Smog Help - Getting Worse After Repairs

[itsmeesc]

Hi all, recently bought a 94 325is from out of state for $1300. Trying to get it to pass smog to get registered in California but each time I’ve tried it has gotten worse. Here’s what’s changed between each:


-1st time: after I bought the car. Tested as I got it. It had just driven from Connecticut to California. Barely fail 15mph HC. https://drive.google.com/file/d/1QGYu_X-hpvnZBuULbLcUAOMl70jt8X9W/view?usp=sharing
https://preview.redd.it/smog-help-getting-after-repairs-v0-nvxxy6z4d4ae1.jpg?width=640&crop=smart&auto=webp&b183ec57


In between 1st and 2nd: replaced spark plugs. Discovered valve cover gasket leak.


-2nd time: day after first (had a free retest). Drove around in the morning to get car up to temp. Only spark plugs had been changed (Bosch OEM). Fail 15mph HC worse. https://drive.google.com/file/d/14nwbe2pZ8-yltNqziyeo_7bCWtDS-Hk6/view?usp=sharing
https://preview.redd.it/smog-help-getting-after-repairs-v0-dwdjm8z4d4ae1.jpg?width=640&crop=smart&auto=webp&a72274e5


In between 2nd and 3rd: car finally throws CEL. Replace o2 sensor (code 1221 then 1222). No CEL since. Replace valve cover gasket. Brakes (not like this will affect anything). Clean MAF with MAF cleaner. Gas mileage increases a good amount. Drive 150ish miles without an issue. Go back to smog (different place).


-3rd time: 10 days after 2nd attempt. All above maintenance done. Car driven to get up to temp. Fail 15mph HC much worse. Fail 25mph HC. NO and CO2 have dropped significantly. https://drive.google.com/file/d/1PKqfprQYAI7olRW5L4nq5GaTlvEznwc8/view?usp=sharing
https://preview.redd.it/smog-help-getting-after-repairs-v0-ymlhm7z4d4ae1.jpg?width=640&crop=smart&auto=webp&38f90cec


I’m really confused how fresh o2 sensor and cleaned MAF didn’t at least improve numbers. All I can think of is a vacuum leak but the car idles with next to no variance at ~500rpm, drives amazing, and pulls well. Any help appreciated before I take to mechanic for a smoke test/diagnosis.


Bought from long time 2nd owner with 160k miles, folder of receipts, and oil changes ever 3k miles since at least the mid 2000s.



https://drive.google.com/file/d/1QGYu_X-hpvnZBuULbLcUAOMl70jt8X9W/view?usp=sharing

[82eye]

smoke test to get rid of any vacuum leaks and consider replacing the cat.

[Eric93se]

Don't replace the cat. Get a set of coils and run a bottle of CRC GTP.

https://www.ebay.com/itm/315186020375

[itsmeesc]

Thank you so much! Will try! What do you think just the CRC GTP would do? I'd rather not replace all the coils for $78/each if possible since the car runs so well already. I was looking to use the car just to beat on for fun and another 600+ is half what I paid for it. Might just sell it out of state again? https://drive.google.com/file/d/1Zh8EFAFRpzlgwYvcpmnmI2tWGG42i372/view?usp=sharing

Also any idea how it got so much worse so fast? I find it so weird how the parts didn't help at all and made it worse.

Edit: $78 for a set of 8? How?

[samy01]

Are you sure that the original factory catalytic converter is installed and not some aftermarket replacement was welded in at some point?

I'm no expert but your CO is also high, I think that means rich mixture in general, or that the cat isn't fully working because it's starting to go out OR it isn't hot enough to work properly. Your 25mph is fine because then there's more gas volume, heating the cat and making it work more.

Did you get the cat as hot as you could by doing high load pulls right before the measurement? You were close the first time, just 3 over.

[gc325is]

The car is 30 years old. There may be more than one thing bad but the OBD I cannot detect them. You say the car is hot but does the DME agree. ICV often are stuck, injector may be leaking. improved gas mileage does not come automatically, something changed. You DME need time to adjust. Intake boots are often cracked in addition to the valve cover or any of the other ~6 hoses or O rings. Was the car smog-ed in the other state? Failing the test is the biggest reason people sold the car in CA especially in the enhanced test limits of LA or they become track cars. OEM plugs? which ones your car may be the ones that only like the copper core.

[Eric93se]

Get the coils and start using the GTP, you should pass.

[itsmeesc]

The car passed in Connecticut where it lived from 1994 til 3 weeks ago. In terms of the car being hot I'm going off the temp gauge after driving it for 30-40 mins before the test around my LA beach town. How long do you think the DME would take to adjust? How would I know which plugs to use? I put these in https://www.pelicanparts.com/More_In...=c&SVSVSI=0129 (https://www.pelicanparts.com/More_Info/12129063428.htm?pn=12-12-9-063-428-M14&bc=c&SVSVSI=0129).If coils and GTP doesn't work I may just sell it in Nevada where someone can register it as a classic.

[Eric93se]

Its going to pass, don't give up so easily. Your only off by a little.

[bluptgm3]

The car passed in Connecticut where it lived from 1994 til 3 weeks ago. In terms of the car being hot I'm going off the temp gauge after driving it for 30-40 mins before the test around my LA beach town. How long do you think the DME would take to adjust? How would I know which plugs to use? I put these in https://www.pelicanparts.com/More_In...=c&SVSVSI=0129 (https://www.pelicanparts.com/More_Info/12129063428.htm?pn=12-12-9-063-428-M14&bc=c&SVSVSI=0129).If coils and GTP doesn't work I may just sell it in Nevada where someone can register it as a classic.

Always use realOEM.com to determine BMW part number requirements including spark plugs. Many aftermarket vendor sites use the BMW part number in reference, to identify replacement parts. I am under the impression that the M/S50 prefer NGK plugs, but perhaps internet lore.
https://uploads.tapatalk-cdn.com/20250101/663db97924ac30a007cb35be96722ad3.jpg



Enter the last seven characters of the VIN in realOEM.com, then look thru the various diagrams.
OBDI does not support adaptations. It works or it does not.

I agree, this sounds like a vacuum leak.

What brand O2 sensor did you use?

The spark plug coil pack extenders 12131730521 (spark plug socket) over time/heat cycles dry, crack, and as result ‘leak’ voltage as they age causing reduced or lack of spark.

[gc325is]

Note Connecticut SMOG is not the same a enhanced CA smog. You have tighter limits to meet that are almost the OEM original levels when new. But if you were close, the variance in the day or engine can cause the problem. The DME has a separate engine temp sensor. Is the charcoal canister doing a purge did the ICV get stuck. The SMOG shops document the attempts you make and after a while you will be sent to a referee station Sounds like you are going to a smog check only shop and not any star station with repair. Note If GTP is STILL ; -) in the tank it will help burn off HCs but that's not written on the instructions

Those plugs look to be the dual tipped plugs which older E36 did not like. Copper core single were preferred.
Bosch FR-7-LDC are duel tips

[Eric93se]

Stick to single electrode spark plugs, platinum or irridium. Those +2 and +4 plugs are known to run a bit cold and foul.


Don't waste your money on coil boots when you can get the whole thing for a couple bucks more. You can hang onto your old coils as a back up, but if you buy that 8 pack you will have two extras. You can inspect your old coils for cracks and black lines, signs of the high voltage shorting to ground. The fine lines look like the roots of a tree spreading out.

- - - Updated - - -

Avoid champion, autolite, moto*.

- - - Updated - - -

Yeah, with the GTP DRIVE the car, hit the on-ramps and romp on it.

[itsmeesc]

I just ordered the coil packs. Planning to try again next week when it gets warmer (71F) and with the GTP. How much of a different do the single plugs make? I can replace them again but it feels like a waste to toss out a brand new set...

Another edit: it seems like my car runs really cold. The temp gauge never sits in the middle. Even after driving it moves slightly to the cold side. Is there any way to keep it warm for the test or is just a weather thing/need to drive it harder before going in?

[Eric93se]

Don't replace the plugs again, they will be fine. Your thermostat could be stuck open.

[bluptgm3]

Don't replace the plugs again, they will be fine. Your thermostat could be stuck open.

+1

[bluptgm3]

.

[itsmeesc]

Amazing. I think it’s stuck open. I drove for an hour on the highway today and the temp gauge was down to the first bar. I’ll get that replaced before I retest. That would explain the unburnt fuel?

[Eric93se]

yeah, its probably why you didn't pass emissions. Be sure to use fresh coolant with distilled water and to fully understand the bleeding process and don't drive the car till the heat works at the feet and the electric fan cycles.

- - - Updated - - -

This is a good time to replace the water pump and the plastic reservoir. Buy Behr/Mahle/Beck arnley, don't cheap out on the reservoir it won't last.

[Thresher]

Sort out your cooling issues first.

Sounds like you drove your car for a bit before getting it smog checked? I took my car in last month for smog inspection. My smog inspection station says the car needs to be hot -- they recommended I drive it for about an hour 30-40 minutes at highway speed and then head straight to their shop for the inspection. Not sure what your smog inspection shop recommends; are they familiar with doing inspections on older BMWs?

[itsmeesc]

I'll do the coolant flush too. I also remembered I have a DINAN chip in the car... do you think that would cause any issues? And in regards to cooling parts, I have receipts for the cooling system (metal thermostat housing, radiator, thermostat, and some cooling lines) from 2013. I'm thinking I should still replace some of it anyways but the lines, thermostat housing, and radiator should all still be good right?

- - - Updated - - -

Going to replace the thermostat and maybe replace the expansion tank (will check if plastic is brittle in the morning). I did drive the car before the tests but I'm thinking the open thermostat allowed it to cool down again before the test. Hopefully that, the new coils, and the GTP fixes it enough.

Another question: 88C or 92C thermostat?

[bluptgm3]

Yes, during warm-up cycle additional fuel is added.
If the engine is not coming to temperature there will be incomplete combustion.

I would run the 92C unless you live in Phoenix, AZ.

The T-Stat you purchase (Wahler) may have an orientation indicator, an up arrow stamped into the body. I don’t know what difference it will make, but install the T-Stat with the indicator ‘up’.
Can be seen in this image.
https://uploads.tapatalk-cdn.com/20250211/7c197c09e10ae8cebd307b45c62acd59.jpg





Only use the Elring Klinger thermostat housing gasket (Orange ‘thingie’)
Do not use a thick rectangular (URO or OE} gasket.
https://uploads.tapatalk-cdn.com/20250105/f7839ad0dd2f6a2f075e1598e93bf30d.jpg

Gasket Discussion (https://www.bimmerforums.com/forum/showthread.php?2424413-Thermostat-housing-recommendation)

[tjm3]

I'll do the coolant flush too. I also remembered I have a DINAN chip in the car... do you think that would cause any issues? And in regards to cooling parts, I have receipts for the cooling system (metal thermostat housing, radiator, thermostat, and some cooling lines) from 2013. I'm thinking I should still replace some of it anyways but the lines, thermostat housing, and radiator should all still be good right?

- - - Updated - - -

Going to replace the thermostat and maybe replace the expansion tank (will check if plastic is brittle in the morning). I did drive the car before the tests but I'm thinking the open thermostat allowed it to cool down again before the test. Hopefully that, the new coils, and the GTP fixes it enough.

Another question: 88C or 92C thermostat?

My 1992 325i Dinan modified always passed with the Dinan chip but I was not in an enhanced area, tailpipe check only, no dyno. Over 200K miles and cat efficiency between 15-20%.

[Eric93se]

At 10yrs the reservoir is done, so that needs replacing. I use an 80c thermo, but thats just me, 88c would be fine too.

[itsmeesc]

Update: HC emissions got even worse after coils, GTP, and thermostat. I’m at a loss for words and just utterly confused.

- - - Updated - - -

Update: HC emissions got even worse after coils, GTP, and thermostat. I’m at a loss for words and just utterly confused.

[Hankdoll]

Sorry to hear. Did you do the CRC GTP yet? I am always on the bubble for high HC. I followed the directions and tested with hot cats. I had the best results in 15 years. It's only a few bucks. Good luck

[Eric93se]

How many miles did you drive with the GTP?? Put more miles on it and drive it a little harder, be sure to use good gas, your supposed to use at least 89aki, but the engine will run better with 91aki. The gtp will take time to burn off carbon. ~200mi

When you get to the inspect shop, keep it idling and while you wait (5-10min) before your turn idle it at 1500rpm.

[gc325is]

Do you want to post the numbers? here are some guidelines on SMOG What is you MPG ?

[itsmeesc]

This is with the CRC GTP. Didn't help and potentially made it worse. Followed all directions.

- - - Updated - - -

https://drive.google.com/file/d/1B86YlIcRlZHGIvLhQPsl73XyAe6xOxEJ/view?usp=sharing
(https://drive.google.com/file/d/1B86YlIcRlZHGIvLhQPsl73XyAe6xOxEJ/view?usp=sharing)
Here are the latest numbers.

I get 28 MPG on the highway and 18-20 in the city

- - - Updated - - -

I drove about 270 miles on the the GTP with 91 octane gas. Mix of highway, city, and spirited driving the past few days. Ran the car for about 2 hours straight (9:30am-11:45am) before the test with 45 mins of that being really hard (3-6k rpm spirited driving in the hills). The car felt great. Thermostat functions flawlessly now (sits at exactly half all the time).

Honestly, I'm at the point where I'm gonna go sell it in Nevada where someone can register as classic/smog exempt. These smog tests, gas for the GTP, and parts keep adding up with a pointless feel with negative improvements. How much would you list a car like this for? I have a bit under 3k in it after all the fees and parts and some extra tools, "meaningless gas", etc. Hoping to break even if possible or trade for something that will pass.

[Eric93se]

Well its up to you, just need to find the cause, if you love the way the car looks you got it for a steal.

So high HC can be rich mixture or lean mixture lol, that helps. The GTP should clean the injectors. Some cars develop a crack in the exhaust manifold and that can allow air to enter the exhaust stream and that will confuse the o2 sensor. One way to test is to put high volume air into the muffler like the exhaust from a canister vacuum cleaner and then make a soapy mix for a squirt bottle and spray the exhaust manifold and check for bubbles. Check your MAFS brand, make sure its oem, Siemens or Bosch.

Your cat should be good because your nox numbers are good. Did you do the first oil change, I know that sounds weird but for some people that makes a huge difference. You should check that the dinan chip doesn't require premium gas. Also check that its not a problem with passing emissions because I'm gonna guess that it will be an issue. How is your low-end power, if it doesn't pull nicely in the lower range then thats a sign that the vanos seals are preventing it from operating.

Also on the earlier e36's the knock sensors are known to crack.

To do better diagnostics you can use INPA software (free, z3 diagnostics thread) and get a USB INPA cable from ebay or Amazon, also needs the 20pin round adapter.

[itsmeesc]

I did the oil change myself the other day. The car pulls nicely (as far as I can tell) but really comes to life at 4k.

Honestly, I'm leaning towards getting rid of it. It's in one of my favorite colors and was one of my favorite cars as a kid (am 20 now), but I don't think I'll have the time or patience to deal with this once I go back to school next week - was hoping it'd pass and I could just enjoy it on the SoCal weekends.

I have 2-3 weeks to decide/make anymore repairs as thats when the title is due to show up.

[itsmeesc]

I did the oil change myself the other day. The car pulls nicely (as far as I can tell) but really comes to life at 4k.

Honestly, I'm leaning towards getting rid of it. It's in one of my favorite colors and was one of my favorite cars as a kid (am 20 now), but I don't think I'll have the time or patience to deal with this once I go back to school next week - was hoping it'd pass and I could just enjoy it on the SoCal weekends.

I have 2-3 weeks to decide/make anymore repairs as thats when the title is due to show up.

[B328iC]

I could be wrong but you say it really pulls above 4k rpm. I have been told that could be an issue with the vanos. Could be the solenoid or the seals might need replacing. That would also explain your low end Hc not getting better but worse.

- - - Updated - - -

[Eric93se]

So from what your saying it doesn't have good low end torque. Vanos seals are a common maintenance item on the e36. The seals and gasket are inexpensive, the job is not difficult but has to be fully understood so no mistakes are made. There are some speicalty tools needed that are now cheap (I made my own they aren't super hi-tech items). There is a guide in the bentley manual (download for free) and there is a guide on the Beisian Systems website. Both should be studied and fully understood. You can buy the seals from ebay or Beisan Systems. They are both fine. The car will make more power doing this job and is considered maintenance.

https://www.ebay.com/itm/233607332375

https://beisansystems.com/single-vanos-6-cyl-e36-e34-e39/

https://www.ebay.com/itm/111598940741

(https://www.ebay.com/itm/111598940741)

- - - Updated - - -

See about reverting your chip back to stock, I'm sure its not going to be cali legal and that could be why its rich.

- - - Updated - - -

Your only 20 and your learning so much about a car your love. If the paint is good and the rust is little, you got the car for a steal. The only way you get an issue free, pristine e36 is if you spend 10x more. There isn't a single e36 on the road that doesn't need some love lol.

- - - Updated - - -

Also you don't need the anti-rattle kit for your vanos if it doesn't make any noise.

[gc325is]

Did the 94 have a VANOS? Can you read the temperature of the CAT both in and the out side with an IR meter. There is a possibility the GTP cleaned the engine but the particles all went into the CAT and now it is dirty. You can try a CAT cleaner. Do you know if it is OEM CAT or a replacement? Then do you see the O2 sensor adjusting from 0.2 to 0.8 V

https://www.aa1car.com/library/o2chart.gif

[Eric93se]

In '92 the M50TU (vanos) was born.

[itsmeesc]

I'm almost positive it's the original CAT.

[itsmeesc]

I'll look into reverting the chip to stock. I'm not sure I'll have time to do the vanos rebuild with engineering school starting Monday.. how much would it cost at a shop? Would also suck to have to replace the valve cover gasket again (assuming it wouldn't reseal even though its 2 weeks old).

Here's the car https://drive.google.com/file/d/1Zh8EFAFRpzlgwYvcpmnmI2tWGG42i372/view?usp=sharing. Has a dent in the trunk and the interior has bad door cards, missing sunroof trim, OBC/cruise doesn't work, and the AC is broken. It's what I wanted (and man that induction noise sounds amazing when it hits 4k) but I'm not sure it's what I need as a college student who wants to camp and haul my road bikes around. I put the e36 on Non Op the other day so I can actually get a title sent to me. May look into a more modern daily. I put the car up for sale and had an offer for a 370whp big turbo mazdaspeed6 trade and another for an 04 volvo v70 wagon. Really considering..

Anyways, thank you for all the advice. I'll have to weigh trying the VANOS rebuild when I have a long weekend, taking to a shop, or trading/selling it once I get the title. I really hate the feeling of just throwing parts at this thing only to get worse results.

[Eric93se]

Don't buy someone else's project car, it won't be reliable. The E36 is reliable once all the bugs are worked out and the cooling system is 100% new and leak free. Never 'limp' home an e36 with a coolant leak it can warp and crack the head very quickly. You can call all your local repair shops but it will be 600+ for vanos job, its not hard to do and yes you can reuse the VC gasket. Did you use a guide to do the VC job? put RTV at all the correct interfaces?

Your e36 is REALLY nice!

Your car is probably worth 5-6k

- - - Updated - - -

Some crazy e36 owners have added a tow hitch, there is an old thread.

[bluptgm3]

Some crazy e36 owners have added a tow hitch, there is an old thread.

The only hitch for E36 is Curt. (https://www.etrailer.com/Trailer-Hitch/BMW/3+Series/1992/C11177.html?vehicleid=19927064&srsltid=AfmBOoqdyWPVMx9eMVv_CIXDUxHlilcLTAcVD71943 1IEiXXGG-wyNKu)

https://uploads.tapatalk-cdn.com/20250113/6007b51d1e3478f8e21112051aa93c15.jpg

[URO Parts]

In general, high HC is too rich, high NOx is too lean (cylinder temp too high), it's a see-saw. Could something be retarding the ignition timing a bit? That can push up HC and pull down NOx.

[Eric93se]

He has a chip that is not cali legal.

[itsmeesc]

It might actually be California compliant. https://www.dinancars.com/products/software-tuning/engine-tuning/engine-chips/parts/ENGINECHIP

[Eric93se]

Just know what they sell now may be different from what they sold 10+yrs ago. I'm just say'n.

[bluptgm3]

I believe Dinan has always been CARB compliant and as result have always been conservative.

[Eric93se]

Usually a performance tune will advance timing and that will require premium gas. If the knock sensors are original then they will be cracked and that will also throw a monkey wrench in engine timing/performance.

[URO Parts]

^ If the knock sensors are misbehaving, won't the engine default to dialing back timing to ensure there isn't pinging/detonation?

[Eric93se]

I have no idea.

[Eric93se]

Updates?

[E36 Em Tree]

I changed this part in my e36 for smog after taking mine off, blowing through it, and realizing that the purge valve was stuck open and dumping extra vapors or whatever back into the intake side.
https://www.fcpeuro.com/products/vemo-bmw-fuel-tank-breather-valve-13901433603?ads_cmpid=21615224579&ads_adid=166033218603&ads_matchtype=&ads_network=g&ads_creative=710407818645&utm_term=&ads_targetid=pla-297546631617&utm_campaign=&utm_source=adwords&utm_medium=ppc&ttv=2&gad_source=1&gclid=EAIaIQobChMIwPXNkMOZiwMVYxatBh1eeiUTEAQYASAB EgLs_vD_BwE

I'ts probably a 2 min job to take this off and check if its bad. I believe it should be closed when taken off, hence why i blew through mine, and when i blew through it air was passing through.


I also changed my spark plugs to some copper one prong ones instead of 2 or 4.

[itsmeesc]

I ended up getting 3k for it from a kid who's probably just going to hot smog it. Found a super cool VW Mk4 jetta wagon for $1500 off this old persian guy and made sure it passed smog before I bought it. Wish I was able to get it fixed but I don't think it makes sense for me to keep chasing an issue like that while being a full time student, working, and interviewing for post-college jobs.

[GG///M3]

Life in Commiefornia


Sent from my iPhone using Tapatalk

[gc325is]

Beware you are still responsible for selling a car in CA with a SMOG certificate or they can return it with $$ fees. How are you bypassing that? Or are they converting to a track car off road use only

[GG///M3]

Beware you are still responsible for selling a car in CA with a SMOG certificate or they can return it with $$ fees. How are you bypassing that? Or are they converting to a track car off road use only

Darn commies


Sent from my iPhone using Tapatalk

[gc325is]

CA SMOG is even worse for those in the major city limits. They impose enhanced SMOG check which is the OEM SMOG limits when the car was sold new. Even if engine has wear or CAT warranty are over you still need to pass with OBD I . Some cars with OBD II can pass with no check engine lights but I do not know if that was granted to E36.

[E36 Em Tree]

Beware you are still responsible for selling a car in CA with a SMOG certificate or they can return it with $$ fees. How are you bypassing that? Or are they converting to a track car off road use only

You can sell a car without SMOG. The buyer has to be made aware and you can just put it in the purchase receipt/bill of sale. That's how I obtained mine and then I eventually got it to pass SMOG. If we didnt have SMOG here i wouldnt have known about several issues with the car like changing the evap fuel purge valve, then looking deeper into different spark plugs for the car, etc. SMOG sucks but it's helped me narrow down some nit picky issues. I wish I didnt have to SMOG my car, or that it was optional for a discount on reg or some incentive.