GTR Forum banner

1 - 20 of 44 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
I previously started a thread on Optimax but at the time there was no real knowledge. I have a 2000 R34 from Middlehurst. It went into Middlehurst for an oil change service. There are 37700 on the clock and only 1700 since the last service. The car has been running rough for the last 6 months at least and I asked the garage to investigate. They replaced the oxygen sensors and the engine runs sweet as a nut. Paul at Middlehurst suspects the Optimax which is the only fuel I use and I suspect he has now seen the same problem arising recently. However, the bill was £800+. The sensors have gone away to Nissan but I dont hold my breath. I am near to Marinello so intend talking to them to see if they are experiencing anything like this with Ferrari engines. I havent any issue with Middlehurst but maybe with Shell.
Any one got any ideas? In the meantime I intend to steer clear of Optimax and would advise any one else to do likewise
 

·
Registered
Joined
·
2,479 Posts
Would love some clarification on this subject as i too have run only optimax with octane booster as advised by vehicle supplier. In fact i was told to run nothing else but opti and booster!!
 

·
Registered
Joined
·
9,034 Posts
Possibly a bit rash to put the blame at Shell's door without having any evidence to back it up. O2 sensors can fail for a number of reasons, running weak/hot, etc. From my own experience and there's been lots written about this subject, Optimax certainly lowers the det levels 'detected' on my car. I won't go into the sensor/octane rating debate but if it offers protection against det when you're tuned close to the edge, it may be cheaper to replace the O2 sensors than have an engine rebuild....?
 

·
Registered
Joined
·
1,670 Posts
Optimax seems to be the fuel of choice for heavily tuned engines, but is it also better to run more standard setups on it, say a stage 1?

Life was simpler when you just had to know the difference between petrol and diesel - but it was a lot less exciting!
 

·
Premium Member
Joined
·
7,806 Posts
I am sure that I remember Tony or Mark at Abbey telling me that the oxygen sensors are a consumable and should be treated as such when I asked why they failed on mine.
 

·
Registered
Joined
·
9,548 Posts
I just checked in the GT-R Owners book and from what I could make out it does list it as a consumable part of the RB26. 37700miles is quite a lot and if your car is slightly tuned you really can't expect things to run forever.
I think Peter E pretty much summed it up....better a couple of sensors than an engine rebuild!
 

·
Registered
Joined
·
11 Posts
Discussion Starter #7
Thanks for comments guys. Maybe I need to open my eyes. Still far less expensive then Porsche but Middlehurst gave me the impression that this was not "normal" and the bill came as a shock when I was expecting a couple of hundred.
 

·
Registered
Joined
·
404 Posts
Sensitive Info

I’ve been told that the oxygen sensors should be changed every 25-30,000 miles on any car (there’s 2 on a Skyline). http://www.jcwhitney.com/product.jhtml?CATID=5599&BQ=jcw2&_requestid=8077

The Platinum tipped type is exactly the same as the ones used by Nismo. :rolleyes:

At £800 there must have been something else replaced as well :confused:

The thing that bothers though me is what makes Paul at Middlehurst think there is a problem caused by Optimax? Ferrari owners in Germany won’t use anything else.

And anyway even is there was a problem with Optimax, Ferrari wouldn’t confess to it as Shell sponsor Ferrari.

Paul.
 

·
Registered
Joined
·
1,885 Posts
Ferrari might not but the ferrari owners would.

I'm sure you would have hear rumblings of uncertainty if they even suspected Optimax of damaging their engines....

I just hope it is a case of bad luck or the part wearing out. There are a lot of Optimax users on this site.

thanks for the heads up. at least we can now listen out for more of the same.

Perhaps if we listen out on the lancer and scooby forums more evidence will present itself.

/Steve
 

·
Banned
Joined
·
3,561 Posts
Piece of advice, if you can remove your Oxygen sensor then once a year, do it, having previously bought a large lemon at your nearby Fruiterers/Supermarket earlier in the day, cut the lemon in half, and insert the tip of the probe in each of the segments for 3/5 minutes, you can with the other half cut it in slices, get a glass and while you wait for this 'mod' to do its work, pour yourself a little gin and a bit of tonic a couple of cubes of Ice, sit down, sip the drnk while you twiddle the probe in the lemon congratulating yourself at being such a cool dude improving your car this way.

Cheap too.
 

·
Banned
Joined
·
3,561 Posts
Also if any of you have never done this then you will also gget MUCH improved fuel economy, that should pay for the bottle of G&T with the first tank.
 

·
Banned
Joined
·
3,561 Posts
This leads on from the Octane booster thread to some extent, so for clarity I'll simply outline how a sensor of this type works;

The oxygen sensor utilises the "Nernst effect." Nernst's law measures the voltage between two materials in close contact, one of which is a known constant. When the sensor reaches a temp. 640degrees F ±25F, it produces a voltage which is interpreted by the ECU and adjusts the fueling to suit.

The outer shell of the sensor is Zirconium Oxide, this material is very sensitive to contamination, think of a nice piece of polished alloy and how easily it will absorb the oil excreted by you skin, well ZircOx will take up all those additives in petrol, but for the most part they don't effect it too badly, but Opt and all those OBs' do contain contaminents and if over applied or applied constantly (as in using Opt continually) the voltage engendered is not as it should be, Citric acid cleans ZircOx perfectly, the acid actually cleans down into this 'rough' surface, we are talking very small scale here, so to the hand it is quite smooth.

Lead, from fuel screws them, Phosphorous (Opt, and most OBs') does the same only slowly, If your turbos have ever blown their seals and blown smoke out the back, the phosphorous in that burn out will kill it fairly quickly, you should always replace the sensor if this has ever happened to you.
 

·
Registered
Joined
·
9,034 Posts
So presumably, when the sensor is dirty, it's response time will be greater leading to inaccurate readings to the ecu? This will only be relevant when the car is in closed lambda situations, idle, cruise, etc. won't it? Can't see how that will dramatically affect fuel consumption but I'll give it go.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #18
Lemon/Citric acid stuff is interesting. Didnt realise that such learned folk read these things.
Anyway just got the Middlehurst paperwork thru the post. Wording of invoice states failure of Oxygen sensors due to Optimax fuel. The problem only showed its head at 3200-3800rpm when the accelerator just didnt respond.
Need new boots now SO3s maybe?
 

·
Banned
Joined
·
3,561 Posts
#Didnt realise that such learned folk read these things.#

Nah, the real smart ones post the stuff!
 
1 - 20 of 44 Posts
Top