2016 BMW M4, previous tune, wont pass smog...

[nn7788]

Hey there I am helping a relative with his 2016 BMW M4.

It was sold without the dealer fully going through it because it turns out it had downpipes and tune.

New Cats were put on and a BMW dealer reflashed the computer. But its still is not ready for CA smog. The O2 sensor heater, O2 sensor and Catalyst all remain incomplete.

New O2 sensors have now been replaced with OEM or OE from FCP Euro, but still same problem.

Is there some piggy back thing somewhere that keeps it from having emissions readiness monitors complete?

I have been looking at the downstream O2 sensor voltages to see if I can figure out anything. Also looking at fuel trims.

The car clock keeps getting set back to 24 hr mode, instead of 12 hours mode, which makes me think there is some piggy back thing somewhere resetting something frequently.

Anywhere I should look or something I should test?

Appreciate any help

[krudmunk]

So you have stock downpipes with primary cats on the car now? Is it OEM and stock downpipe? BMW dealer flashed stock tune?

What about secondary cats on the midpipe? There should be primary cats on the downpipes and secondary cats on the midpipe. The midpipe also has resonators.

Also, which O2 sensors are throwing those codes?

[hellokitty]

If there was a piggy back, they likely located it in the DME box near the passenger side firewall. I would start there.

Otherwise, here is the BMW drive cycle to get the emissions sensors ready.

[BoxKing]

Honestly, this doesn't seem like your problem to fix, but the dealers. go back to where you got the car, and demand they resolve the issue they left you with.

They should fix the issue on their end, and provide you with a free smog inspection for your troubles.

Lastly, the car has to to go the proper driver cycle for all the sensors to reset to "READY" - this could take a day or two pending your driving style for the codes to clear - but like mentioned above, this is something the dealer should correct for you, free of charge (loaner car included). If you want to give it one last crack, look up the drive cycle routine, and follow it to T.

[nn7788]

Thanks all for chiming in.

We have tried to the the drive cycles for several weeks, and daily driving. Scan shows no change to the 3 emissions readiness: O2 sensor, O2 Sensor heater, Catalyst. (old O2's and now with new O2's as well)

The dealer (non-BMW) my relative purchased the M4 from is a distance away, and he is tired of bring the M4 back to them, so I was trying to help. He has already brought it back like twice now, which is like 60+ miles away in traffic one way. He is also mad they sold him a car without going through it and without a smog check.

We know the non-BMW dealer is responsible, and we will attempt to get reimbursed for the O2 sensors of course. We already have a failed smog test sent to the state with "tampered" emissions on it.

I don't want my relative to renege on this M4 though, because I've already serviced a lot on it, like the DCT transmission, and oil, and more. It would be a waste of money, and it runs amazing.

I was thinking maybe it has something to do with the injectors. I know some of the tunes and forums talk about different injectors, and ethanol, and also the air sensors for more boost, etc.

O2 sensors I used from FCP Euro:

Upstream:
https://www.fcpeuro.com/products/bmw...mm-11787848482

https://www.fcpeuro.com/products/bmw...mm-11787848483

Downstream:
https://www.fcpeuro.com/products/bmw...or-bosch-16142

https://www.fcpeuro.com/products/bmw...mm-11787848487

The $1000 cost of the 4x O2 sensors would have probably costed like $2k at the BMW dealer, so the non-BMW dealer that sold the him the M4 would have had to spend more anyway. I was trying to help both my relative from the back and forth and the dealer from exorbitant costs to get this car smog ready. But they do not want us to bring the M4 back to the local BMW dealer because its so expensive, they want the car back to their dealership to look at it, but I doubt they can do anything since they are not a BMW dealer, and since it was heavily modified it will probably need a master BMW tech to figure this out.

But it runs great BTW. Very fast. A little slower now without the tune and downpipes, but still a beast.

It was flashed to stock at a BMW dealer. $750 cost I believe.

It had front downpipes, and now it has new cats from a BMW dealer. $3k cost for these.

I did not know about rear downpipes, but I do think the stock center resonator is still there.

Ill just post a bunch of pictures and see what y'all think.

Also cylinder #2 from the front had oil on the spark plug threads btw.

[krudmunk]

You still have VRSF downpipes. It's a catless downpipe. You need OEM downpipes.

[nn7788]

My bad, these pictures are from before those VRSF were replaced with cats at a BMW Dealer. But ONLY those front cats were done, along with the computer flash. I did the O2 sensors later on as well.

I just wanted to give a visual of everything else.

I will be looking in the passenger side DME box, thank you.

Also the rear O2 sensors will drop down in voltage even with idling and steady speed. They are better now with new O2 sensors, but they still will drop down at constant throttle or idle. I'm not concerned about WOT, but constant throttle. Rear O2 should be constant at about 0.7 volts. Not drop.

I think something is wrong with fuel or air delivery since the Rear O2 sensors will drop in voltage and show a lean condition. I was looking at fuel trims as well, but nothing that out of ordinary ,< +/- 5%.

[nn7788]

I have ISTA if that helps. But they are all new O2 sensors.

[krudmunk]

Try moving bank 2 sensor 1 and sensor 2 place with each other. O2 sensor before the cat and after the cat is probably mixed up. If this fixes it, do the same with bank 1.

Honestly, if you have an ISTA and dealer is involving BMWUSA into it. I'd just let them figure it out. They sold you this car so they should've done the fix before they sold to you. If it takes too long you should get your money back and some additional discount on your next vehicle purchase from them, if you do go that route.

[nn7788]

There's no way sensor 1 and sensor 2 (upstream & downstream) of the same bank are mixed up because they are different types of O2 sensors.

The upstream are AF sensors with a current, while the downstream are the traditional O2 sensors that show a voltage.

All O2 sensors are new right now.

Bank 1 and Bank 2 may be mixed up, possibly the downstream ones. The upstream ones up top I definitely did not mix up since I disconnected 1 at a time and replaced them each. I did look at the realoem.com diagrams.

I will look into the DME box for pig tails and the downstream o2 sensors for mix up.

Thanks

This is a non-BMW dealer so they may not have an applicable M4 going forward to ask for a discount. Also, the problem is that this non-BMW dealer will have to figure something out to get this M4 smog ready, otherwise they are out of $50k. I'm sure they will do everything to get it smog ready and sold to cut their losses, so it might as well be my relative.

The EU6 injector kit on FCP Euro is $550 + tool kit is like $150.

https://www.fcpeuro.com/products/bmw...-13647639994kt

https://www.fcpeuro.com/products/bmw...mover-cta-7658

[krudmunk]

Originally Posted by nn7788

There's no way sensor 1 and sensor 2 (upstream & downstream) of the same bank are mixed up because they are different types of O2 sensors.

The upstream are AF sensors with a current, while the downstream are the traditional O2 sensors that show a voltage.

All O2 sensors are new right now.

Bank 1 and Bank 2 may be mixed up, possibly the downstream ones. The upstream ones up top I definitely did not mix up since I disconnected 1 at a time and replaced them each. I did look at the realoem.com diagrams.

I will look into the DME box for pig tails and the downstream o2 sensors for mix up.

Thanks

This is a non-BMW dealer so they may not have an applicable M4 going forward to ask for a discount. Also, the problem is that this non-BMW dealer will have to figure something out to get this M4 smog ready, otherwise they are out of $50k. I'm sure they will do everything to get it smog ready and sold to cut their losses, so it might as well be my relative.

The EU6 injector kit on FCP Euro is $550 + tool kit is like $150.

https://www.fcpeuro.com/products/bmw...-13647639994kt

https://www.fcpeuro.com/products/bmw...mover-cta-7658

Sorry I meant to say sensor 1 and sensor 2 of the same bank or both banks could be mixed up. Because you're failing the voltage check. Since one bank is longer than other and you have one before and one after the downpipes so any kind of mix up is possible.

Injectors or DME will result in misfire. It's definitely sensor mix up. Or bad O2 sensors

[hC1001]

Hook up Ista and see what its says. It may tell you what your next step should be...

[hellokitty]

You should read this thread. The situation may be applicable to you.

Bootmod3 Flash to stock and other questions https://f80.bimmerpost.com/forums/sh....php?t=1928343

[nn7788]

Thanks for that link. I read the whole thread but that case does not apply to us because we have already had the DME flashed by a BMW dealer, but my emissions readiness monitors are still red/incomplete. see attached pic reposted

[hellokitty]

Originally Posted by nn7788

Thanks for that link. I read the whole thread but that case does not apply to us because we have already had the DME flashed by a BMW dealer, but my emissions readiness monitors are still red/incomplete. see attached pic reposted

Perhaps you could take it back to the dealer and see if they can get the car ready? Dealers are required to get their cars ready for smog as a service. You may have to pay a fee but I would throw it back at the dealer so you don't have to deal with it.

[krudmunk]

I think you also have to drive the car like 100 miles or something for the CEL to go away on its own assuming everything is correct and fully back to stock. Then everything will read complete and ready for SMOG.

[hellokitty]

Originally Posted by krudmunk

I think you also have to drive the car like 100 miles or something for the CEL to go away on its own assuming everything is correct and fully back to stock. Then everything will read complete and ready for SMOG.

This is inaccurate. The dealer was able to get the car ready for smog for me with only 10-15 miles of driving per the procedure above.

[krudmunk]

Originally Posted by hellokitty

This is inaccurate. The dealer was able to get the car ready for smog for me with only 10-15 miles of driving per the procedure above.

I'm pretty sure it takes about 75-100 miles of driving for CEL to go away on its own. I remember this few years ago when I went on stock downpipes and it took a while for CEL to go away.

This is without clearing codes or doing any kind of imitation of certain driving cycles btw

[2sporty]

Originally Posted by krudmunk

I'm pretty sure it takes about 75-100 miles of driving for CEL to go away on its own. I remember this few years ago when I went on stock downpipes and it took a while for CEL to go away.

This is without clearing codes or doing any kind of imitation of certain driving cycles btw

It can take thousands of miles if you're not doing what the drive cycle specifies. I know a guy who sold his car because he couldn't follow directions and do a simple drive cycle that takes 10-15 minutes.

[nn7788]

Thanks for all the help.

I came back to the forum for another car, but thought I would finalize this thread to possibly help a future person.

The dealer ended up NOT successfully flashing the ECU to stock, even though they said they did. The tech must not have understood what was going on.

Finally someone figured it out, and contacted aftermarket tune companies, got the pin and unlocked it.

The original dealer paid for it all to get it smog ready.

Also what clued me into this was that the o2 sensors were not responding like they should, when catalytic exhaust conversion is going on normally.

Thanks again

[Shxyann]

Hey, I'm in a very similar boat to you. Any chance you're willing to help? I'm also in Southern California, didn't buy from dealer but had a car that was previously tuned and on down pipes getting the same 'not ready' signals. Car has been flashed to stock from BM3 with DME locked and stock downpipe was put back on, 120-140 miles driven with proper drive cycle done.