[BMWerkeUSA]

Originally Posted by Owen81

From what I've read, NOx generation takes very high temperatures 2800°F+ so it can't be generated inside the SCR cat. Reading through the FUNCTIONAL DOCUMENTATION, it looks like you could be experiencing "ammonia slip": Page 77. This is from over injection of Urea which would agree with your findings of urea in the tail pipes.

The urea injection is PWM controlled and depends on many factors including urea line pressure and cat temperature. I assume you have good pressure if it is over injecting, and your cat temps are over 200°C so that is good. The other factors that could be off would be the PWM control, sticking/leaking metering valve or another parameter in the process that is requesting additional injection.

I am also reaching to the conclusion that I have a "ammonia slip" problem but the question is: is it due to too much urea being injected or is it due to a non-working SCR catalytic converter?

This question is stemming from the fact that when I measure the temperature before and after the SCR catalytic converter, I always find that it is cooler after the CAT whereas I read that due to the chemical reactions taking place inside the CAT, the downstream temperature should be higher especially for diesel vehicles since the reaction in the SCR Catalytic converter is exothermic in nature.

[robnitro]

There's also a vortex metal piece downstream of the injector that might be improperly mixing the exhaust and urea. You can get to it by undoing the bolts joining the exhaust pipes downstream from the nozzle.

The temperature after the cat will be cooler if you are spraying too much urea. I'm not sure what is normal though.

[BMWerkeUSA]

Originally Posted by robnitro

There's also a vortex metal piece downstream of the injector that might be improperly mixing the exhaust and urea. You can get to it by undoing the bolts joining the exhaust pipes downstream from the nozzle.

The temperature after the cat will be cooler if you are spraying too much urea. I'm not sure what is normal though.

I saw that when I was replacing the CAT but I did not inspect it. I will take a closer look at it to make sure it is not clogged.

[Yozh]

It will not be clogged. But could be installed backwards and may prevent proper urea mixing with airstream. Other item to examine is the EGR functioning.

[Owen81]

I would gut the SCR, sell your brand new sensors and metering valves then tune out the SCR completely. This will get you a nice bump in power, no more SCR issues and I don't know for sure, but I assume OBD readiness for emissions wouldn't be a problem with this setup either.

[BMWerkeUSA]

Originally Posted by Yozh

It will not be clogged. But could be installed backwards and may prevent proper urea mixing with airstream. Other item to examine is the EGR functioning.

I ran the EGR valve test in ISTA. Here are two videos showing the opening/closing of the valve as well as the theoretical versus actual performance of valve opening/closing. Does it look normal?

BTW, the valve moves freely and smoothly by hand while the car is off.

[robnitro]

You can hear the pitch change when it opens/closes, which means it's working fine. At the end was that slowdown when it was testing the throttle valve? If so your throttle works too.

[BMWerkeUSA]

Originally Posted by robnitro

You can hear the pitch change when it opens/closes, which means it's working fine. At the end was that slowdown when it was testing the throttle valve? If so your throttle works too.

Yes. At the end, the throttle valve moved towards the engine and then moved back slowly where it sits when the engine is off.

[BMWerkeUSA]

If the EGR valve is functioning correctly, what does the following code mean?

40D4 (EGR controller position control)

The above code is stored in the fault memory along with 46F2 and 4BDA.

[robnitro]

When did the codes pop up?

I'm not sure of the ista egr test either... What did it say to do and to look for?
I'd think it would check the mass airflow changing, which is what we hear when the pitch changes.

[BMWerkeUSA]

Originally Posted by robnitro

When did the codes pop up?

I'm not sure of the ista egr test either... What did it say to do and to look for?
I'd think it would check the mass airflow changing, which is what we hear when the pitch changes.

They came up during the SCR functional check.
When I go to EGR test, is says the following:
At least one of the following fault codes is stored
-40D4
-40E9

The EGR valve was occasionally detected as being stiff.
Check ease of movement of EGR valve, clean and grease if necessary, see document.

Then check if valve moves smoothly. Use the function test in the test module for this purpose.

At the end of the EGR test it says:
Possible causes of fault if setpoint values are not reached:
-Lines/plug connections defective
-Exhaust gas recirculation valve faulty/jammed

[robnitro]

Maybe carbon makes it stick at times but your test video showed it moving well.

[BMWerkeUSA]

Originally Posted by robnitro

Maybe carbon makes it stick at times but your test video showed it moving well.

Yeah, I am thinking I need to clean it. It probably won't fix my main issue though with the downstream NOx sensor reading more than the one upstream.

[robnitro]

Yeah that's some weird stuff with the scr injector system. Have you updated the dde with ista-p? Latest is sometime in 2017 last I remember. You can also do it with winkfp but I used ista-p.

[BMWerkeUSA]

Originally Posted by robnitro

Yeah that's some weird stuff with the scr injector system. Have you updated the dde with ista-p? Latest is sometime in 2017 last I remember. You can also do it with winkfp but I used ista-p.

No I did not update the DDE yet.
BTW, the dealer paperwork stated that the NOx sensors that were on the car were older versions. They replaced them with never NOx sensors. I wonder if a DDE update can help with that?

I have winkfp but I do not have ISTA-P. Did you use a DCAN or an ICOM cable?
Do you know of a DIY for updating the DDE using ISTA-P?

[robnitro]

I used dcan, the longest update was cic. Make sure your battery charger can keep voltage above 13v.
Ista-p is easy, get it from cartechnology.co.uk free register to get links. Ista-p loader has an option for expert mode where you can choose which module to flash. I just did them all, with failure on one or two modules because I wasn't using icom with fiber.

I'm not sure how to do dde with winkfp, but if you find what files you need, I can grab them from my ista-p install.

[BMWerkeUSA]

Originally Posted by robnitro

I used dcan, the longest update was cic. Make sure your battery charger can keep voltage above 13v.
Ista-p is easy, get it from cartechnology.co.uk free register to get links. Ista-p loader has an option for expert mode where you can choose which module to flash. I just did them all, with failure on one or two modules because I wasn't using icom with fiber.

I'm not sure how to do dde with winkfp, but if you find what files you need, I can grab them from my ista-p install.

Thanks! I will give it a try once I install ISTA-P.

[robnitro]

You don't need the sdp files, which are huge and for F series cars.

[BMWerkeUSA]

Originally Posted by robnitro

You don't need the sdp files, which are huge and for F series cars.

Thank you! That should save me time.

[wardvette]

Did you figure out the issue? My downstream is reading higher than upstream also.

[BMWerkeUSA]

Originally Posted by wardvette

Did you figure out the issue? My downstream is reading higher than upstream also.

Unfortunately, I was not able to figure it out and so I decided to get a tune with the stock hardware with SCR off. I am going with DUDMD Stage 1. In fact, I shipped the DDE today. I will post an update once it comes back.

BTW, I updated all the modules including the DDE to the latest software but it did not make any difference.

Do you have a "no start in X-miles" message?

[wardvette]

Originally Posted by BMWerkeUSA

Unfortunately, I was not able to figure it out and so I decided to get a tune with the stock hardware with SCR off. I am going with DUDMD Stage 1. In fact, I shipped the DDE today. I will post an update once it comes back.

BTW, I updated all the modules including the DDE to the latest software but it did not make any difference.

Do you have a "no start in X-miles" message?

No I dont have the countdown but I do have a rear nox sensor plausibility code and a code related to scr efficiency. I can clear them and the nox sensor code comes back immediately, even before starting it. The other code hasn't returned yet.