855 2.5 20V permanent open loop..

mateuszek · Post by **mateuszek** » 08 Apr 2018, 05:35

Hello
I'm already fighting a bit, that's why I decided to make a separate topic here.
Right to the point.
patient 850 2.5 20V 170HP 1997
Front Lambda sensor - NEW (original bosch according to No.)
Rear Lambda NEW (original bosch according to No.)

symptoms:
permanent OPEN LOOP even when engine is very hot.
The values of the front lambda probe are completely weird, they change when adding gas, but they stand at idle at odd values (from -1.748 to 0.334 etc.)

The other thing is that the engine works very well, nothing interrupts, does not smoke, even the lambdas light does not illuminate (but in the computer VOL-FCR it is a mistake) burning gasolin may be a little bigger, but not spectacularly ..

Please help, I do not know what to look for anymore.... no one what I know, cant help me..

Post by **misha** » 08 Apr 2018, 11:09

Did you disconnected negative battery cable after o2 sensors replacement,in order to reset fuel trim?

mateuszek · Post by **mateuszek** » 08 Apr 2018, 11:24

yes, I disconected battery for +- 10 minutes, and still nothing

Post by **misha** » 08 Apr 2018, 15:08

Try to do that overnight,alowing engine to cool down and re-connect when engine is cold.
After that....drive it normaly alowing it to warm up and it should be ok.
Other than that...you might have leak at flexy pipe(between exhaust manifold and cat),vacuum leak,dirty Maf sensor,ect out of spec.

mateuszek · Post by **mateuszek** » 09 Apr 2018, 13:17

ok, today we switch MAF sensor from my friends the same volvo, and nothing, the same problem.
But today I saw stranger thing on computer.

when the engine was a little colder (arround 70-80 degresese C) it was that:

and when it was a liitle warmer:

maybe is that a water temperature sensor? I know that comp display correct temperature, but who knows....

Post by **misha** » 09 Apr 2018, 14:04

Is that android app?
It could be that it is throwing wrong data.
What engine management your car have...Motronic 4.4 should be the only one in '97.
If so....you have no egr...you have sas system.

mateuszek · Post by **mateuszek** » 09 Apr 2018, 14:05

no, iphone's "car scanner"

Post by **misha** » 09 Apr 2018, 14:10

It can't be trusted.
VOL FCR should be used or a good code scanner which displays live data.