1994 volvo 855 GLT 2.5 non-turbo - fuel consumption

webstyles · Post by **webstyles** » 03 Feb 2015, 19:09

Hi guys,

I recently bought a 1994 Volvo 850, and it runs just fine. Nice and quiet and smooth. No hesitation when accelerating, in any gear. But, even though i know these cars can get thirsty, the amount of fuel mine is drinking up is just plain ridiculous - to the point where i actually thought i may have a hole in my fuel tank, which is not the case.

The only other 'strange' thing I notice is when shifting gears - it's a manual transmission - when I take my foot off the gas pedal and press the clutch, the rpms surge slightly and take about a second to drop.

- I've read all the engine codes, everything is at 1-1-1.
- Trip computer gives me readings of 30 - 40 liters per 100 km.
- I'm a very relaxed driver. I rarely exceed 2000 rpms and I rarely go above 90 km/h.
- Normal route is urban villages with lots of 50 km/h speed limits and a few traffic lights.
- All the trip computer readings were taken after engine reached normal operating temperature.
- Air filter is new.

I'm thinking MAF or O2 sensor, but since it's quite hard to find a MAF Cleaner around here, I'm posting this to be sure if these two sensors can be related to this specific problem, and if there's a way I can test/diagnose this better before going on a rampage changing parts.

Thanks

Post by **misha** » 03 Feb 2015, 19:20

Read the codes from socket A6,that's your ignition ecu because,being a 1994 model,your car have two ecu(s) for engine & ignition.

webstyles · Post by **webstyles** » 03 Feb 2015, 19:36

Thanks for the quick answer and sorry if i wasn't specific enough. I get 1-1-1 from ALL readable ports, except for an airbag sensor error on port B5.

I'm thinking the MAF is working fine but might be dirty, getting incorrect readings... maybe... Is that possible?

Post by **misha** » 03 Feb 2015, 19:47

I would check fpr(fuel pressure regulator) at fuel rail.
Check vacuum line for fuel smell or crack in the line.Gas shouldn't be present in the vacuum line.If it's present,fpr must be replaced.

Start from there.

webstyles · Post by **webstyles** » 03 Feb 2015, 20:08

Thanks. I'll try that tomorrow and get back to you. Also forgot to mention there's no brake binding or anything like that, that could cause excessive fuel consumption. If left in neutral on a very slight slope, it will roll down like butter in a frying pan. I'm guessing the best indicator of a problem is the fact that the rpms take a while to drop when the pedal is released.

webstyles · Post by **webstyles** » 28 Feb 2015, 02:58

Thanks for your help. Turned out to be the O2 sensor. cleaned it with gasoline overnight and all is fine now.

Post by **misha** » 28 Feb 2015, 07:52

Keep us posted.
I read that cleaning o2 sensor sometimes can do the trick but if heater circuit is bad there is no help.I guess that yours was just fouled with carbon and was giving incorrect o2 reading in exhaust.