02 sensor question

[L14MNP]

My Volvo (yes I'm on their forums too!) is running crap, erratic idle/hunting and it feels like it's misfiring/stuttering when you apply any load to the engine, but it levels off sometimes and other times it's fine to drive but only on partial throttle.

Fuel consumption is down and I noticed it seems to be holding back, like it's limited around 4K RPM (still no rev counter wired up!) then it will reluctantly go past this 'wall' but is still very sluggish and down on power.

If I go for a high gear at a low speed (that it would normally pull fine and build boost in) it will stutter more and pop through the inlet.

It seems like the fuel supply is just short of where it needs to be, it will idle fine usually.


I have checked and replaced alsorts and I will update this post in a minute with what I have done, but does this sound like a possible 02 sensor at fault?

When i removed it from the car the tip was mostly white, so it's like it's runnign lean? Which would correspond with how it drives. It also stinks of fuel and makes my eyes water in no time if it's running in a confined space. So rich then lean?

Any ideas? I've replaced and tested loads of sh!t! (had another issue too so that never helped.)

[Angus Closier]

Cant say for the volvo mate, but having the same problem on my mates mk 4 golf. The problem is the o2 sensor and tps. We had the golf tested to find the problem and thats what came up. Im going to be ordering parts today!

[L14MNP]

I have just been informed by Iain that I typed 02 FFS. lol

Cheers 16vxe, I thought TPS but that is fine. I can't test for fault codes without my mates OBDII machine and he hasn't brought it over yet.

Hope you get sorted!

[L14MNP]

Due to a previous dodgy starting issue I have replaced:

plugs
leads
rotor arm
distributor cap
crank position sensor
spark enhancer

and checked/tested:

TPS
AMM
inlet for leaks
injectors for good ground etc.
fuel supply (seems fine, but haven't pressure tested)

I also have removed the EGR system, yet it ran fine for a day when I done this so I don't think it's at fault.

The o2 is only readin 0.2v when apparently I should get about 1v, also unplugging it when the engine is running does nothing. Should it run richer?

[Angus Closier]

Id be looking at replaceing the o2 sensor mate, Iv just orderd one and its really not that expensive....The fualt is the most annoying it can happen at any time for my mate. We can be pulling off at the lights and it will just hold back etc. sometimes if you take your foot off the gas then back on sharply it comes back and keeps pulling. Before this the headgasket had gone before that we replaced the AFM and all the pipe work.
Because I dont have the diognostics machine Im only doing what the vw man says....hoping he is right this time!

[L14MNP]

Yeah I found an OEM spec Bosch job for like £47 at Eurocarparts. Can't be bad. Annoyingly I can't get it until Tuesday though, and my mate who's working at Unipart today has his phone switched off!

I think the engine is still in shock at being uprooted, placed in another chassis, then running no FMIC for a bit and now it has one. Plus my CPS (repaired then replaced) and 3 wires from the loom (repaired) melted on the EGR pipe and the distrib cap looked so worn out and ancient I'm suspried it ran! (guess that was my dodgy start issue) so I bet it's throwing a million and one codes at the minute! lol

As for the Golf, have you tested for resistance at the TPS? It sounds the same as my issues as you say, so probably the o2 which again as you say can just give up the ghost at any time!

Oh by the way, my engine is on about 206K. lol

[MK999]

Oh by the way, most of my engine is on about 206K but a lot of it is brand new now. lol

Fixed :thumb:

[Angus Closier]

The golf is only on about 60k.....Hmmmm Can be kinda dangerous at times....pulling out and that!!

[brucer]

how many wires has your lambda sensor got? if four(which it most likely hasnt got) then 2 wires, normally the same colour, are the heater element part and the other 2 for the sensor.

get a multi meter and connect it between both of the wires for the sensor. when idling it should fluctuate between 0.2v-0.9v. should switch constantly pretty much every second. if the voltage stays high then its too rich and low is too lean.

if its a single wire then i havnt a clue how to test those as i deal with more modern cars.lol.

[L14MNP]

It's a 3 wire iirc mate. Will have to take another look lol.

Cheers for the info. :thumb: