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Discussion Starter · #1 · (Edited)
Hi Guys im still chasing this strong hesitation and lack of power issue below 2500rpm and its worse when the engine is cold. I had to get my turbo reconditioned 2 months ago and the car has never been the same after fitting the reconditioned turbo. I have exhaustively researched this issue and i have done so many test and checks and i am now certain the EGR valve is not being operated by the pressure converter.

I did an Air-mass test using ISTA and it suggested there is a problem with my EGR valve, see pic below.

I did the pneumatic EGR test in ISTA see pic below, it 'activates the EGR valve' and the other one is to 'measure vacuum'. Both of these tests made the engine stall for some reason.

Codes - Occasionally I get 4D03 exhaust backpressure sensor and 419B ambient pressure sensor. I dont know if these are related to the problem or not. I get these codes occasionally and not constantly.

Using a vacuum gauge the EGR is holding the vacuum ok so im assuming its ok. Its also already been cleaned and it was only lightly sooty.

There was no vacuum coming from the old pressure converter so i assumed it was faulty. After replacing it the new Pierburg one it has made no difference at all. With the engine running It has power going to it and the vacuum feed hose is fine tested ok too using the vacuum gauge. So for some reason my pressure converter is not being operated in order to operate the EGR valve.


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So you have vac to pressure converter and you have power to it but do you have a ground to it? Not sure if dde switches live or earth to command operation. However I suspect the root cause is something else and that is causing dde to inhibit egr.

have you checked the map sensor? My e90 had egr issues that turned out to be a blocked map,good clean and all was well again
 

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Discussion Starter · #3 ·
So you have vac to pressure converter and you have power to it but do you have a ground to it? Not sure if dde switches live or earth to command operation. However I suspect the root cause is something else and that is causing dde to inhibit egr.

have you checked the map sensor? My e90 had egr issues that turned out to be a blocked map,good clean and all was well again
Many thanks for your reply. I did not check the ground terminal, do i just check its continuity on an earth point?

I have replaced the map as well as the pressure converter and the map sensor was from the bmw dealer. I have cleaned the MAF sensor, cleaned EGR valve, back pressure tests are passed ok and suggest its not the DPF.
 

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Exhaust Pressure sensor,quick fix 5 mins. get a good one from Autodoc germany.
(had the same symtoms as yours)
 

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I did not even have a specific code for the exhaust pressure sensor .
The main code I had was for EGR despite the fact it bench tested ok.
To be precise I actually replaced EGR and solenoid/pressure converter plus inlet manifold boost pressure and exhaust pressure sensor on top of Cat/dpf.
All these components interact and can lead you down a blind alley.
My suggestion as stated previously is to replace the exhaust pressure sensor and see if this does the trick.
Clear all fault codes before you replace and allow to idle for 5 mins for the system to re learn.
Many will insist you reset adaptions which you may try if you wish but I have found from experience that the ecu/dde
will re learn over a period of time in any case.
 

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Discussion Starter · #7 ·
I did not even have a specific code for the exhaust pressure sensor .
The main code I had was for EGR despite the fact it bench tested ok.
To be precise I actually replaced EGR and solenoid/pressure converter plus inlet manifold boost pressure and exhaust pressure sensor on top of Cat/dpf.
All these components interact and can lead you down a blind alley.
My suggestion as stated previously is to replace the exhaust pressure sensor and see if this does the trick.
Clear all fault codes before you replace and allow to idle for 5 mins for the system to re learn.
Many will insist you reset adaptions which you may try if you wish but I have found from experience that the ecu/dde
will re learn over a period of time in any case.
Thanks for your reply. Do you think this exhaust pressure sensor could be responsible for my new pressure converter not operating?

Thanks for all the information. I can see its very challenging finding the actual fault as some sensors seem to give you a false lead.
 

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Thats a distinct possibility especially since it raised the fault code 4D03.
It took me a long time to pin down an almost identical fault to yours especially after putting the car in to a(so called) independent BMW specialist who had the car for a couple of weeks only to fail in finding the fault.
Only reason put car into him was lack of garage at present and bad weather.
The car should run ok without egr working but air mass readings will be high.
Have you manually applied vacuum to the egr to ascertain it opens ok.?
I believe the hesitation below 2500 rpm is caused by lack of egr function.
It seems unusual that the vacuum solenoid is not receiving a signal from the DDE .
Since you done a test of egr solenoid with ista you can assume all is ok there.
This is sounding remakably like a sticking or malfunctioning egr valve.
Test egr as above.
Applying full constant vac to egr will stall an engine,I believe it normally only receives pulsed vac at low engine speed
opening and closing rapidly.
 

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Discussion Starter · #9 ·
Thats a distinct possibility especially since it raised the fault code 4D03.
It took me a long time to pin down an almost identical fault to yours especially after putting the car in to a(so called) independent BMW specialist who had the car for a couple of weeks only to fail in finding the fault.
Only reason put car into him was lack of garage at present and bad weather.
The car should run ok without egr working but air mass readings will be high.
Have you manually applied vacuum to the egr to ascertain it opens ok.?
I believe the hesitation below 2500 rpm is caused by lack of egr function.
It seems unusual that the vacuum solenoid is not receiving a signal from the DDE .
Since you done a test of egr solenoid with ista you can assume all is ok there.
This is sounding remakably like a sticking or malfunctioning egr valve.
Test egr as above.
Applying full constant vac to egr will stall an engine,I believe it normally only receives pulsed vac at low engine speed
opening and closing rapidly.
Thanks for all the info. As you just mentioned i have already run the car with the egr disabled via a blocked vacuum hose, It goes a lot smoother like that. As you say it definitely seems like the egr valve is causing the problem.

Im not an expert on air mass readings but they seem ok at 780rpm about 12g/s however at 4000rpm they are 120g/s, i read they should be about 5 times your idle speed at 4000rpm but i can guarantee that information. See video below.

I removed the egr valve many weeks ago to clean it, it was lightly sooty and the spring was very stiff indeed, i gave it a spray with a penetrating spray. When i had it out however i did not check to see if the vacuum would move it or not but i should check that anyway to prove its functionality either way.

Yes it does seem like the pressure converter is not getting a signal from the DDE for some reason.

As i mentioned before the air mass system test tells me the egr valve is faulty, when i do the tests for the pneumatic egr valve the engine stalls. See 2 videos below doing the 2 tests. One of the tests asks you to attached your vacuum gauge to take a reading, it stalls too.



 

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The engine will run smooth /smoother with egr vacuum hose plugged disabling the egr.
You will however experience hesitancy around 2000 rpm.
If you operate the egr by means of a vacuum pump on tickover this Will stall engine,this is normal due to excess exhaust gasses entering the inlet manifold.
This does not indicate any specific fault.

At risk of repeating myself.
You have a specific code for the exhaust pressure sensor.
Delete fault codes.Replace this sensor.
Check running and codes from this point.
 

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Discussion Starter · #11 ·
The engine will run smooth /smoother with egr vacuum hose plugged disabling the egr.
You will however experience hesitancy around 2000 rpm.
If you operate the egr by means of a vacuum pump on tickover this Will stall engine,this is normal due to excess exhaust gasses entering the inlet manifold.
This does not indicate any specific fault.

At risk of repeating myself.
You have a specific code for the exhaust pressure sensor.
Delete fault codes.Replace this sensor.
Check running and codes from this point.
Hi mate many thanks for your reply.

If i disable the egr it behave just like you describe. I tested the egr valve today using my vacuum gauge and the engine did cut out so that proves that the egr valve is opening ok. What make of exhaust pressure sensor do you recommend? I dont want to buy cheap rubbish but i also dont want to pay over the odds if i dont need to.

I did an ABL procedure on the backpressure sensor and the values all seem to be ok this is with the engine off. It looks like there is some values or conditions that are not being met somewhere and that in turn is causing the DDE to disable the egr valve function. I will replace the exhaust pressure sensor like you suggest and see if that helps the situation.

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I can recommend a Ridex exhaust pressure sensor from https://www.buycarparts.co.uk/
I have purchased this brand from this company.
Although they come from Germany delivery is fairly quick and at least you have a decent (non chinese) product.
Fitting should take 5 mins max.
 

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This is a quality part which I have installed and tested,hope you have a big wallet Rasa ,you are going to need it.
I have owned and repaired BMWs for over 50 years,only idiots pay inflated dealer prices.
 

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Discussion Starter · #16 ·
I can recommend a Ridex exhaust pressure sensor from https://www.buycarparts.co.uk/
I have purchased this brand from this company.
Although they come from Germany delivery is fairly quick and at least you have a decent (non chinese) product.
Fitting should take 5 mins max.
Many thanks for the reply and for the link mate those Ridex sensors have good feedback on the website. I have placed my order so hopefully it will be here soon. I will let you know how i get on.
 

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This is a quality part which I have installed and tested,hope you have a big wallet Rasa ,you are going to need it.
I have owned and repaired BMWs for over 50 years,only idiots pay inflated dealer prices.
seen loads buy wheel/abs/wear sensors,me included,even more with the likes of circoli thermostats,yup bought twice
 

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It doesnt take much to understand the BMW marketing machine.
The mark up on thier original parts is huge.
Obviously if you are wealthy enough to afford a new BMW and parts are required then it makes sense to demand
original .
I would hazard a guess that most users of this forum are not in that category and looking to save money by doing thier own maintenance or at least seeking advice to save being ripped off by unscrupulous garages/main agents.
If the majority of owners only bought original/main dealer parts then there wouldnt be such a massive aftermarket
supply of them.
If you ignore the snobbery factor of those who drive old BMWs chirping about buying only main dealer parts then the reality of using aftermarket parts is nearer the truth.
Of course we all want quality in our spare parts and I believe this is possible from personal experience.
There is rubbish out there,granted but surely none of us wish to be solely at the mercy of the massive BMW marketeers.
These are great cars for sure and it is good to know there are so many manufacturers making spare parts at reasonable prices helping us keep our chosen cars on the road.
 

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It doesnt take much to understand the BMW marketing machine.
The mark up on thier original parts is huge.
Obviously if you are wealthy enough to afford a new BMW and parts are required then it makes sense to demand
original .
I would hazard a guess that most users of this forum are not in that category and looking to save money by doing thier own maintenance or at least seeking advice to save being ripped off by unscrupulous garages/main agents.
If the majority of owners only bought original/main dealer parts then there wouldnt be such a massive aftermarket
supply of them.
If you ignore the snobbery factor of those who drive old BMWs chirping about buying only main dealer parts then the reality of using aftermarket parts is nearer the truth.
Of course we all want quality in our spare parts and I believe this is possible from personal experience.
There is rubbish out there,granted but surely none of us wish to be solely at the mercy of the massive BMW marketeers.
These are great cars for sure and it is good to know there are so many manufacturers making spare parts at reasonable prices helping us keep our chosen cars on the road.
some parts are just deffo dealers imho,i have and still do buy aftermarket
 

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Discussion Starter · #20 ·
I can recommend a Ridex exhaust pressure sensor from https://www.buycarparts.co.uk/
I have purchased this brand from this company.
Although they come from Germany delivery is fairly quick and at least you have a decent (non chinese) product.
Fitting should take 5 mins max.
Hi mate

I got my sensor fitted today. Im afraid to say that it has not fixed my hesitation and low power issue.

It was still well worth buying though as the code 4D03 has gone and i hope it stays that way. I drove 60 miles today.

I was getting a build up of backpressure and sometimes the code 480A for the DPF would show. I put 2 bottles of Redex dpf cleaner in half a tank of fuel and drove the car for 60 miles with high revs to keep the dpf very hot, i kept forcing regens to keep the dpf temps high, i could monitor this on my bimmerlink app. Once i was finished with my driving, my backpressure tests were much lower and the new sensor and fuel additive and high revved driving has really helped. ;)


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