14 replies to this topic

[Phil-R]

Hi there people. I'be been out of the mini scene with a broken car for so long now. I've recently spent weeks on the damn thing, only to fail the MOT >

I don't normally ask for help, but this time I'm really stumped and begging for your ideas. I've searched the forums, and found some pretty similar topics, which have given me inspiration, but still haven't managed to fix it...


I'm running an SPI with CAT temporarily removed and a carbon monoxide meter to do some tests. With the engine warmed up, she'll hold steady at somewhere betwwen 1.7% to 2.5% CO (sometimes lower). After 60-75 seconds it'll shoot up to 6.5%. It seems to be going into some kind of fail-safe mode, but as you can imagine this has killed the original CAT and failed on this years MOT.

I've replaced the lambda, and water temp sensors. The stepper motor clicks as normal ( and can be reset with the accelorator pedal trick ). The throttle pot reads between 0V and 5V using a multimeter.


??? Any suggestions what to do next ???

[Dan]

Get it analysed.

[Phil-R]

Yeah, but with Rover deallers having all but disappearred, where should i go ? I have little faith in garages, so can't throw money at other dealers who don't know what their talking about

Edited by chrome, 20 August 2006 - 10:20 PM.

[Dan]

Well a Rover dealer would be the last place I'd have taken one anyhow unless it was still under warranty. The guys in most of their dealerships were about as well trained as the guys building the cars.
There are lots of great Mini garages out there but you are right to be concerned as there's also a lot of muppets. Try asking people in your local Mini club if you have one, they can usually recommend good people. Where are you from? Maybe someone on here can help.

[bananaman]

I had something similar to this a few years ago with my 96 SPi, turned out to be the fuel in the tank.

I spent a fortune trying to get it all reset by a Rover Garage, who eventually told me I needed a new engine. (When it felt, pulled and sounded fine) My local garage were stumped too, until I happened to chat to a guy in a pub in Lincoln who used to build metro turbo challenge engines.

He listened to my woes and then had a peek under my bonnet, and chuckled when I told him my fuel came from Tesco's. He told me the fuel from there was so bad that the ECU was altering it's settings to compensate, hence the bad readings.

One drained tank and 20 ltrs of Optimax, plus 30 minutes of whizzing around the A46, and I took Scrappy back to the test centre, he flew through the MOT, the guy testing him was amazed how good the readings where.

From then on, it's all I put in my Mini.

Tony

PS, if you are on here anywhere Tom, thanks mate

[Phil-R]

There are lots of great Mini garages out there but you are right to be concerned as there's also a lot of muppets. Try asking people in your local Mini club if you have one, they can usually recommend good people. Where are you from? Maybe someone on here can help.

I'm around Solihull / Birmingham. At the moment, I cant drive it to a garage as it's sat there with no MOT, no tax, and is def off road with a few other repairs underway, since the verdict of the MOT. I had a quick google for ECU code readers, but unsure what I need. Has anyone here got one they want to sell? lend?

I had something similar to this a few years ago with my 96 SPi, turned out to be the fuel in the tank.

Funny you said this bananaman; The petrol would most likely have been Tesco's ( which I always asumed to be good stuff ) but come to think of it, has sat in the tank for 12+ months . I heard rumours that petrol 'goes off', but never thought to change it. Think I'll try syphonning the tank today, as I've got nothing to loose.

[Sprocket]

has sat in the tank for 12+ months . I heard rumours that petrol 'goes off', but never thought to change it. Think I'll try syphonning the tank today, as I've got nothing to loose.

THAT!!! is you problem

[Faultless]

hope it works let us know n is tesco petrol really that bad

[Guess-Works.com]

There's nothing wrong with tesco's or infact any other suppliers fuel... basically as it has to meet a British standard ( Kite mark ) and are regularily tested; secondly, probably comes from exactly the same origin as shell, texaco, bp etc etc etc...

Optimax is obiously a different fettle of fish, as that's a higher octane fuel..

[Sprocket]

Lifted from Minifinity http://www.minifinit...P...pic&t=42799

Alex, I hope you dont mind

lol ok then

lifted from another forum I wrote it for:

Fuels

In this document I intend to answer some of the questions that keep cropping up from “Does SUL make my car faster‿ through to what is petrol and which grade should I use.

To start with I feel an introduction into the subjects of fuels is required, so I am going to start right at the beginning and cover the basics before getting on to the more complicated subjects.

Introduction – What is petrol?

This is a simple question which is difficult to answer, as each piece of information you find breeds another question.

Petrol is probably the best known of all the products from crude oil. Just under 20% of a barrel of crude oil goes to making petrol - the largest proportion for a single product.

Raw petrol (also called gasoline) is a mixture of hydrocarbons with between 4 and 12 carbons in their chains.

So raw petrol itself is not just one chemical, it is a mixture of several.

Some of these chemicals include:

Hexene (C6H14)
Benzene (C6H6)

Some of these are aromatics which are useful but very harmful.

The refining process is not perfect and some other chemicals find their way into the fuel. A good example of this is Sulphur which doesn’t work well with certain emissions treatment systems, hence the use of low-sulphur fuels.

But this is only half the story. You can’t buy raw petrol unless you are a supermarket or similar!

There are several other substances added to petrol in-order to do several different jobs:

Knock inhibitors – to resist detonation.
Anti-ageing – stability during transportation and storage.
Detergents – to clean the internals of your engine.
Corrosion Inhibitors – stops things rusting.
Icing protection – stops ice forming in the inlet.
Anti-foam – to improve tank filling.
Friction modifiers – to modify your oil!

These are referred to as the Additive Pack. So next lets look at each of these in turn and consider the impact they have on our engines.




Knock Inhibitors

This is the main factor the public are told about in terms of the quality of the fuel, but it is only one of the factors to consider.

Knock inhibitors improve the fuels anti-knock properties (octane rating). The higher the figure the greater the fuels resistance to detonation. There are two methods of measuring this:

RON – Research Octane Number
MON – Motor Octane Number

One point to make here is that in the UK we use RON. In the USA they take an average of RON and MON (ie RON+MON/2). So if you read an American book and they mention a petrol with what seems a very low octane rating (maybe 92) they aren’t using the same numbers we are!

So what’s the difference between MON and RON?

Well the way the work out the ratings of the fuel is very similar. Both use a single cylinder engine with a variable compression ratio. The fuel being tested is compared to two know fuels (n-heptane and iso-octane). These two fuels behave in opposite ways, one knocks easily the other resists knock VERY well. So by comparing a fuel (such as petrol) to these two known fuels a value is worked out.

The RON method uses acceleration as the main condition during testing (i.e. increasing engine speed). The MON method tests at higher engine speeds. Now here’s the crunch, high rpm to this type of engine is only 900 rpm!


Either way, the more octane, the better the fuel resist detonation. The way they do this is by raising the amount of energy that is required before the fuel will do anything (burn/react). So in fact this makes the fuel harder to burn, which is different to the perception that high octane fuels are more powerful.




Anti-ageing

This agent stop fuel going off. If you leave petrol long enough is becomes a sticky yellow gloop that will bung up everything. This is usually only a problem on vehicles that are left with fuel in them for many years!

Another point this raises is how long does fuel last. Fresh fuel is defiantly the best. The best most people will be able to do is to buy their fuel from a large petrol station that sells lots of fuel. The more they sell, the more often their deliveries they will have. This means the fuel you are buying has spent less time sitting in the underground storage tanks.

Over a period of week(s) the aromatic content of the fuel is the first to change as these are the most reactive. As this happens so the actual fuel changes (and often performs less well rather than better!).




Detergents

The purpose of detergents is to keep the inlet tract clean. This includes valves, ports, manifolds and throttle butterflies.

Its often thought that the detergents job is pointless. The opposite is true. On most engines the crank case emissions are pumped back round into the inlet system. Small amounts of oil mist can easily enter the inlet. On contact with hot surfaces (such as the back of the inlet valve) they can burn and form deposits. This reduces the air flow past the valve lowering the overall performance of the engine.





Corrosion Inhibitors

This basically stops metal components such as the tank itself from rusting. It is difficult to protect metal from rust with a substance that is not attacked by petrol. Luckily petrol does this for you.




Icing protection

If you’ve ever got petrol on your hands you will understand that evaporation has something to do with temperature. It take heat to make the petrol evaporate, so as petrol and cause a drop in the temperature of the air. If the air has a high moisture content, the water can freeze cause problems such as carburettor icing.




Anti-foam

As you move petrol about its natural tendency is to bubble. When your filling your tank you might notice this.

If allowed to certain conditions such as bumpy roads would make your fuel into a bubbly foam rather than a liquid fuel.





Fuel choice and use.

There are a large number of suppliers all claiming to have the best fuel.

To supply all the fuel in the UK there are several refineries. Each one of these is owned by an oil company. So for example Shell own the Shell Haven refinery in Essex. All the local BP stations will be filled at the Shell refinery.

The reason for this is that the base petrol is regulated very tightly and so is the same regardless of refinery. It’s the additive pack that changes from company to company.

Exceptions to this include Optimax (Shell might have changed this, but when launched this information was correct). This is(was) made at one refinery and then shipped out to all stores across the country.




Supermarket Fuel

Fuels destined for any supermarket is the same base fuel as any other petrol station. The reasons it is cheaper is that it will contain a cheaper additive pack and the fact that a supermarket buys its fuel in bulk!

Typically the fuel will not perform as well as a oil companies own brand, but like most things you get what you pay for!




What fuel should I use?

Simple. Use the fuel your engine has been designed to run on. If your car was designed to run on standard unleaded (95 RON) then use that. Using SUL will not make your engine more powerful as the engine will not take advantage of the fuels greater resistance to knock.

In more common vehicles (i.e. low performance!) high octane fuel can lower the performance and making cold starting difficult.

Copyright AFRacint LTD 2006

Alex

[Plucky]

Its a shame yourt not closer. My dad has got Diagnostic Scanners.

Edited by Plucky, 21 August 2006 - 06:39 PM.

[Phil-R]

FIXED !!!!

Bananaman saves the day!!

I syphoned the tank this morning and mixed the old petrol into my fiesta's tank.The petrol that came out was definately off-colour ( yellow instead of bluey/ green shade ). Made a couple of trips to Shell and came back with 2 cans of Optimax.

So... started her up and disapointment struck. After warming up, the emissions rose sharply, just as before. But after about 15mins trying, the emissions were staying low for longer and longer. After about 15 restarts, the emissions never went over a rock-steady 1.5% ( with CAT removed) RESULT !! I think it took about 30mins in total for the ECU to relearn enough to not give up and go into fail-safe mode. Compair that to 4hrs of trying with the old fuel, when I could predict the ECU would give up after 60 seconds.


From now on I think I should be using 98RON fuel. The engine's tuned with 271 cam, home-modded head, full exhaust, filter etc... as well as repositioning the reluctor ring to give 1.5 - 2 degrees more advance.



Thats a good guide by minifinity-Alex. Thanks Mini Sprocket for digging it out.

Plucky... don't suppose you know the make of that diagnostics scanner? Is it a useful bit of kit then?

[AlexM]

There surely must be an independant rover specialist who knows how to use the appropriate diagnostics equipment in your area. Remember there are still a fair few rovers on the road that need servicing, they must go somewhere and since all the main dealers have vanished an independant must exist!

[bananaman]

Glad it helped, it had me baffled for weeks when it happened to me, and I spent a bomb trying to sort it. (new injector, and four days in a Rover garage as no one else could check the MEMS ECU)

To be honest, if your fuel was in the tank that long it would have been that rather than where it was from, but hey, looks like you are sorted now.

Tony

[Plucky]

Plucky... don't suppose you know the make of that diagnostics scanner? Is it a useful bit of kit then?

Yeah its Snap-On. Its myu dads actually. He contracts for Tesco, Asda and Sainsburys and uses it to read faults the delivery vans.It was expensive around 1.4k I think

It has nearly all the cars on there though!