Hello. For the start im gonna tell, sorry for bad english, i hope people understand what im trying to explain. :S

Okay so, i just bought 1993 model Volvo 850 T5.

Car got 132 thousand kilometres on it. And yeah, kilometres are true they are checked @ volvo service from ECU or something got documents about it.

Problem is, that car is drinking too much fuel. Its most worse in the city driving.

On the road, when i was driving 250 kilometres with my dads 850 2.4, we got these results:

Dad:s car 7.4l average use
My T5 8.9l

@ city driving fuel usage is like 15-20 litres / 100km.

Car is working normally, got all power and goes like rocked (got simons cat back and KN panel filter) ECU is standard. Car idles normally and steady. When oil change is done in 10 thousand kilometer periods, car isnt using ANY oil from the dipstick. Car got a bit over 12 bars compression in every cylinder.

When im accelerating a few gears with small throttle, problem is most visibly. Around 1500rpm-2000rpm car is "struggling" a bit, its not cutting off and that struggling is very hard no notice, but its noticeable when i carefully watch RPM meter and cars behaving. Its obvisly giving too much fuel to the engine with small throttle openings. It also backfires exhaust a bit sometimes when im hardly accelerating it and chanching bigger gear.

When car iddles and im rolling the rpms around 1500-2000 with small throttle i can hear small buffing sounds from the exhaust, i think fuel is burning a bit there. But that is very small burning sounds.

Im getting desperate with this since i should take my car for ecu programming soon.

I called previous owner about this and he had noticed it too and told me all what he tried to do to get rid of this problem. Car has been mainentanced very well and kept very well allways, thats what he said to me.

Previous owner told me when weather is cold, problem goes a bit away, not sure does the weather help with fuel usage.

I noticed this too: When average speed is 100km/h, usage is like 8.9 with very kind driving. When i raise my speed to average 130, it doesnt increase fuel usage lineary. it doesnt raise radically just a bit like to 9.2 litres around... Feels like theres and rpm range where car struggles a bit and using much fuel...

Things done:
-Mass airflow sensor is brand new, driven less than 10 thousand km (he had broken old one when cleaning it..)
-I added some injection cleaner bottles to fuel, looks like doesnt help.
- Plug wirings are brand new, and he had changed them even two times.
-Coil wire is new
-Plugs are allmost new, and they got VOLVO printed on them. And T5 plugs they are for sure. Checked them, and looked very very good
-He had changed new electric rolling component, inside that spark sharing component where spark plug wirings go. I also changed this even 2nd time to new...
-Car is not giving any problem codes
-Air filter is brand new KN panel filter i changed it myself.
-I cleaned mass airflow sensor anyways it wasnt even dirty since its brand new lol

Please share experiences and what could be the problem? What i should try next? I called volvo service and they couldnt help me just told me bring the car to them lol.
Gas filter is a bit question, but i think it cant cause this? Gonna change it to a new anyways.

Regards

 

Here are the exhaust gas things taken:

Idle

C0% 0.07
HC ppm 30
CO2% 14.9
02% 0.4

>2000r/min

C0% 0.27
HC PPM 17
CO2% 15.0
02% 0.1

Lambda value 1.00

Yesterday, when i went to drive car, somehow fuel usage was normal. In 10 km trip on the road, i was able to get 6.9 litres

This happened after i changed chipped ecu (wasnt done for this exactly car though)

After i reached my destination, and car was parked, it was allways the same around 9 litres when i was driving it back home.

Its also weird, i got 3 ECU:s, one from this -92 model T5 full std, one from my other T5 -95 full std too, and one chipped ecu which came with my -95 T5.

Some reason, my -92 T5 which has this gas using problem, doesnt wanna read / delete problem codes from any other ECU than chipped one.

-95 T5 reads all ecu:s and allows me to delete codes.