D3 MT Flat spot at high revs

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TimboD3
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D3 MT Flat spot at high revs

Post by TimboD3 » Wed May 27, 2020 12:24 pm

Hi guys

I have recently bought a manual D3 MT which I am really enjoying but I am experiencing an irritating problem and wondered if anyone could point me in the right direction as to what the problem could be.

Description of the problem:
Flat spots at high revs and surging of revs. The car seems to have one flat spot in gear 2 at around 3.5k rpm and then in gear 3 onwards there are 2 flat spots in that same rev band between 3-4.5k.
It's a strange sensation as when the flat spot occurs acceleration is greatly reduced the car almost feels like its fighting against something.
With regards to the surging (I think it's called surging) I sometimes get a surge of revs if i am in a higher gear and floor it. It almost looks like clutch slip but I am sure the clutch is fine again I'm no expert here.

Info about the car:
The cars done quite a few miles 157k and shes just recently been serviced at a reputable garage with all new filters including a new fuel filter. The dpf was as far as I am aware replaced at around 120k.

The garage i took it too said to me that this could be a dpf related issue so they forced a regen cycle to be done and said the car needed to be taken on a long run at a constant speed to try and clear the dpf which I followed their advice and did but unfortunately the flat spots and surging are still there.

I do not want to insult the garages intelligence i am no mechanic but could this be a different issue I have read on other forums that a Dodgey map/ maf sensor can cause similar symptoms?

Has anyone else had problems like this before on their D3 I know some people have had their Dpf's removed but I am not really game for that.

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Charles
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Re: D3 MT Flat spot at high revs

Post by Charles » Wed May 27, 2020 12:46 pm

My immediate reaction is that this might be a fueling issue - perhaps connected to a dirty/faulty MAF sensor - or it might be related to the turbo.

However, I am not an expert when it comes to the intricacies of the D3 but I am sure someone else will be along shortly to help
Charles
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Re: D3 MT Flat spot at high revs

Post by DonFlintoni » Sat Jun 06, 2020 11:28 pm

Hi Tim

Sounds like its a blocked DPF issue. The engine is retarded by the ECU above a certain speed to minimise the amount of further damage that could be being done to the DPF.

Do you have access to a code reader? It will tell you if youve got a blocked DPF and some of the better ones/BMW INPA will be able to tell you when you last regenerated. Common problems which cause blocked DPF are glow pugs/glow plug relay & thermostat.

Where in the country are you?

also, given how expensive a genuine new DPF is (£1500), id have thought the previous owner would have kept the receipt if the work had been done.......
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TimboD3
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Re: D3 MT Flat spot at high revs

Post by TimboD3 » Tue Jun 09, 2020 9:38 am

Thanks for the replies guys really appreciate it. I live in the uk and I don't have a fault reader :(

I do agree with you I think it could be the DPF. I do have a receipt for the change of DPF but it looks like it was a reconditioned one?

Also since posting this the DPF light has come on. When the light came on the loss of power at higher revs seemed even greater. Upon seeing this the first thing I thought was to take the car on the motorway for about half an hour trying to keep the car at a constant speed at about 2500-3000rpm to try and make the DPF regenerate.

After half an hour on the motorway the light didnt clear which was frustrating. However after leaving the motorway and thinking maybe I should boot it a bit through some country roads in 3rd 4th gear and the light did eventually clear.

The car now seems a fraction more eager now to accelerate from 2000rpm. However the flat spot is still there and it definitely feels like there is still slow down from 3000rpm it feels like my old 318is no torque whatsoever.
:roll:

Forgive my ignorance but when the DPF is partially blocked why does the light not come on? Is light just a late indication that its fully blocked or blocked to a certain percentage?

Anyway I've got to get this sorted as its driving me bonkers.
What are your thoughts on these mobile DPF cleaner specialists?
I have been quoted £200 for a clean that's not removing the dpf. Loads of good reviews online from people but I have never used one before so I don't know what to expect.

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Re: D3 MT Flat spot at high revs

Post by Charles » Tue Jun 09, 2020 10:26 am

I believe DPF regeneration can be compromised by poor/failing glow plugs.

Have you looked at these as a possible problem before having to go for a far more significant strip down and repair/replace?
Charles
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TimboD3
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Re: D3 MT Flat spot at high revs

Post by TimboD3 » Tue Jun 09, 2020 1:29 pm

Charles wrote:
Tue Jun 09, 2020 10:26 am
I believe DPF regeneration can be compromised by poor/failing glow plugs.

Have you looked at these as a possible problem before having to go for a far more significant strip down and repair/replace?
The glow plugs were replaced this time last year according to a receipt I have found from the previous owner what make they are I could not tell you.

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Re: D3 MT Flat spot at high revs

Post by DonFlintoni » Fri Jun 12, 2020 6:15 pm

Plug AND relay? Relay is notorious for failing too.

where in UK are you? I can lend use of a code reader if you are in around Glos/Bristol/S wales.
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TimboD3
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Re: D3 MT Flat spot at high revs

Post by TimboD3 » Fri Jun 12, 2020 8:59 pm

DonFlintoni wrote:
Fri Jun 12, 2020 6:15 pm
Plug AND relay? Relay is notorious for failing too.

where in UK are you? I can lend use of a code reader if you are in around Glos/Bristol/S wales.
Did you mean the glow plug relay? I am based in guildford surrey.

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Re: D3 MT Flat spot at high revs

Post by DonFlintoni » Sat Jun 20, 2020 4:03 pm

yes, glow plug relay.
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Re: D3 MT Flat spot at high revs

Post by bobbly » Tue Jun 23, 2020 9:49 am

Regen relies on correctly functioning thermostats, too (there are two) so these may need checking via a reader, too (operating temperature, not their function: the former is indication of latter). Plus all the stuff mentioned above to get a full regeneration. BMW installed a chronic and complex system on this engine series.

Good luck

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Re: D3 MT Flat spot at high revs

Post by gIzzE » Mon Jun 29, 2020 12:21 am

I just replied on this thread. So much needs to be right for a DPF regen.

https://thealpinaregister.com/forums/vi ... 9&start=15



99% of replaced DPFs didn't need to be replaced. Of course replacing it will buy you another 5000-1000 miles again, but it will just block up if not sorted.

Anyone running a BMW of this age/mileage should have some software to monitor what is going on.

Carly, Bmimmerlink or similar, or even better INPA on a laptop.

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Re: D3 MT Flat spot at high revs

Post by Charles » Mon Jun 29, 2020 10:57 am

gIzzE wrote:
Mon Jun 29, 2020 12:21 am
I just replied on this thread. So much needs to be right for a DPF regen.

https://thealpinaregister.com/forums/vi ... 9&start=15



99% of replaced DPFs didn't need to be replaced. Of course replacing it will buy you another 5000-1000 miles again, but it will just block up if not sorted.

Anyone running a BMW of this age/mileage should have some software to monitor what is going on.

Carly, Bmimmerlink or similar, or even better INPA on a laptop.
Just read the other post and it pulls together pretty much everything that needs to be considered
Charles
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B3S Touring (49/116) - been to the moon and now on the way back!
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TimboD3
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Re: D3 MT Flat spot at high revs

Post by TimboD3 » Thu Jul 16, 2020 10:18 am

gIzzE wrote:
Mon Jun 29, 2020 12:21 am
I just replied on this thread. So much needs to be right for a DPF regen.

https://thealpinaregister.com/forums/vi ... 9&start=15



99% of replaced DPFs didn't need to be replaced. Of course replacing it will buy you another 5000-1000 miles again, but it will just block up if not sorted.

Anyone running a BMW of this age/mileage should have some software to monitor what is going on.

Carly, Bmimmerlink or similar, or even better INPA on a laptop.
Would bimmerlink work on my car its a 57 reg (late 2007 car). It says on their website its only supported on cars 2008 onwards.

TimboD3
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Re: D3 MT Flat spot at high revs

Post by TimboD3 » Thu Jul 23, 2020 1:21 pm

So I have a big update with my car.

I took it to the BMW specialist I use and they had my car for a few days to diagnose what the issue was. They were quick to come back to me that the diagnosis was a result of the car was NOT regenerating the DPF and this was down to a faulty oil pressure sensor. Happy days. :dance

So I Picked the car up and almost immediately noticed the power was back. However I took the revs up in 3rd gear and .... low and behold the flat spots are still there. :evil:

Now that there is more power available it actually feels like there is a loss of boost? It happens for a sudden second then the power comes back and this happens constantly in and out from approximately 3500 rpm to the red line and ONLY happens in 3rd gear onwards. There is no loss of boost in 1st and 2nd gear.

To complicate matters even more the car doesn't always do this I'd say this fault occurs about 70% of the time i drive it.

I purchased an OBD2 reader as advised above to monitor whats going on. I have been using bimmertool and a carista adapter.

According to this app there are no fault codes..
The dpf is showing:
Soot level 8%
Ash mass 7.8g
Soot mass 5.3 g

I have put about 500 miles on the car since it has returned from the garage these involved several long runs. Accoring to this application the DPF has been regenerating in this time. So basically I am beginning to wonder if this loss of boost has anything to do with the dpf at all.

Could this be another sensor playing up? Possibly the MAP or MAF? I don't want to keep replacing parts on a whim.
If either of them were faulty wouldn't this flag an error code up on my OBD2 reader?

One more thing too fuel consumption isn't particularly great either i am getting about 430miles to a full tank and averaging at 36mpg seems difficult to get the car in the mid 40s.

Thanks again for the help :)

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Re: D3 MT Flat spot at high revs

Post by gIzzE » Wed Jul 29, 2020 12:34 am

Can you read the live data on your map sensor?

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