E61 mpg /emissins problem!

richfive
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E61 mpg /emissins problem!

Post by richfive » 08 Aug 2015, 10:51

My car was in the garage yesterday to try and fix an ongoing problem with poor mpg, and emissions messages. Both these occurred following a new starter motor being fitted a few months ago. The mpg dropped significantly - clearly as a result of the starter being fitted.

My indy has now replaced the pressure converter valve for the EGR valve, which I had hoped would cure the mpg issue. They told me that the EGR diagnostic messages had now gone, but that there was a remaining message relating to the throttle valve. They suggested that this needed replacing.

Despite lots of research, I cannot find much information about the throttle valve, so I am not too clear on what its actual purpose is, and how it would affect the cars running / mpg / etc if it was faulty. I( suppose it is possible that it was the throttle valve that was damaged during the starter fitment - but what does it actually do?

Needless to say on the drive back from the garage last night, the mpg hasn't altered at all, so replacing the pressure converter was not the answer. The throttle valve is easy enough to replace, and is apparently "plug and play" - no coding required (for a change) so I could fit that myself, but as most things BMW, it isn't a cheap part, even buying it from a Factor, so I don't want to chuck more money at the car, unless I can be sure it will make a difference, and fix the problem. The indy said that the throttle was mainly concerned with the DSC, if that's all it does, I shant bother replacing it!

Anyone know the answer??
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Re: E61 mpg /emissins problem!

Post by lizzie » 09 Aug 2015, 08:11

Unfortunately not something I can help you with but I'm sure someone with more knowledge will be along to help you out.


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FAB_BMW
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Re: E61 mpg /emissins problem!

Post by FAB_BMW » 09 Aug 2015, 08:55

Is the car a diesel? If so think I might have the answer to your problem.

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Re: E61 mpg /emissins problem!

Post by M60NJP » 09 Aug 2015, 08:59

FAB_BMW wrote:Is the car a diesel? If so think I might have the answer to your problem.
E61 530D.........

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E61 mpg /emissins problem!

Post by FAB_BMW » 09 Aug 2015, 09:08

Good good, that makes life easier. Diesels don't have conventional throttles like a petrol engine, there is no need for them. This is where the idea of a throttle valve actuator comes in, it is needed for 2 reasons on modern diesels one is not overly important, it's to gently wind down the engine on shut off so it doesn't shake the car to pieces when the ignition shuts off. But the second is very important, it helps the car with its DPF regeneration, but creating a metered airflow restriction to make the lean conditions needed to force a DPF regen. If this is not happening the DPF will become clogged leading to poor emission results, and poor mpg. The valves are quite delicate given the fact they run on cogs, so a slight knock could do it, or they can be coked up, which would tie in with your EGR message. I would say the whole intake system(Intake manifold, EGR) needs a good clean, there are plenty DIY guides online, and then the throttle valve actuator needs replacing. Then go for a good drive on the motorway in a low gear to force a DPF regen, then I reckon you'll be ok.

richfive
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Re: E61 mpg /emissins problem!

Post by richfive » 09 Aug 2015, 11:23

Thanks for that detailed reply - all interesting stuff! My car does seem to regen as per normal however, no different to pre - new starter I would say. The one thing when the starter was changed - was that the mpg changed straight away - it didn't gradually change over a week or so, in which case I wouldn't have thought the DPF was getting blocked.

I think it may be a good idea for me to take the throttle valve off the car, and check it very carefully, give it a clean, and also the EGR valve too if necessary - that was new last summer, so shouldn't be too bad. I saw a post on youtube showing the innards of the valve mechanism, although it didn't show details of how to remove the cover to get at it - I will have to investigate that!!

If the throttle valve is clean, and the mechanism is free to operate over the limits of its travel, and is suitably lubricated - surely this will return the valve to normal working ? The odd thing about all of the problem, is that the performance has been fine all along - not that I drive particularly fast normally - just nice to know the power is there for overtaking when needed, or shock the odd boy racer!!
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Re: E61 mpg /emissins problem!

Post by FAB_BMW » 09 Aug 2015, 11:29

If the DPF is regenerating ok, then I do wonder if maybe you have an unmetered airleak somewhere. Might be worth checking the intake pipes for damage or signs of perishing.

richfive
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Re: E61 mpg /emissins problem!

Post by richfive » 09 Aug 2015, 12:48

I have already had a quick look at the intake hoses, and not found anything amiss - but I take your point - I will have a detailed look with a torch and a mirror to be certain.

It really is annoying that this has happened - it was fine before they messed around with the starter........ :-(
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Re: E61 mpg /emissins problem!

Post by FAB_BMW » 09 Aug 2015, 12:54

Yea I can't see that the starter would have any effect whatsoever on the running of the car. It sounds more like something has been damaged that has been removed in order to get to the starter. Where abouts are you based?

richfive
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Re: E61 mpg /emissins problem!

Post by richfive » 09 Aug 2015, 17:23

Nowhere near you I am afraid - we are near Axminster in Devon!

Yes I agree totally about damage - the problem is what!! I have replaced the vacuum hoses, and now the pressure converter, I checked the intercooler hoses this afternoon - all seemed sound, and I looked at the throttle valve - a bit oily, but no soot, and the throttle plate moves easily from shut to wide open. I was intending to look at the mechanism too - but gave up on getting the cover off in case I damaged it - it looks like the flange would have to be eased all the way around to be able to get it off.

I did wonder about the boost pressure sensor at the rear of the manifold, but you have to take off the pollen filterhousings and other bits off to get at it!
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