Hi, i have strange problem with my stilo. Car starts with no problem every single time, just 2 - 3 turnovers and engine starts. There is no smoke at all when starting, on idle or when driving with constant speed. Just when its accelerating, doesnt matter if around 2000rpm or 3500rpm and what gear im leaving big black / gray cloud behind. Already checked all IC hoses, no oil inside, no cracks or splits. EGR cleaned and seems to be working ok. Blenked it off for test, car seems like slightly more powerfull in low rev range but dark clouds still there. Overboost valve cleaned and moved to battery tray. Timing belt, all the filters and oil changed, MAP cleaned, MAF cleaned - disconnected it for test - less power, more smoke and MIL. Took it for a spin today with FES connected to see live parameters. Can anybody tell me why there is so big difference between Fuel Quantity vs Total Fuel Quantity and Intake Air Quantity vs Desired Intake Air Quantity? What can likely be the problem, MAF, injestors? Any help would be greatly appreciated :bang:

FES log attached

you need a better log to tell for sure but looks like for sure boost is down, if your 100% no leaks look at actuator of turbo.
it should be in max spool position at idle and then turn engine off , actuator should move out into min spool position, restart car and it should pull in again at least 10mm or so.
if it doesn't you may have a stuck vnt inside turbo, or vac leak to vnt actuator, or boost solenoid issue not supplying vac to actuator.
for a better log stck in 3rd or 4th gear and floor accelerator from under 2000rpm to 4000rpm.
injection is split up into pre and pilot also so only total fuel is important
log revs ,total fuel, actual maf, actual boost , desired boost, vnt%.
maf values look realistic compared to actual boost
map sensor looks realistic compared to maf and atmospheric(desired around 1000mbar or less)
as for injectors? if blocked and delivering less fuel=big mpg increase ?
if delivering too much fuel mpg would be really low? and id expect boost to be higher almost always higher than desired?
chech that vnt actuator function
your looking for this sort of travel

if you look through I have a few close up vids

viewed from above in car

Thanks for the hint, ill check vnt actuator and make better log tonight. As for consumption, mostly city, distances about 15 - 30 miles from start to stop car delivers around 40 - 43mpg but its "driving miss daisy" style, more dynamic driving measures around 35 - 40mpg. Ill upload the logs later on. Thank you again

Couldnt check actuator today (nightfall + need another pair of hands to start/stop) but here are logs of two runs from 2000 to 4000rpm. What parameter you meant by VNT%? boost control/selenoid%?? Thanks

heres your log as graph

and heres with added data of afr(air fuel ratio) and boost divided by maf(which I use to compare realistic values to abnormal values such as would occur with boost leaks or high low reading map / maf sensors)

and to compare to one of my logs


as long as egr is disabled/blanked the value of boost/maf has always been around 1.9-2.0 and maybe 1.8-2.0 but as can be seen in your logs value drops a fair bit lower so could be maf is over reading , or map is under reading, maf is real and boost leak is present as an additional issue ?
also the afr only drops to around maybe 24 I would expect this to be fairly clean burn, a faily smoky figure would be below 16-17afr maybe and black smoke less than 15afr possibly, so again leads me to think the air the maf is reading is not getting to the cylinder so possibly a boost leak or again maf reading is falsly high?
is maf sensor original or fairly new?
check the visual on the actuator first, if you have access to a vacuum gauge you can pull the vac pipe off the turbo actuator and read directly the vac supplied to it at idle (id expect at least negative 600mbar)similar to this

Compoared to yours there is definitely some boost pressure and boost control problem. Ill check vnt actuator, solenoid and all vacuum lines tomorrow. Thanks a million

my log was not meant to compare figures asim a modified jtd150hp figures will naturally be higher in boost and maf.
just the boost/maf calculation has stayed at a fairly constant value around 2 through many logs and also other car logs off forums(mostly tuned versions though) so maybe a 115hp standard car naturally has a figure lower like yours around 1.75?

EGR is functional, MAF is not new, probably as old as the car. seems to be bosh but can not read the number. Found strange issue, intake air temp sensor is inside MAF, right? sometimes it reads -40 degrees under FES, sometimes reading is right so there is something not right here. Just ordered original 2nd hand MAF of ebay, pn matches with eper. Before it arrives Ill check all the vacuum lines and actuator and report back. Thank you

im not 100% sure where the 115 gets its air temp from I know mine has 2 one is in maf and again in the map sensor?
when its right is it same as outside air ? or about 15-20c higher than outside air? if so its probably measuring at the map only maybe.

When its right its about the same as temp on the dashboard, today dashboard was at 11.5 degrees and intake air temp was 13. few times fes said -38 and spit out Air Intake Temp Sensor fault, didnt activated the MIL

sussexa said:

im not 100% sure where the 115 gets its air temp from

Click to expand...

115 JTD inlet air temperature sensor is combined with the MAF.
.

115 JTD inlet air temperature sensor is combined with the MAF.

Click to expand...

Its what I was thinking.. Thanks for confimation

Received and fitted original MAF at friday. The old one was not bosh and had completely different part numbers. Not sure about consumption yet, seems to be slightly better but surely car has much more life and response, more power and there is much less smoke. Still a bit cloudy under hard acceleration but much better. Thank you all for your help, thread can be considered closed

could you possibly repeat a log of revs, total fuel , boost and maf again similar to above to compare how that value has changed(boost/maf)
it may help out others in the future.

sussexa said:

could you possibly repeat a log of revs, total fuel , boost and maf again similar to above to compare how that value has changed(boost/maf)
it may help out others in the future.

Click to expand...

Yeah, no problem, will do the logs tomorrow

sussexa said:

could you possibly repeat a log of revs, total fuel , boost and maf again similar to above to compare how that value has changed(boost/maf)
it may help out others in the future.

Click to expand...

Here are 2 logs, 3rd and 4th gear ~2000 to ~4500. There is definitely difference in boost pressure. Wouldnt expect this to be MAF fault.

thanks for those logs, its definitely changed the maf value and hence the boost/maf value although now it appears too high(over 2)
heres your old maf log

and here are the other 2 with new(used )maf




as you say boost has increased for sure but as a consequence of maf change or that temperature sensor in maf ?
looks like vnt is nearly 10% higher to achieve actual boost in later log, theres still a possibility that your map sensor is over reading or that new maf is under reading slightly(or possibility of air leak after maf from split turbo inlet pipe or common broken vapour trap under airbox, letting unmetered air in that bypasses maf giving low reading).(having replaced the maf any chance its loose clip around hose ?)
if all is ok all well and good, thanks for the extra logs

sussexa said:

as you say boost has increased for sure but as a consequence of maf change or that temperature sensor in maf ?

Click to expand...

Replaced whole thing (MAF sensor) for used but tested and guaranteed ok original Bosh witch P/N matching to what eper showed for my vin number. As Davren said, temperature sensor is embedded in MAF so it was also replaced.

Old MAF has some weird part numbers and there is no manufacturer on it (some Chinese crap probably), tried to google it but found nothing particular so im not even sure if it was the right sensor for this engine or maybe previous owner put whatever he could get on scrappy with the same connector and pipe size just to sell the car

sorry what I meant was ,the new maf reading is less than the old one even though boost is higher so it doent make sense that smoke is less purely from the maf flow reading difference.
so maybe the faulty temperature reading from the old maf was limiting something in ecu ?.

Cold air has different pressure and density than hot air, maybe temp sensor was the problem, ecu was getting false temp reading and calculated wrong amount of fuel or injection timing?
Total fuel values looks slightly lower and after 2 days of driving i can see that average consumption when driving quite aggressive manner changed from 36 - 38mpg to 42mpg