logs logging different groups is better than 1 log with all groups.
id start by checking visuals on vnt movement(checking you have full max open and close)
check swirl flaps (if there and working, there but broke flopping round, or even missing and blanked off)
then maybe gently remove and clean the map sensor (plenty of guides about)
try to contact previous owner about mapping, i rekon the clutch limit of std car was about 360nm judging by most generic maps and yours sounds to be above this figure from your description.
also there is the capacity to tune the throttle pedal via the maps to get a very aggresive response for partial pedal pressing(same as pedal boxes that half pedal travel for 100% or sport buttons on some cars do the same )
try being gentler on the throttle(you can pull that up in mes also, to see how far your pressing)
if your getting max boost at 50% throttle id guess something like this has been done.
also 5w30 oil is mainly mpg biased id say its on the thin side for a hard driven turbo you might want a 0w40 or 5w40 .
also with such high rail pressure you might want to consider a fuel lubricant additive .

Don't forget that the inlet pressures you are seeing are abolute pressure so 1080mb is only slightly over standard of 1013mb (depending on the weather and height above sea level. So the "boost" is about 25 PSI (1.7bar) not 40. Does sound like a re-map though.

Robert G8RPI.