Hi. I'm having some performance problems with my Stilo 1.6. The symptoms I've been experiencing are:

• Very often takes a few attempts to start up. I find it easier to start when putting my foot on the gas.
• Going up steep hills can sometimes be a major slog.
• When idling there is often small pulssating sound / vibration. As if it's about to cut off and then resumes again.
• Accelerating is sometimes slow initially then jumps forward at speed.
• Traveling in stop start traffic sometimes causes a stall.

I've had the car fully serviced recently with Fiat. I'm thinking that maybe I have an issue with my air intake, so maybe throttle body or MAP sensor. Though I did clean out my throttle body a while ago using the helpful guide from this forum.

Does anybody have any ideas or suggestions? Is there any way I can determine what the cause is? :shrug:

Thanks in advance.

did they change the plugs?, sounds typical for worn sparkys mate.
also the hunting you described may go away with some new plugs but it dosent take to long to clean up the sensor in the thottle body, a little bit of degresser removes the carbon deposits a treat and the hunting stops.
roy
my bad you already cleaned it, that will teach me to post at 3am.......
defo plugs at a guess then mate

• Very often takes a few attempts to start up. I find it easier to start when putting my foot on the gas.

That one sounds like crank/rpm sensor- too big an air gap. ECU won't allow a start until it's happy where the crank position is

Accelerating is sometimes slow initially then jumps forward at speed.
When idling there is often small pulsating sound / vibration. As if it's about to cut off and then resumes againTraveling in stop start traffic sometimes causes a stall
Sounds like MAP sensor. Bad MAP values making over weak mixture will make it very low power then take off. If rich then it will be unpleasantly sharp to accelerate at low rpm and not so economical. All under the heading of poor "driveability"

But don't go out buying new ones, you may not need to replace anything. What you need is to be able to "see" what's going on so a fault code reader/eraser combined with a diagnostic program would save you a fortune of guessing. FES diag program above is free, there'a slso a few free ones around like Digimoto which will work on your car and laptop to car EOBD interface connectors are very cheap

First thing I'd do is read any stored fault codes.
Study the MAP sensor output v rpm/load
Study lambda sensor outputs
Then
Get it to recalibrate the MAP sensor

Whilst you're waiting for your diagnostics gear to arrive, get it to recalibrate by disconnecting the battery maybe overnight and then do a throttle relearn procedure (use search).

It was a full service so I'm pretty sure they changed the spark plugs. I didn't realise I could connect odb to a laptop so cheaply! Thanks. I'm having a look on ebay for a good deal. So far I've found a ODB-II Interface scantool for about £14.

I also found a relearn procedure on one of the threads so I'll give that a go over the weekend and let you know how it goes

Thanks for all your help!

My cable arrived pretty quickly. I found a program called FiatECUScan which I've been running, though to be honest this is all new to me so I'm not completely sure what Im looking for. I've attached some data and a graph and I see a lot of dip in air pressure and throttle.

I've just disconnected the battery. In the morning I'll connect again and try the throttle relearn.

I did the throttle relearn and it's running much more smoothly now. Thanks! I still see dips when I run FiatECUScan but I think that's my connection. I keep getting "latency too high" even though I have it set to 1.

Next step is to check that air gap between the rpm sensor and the pulley. Is there a simple way of checking this? Looking through the forum it looks like it's towards the low end of the back of the engine on the drivers side. Could I access this easily by going under? I think I know what I'm looking for after looking at the thread at https://www.fiatforum.com/stilo/234993-stilo-1-6-hot-starting-problems.html

From those graphs your MAP is going from max to min constantly in a split second and nothing in between so you're on the right track with investigating your MAP output


Re rpm sensor then it's quite easy to get to the crank pulley from front rh side and a gap between it and the pick up serrated ring on the pulley about the thickness of a business card is fine. Just loosen the bolt and lever it to move it if it needs it. Too much gap or metal contamination on the face of the sensor there will often prevent first time start up

See if you can do a trace of idle then snap up to 2000rpm then snap off to idle then snap up to 3000rpm etc then split second wide open throttle and back to idle. That'll put the MAP through its paces

Righ, I managed to close the rpm sensor gap. It's pretty close now so I can barely get a piece of thin card between it. I then reset my ECU and did another throttle relearn. It seemed to drive nicely at first but after a few days started deteriorating again. It seems to happen once I start driving in low gears or stop start traffic.

I'm not sure if I trust the graphs I've been getting from FiatECUScan as I keep getting the "Latency too high" error. Not sure what to do now.

When you reset your ECU then it runs on base known good settings and then it fine tunes over time. As it was running well but then getting worse then, as we suspected, you have an air/fuel problem which could easily point back to your MAP again. Could really do with a decent rpm v MAP readout or the raw figures but your previous graphs were showing wild MAP readings which looked like the sensor giving bad output rather than the program being unreliable

Have you looked at the FES forum for any help with latency errors?

With poor acceleration and then sudden surging that sounds very much like the MAP

Thanks Deckchair. Yes, I had a look at the forum and had already tried the suggestions. Didn't get the latency error as much as before but still got it.

I'll try and get another reading tomorrow. I don't mind forking out for a MAP sensor if I have to, as long as I know it's the problem.

If you have a multi meter you can do some basic checks on your MAP

Awsome What a coincidence. I just got one! What should I look for?

Consistency and expected response
"But I don't know what i'm expecting"
Very true and it's easier once you've seen a few

This guy is removing the MAP and testing with a vacuum pump. What you can without removing the MAP or a pump is look at the MAP output for various rpm
It should be around
4.5v for just ignition on with engine off ie ambient pressure reading
1.0v approx for warm engine idle. The actual figures aren't so important as it will adjust to that but the consistency and good quick response is what you are looking for.


Here's a 306 being strangled but the MAP figures look good

When you press gas look for MAP response and does it settle back to idle value again?
Easier to see it on a chart but it should look like this

If you go to wide open throttle then you should see it also go up towards the max
Sudden jumps for no reason, inconsistency, sticking are bad signs

Ok Where do I plug in?

In here, pos to sensor green wire, neg to battery -ve and set your meter up so you can see it though the bonnet gap so you can see the response to your own foot on the gas pedal as Stilo is fly by wire

Looks like it might be knackered then. If so then that's good as I know what I need to replace. Set on 20v, the multimeter was showing 0.75ish volt when idling. Well... typically ranging from 0.7 to 0.8, but after a short while started going about 0.8 and sometimes jumping to a little over 1.0. The higher it went the more the engine seemed to struggle.

On reving to about 2k rpm, it seemed to jump to over 1.0 then immediately go down to about 0.5. I never saw the typical 4.5 volts you mentioned :/

I also took the sensor out to insepect it and it was covered in a thin film of oil. Is this normal?

scubamandan said:

I never saw the typical 4.5 volts you mentioned :/

Click to expand...

Deckchair said 4.5v for ignition on but engine not running. Around 1.0v when idling.

Deckchair5 said:

It should be around
4.5v for just ignition on with engine off ie ambient pressure reading

1.0v approx for warm engine idle.

The actual figures aren't so important as it will adjust to that but the consistency and good quick response is what you are looking for.

Click to expand...

Cheers Shadey
Output shouldn't jump unless you hit the gas although that's tricky with a multimeter I know. It should move fast with fast gas action

If you're convinced then a 1.6 MAP is around £25 from Ebay. It will do no harm and they get a bit sloppy with age

Small amount of oil on the surface is normal

First one I obtained from Ebay had no thermocouple in it

New one of the left, spot the difference? Ha!
That one jumped - straight back to the supplier

Cheers Shady. Yeah, would probably help if I sat down and read properly when running back and forth from the car And thanks Deckchair... yeah I found one on eBay for £23, including delivery. And one for about £70 on shop4parts. Pretty much a no-brainer . I'm gonna give it a go and let you know.

Once again, thanks for all your help. You are the Fiat Guru.

I used to be good at these games when I was a kid. The stick like thing in the middle... that must be the thermocouple I presume. The photo of the sensor I saw on eBay didn't have one either. May have a hunt around for one with it if it's a problem. What does it do? Think I'll go for the 3rd one below. It seems to be a legit Magneti.

http://bit.ly/b1LOCq
http://bit.ly/clCU9N
http://bit.ly/9er3uU

scubamandan said:

I used to be good at these games when I was a kid. The stick like thing in the middle... that must be the thermocouple I presume. The photo of the sensor I saw on eBay didn't have one either. May have a hunt around for one with it if it's a problem. What does it do? Think I'll go for the 3rd one below. It seems to be a legit Magneti.

http://bit.ly/b1LOCq
http://bit.ly/clCU9N
http://bit.ly/9er3uU

Click to expand...

They all look different to mine(JTD)
Mine looks like this one.
http://www.worldcarparts.co.uk/Default.aspx?TabId=144&CategoryID=286&ProductID=1229

Yes, I saw a bunch of those on eBay as well. JTD seems to be popular