deleted_user_160
when i got your old 7 wagon nick. 15/100 or there abouts. maxed 350klm for tank.
now it just averages 10-11 city/hwy/spirited.
i dare say the gear im about to put on, will bright that back up to 15 or so. ;P
jamesinc
Nick I sort of hate you, your fuel economy is amazing.
I did boost and vac tests and couldn't hear anything. I found a few small leaks between the AMM and the turbo, but they were only boost leaks and as that system never gets positive pressure I imagine they're not serious. Even so, I added some clamps and replaced a hose to get it all sealed.
I put a screw into the drain hole on the intercooler, mostly because I needed the damn thing to stop hissing so I could listen for other leaks).
Ex850R
I am going to swap over the coolant sensor on mine to see if it helps me.
Maybe you can get the one off the V70?
Give that a run?
nickm
Guess check the O2 senor and see if the CAT is blocked. I think if you run rich you can damage the cat.
nickm
And what Les said
Ex850R
Mmmmm , I run real rich , maybe should gut the cat.
nickm
Only if you play violin
Ex850R
Twang!
CamZH
Are you actually using that much fuel, or are you just being told you are ?
my stop start driving in my 850 has it around 14-15l/100 (or so it says)
jamesinc
I calculate the fuel economy based on the odometer and litres needed to fill tank.
The car's in-dash meter is not far off, though it reads 18L/100km (it is still averaging old values where the economy was better).
deleted_user_160
I've got a feeling Alex was saying if you gut the cat, you end up with more lag due to having to fill the cat with exhaust fumes.
drvolvo
Over the years I have chased and resolved several fuel system/economy issues.
- on a Daihatsu, a split MAP vacuum hose
- on an 850, fuel pump pressure fade due to pump sock filter rubbing on bottom of fuel tank, eventually wearing a hole and letting in grit to kill pump.
- on an S40 T4 and 240 both had at some time or other the following:
- thermostat not closing properly, engine took too long to warm up (or not at all on a -5 Canberra morning)
- faulty fuel pressure regulator. Starts out as hesitation on cold mornings, then as it gets worse fuel system will depressurise when engine off, and be difficult to start. Hard to spot as fuel pressure statically checks out, just not under dynamic driving conditions.
Of course in all cases your fuel economy goes to pot in stop start traffic, but is often ok on the highway as the O2 sensor sorts things out. Stuck open thermostat is no good on a trip to the snow either :-)
I am currently chasing a small increase in fuel consumption on an S60 2.4T. I swapped over the Turbo Control Valve from my S40 and it seems to have helped, but will need more time to see for sure. A failing TCV apparently limits your boost to spring pressure, so the turbo becomes more of a drag on the engine and never reaches the optimal boost pressure the ECU is trying to achieve.
For comparison sake, both the S40 and S60 normally get around 7.6/100 on the highway and maybe 9.7/100 around town. (granted the "town" only has 350,000 people in it)
jamesinc
The 850 didn't even notice the snow when I was down there in August/September. So let's see, the boost/vac issues are more or less ruled out, but it doesn't seem to have helped.
The state of the following is unknown:
* Rotor
* Cap
* Leads (I tested the coil lead and got 2.5kΩ but then the storms hit so I abandoned
* Thermostat
* O2 sensor
Known:
* Spark plugs are NGK with 5000 or so km on them
* No apparent boosting issues
drvolvo
Hmm you mentioned some hesitation before, my money would be on the Fuel Pressure Regulator not being up to snuff. Is the one on the 850R buried in amongst the injectors under the fuel rail or on the end of the fuel rail ? Not sure if you can remove it without taking off the whole rail.. I suppose you could do some basic tests with the engine idling, sucking and blowing on the vacuum line to see if it responds to both positive and negative pressure.
The only way to tell for sure would be to drive around with both a boost and fuel pressure gauge, and there should be a constant delta between the two. (a differential pressure gauge would be ideal, probably not cheap to get hold of) I think usually around 3 bar or 45 psi?
I do recall a bit of a flat spot on acceleration when my S40's FPR was in its final death throws.
Ex850R
Coolant temp sensor too.
Pulled one out of low K NA donk but failing light and failing Les got as far as pulling bonnet up undoing coolant hose to thermo housing but still too hard to get to sensor so called it for evening.
Running a bit better after a tank of 70/30 95 petrol and 85 United and now with Shell 98 but still showing 14-16+ l/100k.
O2 I have spare one that should be good but its a fun job getting to it without a hoist....
Maybe your NGK plugs are not good as Mark and others say , keep the Volvo brand ones in there , they are like voodoo to a Whiteblock.
Same for Bougicord leads , they are good.
Can't wait for pictures of inside your dizzy cap n rotor!?
jamesinc
Okay so the solution seems to be to replace everything, starting with the cap and rotor. How much do Volvo plugs cost? @iceton1975
jamesinc
I'd like to get a multimeter on the O2 sensor to see if it's frozen. I remember in my old 740 when the sensor died it just read "0.5V" and never moved. Problem is it's a pain to get the probes onto it as the plug is hidden away down near the turbo on the port side.
Ghettobird
I get about 16L/100 on my NA 99 wagon, but do drive it pretty hard
Even when I granny mode it, I still only get 420 kms/tank which sucks ass :(
Ex850R
Ghettobird;36038 wroteI get about 16L/100 on my NA 99 wagon, but do drive it pretty hard
Even when I granny mode it, I still only get 420 kms/tank which sucks ass :(
That sounds like an issue somewhere as well!?
Ye can keep the felching to yourself....
timbo
+1 coolant temp sensor i replace them all the time on turbo models $45 only thing that can effect the fuel economy that much and not code. they will usually look pretty coroded if they're on their way out