4.1 02 Sensor

[Grenadekidffere]

Hi all

I have been looking around for a couple of days now and can find no internet related searches on a 4.1 with only 1 02 sensor fitted mid exhaust or under drivers floor pan.

I have a 1994 gs with the 3s-fe engine as standard. Was only certain models fitted with the 02 sensor at the exhaust manifold as mine hasn't got one and never had as I am sure the original manifold is original on the car. My 02 sensor doesn't screw into the exhaust but instead is held in place by a 2 hole plate on the sensor fixed with m8 nuts.

The reason I ask all this is I suspect the 02 sensor is faulty as it just scraped through the mot (with the help of the tester) because the co2 test was so high, there is no engine fault light illuminated and its a pig on juice.

regards kev

[the fox]

hi yep your right only one sensor it's fitted in the cat I was involved in making some de-catting kits for this model, you still keep the sensor unlike some which did not, you get about 10/15% more power, you will not get a engine light fault you need to bridge out two contacts in the plug under the bonnet and count the flashes to give you the codes, search and you will find this info, I still have a kit second hand does anyone want it pick up only, Darwen free

[Grenadekidffere]

Hi fox thanks for reply, I don't think there is a cat on mine, just a middle box. The 02 sensor is just bolted into the pipe between the joint to the front pipe and the middle box if that makes sense. The only way I have seen this done on a rav 4 is a different short pipe about a foot long with a sensor the same as mine in the middle of that pipe (could be a 4.2 photo I seen or a decat mod), I cannot find a diagram or photo of a rav 4 exhaust like mine anywhere. Is there a chance that the first year of the rav4 was different from the rest of the years of the 4.1 as I don't think it was de-cat job as the sensor screws into any cats ive seen and my sensor would have to been changed which would not be financially viable at the time it was done. I will search for this bridging to get the codes, thanks I bought a lead to fit the dianostic plug under the bonnet but could not find a program to read the ecu as its not obd protocol.

On another note I have priced a new 02 sensor in the local motorfactors and it was £139.00+vat, are the ones on eBay at £35.00 cheap crap or is this a serious markup.

regards kev

[Grenadekidffere]

i have found an exhaust like mine on eBay and it is a middle silencer as i thought and its listed as fitting models from 94-00. I only ever saw or heard talked about on the forums cat exhausts, I'm baffled pardon the pun

regards kev

[the fox]

Hi I have worked on many 94 Rav4's all had a Cat and the sensor was bolted via two nuts, maybe your exhaust is not the original one and it's been replaced with a straight through exhaust minus the Cat, the bridging out is TE1 and E1 put ignition on and count the flashes....If you don't get any faults do a decent service, the dizzy on this model gets a bit worn try new plugs rotor arm and cap and you can adjust the ignition timing all will make a big difference to the MOT test good luck

[the fox]

see pic sensor just before Cat but it's in the same pipe work

[Grenadekidffere]

Thanks Fox, I will flash test it at the weekend. The plugs are nearly new but the part no didn't correspond with the Haynes manual ( sorry cant rem what part no the plugs were now) I cleaned the distributor cap but I will replace the cheaper parts you recommended first and leave the 02 sensor last, I will also change the thermostat even though I did about 2 years ago as ive noticed while driving that the heater is cool and temp hand is between normal and cold (car hasnt done 2000miles since I changed it unless sitting about). I will check timing as well thanks

regards kev

[Grenadekidffere]

Yes this is like mine just the sensor is mounted just behind the hanging bracket if I was nit picking.

regards kev

[the fox]

Hi Kev that is the CAT it may worn out causing the MOT problems, must be plenty on the scrap heap, but I have serviced a few after a MOT fail and checking the ign tiiming may help, you need to get it red hot and blast it down the motorway at 80 for half hour it will blast out the CAT good luck

[the fox]

Hi Kev that part is the CAT it may be goosed try blasting the Rav4 down the motorway at 80 get it red hot it may revive it

[Grenadekidffere]

ok fox i will try that after replacing a few bits but its 30 miles to the nearest motorway and the way its consuming juice i will need a full tank for that trip if the mpg doesn't rise lol.

getting dizzy and rotor arm, also a new set of plugs, would the platinum or Iridium be better than standard or recommended ?

regards kev

[the fox]

I would buy the cheapest if it may not pass the MOT I have a concern your CAT is faulty or you have bad injectors if it's using that much fuel, but I would be checking the OBD to see if the 02 sensor or any other faults, try cleaning the sensor in air filter...

[Grenadekidffere]

Hi sorry for not getting back to update but waiting for nearly a week on exhaust washers (long story) anyways get her running again with new thermostat and still no lasting heat in heater. I haven't checked to see if the core is blocked yet, but I did take off the left hand pipe and there was no coolant in it, so thought it was a bit of an airlock. I poured some coolant into the rubber pipe that heads back to the stat housing and when I keep filling it it runs out of the left hand heater pipe. I'm guessing at the minute that the system isn't pressurising and the water pump is definitely working so I was thinking rad cap?.

Still have the new distributor cap, plugs, oil to change and fuel rich prob to sort out yet but Cleaned egr valve, egr vaccum and sensor in air filter when I was waiting for exhaust seals, The cat isn't blocked either so getting closer to the truth( however painful that might be) I still haven't got around to reading the codes but hopefully tomorrow or tues if time allows.

[Grenadekidffere]

Checked for ecu trouble codes this evening and none stored. fitted new plugs, cap and rotor arm. Took it for a run this ev​ening and I can still see its drinking juice so I think next I need to do an ohms test on ait sensor and 02 sensor, also check the wiring. It is running better and more responsive under load but when travelling about 30mph noticed missing and surging or kangarooing a bit. Don't think its a vac leak as it purring like a kitten at tickover. If I have no joy with the sensors I will take it for a C02 exhaust test at a mechanic mates. Any other suggestions as to where I should go next (besides the breakers) lol

[Grenadekidffere]

Ok back to talk to myself again

I checked the AIT sensor today and its coming back ok on the ohms readings whereas the lambda sensor heating circuit is not, so new 02 sensor ordered and hopefully thats it. i will update when i know more in case this topic is ever useful to anybody.

[Grenadekidffere]

Ok back up to 25 mpg with new 02 sensor, old sensor was showing same values with ohms test but it had got lazy. Still got a miss when driving but getting closer to sorting it. Hope to have it closer to 30mpg when sorted.

Heater core was silted a bit so flushed it but learned impossible to bleed heater pipes without using a large funnel in the rad cap hole, this enables the head to be higher than the heater core pipes for expelling air.