Unable to pass smog inspection in California

[distinctperson]

It's been a very long time since I last posted. Hello everyone.

I will need to pass the smog test for the first time on my Z4 in California ('14 E89 35is), but I no longer have the old parts that would normally be fitted back for the inspection and then taken off again.

The car is MHD Stage 2+ with the usual upgrades. The auto shop is advising me to purchase a genuine cats + core (18-30-7-647-040 or 18-30-7-647-041) which equates to roughly $2.6k to $3k to solve this problem.

Are there alternative solutions here? As far as DP fixes go (and I have no experience here since I've neither researched in-depth (yet), nor even gone to a smog test before ever), the shop is telling me the following:

[There used to be modules that sometimes would work and set the readiness but I have not seen one set readiness codes and in today's day and age they are getting super strict and we have seen people fail smog checks due to aftermarket metal charge pipes. The first link you sent just keeps the Check engine light off but I don’t believe sets readiness monitors. They are now physically checking to be sure the cats are there and they have to write in the numbers that they see.

Also, I would not recommend those adjustable ohm DP fixes as the car uses the oxygen sensors to determine how the car is running and if the catalytic is working. If you install those that car will not truly adjust fuel trims and isn't running 100%.

If we weren’t in California I would say it may work but they are insanely Strict nowadays.]

The modules that I suggested were:
https://e89.zpost.com/forums/showthread.php?t=1768534
https://www.e90post.com/forums/showthread.php?t=1253637


To recap, am I out of luck here being in Cali and have to purchase new cats + core to solve this problem? If not please suggest a solution, otherwise, is anyone selling used ones here?


Thank you for the help!

[MRCW]

How often do you need to get a smog test? Did you just realize you need to get it?

Hate to state the obvious but... what about registering car in a different state... also isn't defeating the emissions illegal? If you want to get help defeating illegal mods to your car, perhaps California is not the place to live...

[smwalker]

So I am assuming you have a tune on it as well?
That will need to come off you know that right?

[Marcoose]

My car hasn’t yet required a smog test for licence renewal. So all this is hearsay.

On another thread, some say you need to remove the mapping modules and drive several miles to reset everything to factory. Some say you can leave the app, but just revert to stock map, and no need to drive the car before the test. Honestly I don’t know.

My car has all stock physical emission parts. I plan on keeping it like that. Since the emission scandal of a few years ago, California became even more strict. I simply just don’t want trouble.

OP, where are you located ?

[distinctperson]

I assumed there would be a straightforward solution to this, given the large number of modders on Cali that no longer own the original parts or simply don't want to fit them back again for a smog test. Perhaps I'm just out of touch here.

I'll just purchase new cats + core and take them off again after testing.

Marcoose, I'm in SF.

[Marcoose]

DP, me too ! Let’s try to meet.

Things I know and hear:

My trusted indy owns a M6, heavily modded, and has all the OE parts for the smog test. Naturally, being a mechanic with his own shop, is easier to swap things back and forth. He says mods are becoming a pain in the arse.

My trusted tuner won’t touch a car or bike unless it’s for track ONLY. He says emissions liabilities can revert back to him.

Obviously owning a MHD’ed bi-turbo I6 makes me the biggest hypocrite ever. But I understand the science of emissions. It’s serious. Unsustainable. I’m not surprised they’re putting you through the wringer. Hopefully you’ll get this sorted out soon.

Let’s try to get together.

[Lurcher]

I'm looking at a set of cats I took off at ~ 20k (2015'ish) sitting in my garage. HMU if interested, as I can't decide if I want to look at them much longer.

[Tangent]

For a legal and sure-thing pass you'll need OEM cats and reflash to stock tune. Those fixes for catless downpipes won't help since you'll still instantly fail the visual check though they might be useful if you decide to install gutted stock cats. Any non-approved (MHD is not approved) aftermarket tune will immediately be detected when they plug it in and will be another instant-fail. Flashing to stock about a week before the test is plenty to run the readiness tests and takes less than half an hour anyway.

[CarAbuser]

There are tuners that can provide custom tunes on the Z4 that will allow all monitors to pass for a decatted vehicle.

That doesn't help with the shop claiming that they visually inspect the cats but I think that's not the norm. Other people in Cali get around the inspection issue is using a tune that lets a catless car complete the readiness checks or just using those dodgy DP fix devices temporarily.

[Tangent]

Originally Posted by CarAbuser

There are tuners that can provide custom tunes on the Z4 that will allow all monitors to pass for a decatted vehicle.

That doesn't help with the shop claiming that they visually inspect the cats but I think that's not the norm. Other people in Cali get around the inspection issue is using a tune that lets a catless car complete the readiness checks or just using those dodgy DP fix devices temporarily.

That doesn't work in California anymore; as of July 2021 they check the DME to make sure it's unaltered. You are allowed to have a factory tune or a CARB approved aftermarket one. (Considering the expense of getting CARB approval I'm not sure any even exist at this time) It doesn't matter if all monitors pass or even if the result is cleaner tailpipe emissions, the computer that they plug in will detect it's not factory or one of the approved ones and will automatically fail you.

[Marcoose]

Bump-oo-roo. My SMOG test is coming up. Checking if anything has changed or folk here have had 'interesting' recent experiences.

The car has a MHD Off-The-Shelf Stage 1 map, and a bespoke xHP map. For peace of mind, I'm going to totally remove the two modules, revert everything to factory stock. Then drive 200 miles, have and a couple of cold starts and a couple of hot starts to reset all parameters and counters.

From your recent experience, is it too much, not enough, what did you have to do to pass the SMOG test ?

Thanks.

[Tangent]

The xHP isn't a problem at all; they don't care what you do with the trans tune and don't even check.

For the MHD, simply flash back to stock (not stage 0, the full long-write back to stock. I used the built-in one, not a backed up one) and go for a few drives. I didn't go nearly as far as 200 miles. I did double check that the monitors had completed though. I passed the test this last September.

Here's the drive cycle guide that I use to get the monitors completed in a minimal amount of time. It's not mandatory but it speeds things up.

1. Cold Start
In order to be classified as a cold start the engine coolant temperature must be below 50ºC (122ºF) and within 6ºC (11ºF) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.

2. Idle
The engine must be run for two and a half minutes with the air conditioner on maximum and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.

3. Accelerate
Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.

4. Hold Steady Speed
Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.

5. Decelerate
Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.

6. Accelerate
Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.

7. Hold Steady Speed
Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.

8. Decelerate
This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.

[Marcoose]

Thank you, Tangent. The SMOG test is not due for 3-4 weeks. If I don't follow your procedure, and rather just drive around, run errands, etc, for the next couple of weeks, will that work ?

Do you have xHP on the car that passed the test in September ?

Thanks again.