MHD single bank fueling: O2 sensor readiness?

n54praiser

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Sep 6, 2022
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Hey guys, a little intro: I've been FBO for a few years and now looking into going ST. Doing some research and got stuck on something that I need to solve before I can even consider going ST.

A recent MHD update allows for single bank fueling meaning only bank 1 O2s can be used and DME can control boost. This is specifically for ST setups. I'm interested in this setup so that I can directly hook up a MAC solenoid to the stock solenoid connector and get boost control via MHD.

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Now what I'm not sure about is if this setup will allow both O2 readiness tests to pass. I need these to pass emissions. On my current setup with the normal O2 config, catless downpipes and a DP fix, I can pass all readiness tests. Knowing this I'm sure the cat readiness should pass but I'm not sure about the O2 ones since obv only bank 1 is now plugged in. Couldn't find anything on this as I assume not a lot of people run this setup.

My questions are:
1. Does the single bank setup still let both of the O2 sensor readiness tests pass with a DP fix?

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2. With the DR700 kit from DOC Race, both O2 sensor bungs are at the end of the downpipe, post cat. Can both bank 1 sensors be mounted there for this setup? Because MHD mentions bank 1 must be installed post-turbo/pre-cat (primary) and post-cat (secondary).

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Pete

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Aug 21, 2023
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To answer your question, "Does the single bank setup still let both of the O2 sensor readiness tests pass with a DP fix?", the answer is no.

I run the single bank fueling on my doc race top mount setup and the monitors for catalyst, oxygen sensor, and o2 heater are permanently incomplete. Somebody correct me if I'm wrong but I believe it is because the code is being auto cleared. If somebody else could reply to this post on how to force the readiness monitors to set, it would help us both.

To answer the question "Can both bank 1 sensors be mounted there for this setup?" the answer is you could, but it is not advisable. I believe the optimal point is about 6 inches post-turbo. The farther away the lambda sensor is from the cylinder head, the more the lambda values will oscillate at low RPM. Maybe you could get away with it because of the log style header on the DR700 kit, but I just welded an o2 bung 6 inches post turbo. You could get 2 NTK 24322 sensors and put them pre-turbo with much better reliability than the bosch sensors, but it does not account for the lambda distortion under boost like the ADV kit does.
 
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n54praiser

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To answer your question, "Does the single bank setup still let both of the O2 sensor readiness tests pass with a DP fix?", the answer is no.

I run the single bank fueling on my doc race top mount setup and the monitors for catalyst, oxygen sensor, and o2 heater are permanently incomplete. Somebody correct me if I'm wrong but I believe it is because the code is being auto cleared. If somebody else could reply to this post on how to force the readiness monitors to set, it would help us both.

To answer the question "Can both bank 1 sensors be mounted there for this setup?" the answer is you could, but it is not advisable. I believe the optimal point is about 6 inches post-turbo. The farther away the lambda sensor is from the cylinder head, the more the lambda values will oscillate at low RPM. Maybe you could get away with it because of the log style header on the DR700 kit, but I just welded an o2 bung 6 inches post turbo. You could get 2 NTK 24322 sensors and put them pre-turbo with much better reliability than the bosch sensors, but it does not account for the lambda distortion under boost like the ADV kit does.
Thanks for your reply. This is what I feared as it'd mean I can't pass emissions with the single bank fueling setup. I read somewhere on here that it's possible to force readiness via a tune but I have no idea who to approach for this. Just to make sure, you're failing the tests without a DP fix?

The part where you mention the NTK sensors, this would be on a "normal" 4 sensor ST setup, right? Shouldn't all tests pass then (with a DP fix) since it's the same as the stock sensor configuration?

Presuming they'll pass in that case, if I can't find a way to force the readiness I'd need to look into other ways to control boost via DME with a 4 sensor setup. I see that Motiv Boost Box was pretty popular but it has apparently been discontinued. Are there any good alternatives?
 
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Pete

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Thanks for your reply. This is what I feared as it'd mean I can't pass emissions with the single bank fueling setup. I read somewhere on here that it's possible to force readiness via a tune but I have no idea who to approach for this. Just to make sure, you're failing the tests without a DP fix?

The part where you mention the NTK sensors, this would be on a "normal" 4 sensor ST setup, right? Shouldn't all tests pass then (with a DP fix) since it's the same as the stock sensor configuration?

Presuming they'll pass in that case, if I can't find a way to force the readiness I'd need to look into other ways to control boost via DME with a 4 sensor setup. I see that Motiv Boost Box was pretty popular but it has apparently been discontinued. Are there any good alternatives?
I am failing the tests without the DP fix, but the DP fix only affects the catalyst monitor, not the oxygen sensor and o2 heater monitors.

I know there is a way to force readiness monitors to set. Jordan did it on my E46 after putting a tune on it, but he will not touch N54 cars.

It is true that all the monitors will pass with the 4 o2 setup with the DP fix.

I do not have any experience with the Motiv boost box, but what you need from it is precisely the function it was designed for. You can still find them used on Facebook marketplace. The Motiv reflex is what I use because I have a port injection setup and I was having problems with the MHD boost control system. You will also find setups with a JB4 and a back end flash. I used to run this setup and I hated it. The car made power very inconsistently, the hardware and software system is very outdated, and it let the car lean over boost without triggering any safeties, costing me a motor.

A GFB GeForce 3 controller is also a popular option on our cars, even though it is not DME controlled. I have no experience with it, but they do say it has over boost and AFR safeties equipped.
 
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n54praiser

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I am failing the tests without the DP fix, but the DP fix only affects the catalyst monitor, not the oxygen sensor and o2 heater monitors.

I know there is a way to force readiness monitors to set. Jordan did it on my E46 after putting a tune on it, but he will not touch N54 cars.

It is true that all the monitors will pass with the 4 o2 setup with the DP fix.

I do not have any experience with the Motiv boost box, but what you need from it is precisely the function it was designed for. You can still find them used on Facebook marketplace. The Motiv reflex is what I use because I have a port injection setup and I was having problems with the MHD boost control system. You will also find setups with a JB4 and a back end flash. I used to run this setup and I hated it. The car made power very inconsistently, the hardware and software system is very outdated, and it let the car lean over boost without triggering any safeties, costing me a motor.

A GFB GeForce 3 controller is also a popular option on our cars, even though it is not DME controlled. I have no experience with it, but they do say it has over boost and AFR safeties equipped.
The Boost Box is indeed exactly what I need as I plan to stay with DI. Sorry to hear about the motor! I tried searching Facebook marketplace but it doesn't seem to let me search in the whole US. Are there by chance any in your area that are for sale? If so, could you PM me?
 
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Pete

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I am too new to this forum to dm lol. I did find one in richardson texas which is nowhere near me. Move your location to there, find it, and message him to see if he will ship it
 

KClemente

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MSD80/81 is much more emissions compliant than E46 MS43's in which a simple set of toggles will force a ready state for the monitors.

We have a lot going under the hood with single bank fueling and as of right now, o2 monitors will not ready up no matter what you try. You will need to rewrite the program section in order to get the monitors to force ready.

You guys are mentioning the motive boost box and issue with o2 sensors simultaneously, the boost box doesn't care about the o2's and the dme can already control a mac solenoid so the boost box will forever be obsolete.
 

Pete

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Aug 21, 2023
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MSD80/81 is much more emissions compliant than E46 MS43's in which a simple set of toggles will force a ready state for the monitors.

We have a lot going under the hood with single bank fueling and as of right now, o2 monitors will not ready up no matter what you try. You will need to rewrite the program section in order to get the monitors to force ready.

You guys are mentioning the motive boost box and issue with o2 sensors simultaneously, the boost box doesn't care about the o2's and the dme can already control a mac solenoid so the boost box will forever be obsolete.
The reason we are talking about the boost box is because to use a mac solenoid through MHD, you have to use single bank fueling. The boost box is an alternative which allows us to not use single bank fueling.
 
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