Agonising Issues - Help

Bargain Bucket · Post by **Bargain Bucket** » Wed Jun 13, 2012 12:18 pm

Sounds like there's an awful lot of straw clutching going on.

X5Sport · Post by **X5Sport** » Wed Jun 13, 2012 12:23 pm

Was just thinking the same.... It took one Dealer five attempts to try to identify the poor starting issue on my E53 and they never did find the real fault. Another dealer found it at the first attempt...starter motor faulty. BMW were paying all the bills, but I after my recent 'discussions' with BMW about the X6 I really feel these garages just don't know what to do if the computer doesn't tell them.

There were so many things that I was told were the cause, along with one that said the instrument cluster shuts down when the battery gets low, that my faith has yet again taken a knock. I don't know if it's poor analysis, poor training, poor technicians or what, but it isn't inspiring!!

Bargain Bucket · Post by **Bargain Bucket** » Wed Jun 13, 2012 12:48 pm

BMW are no different from any other manufacturer. Dealerships (and many independents too) have no fault finding skills these days. If the computer doesn't tell them what's wrong then they are at a total loss for what to do and will replace random parts until the fault goes away.

timharding · Post by **timharding** » Wed Jun 13, 2012 5:08 pm

Michael has just called from Cooper BMW Sunderland,

They removed the Exhaust today and advised that the car ran well without the Exhaust, Albeit loud.

So a left Catalytic Converter is required.

They are going to look further into the electronic issue tomorrow and let me know.

I will keep you all updated.

Tim

X5Sport · Post by **X5Sport** » Wed Jun 13, 2012 5:31 pm

Can someone explain why a 'bad cat' would make an engine run lumpy? I thought the oxygen sensors were upstream as the idea was to make sure the cat wasn't being fed 'rich' fumes and therefore their input is pre-cat, or are they post cat, in any event they can be bridged and the systems 'fooled' into believing everything is fine.

Taking the exhaust system off just removed back pressure and the engine will run totally differently (yeah..and LOUD too

) they need to put a 'dummy cat' into the system, or at least something to ensure identical back pressure or else the test is surely flawed isn't it?

timharding · Post by **timharding** » Wed Jun 13, 2012 5:45 pm

[quote="X5Sport"]
Can someone explain why a 'bad cat' would make an engine run lumpy? I thought the oxygen sensors were upstream as the idea was to make sure the cat wasn't being fed 'rich' fumes and therefore their input is pre-cat, or are they post cat, in any event they can be bridged and the systems 'fooled' into believing everything is fine.

Taking the exhaust system off just removed back pressure and the engine will run totally differently (yeah..and LOUD too

) they need to put a 'dummy cat' into the system, or at least something to ensure identical back pressure or else the test is surely flawed isn't it?
[/quote]

Would be great to know answer to this as would save buying a cat

macky1986 · Post by **macky1986** » Wed Jun 13, 2012 5:57 pm

[quote="X5Sport"]
Can someone explain why a 'bad cat' would make an engine run lumpy? I thought the oxygen sensors were upstream as the idea was to make sure the cat wasn't being fed 'rich' fumes and therefore their input is pre-cat, or are they post cat, in any event they can be bridged and the systems 'fooled' into believing everything is fine.

Taking the exhaust system off just removed back pressure and the engine will run totally differently (yeah..and LOUD too

) they need to put a 'dummy cat' into the system, or at least something to ensure identical back pressure or else the test is surely flawed isn't it?
[/quote]

If the cat is blocked enough then it doesn't let the pressure out causing the vehicle to run very lumpy. The cat should glow red.

I had the same problem with a suburban out here and it took awhile to figure out the problem. Removed the exhaust and it ran sweet, replaced the cat and the vehicle ran perfect. It was a petrol and when it was running the fumes coming out the exhaust filled the workshop and we couldn't breath.

Most newer vehicles will have an 02 sensor before and after the cat to make sure the gases going in are correct and the gases after the cat are correct. That would make me think the downstream sensor should be bringing up faults if the cat is faulty. That is if the X5 has sensors before and after, maybe someone else could answer that.

macky1986 · Post by **macky1986** » Wed Jun 13, 2012 6:00 pm

Also that suburban was giving various cylinder misfire codes.

X5Sport · Post by **X5Sport** » Wed Jun 13, 2012 6:06 pm

[quote="macky1986"]
Most newer vehicles will have an 02 sensor before and after the cat to make sure the gases going in are correct and the gases after the cat are correct. That would make me think the downstream sensor should be bringing up faults if the cat is faulty. That is if the X5 has sensors before and after, maybe someone else could answer that.
[/quote]

And that's the bit that puzzles me too. A blocked cat makes sense, but the sensors should flag it?

macky1986 · Post by **macky1986** » Wed Jun 13, 2012 6:11 pm

[quote="X5Sport"]
[quote="macky1986"]
Most newer vehicles will have an 02 sensor before and after the cat to make sure the gases going in are correct and the gases after the cat are correct. That would make me think the downstream sensor should be bringing up faults if the cat is faulty. That is if the X5 has sensors before and after, maybe someone else could answer that.
[/quote]

And that's the bit that puzzles me too. A blocked cat makes sense, but the sensors should flag it?
[/quote]

That's the part I dont understand either. One thing I have learned though is some faults don't always make sense lol.

If it runs well without the cat on then the cat should be the problem. But wether or not it actually has ran well without the exhaust on, only the garage knows.

timharding · Post by **timharding** » Fri Jun 15, 2012 5:25 pm

Car now back from Cooper BMW

Excellent service from them again.

Had the car a few days and the total bill was £78:00

They have confirmed that the Left hand Side Catalytic Converter needs changing and also that the Alternator is at fault.

The alternator on the vehicle was reconditioned from a supplier, however it is confirmed faulty, the company only offered 30 day Warranty and even though the car has only been driven 18 miles in 30 days they will not replace.

Next steps

Order new Type Approved Catalytic Converter - will need to be re-manufactured into existing exhaust pipe as it is not a like for like, as they are not available, and only available rom BMW @ £847 + VAT = £1000 PLUS

Then obtain another alternator.

Then hopefully all sorted.

Watch this space.

Tim

Cannondale · Post by **Cannondale** » Fri Jun 15, 2012 5:26 pm

Good luck Tim, its about time you had some good news

X5Sport · Post by **X5Sport** » Fri Jun 15, 2012 5:32 pm

[quote="Cannondale"]
Good luck Tim, its about time you had some good news

[/quote]
+1 on those thoughts.....

Rusty · Post by **Rusty** » Fri Jun 15, 2012 5:48 pm

Must be a relief to get some definitive answers.
Hope the work goes smoothly for you.

Sent from my iPad using Tapatalk

Riggie · Post by **Riggie** » Fri Jun 15, 2012 5:51 pm

Glad it's been identified, must be a relief. I think the reality is most places now employ fitters rather than mechanics who are capable of diagnosing faults without a computer.

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