[fortythirtyfive]

So I run MHD with a catless dp, however the CEL is starting to get a lot of attention by passengers in my car.

So I’ve decided to do something about it, I know bm3 has catalytic monitor options to disable it, however MHD don’t seem to have added this.. is there a way I can achieve this by coding instead?

[Munchi435i]

Originally Posted by producerlawson

So I run MHD with a catless dp, however the CEL is starting to get a lot of attention by passengers in my car.

So I’ve decided to do something about it, I know bm3 has catalytic monitor options to disable it, however MHD don’t seem to have added this.. is there a way I can achieve this by coding instead?

If your check engine light is on and you have a catless or upgraded down pipe, then you have e another issue. By default MHD will not trigger a CEL for upgraded DP.

[mcintoshf30]

Originally Posted by Munchi435i

If your check engine light is on and you have a catless or upgraded down pipe, then you have e another issue. By default MHD will not trigger a CEL for upgraded DP.

Tbh I don't think this is true at all. I'm running stage 2 and still get my CEL every few hundred miles but I just clear it with Bimmerlink. It's usually just 1-3 delayed catalyst code and as soon as I clear it the CEL goes away and I have no other codes

[Munchi435i]

Originally Posted by mcintoshf30

Tbh I don't think this is true at all. I'm running stage 2 and still get my CEL every few hundred miles but I just clear it with Bimmerlink. It's usually just 1-3 delayed catalyst code and as soon as I clear it the CEL goes away and I have no other codes

I have been catless downpipe for over 10k miles and have never had a CEL for downpipe.

[DreamerJoe]

in MHD before you flash, go into the options. in the options section, where you adjust for burble/performance cooling/top speed limiter/startup roar, there is a box that you can check or uncheck (I forget which) if you have an aftermarket dp. if you already have that box checked and you are getting a CEL, then something else is causing it.

[mcintoshf30]

Ok so it's probably bad O2, likely just tapped it on installation; but my new tune with -29 degrees of timing ain't helping

[fortythirtyfive]

My error code varies, however the most prominent one that shows is Excess Air 128b01 on sensor #1.

I'll try swapping it out for another.

In the meantime can someone explain what unticking the OEM DP option actually does then? MHD have previously posted that this isn't a DP fix to remove the CEL, as far as I was aware it just makes sure catalytic efficiency codes don't get disabled

[ronanz]

Originally Posted by producerlawson

So I run MHD with a catless dp, however the CEL is starting to get a lot of attention by passengers in my car.

So I’ve decided to do something about it, I know bm3 has catalytic monitor options to disable it, however MHD don’t seem to have added this.. is there a way I can achieve this by coding instead?

Are you running ethanol? Mixture too lean code??

.

[fortythirtyfive]

Originally Posted by ronanz

Are you running ethanol? Mixture too lean code??

.

Nope, just V-Power from Shell.

The previous garage that originally fitted my dp screwed it up twice, they also managed to crush sensor 2 some how during removal. That was fixed after I made them replace it.. maybe they screwed up sensor 1 as well?

[thejeremyman9]

Originally Posted by producerlawson

My error code varies, however the most prominent one that shows is Excess Air 128b01 on sensor #1.

I'll try swapping it out for another.

In the meantime can someone explain what unticking the OEM DP option actually does then? MHD have previously posted that this isn't a DP fix to remove the CEL, as far as I was aware it just makes sure catalytic efficiency codes don't get disabled

I think you are getting confused between a "DP fix" and just removing the codes/CEL that are triggered by a catless DP. The MHD and BM3 flash options remove the CEL that is typically triggered by a catless downpipe. However, they are not a "fix" in the sense that they will allow your emission monitors to be in ready state. So basically, you will not get a CEL, but your catalyst monitor will still be in not ready state. There is no impact (performance or otherwise) other than not having the CEL show up.

[fortythirtyfive]

So I had bank 1's O2 sensor replaced and everything is now good in terms of the CEL light.

However, the garage (indie) said they had to reset the engine adaptation, now I'm getting a horrific stalling / hesitation when setting off in low gears. Could it just be they've screwed with the MHD map by reseting it via ISTA? I'm going to try reflashing both MHD and my XHP map pretty soon.

[Munchi435i]

Originally Posted by producerlawson

So I had bank 1's O2 sensor replaced and everything is now good in terms of the CEL light.

However, the garage (indie) said they had to reset the engine adaptation, now I'm getting a horrific stalling / hesitation when setting off in low gears. Could it just be they've screwed with the MHD map by reseting it via ISTA? I'm going to try reflashing both MHD and my XHP map pretty soon.

Yes reflash is needed

[fortythirtyfive]

Originally Posted by Munchi435i

Yes reflash is needed

Reflashed MHD, XHP and reset the throttle adaptation just in case via MHD's settings.. everything runs buttery smooth again.

Strangely I feel like I have a fair amount more power too, I presume the faulty o2 sensor was holding things back.

[Munchi435i]

Originally Posted by producerlawson

Reflashed MHD, XHP and reset the throttle adaptation just in case via MHD's settings.. everything runs buttery smooth again.

Strangely I feel like I have a fair amount more power too, I presume the faulty o2 sensor was holding things back.

Absolutely the faulty O2 was giving misinformation to the DME. Enjoy the new found power and post some logs so we can all give more feedback

[fortythirtyfive]

Okay so last night I had the slightest bit of stuttering again setting off from a red light.

About 3 minutes later CEL, so I pulled over to read the code and here's what I'm getting:

128901 - Oxygen sensor before catalytic converter, dynamics: Slow response.
12BD52 - Oxygen sensor before catalytic converter, electrical: Signal line open circuit.

- DME shadow (inactive codes) -
123BD80 - Oxygen sensor before catalytic converter: Multiple fault.


I can't post any logs currently as my MHD license doesn't cover logging and actually, I think it's pretty ridiculous that we have to pay extra just to read the output logs.

Since clearing the CEL I've had nothing, but stuttering and rough idle has gotten worse, especially when the engine is cold.. shifting between first and second when pulling away almost sounds like the car is cutting out. Can anyone recommend what else I should be checking? I did my spark plugs 3.5k miles ago, I went for 97506 and gapped them as per recommendations on here. I'm running Shell V-Power, XHP stage 4 and MHD Stage 2+.

I must admit, apart from the lack of power there were 0 issues before having this replacement O2 sensor

[DreamerJoe]

if all you wanted to do from the start is get rid of your CEL from the catless dp, did you ever try unchecking the "OEM/catted dp" option in the mhd map write options? I have MHD and a catless dp, no CEL with that setting.

[thejeremyman9]

Originally Posted by producerlawson

Okay so last night I had the slightest bit of stuttering again setting off from a red light.

About 3 minutes later CEL, so I pulled over to read the code and here's what I'm getting:

128901 - Oxygen sensor before catalytic converter, dynamics: Slow response.
12BD52 - Oxygen sensor before catalytic converter, electrical: Signal line open circuit.

- DME shadow (inactive codes) -
123BD80 - Oxygen sensor before catalytic converter: Multiple fault.


I can't post any logs currently as my MHD license doesn't cover logging and actually, I think it's pretty ridiculous that we have to pay extra just to read the output logs.

Since clearing the CEL I've had nothing, but stuttering and rough idle has gotten worse, especially when the engine is cold.. shifting between first and second when pulling away almost sounds like the car is cutting out. Can anyone recommend what else I should be checking? I did my spark plugs 3.5k miles ago, I went for 97506 and gapped them as per recommendations on here. I'm running Shell V-Power, XHP stage 4 and MHD Stage 2+.

I must admit, apart from the lack of power there were 0 issues before having this replacement O2 sensor

Did the issues start after changing the plugs? You might need to go back to stock plugs. Some people have issues with the NGKs and/or the smaller gap. I have stock plugs with 45k miles on them (never been changed) and the car runs fine with MHD 2+. Theres really no reason to go to the NGK or gap smaller unless you have issues with stock.

In terms of the O2 codes, i would check the wiring, connection, etc.

[fortythirtyfive]

Originally Posted by DreamerJoe

if all you wanted to do from the start is get rid of your CEL from the catless dp, did you ever try unchecking the "OEM/catted dp" option in the mhd map write options? I have MHD and a catless dp, no CEL with that setting.

Already had that on, I switched that setting across last year when I went catless.

Originally Posted by thejeremyman9

Did the issues start after changing the plugs? You might need to go back to stock plugs. Some people have issues with the NGKs and/or the smaller gap. I have stock plugs with 45k miles on them (never been changed) and the car runs fine with MHD 2+. Theres really no reason to go to the NGK or gap smaller unless you have issues with stock.

In terms of the O2 codes, i would check the wiring, connection, etc.

The plugs seemed fine after doing the service at 60k (it was my first plugs swap for the vehicle) if anything it ran a little smoother. I kept the older ones though which I can always give a try.. I'm still pointing the blame at this newly fitted O2 sensor though, it wasn't brand new but came from a breakers yard with a supposed 20k miles on it, it was pretty cheap too so I'm not really out of pocket.

The only reason for suspecting the O2 sensor is that I have had the slow response code, after doing some digging around I found this:

Rough engine idle and misfires
As your oxygen sensor is going bad you may notice your vehicle is running rough, misfiring or running irregularly while idling. You may also observe other engine performance problems, such as loss of power, hesitation, or stalling.

it seems to tick all of the boxes for issues I am having

[fortythirtyfive]

Update..

Finally got chance to strip the underplate off.. it looks like the garage that initially installed it for me (who I've not used since for various reasons) installed a right angle spacer on Bank #1's O2 sensor, presumably to stop it rattling against the steering column as there's no room.

Looks like I'll need a new downpipe then with better spacing ��

[thejeremyman9]

Originally Posted by producerlawson

Update..

Finally got chance to strip the underplate off.. it looks like the garage that initially installed it for me (who I've not used since for various reasons) installed a right angle spacer on Bank #1's O2 sensor, presumably to stop it rattling against the steering column as there's no room.

Looks like I'll need a new downpipe then with better spacing ��

To clarify, you mean the primary, upstream (closest to turbo) O2 sensor, right? I have never heard of a DP having fitment issues with the first O2 sensor, only the secondary, when the bung placement doesn't give enough wire length...

In any case, having that spacer can definitely lead to the slow response code and odd behavior since the O2 is not actually in the exhaust stream...

[fortythirtyfive]

Originally Posted by thejeremyman9

To clarify, you mean the primary, upstream (closest to turbo) O2 sensor, right? I have never heard of a DP having fitment issues with the first O2 sensor, only the secondary, when the bung placement doesn't give enough wire length...

In any case, having that spacer can definitely lead to the slow response code and odd behavior since the O2 is not actually in the exhaust stream...

Correct, the very first sensor from the turbo side.

The fitment issue is that the threaded O2 hole isn't angled enough away, therefore when you place your O2 sensor in, it angles it enough to cause steering column conflicts, it basically rests against it.

The make of my current downpipe is MTC Motorsport, although it sounds like I somehow received one of the older batches as this doesn't appear to be an issue anymore on them. I believe they're also a very similar product to the Scorpion Decat downpipe available on the market over here.