[doughboy]

Calling all Primary CAT Decat 335i's.....

Well, finally the date came for my MOT with Decat DPs.

It failed!! Well, not quite, it was borderline and the MOT guy passed it as he knew me and knew the car was sound.

The problem was yoyoing CO and Lambda.

As he held the revs at 2500ish the CO came down into green (pass), so the Secondary CATs are OK, but then the Lambda went into red (fail).

And Vice versa, if he modulated the revs the CO would go red and then the lambda green. He couldn't get them both green for the required time. (10 secs or so).

We took it for a blast to make sure it was all hot and the problem was the same.

I'm still using the old hardwired BMS DP fix which frigs the post CAT o2 sensors which I suppose will mess with the closed loop lambda control.

Some of you on here (Philtdi) have passed MOTs ok, do you use DP fix or just auto code clear?

[RagingKileak]

Hi mate,

Mine passed (at the BMW dealer) with the AP decat pipes fitted without a problem. Or at least they didn't tell me about a problem anyway!

I use the JB4 autoclear to sort mine out and to be honest, I run with the JB4 off a LOT of the time (if I am cruising or when it is mega cold) and the dash light rarely comes on. It's happened maybe 1-2 times in what will probably be over 40-50 days of driving without the JB4 enabled. By not enabled I mean on map 0, which I understand is a pure passthrough.

The DP fix sounded like a pain to fit as I acquired it after the JB4 itself, so couldn't fit it at the same time. This thread has reminded me I need to sell it really!

Matt

[doughboy]

Hi matt,

I'm sure BMW would have used any reason to give you a stiff one, so it's most likely that yours passed properly.

I kind of steered away from autoclear as I though if it was on map zero (which I put it on when it goes for any garage work or else the OBD port doesn't work) then the emissions light would come on, which is a MOT fail now AFAIK, or at the every least it would raise questions.

But on second thoughts. MOT doesn't use OBD so I could just leave it on map1.

I didn't want to be masking real codes but equally I didn't want the dreaded bong and xmas tree dash lights every damn trip.

I've still not fitted the meth kit which is gathering cobwebs in the barn, so I need to do some JB4 tinkering soon, I'll remove the DP fix and take it back for another MOT emissions test and see if that is any different.....

[RagingKileak]

Hmmm,

I hadn't thought about the OBD being disabled - I didn't even know the JB4 did that... Or are you referring to your own 'disabling' of the OBD port? If that's the case, I had a chuckle explaining to BMW (even drawing them a map) of where I had ran the OBD port too.

Believe it or not? The service girl didn't bat an eyelid, she knew EXACTLY why I had done it. They also applied the so-called 'security update' and left my OBD port relocated as well.

Anyway back on topic...

As I said I rarely get an engine light with the JB4 on map 0 and I really do run it in that state quite a lot of the time. I might try and get a more friendly garage to MOT it next time so that I can ask a few questions about what emissions she blows etc. That won't be until August though so might not help you out much.

If you've put the DP fix on then taking it off should be a breeze at least. Maybe trial it for a bit and see how you find it.... This could be one of those 'car by car' things that someone gets lucky on and someone else doesn't.... I hope when you take the fix off that your's is like mine mate.

Matt

[phil200tdi]

I left it on map 1 with auto clear enabled..

I made sure the car was hot, not warm, hot... So the secondaries were still fully upto temp when they tested the emissions at the end of the test..

[doughboy]

Phil,

He did the emissions first off, I booked a while-you-wait appointment, drove it straight on to the ramp and asked he checked the emissions first.

They often do the emissions last as that covers for a cold car that's been standing around, as it will be warm by the time they've done all the other checks with it running.

Like I said, the CO was coming down, as it does after a few seconds on the fast idle test, but then the Lambda was going out (high, weak)

This shows the secondary CATs are sufficient to pass the CO test, but some other issue is losing control of the Lambda (fuel / air ratio) making it read weak.

I can only suspect the old DP fix is somehow messing it up OR I may have a dodgy pre-cat Lambda sensor OR an air leak in the exhaust somewhere OR a partial misfire which can all give high lambda....

The MOT test is done at the tailpipe of course, so any air leak in the entire system will rasie the O2 content and appear that the engine is running weak.

[phil200tdi]

Strange.

Well at least you passed! As he was friendly I guess he jut ignored the catless dp's on visual inspection.

Turn the dp fix off next time, just incase thats the problem. We don't have the readiness check in UK luckily.

[RagingKileak]

With all of the plastic shielding and as far up inside as they are, I doubt even a reasonably knowledgeable mechanic could spot them as cat/decat without a full height ramp and a torch and a few minutes to spare.

I reckoned (gambled on really) that if the midsection cats were there, that BMW wouldn't check the downpipes and I was either right, or (as per the above about emissions) someone inside BMW was working on my side without me knowing it!!!

Matt

[doughboy]

Originally Posted by phil200tdi

Strange.

Well at least you passed! As he was friendly I guess he jut ignored the catless dp's on visual inspection.

He asked if it was de-catted I said they were high flow cats up front and standard secondaries....

But he said he thought they must be Catted DPs else I would have had emissions warnings up

At the end of the day he said if it passes the emissions thats it as far as he's concerned.

[fastloop]

Mine's gone through 3 MOTs so far with catless DPs, but I do worry every time that it will fail. With age the mid-cats may become less efficient, but perhaps doing a number of track days burns off all the crap.

I don't have any numbers from the tests, but I wouldn't mind seeing if it's close or not....

[doughboy]

Originally Posted by 335rocks

Mine's gone through 3 MOTs so far with catless DPs, but I do worry every time that it will fail. With age the mid-cats may become less efficient, but perhaps doing a number of track days burns off all the crap.

I don't have any numbers from the tests, but I wouldn't mind seeing if it's close or not....

Thanks, what did you user for error cancelling, JB4 or DP fix or remap?

Unusually you get the emissions print out with the MOT cert, but this year I didn't obviously....

[fastloop]

Originally Posted by doughboy

Thanks, what did you user for error cancelling, JB4 or DP fix or remap?

Unusually you get the emissions print out with the MOT cert, but this year I didn't obviously....

PROcede with O2 settings set to 50%.

I have never received a print out from the MOT, but I can live with that as long as it passes.

[doughboy]

Thanks guys.

As I know the MOT guy, i'll keep taking it back for re-checks (a pint usually covers ) to see what changes I get.

Order of work:

1) Reset all adaptations including AFR / LSV etc and re-adapt with JB4 on map 0

2) Check all exhaust / DP joints and fit new spark plugs (most common cause of high MOT lambda and it could do with new plugs anyway)

3) Change out hardwired DP fix and use with auto code clear instead

4) Check lambda sensors, any 1 iffy can cause lambda issues

5) scratch head......

[Josh1a1h]

This is a useful thread as mine is coming up.

I guess DP fix is not necessary then.

I will give map1 a go with auto clear and see what happens. I am tempted to try and terra clean my engine before hand too.
It may not help with carbon build up but it has been proven to clean your emissions up significantly within the engine after the fueling.

[phil200tdi]

I'm not sure Terraclean cleans up anything on a Direct Injection engine.

The issue with 335i injectors is due to the piezo crystals and not through clogging. Moreover with our HPFP problems, putting a harse chemical through may cause you more headaches.

I'd leave it...

[ip789]

Hi guys sorry to resurrect a old thread but will be installing some Wagner catless downpipes pretty soon on my n54 335i just wondering if the auto clear function is still available on the jb4 or if I will need a Dp fix also would 02 sensor spacers work?
Thanks in advance for your help

[doughboy]

hi, the JB4 still has autoclear so that is the easiest way to go.

DPfix can be a bit problematic come MOT time.

[Aragorn30d]

This is why JB4 is such a bodge.

The proper solution is to alter the ECU maps so its not looking for cats at all, rather than feeding the ECU with bogus info trying to trick it into thinking they are there and working.

Your lambda shouldnt be bouncing around. With light load it should sit bang on lambda 1.0

[doughboy]

The JB4 is a fine bit of kit in its own way, it's the extra "DPfix" hardware item that BMS made that gives the possible Lambda issues for UK MOT test. The DPfix was an early item since Jb3 days, before CAN bus integration in the JB4.

In any case an ECU map doesn't stop the ECU looking for correct post-CAT readings, that would be unnecessarily complicated, it just blocks the presentation of the fault itself, much like the Jb4 does via CAN bus.

BTW, N54 MOT spec for Lambda is 0.91-1.05, most will sit at .94-5 at fast idle.

[Dopeslope]

Ooh this I hope is good news for me, going catless on my 330i (N53) and using secondarys cut out and flanged from a 335 come MOT time

[Aragorn30d]

Originally Posted by doughboy

The JB4 is a fine bit of kit in its own way, it's the extra "DPfix" hardware item that BMS made that gives the possible Lambda issues for UK MOT test. The DPfix was an early item since Jb3 days, before CAN bus integration in the JB4.

In any case an ECU map doesn't stop the ECU looking for correct post-CAT readings, that would be unnecessarily complicated, it just blocks the presentation of the fault itself, much like the Jb4 does via CAN bus.

BTW, N54 MOT spec for Lambda is 0.91-1.05, most will sit at .94-5 at fast idle.

Well i've never dealt with the 335i ECUs, but the VAG stuff i've played with you do infact just turn it off.

Yes, some people bodge it up and just hide the error classes, but its FAR nicer to properly disable the cat efficiency monitoring. Info is readily available on how to do that on Motronic ME7.5 and MED9. You can even go as far as completely removing the rear O2 sensors from the ECU program.

eg: http://s4wiki.com/wiki/Tuning#Rear_O2_Sensors


335i world seems to me to be full of bodges, not sure why. Perhaps its the lack of info and stagnation of development that happens when everyone just clags on a JB4 rather than properly tuning the ECU.

If people were tuning the ECU's properly they'd have figured all this out.

[doughboy]

Originally Posted by Aragorn30d

335i world seems to me to be full of bodges, not sure why. Perhaps its the lack of info and stagnation of development that happens when everyone just clags on a JB4 rather than properly tuning the ECU.

If people were tuning the ECU's properly they'd have figured all this out.

There's plenty of good BMW ECU tuners. DMS and Evolve in particular.

But I think the JB4 wins fans because it's adjustable / adaptable and removeable by owners at home. My 335i was a beast and I loved the way I could adjust the JB4 for different bolt on mods and control maps via the wheel buttons. No remap does that. I could use it to log fueling, ignition, boost etc etc and discuss these on the JB forum with other users.

IMO the VAG world due to sheers numbers is much more associated with bodge tuners and cheap / nasty low quality remaps created in europe and installed by people who have no clue what they are doing.

A friend of mine had a 3.2 V6 TT mapped, they bricked the ECU and just pushed him into the road and told him to call the AA. Audi replaced the ECU under warranty.

My brother worked technically with Revo and AMD and they were forever fixing VAG cars ruined by crap "remaps" loaded up by "Gazza's Tuning shop" or whatever.