JTD Poor MPG problem.

**Xen** · 11-03-2010

Hi guys, I'm quite new here and unfortunately my first post is a problem post :(

Basically I sold my 1.2 stilo for a 115 JTD a few months back, and its been great :D ...up until now. The last couple of weeks, the MPG has been awful. If I get over 30mpg, its an achievement.
I did have a preheat fault for a few weeks, that i sourced to a corroded relay module live connector on monday. Thats been repaired now, but the MPG hasn't improved.
Removed and cleaned the MAF sensor as recommended by a lot of things i read online, and also because Fiat ECU Scan showed a desired air intake quantity of 300mg/i but an actual air intake quantity of 45mg/i. When replaced, there was no improvement in MPG or actual air intake quantity reading. I've now just read from 2 sources that this is a bug with the software and infact 300 and 45 are normal readings.

Doesn't feel like shes down on power (although i have stalled it a couple of times from a standstill, which i would very very rarely do.) Engine sounds good, and doesn't look to be excessive smoke. No engine management light, no error codes.

So any suggestions guys? Shes costing me a fortune to run atm.

**MEP** · 11-04-2010

Hiya welcome to CF

Have you changed fuel source or filling at a regular place? Just wondering if it could be bad diesel?

Jon

**scottie2065** · 11-04-2010

i would perform a general service and change air filter/ oil filter & fuel filter
that may gain some mpg mate
i would also try adding millers diesel power sport to the tank, it can be bought at any good motorfactors

**PNL** · 11-04-2010

From what I have read onthis the MAP sensor seems to be the problem as well on the JTD ..cant find in your post that you have changed that one..we dont have many diesel owners on here so anyone has then it certainly would be nice to here your comments..

Pweeeeees

**scottie2065** · 11-04-2010

your correct there phil, i forgot all about the air flow meter
i had this problem with my 200hp gttdi golf, it was averaging around 25mpg and went like a 90bhp
changed the air flow meter and it restored mpg and performance.
definitely worth a look mate
i don't think i have an airflow meter for the stilo i think i sold it

**PNL** · 11-04-2010

Originally Posted by scottie2065

your correct there phil, i forgot all about the air flow meter
i had this problem with my 200hp gttdi golf, it was averaging around 25mpg and went like a 90bhp
changed the air flow meter and it restored mpg and performance.
definitely worth a look mate
i don't think i have an airflow meter for the stilo i think i sold it

I said MAP not maf..map sensors ..and all cars that have them can experience loss of MPG..

Fiat Stilo Map Sensors

Number 4 0n the diag

**Shadeyman** · 11-04-2010

Start with the easy stuff.
Clean your MAP with a good electrical cleaner and a soft cloth.
Clean your MAF with a good electrical cleaner.
Clean your EGR and add the new swirl gasket while your on.
Replace your air filter.

Dont use any fuel additives, just fill up with BP Ultimate Diesel will do a much better job than any additives.

Take her for a spin.

No increase in MPG try replacing the MAP. It has a big effect on the turbo so will effect MPG.

Still no increase in MPG try replacing the MAF. Expensive but got to be done if MPG is still poor.

**Xen** · 11-04-2010

Thanks guys, You've been massively helpful! :)

I've since found out that the false readings in FES only apply to certain versions of the EDC15C7 ECU, and others that have used it on the CF3 ECU get true readings. So perhaps something is wrong there?
I will definitely check the EGR, make sure its not stuck open. Is there anyway I can temporarily block it off to test?
I think the MAP is fine... The pressure and desired pressure readings run more or less alongside each other, but i'll clean it anyway - can only do it good.

I havent tried other fuel... I usually use tesco (yes, i know :S ) but ill try some of the BP ultimate stuff too.

**Shadeyman** · 11-04-2010

Originally Posted by Xen

Is there anyway I can temporarily block it off to test?

Rip an old Coke can open, flaten it out and cut yourself a new gasket but only cut out the bolt holes. Use it to blank off the EGR.

**Xen** · 11-04-2010

That was a great idea! I gave it a go, but unfortunatly blanking off the EGR made no difference to the reading or the economy :(

And since the MAP is returning plausable readings, I think its probably time to replace the MAF and fingers crossed!