i can try

Had another random idea today for a possible cause of the squeak/chirp- aux belt and/or tensioner.

I remembered a Service News for Doblo's where the materials used in the belt, combined with the tensioner and crank damper pulley, would create a chirp under intermittant load (like lightly blipping the throttle). I don't remember anything similar being out for the Croma, but if the belt or auxiliary components are getting worn, it may cause this. Only way to test though is to remove the belt and see if the noise stops.

Obviously it wouldn't cause the misfire, but I suspect the misfire is causing the squeak.

D4nny8oy said:

Had another random idea today for a possible cause of the squeak/chirp- aux belt and/or tensioner.

I remembered a Service News for Doblo's where the materials used in the belt, combined with the tensioner and crank damper pulley, would create a chirp under intermittant load (like lightly blipping the throttle). I don't remember anything similar being out for the Croma, but if the belt or auxiliary components are getting worn, it may cause this. Only way to test though is to remove the belt and see if the noise stops.

Obviously it wouldn't cause the misfire, but I suspect the misfire is causing the squeak.

Click to expand...

The problem was more of a surging on light throttle.

had the boost pipe off today, no splits or holes.

whats best way to get to turbo to stick my fingers in a check for play, take drives side wheel arch liner out?

D4nny8oy said:

Can you get a 'snapshot' of the parameter data when it does it?

Click to expand...

i recored 3 more files. it did it most on the asda one, i dont seem to do it when cold

text files in here
View attachment 91611

Kinda hard to read a text file compared to a graph, plus it only shows "chunks" of data. Can you get a 3 minute snapshot graph of the EGR opening vs. MAF airflow?

The only possible concern I can see in that data is the injection correction for cyl 4 being consistantly higher than the others by some margin, but it may be a red herring.

The fact that the fault occurs only when hot points to the EGR playing up (as it doesn't operate until engine is upto temp). Have you tried blanking it?

no but its a new one i cant work out how to save a graph apart from screen capture, i'll give it a go tomorrow

i did 2 graphs today, i didn't do it much today untill i disconected and packed leads an laptop away

https://www.fiatforum.com/gallery/data/616/graph_1_14_june.JPG

https://www.fiatforum.com/gallery/data/616/graph_2_14_june.JPG

Any chance of the two I really wanted? -

D4nny8oy said:

Can you get a 3 minute snapshot graph of the EGR opening vs. MAF airflow?

Click to expand...

Ideally with the engine upto temp and idling, car stationary, start recording, floor throttle and release and leave to idle, end recording after 3 mins.

Maybe drive around first until the engine is playing up, then record the test above.

be easier if i drive up an show you?

this right?

https://www.fiatforum.com/gallery/data/616/egr_v_maf_3.JPG

dave said:

this right?

https://www.fiatforum.com/gallery/data/616/egr_v_maf_3.JPG

Click to expand...

No.

Need air mass (ie air flow), not temp.

Was that stationary as well?

yeah was parked in asda waiting for the rain to stop, i ticked box that said MAF

first time i forgot to rev it 2nd time i forgot to print screen, this one i reved it took foot off then clicked button

how about this? https://www.fiatforum.com/gallery/data/616/graph_friday_1.JPG

still not sure if its right, this is the list of things i can choose

View attachment 91737

View attachment 91738

View attachment 91739

View attachment 91740

View attachment 91741

something else happened today, i pulled on to a busy roundabout fast and pas went for a few seconds, could this point to nackered auxiliary belt tensioner mentioned earlier, making belt slip?

bump :devil:

oh btw ive now heard the noise you get when turning off, my problem noise is nothing like that

Still no luck Dave? I wish I could be more help but its really a Fiat tech who will have the answer to this, someone will have seen it before.

i think ive posted what danny asked for but he not replied, dont think he loves me any more
looks like this is going to take ages, you want me to send the box back?

hopefully I'll get cam belt and auxiliary belt and tensioners done next week to rule them out

No Dave no panic on the box, I hope you get the car sorted.

Sorry Dave, I've been busy and keep forgetting to reply to this.

Rather than going back and forth with graphs and data, I thought I'd give you a rough picture of what I'm expecting to see if the EGR is working correctly.

Vehicle stationary, engine warm and idling (EGR valve closed), rev engine- after returning to idle, the EGR will open for approx 2 minutes before closing again, during which time you'll get a graph like below-

EGR opening % in red
Mass Airflow volume in green

View attachment 92201

As you can see, the EGR valve opening and MAF readings are closly linked and work in opposite directions. With the EGR open, the MAF reading will drop slightly, then return to the original figure once the valve closes.

If the EGR is sticking once opened, you'll see this-

View attachment 92199

Everything is ok until the ECU tells the EGR to close. The ECU has shut-off the valve and assumes the opening % is 0, but the MAF reading not returning fully and quickly (or worse, staying low) shows the valve is not actually as closed as what the ECU thinks, and is therefore clogged or faulty in some way.

This can be recorded while the vehicle is being driven, but other factors can affect the airflow readings and it won't be as easy to tell.

like this? its a bit like it but more wiggly


View attachment 92215