Very Very Confused - please help...

[OmniCognateNeutronRangler]

Ok, now I am very very confused. Those of you that have been reading the “contaminated fuel” thread will be aware that I have seemingly been inflicted with said fuel and have been presented with an enormous bill to have it fixed (£1360.00). I was advised by TP not to drive the car any more than was absolutely necessary but that they couldn’t get the parts for a week due to demand. So I arranged to drop the car off today and pick up a rental car – Tesco have said they will cover reasonable costs including a hire car.

Here’s where it all goes wrong (or right). I got in the car, started it up and……no warning light. I drove the 30 miles to TP, stopping several times on the way to turn the car off and start it up again but still no warning light. So I discussed this with the service guy at TP and he says “if the light isn’t on then there is no problem with the car”, so he recommended I continue driving it and cancel the hire car. He also said that he has never known an O2 sensor to fix itself (let alone 4).

I then drove the car home in various styles (e.g. old man and lunatic, to see if it made any difference) and I still have no warning light.

So, here is a list of what adds up and what doesn’t.

Adds-up:
1. I did fill up at Tesco
2. I have had Tesco confirm that the garage I used did have a contamination problem
3.The warning light came on in the car
4. TP attached the STAR diagnostic thingy and showed me the results, they said “O2 Sensor Aged” (or somesuch), and also then shows 3 readings of “above tolerance levels” and one of “under tolerance levels” (the car has 4 sensors)

So based on that it looks cut and dry, right?

Doesn’t add up
1. After filling up at Tesco it was probably 600 miles before the warning light came on (and 150 miles after I filled up at a Jet station) – TP say the most they have ever heard of before problems occurred was 50 miles.
2. TP say they have never seen an O2 sensor clear itself
3. TP say that if the light is out there is no-longer a problem.
4. Warning light stayed on for a day and a half (about 120 miles) and then went away again
5. Getting very good economy (better than normal) and the car is running really well.

Also cut and dry but a bit contradictory.

So, the really big question…..what the hell do I do now? TP are saying that the problem may come back and that I should have the work done anyway. Given that Tesco have said they will pay for it I’m tempted to go this route, however it will be a lot of hassle and still means I need a hire car for a couple of days and go through all the stress of getting the money back from Tesco.

To me something doesn’t add up here. I will definately get TP to hook it back up to the STAR thingy when they get the part in and before they do any work.

All you technical wizzes out there, can you let me know if you can think of anything else that would have caused these symptoms and comment on why it took the best part of 600 miles to manifest itself if it is the contamination problem?

Could I have got some different type of contamination at the Jet station (such as water) that caused the problem but has then cleared itself?

Could the other drivers have cleared their cars if they had driven them as many miles as I did? I suspect most people saw the problem and had it fixed immediately (and in some cases the cars became undrivable) so they never found out what happened after 600 miles of driving.

Could the contamination have been very minor and the fuel from Jet cleared it out?

Ideas?

 

[eric242340]

Ok,
Hi Neil, its seems you have a real nightmare here, but as the car is driving ok and no check engine light(you filled the car up twice, possible dillution thing), then I feel you have very little to worry about. On the other side, we havent experienced this sort of contamination before and who knows what could happen next. I would go for the repair and the hasstle that brings, because if anything goes wrong after this you have a leg to stand on. Best regards Eric.

 

[littlebrooklyn]

My instinct would be to have the work done based on the fact that something must have been wrong at some point surely? I know nothing about cars as I'm sure you are aware, but perhaps as they have offered to do the work at least you know you have covered yourself by having the work done

 

[OmniCognateNeutronRangler]

My instinct would be to have the work done based on the fact that something must have been wrong at some point surely? I know nothing about cars as I'm sure you are aware, but perhaps as they have offered to do the work at least you know you have covered yourself by having the work done

well, as I understand it you effectively have the work done and then put in a claim. It is always possible that Tesco will come up with some reason for saying no to the work and then I'm lumbered with a £1360 bill.

 

[Timechaser]

Tesco's admission in the general press has pretty much established a precedent here.

It will be on Tesco to somehow prove that it wasnt the petrol which caused the fault in your car. The part being replaced is the same as with a squillion other cars so guess what - the money making machine will not waste its breath on you but refund you the money easy.

I dont think for a moment you will have any issues getting the claim back, unless it is some other part which your stealer replaces rather than the one getting replaced in other cars... as you can see I am not too technical minded, but am sure about law

 

[Blobcat]

So, the really big question…..what the hell do I do now?

Tesco are discounting their fuel by 3ppl as long as you buy something in one of their shops so you could always go back for some more fuel

Have TP read the codes again and possible just get the 02 sensor changed if everything comes up good.

 

[littlebrooklyn]

well, as I understand it you effectively have the work done and then put in a claim. It is always possible that Tesco will come up with some reason for saying no to the work and then I'm lumbered with a £1360 bill.

If you had the work done based on the fact that you believe the Tesco fuel to have caused the problem is there any way Tesco would ever know that at some point your car seemed to be running okay again before it was repaired

 

[television]

Ok what does the o2 sensor do, it monitors the burnt fuel passing through the Cats and exhaust.

This cannot hurt the engine and that is shown by the fact that the Light is not on

What does the engine check light do normally it shows any serious malfunction or something minor where a component has deviated from its stored setting, in this case the settings for the sensors has returned to normal.

Long term effects The only thing that could be damaged is the cats,but if the light is not on then the fuel ratio is probably correct.

O2 sensors , Since this has never happened before, no one knows if the contamination will go. These things are running at 600c and thats hot, thats half the melting point for cast iron. I sprayed some silicon onto a heated ring and it turned to black powder within seconds. So no one has this answer.

What would I do,, I would drive the car if the lamp did not come on,if it did come on,that is the point at which I would hire one,and that is my veiw.

Malcolm

 

[OmniCognateNeutronRangler]

Thanks Malcolm,

so the general consensus seems to be drive it as long as the light is out but get the work done anyway if Tesco are goint to pay for it.

btw blobcat, they didn't restest it with the STAR doobry today but I will make sure they do when it goes back in before they do the work

 

[124coupe]

Silicon contamination of the O2 sensor(s) - not sure what model you have but you may have between 1 and 4 of them - will result in white deposits building up on the sensor itself.

Result is that the O2 sensor indicates lean mixture and so the ECU richens things up.

A healthy O2 sensor will read the O2 levels correctly AND respond quickly to changes in levels.

TP should read the codes, look at the waveform from the sensor(s) to check the reaction times AND do an exhaust check to see if its clean.

You may have has limited contamination that has burnt off enough to make the ECU happy but still have the negative effects of an out-of-ideal spec sensor(s).

You should still plan to have new O2 sensor(s) provided by Tesco.

(if you don't, TP will have logged the work and you will not get them from Merc later without paying full whack!).

I would still ask for a breakdown of the costs - how do max 4 x £100 sensors come to £1300?

 

[television]

I would still ask for a breakdown of the costs - how do max 4 x £100 sensors come to £1300?

Very easy when it comes to MB They cost around £60-£70 each. I do believe the 2 of these are in the down pipes and hard to get to, type 49 will know.

Malcolm

 

[OmniCognateNeutronRangler]

Silicon contamination of the O2 sensor(s) - not sure what model you have but you may have between 1 and 4 of them - will result in white deposits building up on the sensor itself.

Result is that the O2 sensor indicates lean mixture and so the ECU richens things up.

A healthy O2 sensor will read the O2 levels correctly AND respond quickly to changes in levels.

TP should read the codes, look at the waveform from the sensor(s) to check the reaction times AND do an exhaust check to see if its clean.

You may have has limited contamination that has burnt off enough to make the ECU happy but still have the negative effects of an out-of-ideal spec sensor(s).

You should still plan to have new O2 sensor(s) provided by Tesco.

(if you don't, TP will have logged the work and you will not get them from Merc later without paying full whack!).

I would still ask for a breakdown of the costs - how do max 4 x £100 sensors come to £1300?

£1360 actually. I have seen the quote but don't have a copy so can't give you a break-down. It does have 4, it's a V6 W203. This price does not include any possible damage to the cats, which TP are suggesting may add another £1000 to the bill

 

[television]

£1360 actually. I have seen the quote but don't have a copy so can't give you a break-down. It does have 4, it's a V6 W203. This price does not include any possible damage to the cats, which TP are suggesting may add another £1000 to the bill

Your last point is a hard one,my car with the same engine passed with only 2 of the 4 Cats I do not think that they can be measured, also I think that they are £1500 the pair plus fitting.

Malcolm

 

[OmniCognateNeutronRangler]

Your last point is a hard one,my car with the same engine passed with only 2 of the 4 Cats I do not think that they can be measured, also I think that they are £1500 the pair plus fitting.

Malcolm

ouch. What TP have said is that they can't tell if there is any other damage until they fit the new sensors and then re-test everything. I guess if the emission are off they wont know if it's the sensors or the cats until they replace the sensors. Does sound a little hit and miss to me though

 

[television]

ouch. What TP have said is that they can't tell if there is any other damage until they fit the new sensors and then re-test everything. I guess if the emission are off they wont know if it's the sensors or the cats until they replace the sensors. Does sound a little hit and miss to me though

This is a hard unknown topic, tha CAT is a kind of cermic and looks like a bee's honeycomb, their purpose is to keep harmfull particles/gas within them selves so that they do not pass into the open air.
When an exhaust fails the MOT through the CAT it normally means that the holes are blocked or with oil.

If you read the link on 2 way cats it tells you over fueling is not a real danger to them
http://en.wikipedia.org/wiki/Catalytic_converter

malcolm

 

[OmniCognateNeutronRangler]

This is a hard unknown topic, tha CAT is a kind of cermic and looks like a bee's honeycomb, their purpose is to keep harmfull particles/gas within them selves so that they do not pass into the open air.
When an exhaust fails the MOT through the CAT it normally means that the holes are blocked or with oil.

If you read the link on 2 way cats it tells you over fueling is not a real danger to them
http://en.wikipedia.org/wiki/Catalytic_converter

malcolm

I'm not convinced there ever was an issue with the car running rich. As I said in the other post I seem to be getting better economy not worse. When I ran from the office in Hungerford, to Heathrow on Tuesday the car was recording and average speed of 64mph and 38 mpg! The most I ever get is about 33 and normally only about 30 so it's using less fuel not more.

Hopefully the cats will be ok. I'm just curious to know if the O2 sensors can show a problem, have the problem go away and then (more importantly) come back. Once it's gone is this problem likely to have been resolved or is it likely to re-occur?

 

[television]

I'm not convinced there ever was an issue with the car running rich. As I said in the other post I seem to be getting better economy not worse. When I ran from the office in Hungerford, to Heathrow on Tuesday the car was recording and average speed of 64mph and 38 mpg! The most I ever get is about 33 and normally only about 30 so it's using less fuel not more.

Hopefully the cats will be ok. I'm just curious to know if the O2 sensors can show a problem, have the problem go away and then (more importantly) come back. Once it's gone is this problem likely to have been resolved or is it likely to re-occur?

I would have said that things can only get better,the face of the LAMBDA is shielded with slots where the gas passes across, whats on the cant get worse and I would have thougth the other way around. If you get them changed free all so well and good, Will Tesco argue that they must be OK as your car has not stopped.

malcolm

 

[OmniCognateNeutronRangler]

, Will Tesco argue that they must be OK as your car has not stopped.

malcolm

I don't think so. According to TP some stop and some don't. I depends on the car.

 

[Uncle Benz]

Just to add a little bit to this...

I have a few cars in to fix that have contaminated fuel from Tesco.

Deposits on Lambda sensors are light grey in colour.

I have not found them to burn off, even after lengthy high speed with known good fuel.

Readings from contaminated sensors indicate a falsely rich mixture, so management tries to lean the mixture off, resulting in very poor running, stalling, etc.

This would lean towards your findings of better fuel economy.

I can only comment from the two cars I have so far looked at, (both Peugeot).

If I were you, I would take the others advice and have the work done.

Long term damage to catalytic converters can only be speculated about at this stage. It will be a while before any long-term damage is uncovered.

Hope this helps.

UB

 

[television]

Thank you Uncle Benz for this info,you cant beat it first hand.

As your samples were running weak,that would make more sense than running to rich,as black smoke would come out of the exhaust,and a car can be a lot richer than it can be weaker, as being too weak you cant drive it.

This would show that there should be no damage to the cats.

malcolm