Technical help Stilo JTD lots of boost

[rattystilo]

my Stilo has been going bananas of late. When you put your foot down hard it will flick the eml on and cut the power.

The spec of the car is: decatted exhaust incl the top cat, and a celtic tuning remap.

Shortly after decatting the car i had it mot'd and in order to ensure the emissions would be clean i ran a tank of diesel through with injector cleaner. then the trouble began. It appears to be a boost issue, as soon as i touch the throttle the turbo is pushing 30psi rather than the usual 23psi. I daren't hold my foot down to see what max boost it will go to.

We are looking on other forums for clues but thought i would see what you guys thought. Fave is overboost valve but when this fails its normally loss of boost you see. Other items is crank sensor. I might just change all the usual sensors for peace of mind. If i spend a few hundred quid i will keep the car for a couple more years.

 

[Shadeyman]

The crank sensor regulates injection timing, I'm pretty sure it has nothing to do with controlling the boost.

If it were the Boost Valve(Overboost) or its connecting pipes you would get power loss, your getting a power gain.

My guess is its MAP sensor related.

The MAP sensor measures manifold pressure and via the ECU regulates boost accordingly. If the MAP sensor is faulty or covered in crap it may be sending incorrect data to the ECU resulting in overboost.

The MAP sensor does get very dirty if the EGR doesn't have the Restrictor Plate or and Blanking Plate installed so fit if I were you I'd get one of them fitted soon.

Remove the MAP sensor, give it a clean using electrical cleaning spray(about £5 from Halfords) and see if things improve.

 

[sussexa]

23 psi is 2.58 bar so your already over the range of your map sensor which should be 2.5 bar.can you log actual boost desired boost and vnt% to see if it's going over range then asking for more boost by vnt, or of vnt is already at 20% it's boost creep due to de cats and possibly more fuel from cleaner injectors. You could look into swapping to a 3bar map anyway, remap needs tweaking for new sensor though.

 

[Shadeyman]

Whats the standard boost pressure of a 1.9 JTD 8v?

I'm sure the max boost of my remap was set to 1.4 bar to help prevent component failure ...

 

[rattystilo]

i already have the egr blanked off. Cheers for the info so far guys. Interesting point about more fuel due to clean injectors. Have to admit to having no idea hog to log info etc.

 

[rattystilo]

Well i finally bit the bullet and started flooring the car through the gears taday and no problems, no lights or loss of power. It still spools up to 30psi but then settles to 23psi.

There is one major change from when the problem started to today that i didn't think was relevant but it may well be the reason for the problem.

i had two out of shape tyres with delaminated sidewalls on. It looks like the vibration from these which was not noticeable through the steering wheel but was felt through the chassis may have been shaking a connector around causing a false signal to be sent.

happy days again so far.

Oh, with the faulty tyres on i had forgotten just how quick my car is. its like having it remapped again for the first time