[PCW8256]

Hi, I've had my remapped 2006 325D for about a month now.
When I picked it up, it felt like a powerhouse. The engine was strong and delivered instant power in every gear. Traction control would kick in and cut the power especially in 3rd and 4th.
Now, it seems to have a light hesitation and drop in performance. When I say light, it isn't severe enough to put my finger on what it could be.

It's only done 95K and has a good service history so I am confident that mechanically it's fine. No errors and I have a dyno print which suggests it should be making about 248BHP.

The only way I can describe it is the throttle feels less responsive than the day I got it and the power is less at low revs.

Where do I start or is it all in my head and I have just got used to the car's performance?!

[Andy198712]

can you read the codes? first place to always start

[Silver Streek]

Mine started a slight hesitation especially on small throttle inputs. Traced it to the EGR valve not working smoothly. Mine is also a 325d.

[PCW8256]

Thanks so I've got three glowplug errors. Controller error isn't present.
I've checked the DPF it registers 50g which isn't amazing.
Interestingly Bimmer tools didn't register information on when the car has last regen. Sadly it would not complete regeneration manually despite fulfilling the requirements.
Exhaust flow registers as a high number but doesn't change.
Perhaps I should disconnect the EGR and try that?

[rasa bmw]

check vacuum lines also and coolant temps .shpuld see over 88 degrees and into the 90's

[PCW8256]

I've checked all vacuum lines and it's all fine.
It also appears that the EGR has been mapped out as I disconnected the vacuum line and never had an engine management light come on.
I am also fairly certain the DPF has also been mapped out because the readings for soot/carbon have not moved and the flow rate of the exhaust system switches from 0 to a very high number off the scale every second.

Is there anything else anyone could suggest? The engine seems pretty faultless other than this throttle response thing.

[PCW8256]

So, I got in touch with the tuners who did the car and I finally got a reply.

EGR and DPF are mapped out, so that's two things off the list.

Winter has hit now and I've put up with the problem for months.
MPG has plummeted to only about 25 and performance seems even more hesitant and laggy.
Driving the car feels like effort now rather than enjoyable.

Engine temps reach about 60c but I only drive for about 20 minutes max at the moment sadly. (still I would have expected higher temps)


Has anyone got any ideas? I had thought to take it to be mapped again to see if I can bring more power out of it.

[E60525d]

To clarify, you have mapped DPF out but have you physically removed it?

[PCW8256]

I can only presume it has been removed because it's physically there. It is likely the innards have been removed and you can certainly tell from the exhaust note and the difference in fumes.

You make a valid point though. Is there an easy way to tell? I would have thought a DPF that had been mapped out but not removed would eventually strangle the engine into stopping entirely.

[Tambohamilton]

No easy way to tell that I know of...I think you'll have to disconnect it and look. My suspicion is that it's not been physically removed/modified.

I'd want to have it retuned properly, and map the dpf and egr back in, if the dpf is still present...but that's just me. Bw chiptune seem to have the best rep.

[E60525d]

That's quite a big assumption to make about the DPF has been gutted out.

If it hasn't, then yes eventually you will block the exhaust system and potentially causing serious damage.

Your engine temps also seem low. 20 min drive should get it higher than 60 degrees.

[PCW8256]

Thanks for the quick replies.

I wonder if I could inspect the DPF without the pain of removing it, perhaps using a borescope down a sensor?
It would take a really bad company to remap a car, mapping out the DFP and leave it physically in place surely.
You have certainly made me think though because smoke levels are low too and the exhaust tips aren't that sooty.

I've owned the car over 6 months, I would have surely destroyed it by now if the filter was still in place.


Maybe I need to replace my thermostat then by the sounds of it too.

[PCW8256]

Can I clarify that I purchased the car in this condition, I didn't get these items mapped out.

[Tambohamilton]

The dpf regenerates passively as well as actively. Meaning, exhaust heat from normal driving will also burn off some soot; it doesn't only burn off during active regen (which is what's been mapped out). Hence why you can drive a fair while before it completely clogs. If your exhaust tips are clean, I'd say it's still there.

If you can get a scope down the lambda hole, that should work best. The other sensors are much smaller. You'll either see a honeycomb-ish structure coated in soot, or a big hole through the middle of a honeycomb (if it's been hollowed out).

Yep, I'd replace the main and egr thermostats too, with new OE ones.

[PCW8256]

Very good points thanks, hadn't thought of passive burning of soot.

I will hang my head in shame if I find a filter inside the DPF...(not that I commend the removal of DPF filters).

Watch this space!

[rasa bmw]

get some diagnostic like ista,,then you can see dpf results etc etc

[Tambohamilton]

Originally Posted by PCW8256

Very good points thanks, hadn't thought of passive burning of soot.

I will hang my head in shame if I find a filter inside the DPF...(not that I commend the removal of DPF filters).

Watch this space!

Yeah, +1 on dpf removal not being very clever. It's simply not necessary at these power levels, so long as the engine is running properly.

[dave330]

if it has no dpf filter it will smoke under load.

[PCW8256]

I can confirm the DPF is definitely not in place. I used a scope to pry through the oxygen sensor and the DPF is an empty shell.
You can just about make out where the honeycomb filter sections would have been.

I've also done the thermostat, however I wasn't happy with the quality of the OEM one so I have opted to purchase a genuine BMW model which I will fit shortly.
The temperatures are much better, however the performance side of things have not improved at all. In fact I'd say power down the bottom end has reduced and so has the top end where it feels much flatter!

Further ideas very much appreciated!

[Tambohamilton]

Any change in codes?

[PCW8256]

Hi thanks for getting back to me.

Indeed there are no codes other than the 'normal' Glow Plug errors.

I am using Bimmertool because I've not been able to get Ista and the other tools working. Funnily enough I used to have them working fine on a slightly newer 330d I used to have but I don't seem to be able to use them on this car, it won't connect to any of the modules.

[Tambohamilton]

Try checking your com port settings...I think that is probably the issue. Can't remember exactly how or what to do with it though