Technical My stilo

[Seraph]

Your engine's taking such a bruising it's difficult to know where to start. The throttle and ecu should hold tickover rock steady at 700rpm.
Are the plugs good?
Does it sound rich? blub blub at the exhaust.
Is it hunting? ie sound weak and "splashy" at the exhaust?
Does it pick up acceleration ok?
Is it misfiring at all?
What's this low oil pressure all about? How long has it been doing that and when does it do this?
Does it have poor idle when cold and when hot?

plugs are good and new.
i think that it does sound rich actually.
accceleration is quite good to be fair, but I've been without a car basically for 6 months so I can't tell.
it's not misfiring that i've noticed.
the low pressure thing started only a few days ago, and only when the engine is cold and starting up.
when it's cold the idle value is high, we're talking 1100 revs. but stable. when it's warm that's when the idling is poor...it's at 700, but dips as low as 500 (some times lower). you can hear my zorst knocking on the rear bumper then and feel the car shake a little.

 

[Deckchair5]

Ok Low oil pressure warning can happen easily at start up with low battery after a few starts

Hi idle of 1100 rpm when cold is correct

700rpm falling to 500rpm and bouncing up again to 700rpm on hot idle is often the throttle valve but if you're happy with that then maybe the O2 sensor needs a check which is why i ask if it sounds rich. How's your mpg as that's a bit of a clue?

What gear have you got? Do you have a multimeter? A fault code reader?

 

[Seraph]

Ok Low oil pressure warning can happen easily at start up with low battery after a few starts

Hi idle of 1100 rpm when cold is correct

700rpm falling to 500rpm and bouncing up again to 700rpm on hot idle is often the throttle valve but if you're happy with that then maybe the O2 sensor needs a check which is why i ask if it sounds rich. How's your mpg as that's a bit of a clue?

What gear have you got? Do you have a multimeter? A fault code reader?

just bought an obd2 to pc cable.
mpg has been rubbish, like 24mpg rather than 30mpg.

 

[Deckchair5]

Sounds like O2 sensor then. Poor ecu can't find out whether it's rich or lean and goes all over the place on a warm tickover. Do you have an EOBD program that can read the O2 sensor output?
O2 output voltage should swing from around .8volts to .1v about every sec at tickover

 

[Seraph]

Sounds like O2 sensor then. Poor ecu can't find out whether it's rich or lean and goes all over the place on a warm tickover. Do you have an EOBD program that can read the O2 sensor output?

I have nothing yet.
Once I've got the cable through (it's being delivered) I'll start to practice.

 

[Deckchair5]

Ok if you have a multimeter you can back probe the top O2 sensor pretty easily (see guides how to do that) and check the voltage outputs on warm tickover for the above values ( has to be warm engine though)

Disconnect the top O2 sensor and see what it happens. If nothing happens or it gets better you know you're on the right track

New O2 sensor is about £60 from Fiat if you need one


Here's mine on warm tickover. Top graphs show the two O2 sensors the red one is the one you're interested in, the pre cat one and is changing every few seconds and swinging from around .8v to .15v. That'll be the pattern you'll be looking for on yours

The rpm on the bottom graph is so rock steady at 710rpm you can't see it as it's a straight line. Hope we can get yours to look like that too

 

[Seraph]

OK, so I've got my OBD interface, had it plugged in and it runs...however...
the software that came with it doesn't seem to play fair, and the scanmaster software i have is demo only. it seems that i'm expected to pay just shy of £200.00 for the software...rubbish.

fair to say i wont be buying that this month.:bang:

 

[Deckchair5]

If you just want to read and clear fault codes there's a load of free software available. Just Google for it

Or have a look on Ebay for sellers sending OBD interfaces as they often list the websites of where to obtain compatible software. Yes most of it will be trials but most will read and clear fault codes. If you want more sophisticated stuff then you need to pay for it but not £200

Gendan engine check Pro software is about £55 last time i looked www.gendan.co.uk
That'll do more than you'll ever need

 

[Seraph]

so I've run the tests, what do you think?

 

[Deckchair5]

Your O2 No.2 -that's the one post cat - is flatlining- no response. Thats not good. I would have thought that was enough to flag a warning message in your car but maybe it's stuck within limits. It looks like it needs renewing or maybe it's just not got up to temp yet but it's "off the chart"

Your tickover isn't stable at all- but then you knew that

O2 No.1 is doing it's job of switching form 0.8 to 0.15v.

Include something useful like rpm and eng temp or rpm and car speed on the bottom chart and do a run coming back to tickover again with engine wamed up and blown out.

Do a 5 min runaround with O1 and O2 on the top chart and rpm and eng temp on the bottom. You can save the results to disc

Look at the chart I posted earlier, yours needs to look like that

 

[Seraph]

yes, i realised it would need to run like yours, I did two test runs to get the engine up to temp, and this is what the map came out like at the end.

i had coolant temp on it at one point but that was steady at 93deg, no movement at all.

I'm off over to Stilosportings as soon as my lazy fat housemate gets her ass outta bed to help me load up my car...so i'll get the interface running while I go...

 

[Deckchair5]

i had coolant temp on it at one point but that was steady at 93deg, no movement at all.
Yes that's fine, it's just we need to know if the engine is fully warmed up

Rpm and car speed at the bottom let's us know what you're doing with the car. Oi Stop that! People might be watching

Do you have any obvious exhaust leaks up by by the cat like blowing or noise?

 

[Seraph]

wow, it's like 20 questions, I wish you could just see it running..

the exhaust is blowing a little bit, but there are no obvious holes or leaks. I assume that's something to do with the way it's idling, not the other way round.

typically, i've run it a while today and it's not managed to stall when my laptop's been plugged in, but it did come very close.
here's a graph of it.

 

[Seraph]

oh yea, and this is it idling after a day being run in. with the MAP readings on it.

 

[Deckchair5]

Ok well results are in, it's time to put your thinking cap on
Your O2 No.2 sensor is saying chronic rich down the exhaust pipe at tickover

Your eng temp is good. It's saying a correct 93 degrees and the ECU knows that so it's not thinking the engine is cold and providing a rich mixture as that can often be the cause of over rich

Your O2 No.1 seems to be sensing rich and lean at warm tickover as it should

Inlet control valve is really struggling trying to maintain tickover though isn't it. You can see from the MAP sensor at tickover that the ICV is making huge adjustment steps just to maintain tickover

Possible cause might be a misfire at tickover As you've had a tough time in your cylinder head, did it tickover at all well straight after having the head repair work done?

 

[Seraph]

Ok well results are in, it's time to put your thinking cap on
Your O2 No.2 sensor is saying chronic rich down the exhaust pipe at tickover

Your eng temp is good. It's saying a correct 93 degrees and the ECU knows that so it's not thinking the engine is cold and providing a rich mixture as that can often be the cause of over rich

Your O2 No.1 seems to be sensing rich and lean at warm tickover as it should

Inlet control valve is really struggling trying to maintain tickover though isn't it. You can see from the MAP sensor at tickover that the ICV is making huge adjustment steps just to maintain tickover

Possible cause might be a misfire at tickover As you've had a tough time in your cylinder head, did it tickover at all well straight after having the head repair work done?

quite frankly, it's not run well for maybe 7 months, that's about when the head started to go.

please bear in mind, i'm not a mechanic and most of the things you said above make little sense... lol.

 

[Deckchair5]

Ok Your O2 No.2 is saying you have huge amounts of unburnt fuel going down your exhaust at tickover, it's flatlined at 0.8v = fully rich.

Your O2 No.1 is swinging correctly from lean to rich so it's seemingly doing its job and the mixture is altering to suit but tickover is extremely lumpy

So it looks like a misfire at tickover is putting unburnt fuel down the exhaust and it won't have a chance of a decent tickover if it's misfiring

So, did it have a poor tickover straight after when it left the garage the last time? If so it should have gone straight back

So suck- squeeze- bang - blow- to fire properly all have to be just right
Go for cheapest options first, after you've checked air filter, plugs and coils you may need a compression test on the head to check those head valves are sealing properly

 

[Seraph]

groan, plugs air filter both fine.
as for coils/head, i'll have to get it back for the compression test.. i was hoping the fix would be something i can do myself...
rubbish

 

[Deckchair5]

Maybe one of the Fiat techs here can give a second opinion as to why your O2 sensor is flat lining full rich at tickover. It seems to be working as you can see from your trace of you on the move that both O2 sensors go to zero- full lean- when you throttle off at speed- as they should as the injectors are switched off then

But you've had the equivilent of a hand grenade going off inside your engine with a cambelt failure

 

[Seraph]

is it possible it could be that the o2 number 2 is reporting wrong so the engine is trying to compensate in some way?