325D - Remapped - Hesitation / Drop in performance

0l0dom0l0 · 01-10-2021, 06:52 PM

Did you plug the EGR vac line you unplugged? Or have you plugged that back in now? Don't want any open ended vac lines anywhere!

PCW8256 · 03-14-2021, 11:20 AM

Hi I thought I'd revive this thread again.
I thought I'd cracked it after replacing my thermostat and also cleaning out my boost pressure sensor as suddenly it seemed to be lively again but it's gone back to its hesitation again I'm afraid.

I can confirm egr hose isn't in the open air and is plugged.

Any other ideas?

0l0dom0l0 · 03-14-2021, 04:23 PM

I would replace all vac hoses. Even if they look fine it only takes one frayed end. They are a nightmare and don't last 5 minutes.

PCW8256 · 03-15-2021, 03:06 PM

Quote:

Originally Posted by 0l0dom0l0

I would replace all vac hoses. Even if they look fine it only takes one frayed end. They are a nightmare and don't last 5 minutes.

Does the 325D use vacuum to control anything that could be to do with power out of interest?

Boost is electronically actuated, EGR is disabled. I can't think of other systems that it might affect.

This car really is a head scratcher.

0l0dom0l0 · 03-15-2021, 06:59 PM

Sorry I forgot about the EGR being mapped out.

It's probably still worth doing though but unlikely to be related to your issue.

CarAbuser · 03-22-2021, 07:55 PM

I went through this kind of issue on my old 320d. The only way to pinpoint the issue is to use something like Bimmergeeks ProTool to log the fuel pressure, maf and map along with their target values and see which is failing to meet target.

With a diesel you can get an idea where the fault is by looking in the rear view mirror when flooring it. Too much soot and the problem is a boost leak or poor air metering, no soot and it's probably a lack of fuel which could be caused by a weak fuel pump, bad fuel pressure regulator or bad fuel pressure sensor.

I don't know the full workings of the 325d or their parts prices but on my 320d you could pick up the entire fuel rail with pressure sensor and regulator attached for peanuts from scrappies on eBay so it was almost easier to just replace all the parts than actually doing the data logging.

PCW8256 · 09-09-2021, 02:57 PM

Thanks very much I've only just seen this post, I'll give that a go.
It's really strange that I've still got a problem with it.
For the last week or two it's been really nice to drive and then all of a sudden I start it in the morning and it feels sluggish again.

PCW8256 · 10-24-2021, 06:08 PM

I've finally got round to logging some data. It seems fairly normal on the graph attached but you can see the boost pressure isnt really high enough (though it does seem to hit the expected result at one point) even despite some obvious errors in my logging making the graph a little difficult to read on the climbing stage.

There's a point where its expecting 2400 hPa but only getting 1400 hPa.

What could be causing a lack of boost build up there?
Fuel pressure seems ok?
Air mass looks pretty ok.

CarAbuser · 10-28-2021, 07:10 AM

Boost leak most probably but there's plenty of reasons for pressure to fall off like that.

Check all connections between the turbos and intake manifold.

01-10-2021, 06:52 PM	#23
0l0dom0l0 First Lieutenant 71 Rep 318 Posts Drives: BMW E92 330i Join Date: Jun 2020 Location: Uk iTrader: (0)	Did you plug the EGR vac line you unplugged? Or have you plugged that back in now? Don't want any open ended vac lines anywhere!
	Appreciate 0 Quote

03-14-2021, 11:20 AM	#24
PCW8256 New Member 1 Rep 16 Posts Drives: BMW 325D Join Date: Aug 2020 Location: East Anglia iTrader: (0)	Hi I thought I'd revive this thread again. I thought I'd cracked it after replacing my thermostat and also cleaning out my boost pressure sensor as suddenly it seemed to be lively again but it's gone back to its hesitation again I'm afraid. I can confirm egr hose isn't in the open air and is plugged. Any other ideas?
	Appreciate 0 Quote

03-14-2021, 04:23 PM	#25
0l0dom0l0 First Lieutenant 71 Rep 318 Posts Drives: BMW E92 330i Join Date: Jun 2020 Location: Uk iTrader: (0)	I would replace all vac hoses. Even if they look fine it only takes one frayed end. They are a nightmare and don't last 5 minutes.
	Appreciate 0 Quote

03-15-2021, 06:59 PM	#27
0l0dom0l0 First Lieutenant 71 Rep 318 Posts Drives: BMW E92 330i Join Date: Jun 2020 Location: Uk iTrader: (0)	Sorry I forgot about the EGR being mapped out. It's probably still worth doing though but unlikely to be related to your issue.
	Appreciate 1 ewanc2.50 Quote

03-22-2021, 07:55 PM	#28
CarAbuser Lieutenant Colonel 486 Rep 1,550 Posts Drives: Z4 35i DCT / E92 335i DCT Join Date: Jul 2010 Location: United Kingdom iTrader: (0)	I went through this kind of issue on my old 320d. The only way to pinpoint the issue is to use something like Bimmergeeks ProTool to log the fuel pressure, maf and map along with their target values and see which is failing to meet target. With a diesel you can get an idea where the fault is by looking in the rear view mirror when flooring it. Too much soot and the problem is a boost leak or poor air metering, no soot and it's probably a lack of fuel which could be caused by a weak fuel pump, bad fuel pressure regulator or bad fuel pressure sensor. I don't know the full workings of the 325d or their parts prices but on my 320d you could pick up the entire fuel rail with pressure sensor and regulator attached for peanuts from scrappies on eBay so it was almost easier to just replace all the parts than actually doing the data logging.
	Appreciate 0 Quote

09-09-2021, 02:57 PM	#29
PCW8256 New Member 1 Rep 16 Posts Drives: BMW 325D Join Date: Aug 2020 Location: East Anglia iTrader: (0)	Thanks very much I've only just seen this post, I'll give that a go. It's really strange that I've still got a problem with it. For the last week or two it's been really nice to drive and then all of a sudden I start it in the morning and it feels sluggish again.
	Appreciate 0 Quote

10-24-2021, 06:08 PM	#30
PCW8256 New Member 1 Rep 16 Posts Drives: BMW 325D Join Date: Aug 2020 Location: East Anglia iTrader: (0)	I've finally got round to logging some data. It seems fairly normal on the graph attached but you can see the boost pressure isnt really high enough (though it does seem to hit the expected result at one point) even despite some obvious errors in my logging making the graph a little difficult to read on the climbing stage. There's a point where its expecting 2400 hPa but only getting 1400 hPa. What could be causing a lack of boost build up there? Fuel pressure seems ok? Air mass looks pretty ok. Attached Images
	Appreciate 0 Quote

10-28-2021, 07:10 AM	#31
CarAbuser Lieutenant Colonel 486 Rep 1,550 Posts Drives: Z4 35i DCT / E92 335i DCT Join Date: Jul 2010 Location: United Kingdom iTrader: (0)	Boost leak most probably but there's plenty of reasons for pressure to fall off like that. Check all connections between the turbos and intake manifold.
	Appreciate 0 Quote