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My 182 is killing O2 Sensors



  Renault Clio RS 182
I've just ordered another O2 sensor... this is the third one that the car's had in under a 1,000 miles of driving :( Something's not right.

The background.
-----------------------
The car is a 2005 Renault Clio 182 with 78,000 miles.

The car was throwing a P0130 error [upstream O2 sensor] when the previous owner had it, so he replaced the O2 sensor with a Bosch one. It didn't last long. When I bought the car, it had the error. When the ignition on, but engine not running, the sensor was registering 1.275v. It should be registering around 0.4v to 0.5v. I replaced the Bosch sensor with a brand new Genuine Renault one [which is actually manufactured by Bosch !]. The car was running fine for a while, then it started to exhibit a lumpy tickover, was dying around 3000 rpm, and low and behold the P0130 fault code has returned.

I did quite a bit of live data logging. From cold start to running temperature at constant idle, the O2 sensor does appear to move to switching between around 0.1v and 0.8v. However the STFT appears to be oscillating with negative values at various rpm when the engine is under load [i.e. driving]. It should be oscillating around zero. So the O2 sensor is definitely not working properly. The LTFT is constant at 4.69%

The downstream O2 sensor is a Denso sensor and has been working fine.

In other information... the manifold air pressure is 369-393 at idle, so that seems around where I'd expect - i.e. it's not leaking.

I started the car from cold yesterday and had it running for around 3 mins before I took the faulty upstream sensor out. The sensor probe was very sooty - see photo - but this may have been as a result of the car being 'on choke' after starting, so to speak.

I've looked around online to try and figure out what could be killing these O2 sensors :

Fuel contaminants - unlikely as the fuel has been bought from different suppliers at different ends of the country... and I've used my local filling station with other cars and they've been fine.
Silicone in the induction system - I've had the induction system to bits and it's clean. I also fitted new inlet manifold gaskets while I was at it.
Coolant leaks - I recently replaced the coolant. The level hasn't budged a millimeter.
Oil contaminants - the car has had an oil and filter change, also the car isn't burning oil and the MOT emissions [it had one two weeks ago] were perfect.

So to coin a phrase, if I'm about to load the parts cannon for firing [not that it hasn't been liberally fired recently], my first port of call would be to replace the injectors. They sound fine, aren't issuing fault codes, but I know that doesn't tell the whole story. Thing is... I'd be replacing these on nothing more than a hunch as at this point I don't have evidence to prove they're faulty.

Thanks for reading... I'd be deeply appreciative of any suggestions on possible ideas or next steps... or questions in case I've left something out.
 

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Louis

ClioSport Club Member
If you're killing lambdas it's most likely the injectors.
Check them all and their associated resistance measurement
 
  Renault Clio RS 182
First off, thanks so much for this guys.

Has it been mapped? Looks like it is running really rich.
That's a good question. I honestly don't know. I didn't remap it and there's no evidence in the documentation that the previous owner did. Is there any way I can find out from looking at the live data parameters ?

If you're killing lambdas it's most likely the injectors.
Check them all and their associated resistance measurement
This is my suspicion. Is there a thread anywhere that will help walk me through testing these... i.e. what I should do and what measurements I should be seeing ? Really appreciate all/any help.
 
  Renault Clio RS 182
resistance of an injector should be about 14.8 ohms from memory

Isn't there something you can do with scoping them - i.e. to see a trace profile of some sort. I'm not sure if I have the kit to do it though. Also, not sure how you can test for the things physically leaking.

Speaking of injectors, does anyone have opinions on what to use for replacements ? Are Magneti Marelli OK ?
 

Radugns

ClioSport Club Member
  Clio 172 ph2
If you ecu has different map, 99% the revlimit is 7500rpm and idle at 900rpm+. Maybe the map is not right and cause very rich afr value. Try to measure the injectors resistance value, but in most cases when they are gone, the did not provide enough fuel, not the other way around.
Do you have any smoke from exhaust?
Also did you check for wiring? Maybe there is some problems with harness and the "glow" wires are always on.
 
  Renault Clio RS 182
If you ecu has different map, 99% the revlimit is 7500rpm and idle at 900rpm+. Maybe the map is not right and cause very rich afr value. Try to measure the injectors resistance value, but in most cases when they are gone, the did not provide enough fuel, not the other way around.
Do you have any smoke from exhaust?
Also did you check for wiring? Maybe there is some problems with harness and the "glow" wires are always on.

I've not checked where the rev limiter's kicking in but it seems to be idling [when warm] around 750-850.

I'll need to get hold of a new multimeter and check the resistance on the injectors - the one I have at home here isn't good enough.

No smoke from the exhaust - there does seem to be carbon deposits [similar to the O2 sensor] at the tailpipe ends.

I haven't checked the wiring... when you say the 'glow' wires being always on, are you talking about about the O2 sensor heater circuit ?
 
  Renault Clio RS 182
As I am right now, the current working Denso sensor positioned upstream is registering 0.4v when the ignition is on, but the engine's not running. This would indicate that the heater is getting power from the beginning. After starting [from cold] the voltage then moves to around about 0.9v and sits there for about 30s before it begins oscillating [from 0.1v to 0.7v]. I'm not sure how I can figure out when the heater goes off - or what parameter/trace I should be looking for.
 
  Renault Clio RS 182
Denso? You should be running a Bosch.

It's killed two brand new genuine Renault [Bosch] sensors and a Bosch OEM one all positioned upstream. I decided to try a Denso sensor downstream and it's survived there. I've now moved it upstream [as it's the only working sensor I have] until I get the new ones.
 


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