hi i have A fiat stilo 1.9 jtd... i think i have an aux pulley that needs adjusting, when the sound started on changing gear i also noticed slight hesitation when slowing down in traffic, not really on accelerating... could i have a split hose any ideas
Stilo hesitation on decelerating
- Thread starter simpy
- Start date
Currently reading:
Stilo hesitation on decelerating
The Aux' pulley only drives the alternator and the air conditioning pump, so I'm not sure why you think it needs adjusting. In any case, it has an automatic spring-loaded adjuster that compensates for any stretch in the belt.
If the car is moody while accelerating and decelerating, then it's probably a sensor that isn't doing it's thing. The only other contender might be the fuel pump but that tends to only show up when you want to go, rather than slow.
The JTD has a jungle of pipes so any of them could be loose or split. The main one is the flexible "octopus" pipe that connects the MAF sensor to the turbo. The big clamp at the MAF can work loose.. or it gets overtightened, because it can work loose, so then can't be tightened properly.
On the other end, there's the clamp on the turbo but that tends to make an oily mess if it's loose, so you'll be able to tell. Obviously the octopus baffles mustn't be split or leaking either.
Also check that the small (8mm) pipe (usually blue) next to the turbo is still attached to the wastegate actuator and has no splits in it. Check that the wastegate actuator is working - you should be able to move the plunger up and down. It could have a split diaphragm inside it.. but at £13 it's easier to swap it, if you're in doubt.
Also check the connections on that suspended steel pipe that runs from the turbo to the intercooler.. although again, the neoprene hose at the turbo end tends to only leave an oil film if it's loose. The airbox pipes and the hose to the little catch tank under the airbox are less likely to cause problems if they're loose, as they're on the other side of the MAF, but it doesn't hurt to have a proper nose about while you're down there.
If the beast is all airtight and the wastegate actuator looks okay then it could be a failing MAF and/or MAP sensors. These are tricky to test if they're not giving any stored errors... and the MAF is a bit dear to just swap it on the off-chance... but if you end up going that way, get a Bosch one, not a copy or cheaper part.. those tend to be worse than even a duff Bosch one.
The MAP is a bit cheaper.. it lives on the back of the inlet manifold at the top of the engine, so you can take it out easily and give it a good clean with some kerosene (WD40) followed by shaking it out and blasting it with electrical contact cleaner. If you run your oil level at MAX, you'll have a lot of oil inside the manifold, which can pollute the MAP... I tend to run at about 80% full oil level.
Apart from that, there's a vacuum accelerator down below the RHD passenger (left) headlamp. It's at the other end of the blue pipe from the wastegate actuator up there ^. They can get seized up if the shielding around it is missing so that they get wet. They're £60 from memory, so not one to just swap and see... Listen to it when the engine is being blipped, to feel for it working, or disconnect the pipe and feel for it sucking.
It's not the EGR anyway..
but if you're getting a load of oil in the manifold (the MAP will be all oily) then you could take the EGR off and give it and the pipework a good clean out too.
Ralf S.
If the car is moody while accelerating and decelerating, then it's probably a sensor that isn't doing it's thing. The only other contender might be the fuel pump but that tends to only show up when you want to go, rather than slow.
The JTD has a jungle of pipes so any of them could be loose or split. The main one is the flexible "octopus" pipe that connects the MAF sensor to the turbo. The big clamp at the MAF can work loose.. or it gets overtightened, because it can work loose, so then can't be tightened properly.
On the other end, there's the clamp on the turbo but that tends to make an oily mess if it's loose, so you'll be able to tell. Obviously the octopus baffles mustn't be split or leaking either.
Also check that the small (8mm) pipe (usually blue) next to the turbo is still attached to the wastegate actuator and has no splits in it. Check that the wastegate actuator is working - you should be able to move the plunger up and down. It could have a split diaphragm inside it.. but at £13 it's easier to swap it, if you're in doubt.
Also check the connections on that suspended steel pipe that runs from the turbo to the intercooler.. although again, the neoprene hose at the turbo end tends to only leave an oil film if it's loose. The airbox pipes and the hose to the little catch tank under the airbox are less likely to cause problems if they're loose, as they're on the other side of the MAF, but it doesn't hurt to have a proper nose about while you're down there.
If the beast is all airtight and the wastegate actuator looks okay then it could be a failing MAF and/or MAP sensors. These are tricky to test if they're not giving any stored errors... and the MAF is a bit dear to just swap it on the off-chance... but if you end up going that way, get a Bosch one, not a copy or cheaper part.. those tend to be worse than even a duff Bosch one.
The MAP is a bit cheaper.. it lives on the back of the inlet manifold at the top of the engine, so you can take it out easily and give it a good clean with some kerosene (WD40) followed by shaking it out and blasting it with electrical contact cleaner. If you run your oil level at MAX, you'll have a lot of oil inside the manifold, which can pollute the MAP... I tend to run at about 80% full oil level.
Apart from that, there's a vacuum accelerator down below the RHD passenger (left) headlamp. It's at the other end of the blue pipe from the wastegate actuator up there ^. They can get seized up if the shielding around it is missing so that they get wet. They're £60 from memory, so not one to just swap and see... Listen to it when the engine is being blipped, to feel for it working, or disconnect the pipe and feel for it sucking.
It's not the EGR anyway..
but if you're getting a load of oil in the manifold (the MAP will be all oily) then you could take the EGR off and give it and the pipework a good clean out too.Ralf S.
Last edited:
