Technical Broken Thermostat?

[Enpee]

Hi



Ihave a '55 plate Croma 1.9 8V. It has been fantastic for first 4 years I'veowned it, but I have been having problems with engine light and DPF errors overthe last few months.



Problemsstarted when the car developed less and less power, went into limp mode, then Iwas advised to take it on a long run to force it to regen, at which point it becameworse.



Astroke of luck: I got talking to a main dealer's engineer who said he'd regenit for free. However he said it refused to Regen because the Engine Temperaturewas 'all over the place'. He advised me to change the Engine Temp Sensor.



Ibought a full version of ECUScan, as it became apparent that no one seemed tobe that sure what the issue was, and that I was going to have to pay asubstantial amount for a Regen next time.



BeforeI could use my new toy, the car choked and wouldn’t even start.



Ihad the DPF and the Engine Temp Sensor replaced, and I reset all the necessaryparameters which seemed to solve the problem.



However, aftera few hundred miles, the engine light and DPF Differential Pressure Errorre-occurred and it went into limp mode again. I guess it was not regening undernormal conditions.



Iused ECUScan to force a Regen, but I had problems getting the Engine Temp >70 Deg. It seems that a forced Regen will not occur unless the Engine Temp >70 Deg.



Isit possible that the car will not regenerate under normal driving conditionsbecause it’s not staying > 70 deg?



Whattemp should the engine run at?



Ismy Thermostat malfunctioning?


Any ideas?



PSI logged this Engine Temp graph the other day: this was 1 mile urban, then motorwaydriving. X Axis is approx. 5 samples per second. (1 min = approx. 300 samples)

 

[Enpee]

I tried posting the graph but it didn't work.


Can anyone tell me how to post it?

 

[s130]

What does your dash temperature gauge indicate? Should be vertical when warm.

When gauge is vertical what does MultiECUScan say the temperature is?

When you drive gently what does the gauge say?

If your thermostat is working OK then the gauge should for all general driving conditions be *steady* in the vertical position.

 

[BrianMcL]

Hi Enpee,
First of all welcome to the club!

Secondly I'm not at all convinced that the thermostat is the main problem. As S130 says the gauge should be in the middle but I drove about with a broken one in my 8v 1.9d for a couple of years and didn't have any problems with regens.

Do you know if the oil degradation counter's been getting reset at oil changes? This is vital and if the computer says that the oil isn't good enough then it won't regen no matter what you do. This is very different from the service indicator and you can't check it from the dash display although the oil change light should have flashed for 1k miles or so before giving up.

Check this using mes / fes and let us know what the oil degredation and # of oil changes is reported as.

Next think with limp mode problems is the air flow sensor (unplug it and see if that helps) and the EGR (which should be partially blanked with a bullet hole mod plate - see various threads else where by searching for egr). Neither of these things are particularly difficult to fix.

But start with the oil counter details please and let us know what you find.

 

[Enpee]

Dummy post, so I can post a link

 

[Enpee]

Dummy #2 post, so I can post a link

 

[Enpee]

Dummy #3 post, so I can post a link

 

[Enpee]

Hi All
Please accept my appologies for the lateness of reply.
Hi s130
The dash gauge mainly sits around 11 oclock, but does vary abit from 10:30, and occasionally gets to 12.
It varies slowly over the course of several minutes.
This link shows the graph of Engine Temp from Cold, 1 mile urban and then motorway. Approx 300 samples per min (sorry for poor scale!)
https://dl.dropboxusercontent.com/u/16982005/Graph of Engine Temp.JPG
I would expect it to increase when driven hard, but it doesn't seem to.
A few minutes after I come off the motorway, the temp seems to temperarily rise up abit.
Hi BrianMcL
Oil Change Counter is 3 (This seems low: Current Mileage is 54k)
Oil Degredation Level 69%
Oil changes done by a independent garage.

 

[g8rpi]

Oil Change Counter is 3 (This seems low: Current Mileage is 54k)
Oil Degredation Level 69%
Oil changes done by a independent garage.

So how many oil changes does the book say it's had? The ECU value should match. Not many independants, and if my Croma way typical, some Fiat dealers know to reset the ECU oil counter. If the last oil change was more than 3000 miles ago I'd suggest a change and make sure the counter is reset.

Robert.

 

[BrianMcL]

The current oil degradation of 69% indicates that it was done not that long ago, although exactly how long ago depends on how the vehicle's been driven.

If we assume that at least one was done by the original dealer after purchase it does feel as though the car went a long time in between being told that it's had an oil change.

If this is the case then damage to the dpf itself should certainly be investigated as it will fail as a result of not being able to regenerate.

Having said that, the mileage required for that to have happened is quite high so it's by no means certain to be an issue, and hopefully it won't be.

 

[Enpee]

Hi


Problem Solved!


Replaced thermostat, which now reads TDC as it should.


Forced a DPF regen successfully this time, as the engine temp interlock no longer prevented it.


Thanks for all your help.
S