My 1994 E32 740i will not pass California smog

[LysanderSpooner]

I am having issues getting my 740i to pass smog in California due to high hydrocarbon output. The engine always starts right up, runs very strong and makes no noticeable noises despite 260k miles.

Here are the results from the last test:

15mph HC=123 (Max allowed=56)
25mph HC=142 (Max allowed=45)

Results from my 2017 test:

15mph HC=41
25mph HC=41

2015 test:

15mph HC=8
25mph HC=1 <—!!!

I bought it in 2015, and it passed on the first go in 2015 and 2017 without me having to anything. During that period I only did basic maintenance such as oil and filter changes (LubriMoly 10/40w - the best oil I've ever used!), plugs, air filter, etc.

Things I have done since my last test to try to get numbers back into range:

New O2 sensors (Bosch)
New spark plugs (NGK)
New intake manifold to block gaskets
New throttle body to manifold gasket
New injector o-rings
Fixed several vacuum leaks (brake booster hose, FPR)
Swapped out several known working Bosch MAF sensors
Cleaned and tested the Idle Control Valve

The car seems to me to be now running better than ever despite these numbers. The CEL is off, a smoke test reveals no leaks, and a stomp test shows no codes.

One thing to note is that each test was done at a different shop. The tech at the last shop I used said that the V8 will almost never pass if there is even a slight lumpiness to the idle, which mine admittedly has, though as far as I can recall the idle has always been a little lumpy, even when I first got it and the numbers were ridiculously low.

There are two more things I want to try before I take it back for another test:

New spark plug boots - The car has always had issues with oil around the plugs. I have hesitated to change valve cover gaskets because of the stories I’ve read about blowing main seals on high mileage motors after doing this.

New PCV valve - There was a pretty fair amount of oil residue in the intake manifold. I am not getting the telltale smoke of a bad PCV, but before I fixed the vacuum leak to the FPR I did get the roaring sound of a bad PCV when accelerating on the highway.

One last question… Is there often a large discrepancy between testing stations’ machines? If so, I may go back to the same station that I used in 2015. One thing I like about the last station I used is that he only charges if you pass, no matter how many tests he does. Pretty cool in that regard.

Any other ideas before I do the plug boots and PCV would be greatly appreciated!

[theBMWbeast]

I couldn’t get my 750 to pass smog here either. Hydrocarbons are unburnt fuel, so incomplete spark from cracked boots on the ignition coils would be a good place to start. I found that a little under a gallon of denatured alcohol, and hot hot cats, did the trick for me on getting it just under passing. You’ll have to order the denatured alcohol off eBay or wherever you shop online, as they do not sell it in the state of California any longer.
.

[LysanderSpooner]

I couldn’t get my 750 to pass smog here either. Hydrocarbons are unburnt fuel, so incomplete spark from cracked boots on the ignition coils would be a good place to start. I found that a little under a gallon of denatured alcohol, and hot hot cats, did the trick for me on getting it just under passing. You’ll have to order the denatured alcohol off eBay or wherever you shop online, as they do not sell it in the state of California any longer.
.

I was planning on heating the cats up for sure, but I've never heard of the denatured alcohol trick... so you pour that right in with a full tank of gas, huh? Wow, good to know!

[Rich in Boston]

Nice that in Massachusetts we have safety only inspections for OBD1 equipped cars. No more exhaust tests!!

[jclausen]

Of course with any older BMW having the cats completely hot is a must. Not just idling, , drive on the freeway for at least 30 mins, the on to the machine

[LysanderSpooner]

So I think I've got it licked. Yesterday during a trip to the Pick-A-Apart I found an E38 740iL with a PVC valve that looked suspiciously a little cleaner than the intake manifold. Expecting the usual hassle with the T30 torx screws, I was elated to find out that they were in fact hex bolts - yahoo! The PVC turned out to be a factory BMW part that was still in good nick and had obviously been replaced due to the bolts that were used. If I hadn't found that one I was ready to pop ~$20 for an eBay knockoff (yeah, I'm cheap - especially after pouring so much into all the other parts lately).

While I was at it I also nabbed a (new to me) Idle Control Valve. Installing both parts smoothed my idle out big time. I'm 97% sure it was the PCV that did it, even though I installed it first and the idle still seemed lumpy. After installing the ICV it really smoothed out, but I think it just took a little while for the ECU to catch up (I didn't do a battery reset).

Wish my luck today, I'm off the testing station!

[LysanderSpooner]

And.............. Fail.

Numbers are quite similar despite the improvement in idle. I saw in another post somewhere that the owner could "balance a quarter on its edge" while his M60 was idling... Mine is not quite that smooth yet after all the work I've done, but it has gone from a lumpy rocking sensation to a higher frequency and much less pronounced buzz at the outer edge of the driver's door when it's wide open.

I'm starting to think I need cats. But today I did try a bottle of that magic "guaranteed to pass" stuff and then a 70 mile round trip at 75mph+/3k rpm in 4th gear. It does seem to be idling just a tad smoother now.

I am also considering a brand new PCV valve. I didn't pop the cap off the used one I installed because it looked pretty fresh and I didn't want to disturb it. On a related note, there was a fair amount of oil in the intake manifold from the bad PCV. I had no easy way to clean it out, so rather than introduce a bunch of new debris, I just left it as is. I suppose it's possible that this oil is being burnt off, causing the high HC readings. If so, hopefully this will subside after I run this tank of fuel through it. I'm just hoping this doesn't further clog my old cats.

By the way, anyone in San Diego county got a laptop with INPA or DIS on it? I'd sure love to see some more detailed info on it.

[theBMWbeast]

I used to have an e38 740il. I recommend going straight to OEM for PCV plate. Simply put, eBay ones do not work. If it does work, you’ve probably only got a few minutes before it doesn’t.

Also make sure those ignition coils are working well, a complete burn is your friend here. If you get everything all sorted, it may just be possible to slide through. I fixed my VCV, ran the car hot, and poured in the denatured alcohol. Went from failing for 98ppm of hc in the 25mph, down to 36ppm, passing. I wish you luck, as smog really is the big killer for older cars here in California.

[shogun]

By the way, anyone in San Diego county got a laptop with INPA or DIS on it? I'd sure love to see some more detailed info on it.

check here in the CA forum, there are several meetings, maybe you drive to one of these meeetings and ask around, or post there if there is someone with such a tool near San Diego https://www.bimmerforums.com/forum/f...Avus-Autosport

[LysanderSpooner]

I used to have an e38 740il. I recommend going straight to OEM for PCV plate. Simply put, eBay ones do not work. If it does work, you’ve probably only got a few minutes before it doesn’t.

Also make sure those ignition coils are working well, a complete burn is your friend here. If you get everything all sorted, it may just be possible to slide through. I fixed my VCV, ran the car hot, and poured in the denatured alcohol. Went from failing for 98ppm of hc in the 25mph, down to 36ppm, passing. I wish you luck, as smog really is the big killer for older cars here in California.

Duly noted on the PVC...

As for checking coils, replacing one at a time seems pretty tedious... that's why I'm looking to get her hooked up to some software. Thanks for the good vibes, I need 'em!

[goinstrong]

Almost every time it is the diaphragm that goes bad on the PCV/CCV valve. I buy a new one off Amazon, pop the cap off of it, pop the old cap off the one on the engine, and snap the new cap on after cleaning up the base of the valve. In every case, (5) it has worked well vs. full replacement. It is SIMPLE!! Going slowly, it will take 15 minutes max...
Hope this helps!
Tim

[LysanderSpooner]

Almost every time it is the diaphragm that goes bad on the PCV/CCV valve. I buy a new one off Amazon, pop the cap off of it, pop the old cap off the one on the engine, and snap the new cap on after cleaning up the base of the valve. In every case, (5) it has worked well vs. full replacement. It is SIMPLE!! Going slowly, it will take 15 minutes max...
Hope this helps!
Tim

Thanks for the tip Tim, but for the life of me I can't figure out how anyone could get that cap off with the PCV still in the car. It's a very difficult thing to do even with the PCV on the bench. Those little tabs are by no means easy to release without fear of breaking something. Anyhow I now have hex bolts holding on the PCV, and that makes it pretty simple to swap the whole thing out.

I did take the cap off the used OEM PCV that was on the car, and the diaphragm had a very small 4-5mm split in it along the edge.

The issue I am having now is that the car is idling worse with the new PCV. Whereas before the idle was pretty smooth with just some faint intermittent hiccups, the engine now rocks like a 350 Chevy with a race cam. And yes I did a battery reset (not a full "magic reset", just left it disconnected while I was installing the PCV without touching the two cables together) and I have driven the car for probably 100 miles with no improvement. The vacuum at idle is still reading around 15-16hg/in.

I think it's time to pull the cats and give them a citric acid bath. I don't know what else to do at this point. New OEM cats are out of the question, and I don't want to put some cheap cats in that will fail before my next test in two years.

[Timm]

Those symptoms after replacing the PCV usually means that you have introduced a large vacuum leak - and that is often due to not reconnecting the vent pipe correctly. This can be the front of the vent tube where it connects to the OSV output. I did exactly the same after replacing the PCV for the first time on my E32, the engine revs would rise and fall the engine shook like mad!

All explained here:

https://www.meeknet.co.uk/E32/PCV/Index.htm

...and more info here:

https://www.meeknet.co.uk/e31/BMW_M6...cuum_Leaks.htm

[LysanderSpooner]

Those symptoms after replacing the PCV usually means that you have introduced a large vacuum leak - and that is often due to not reconnecting the vent pipe correctly. This can be the front of the vent tube where it connects to the OSV output. I did exactly the same after replacing the PCV for the first time on my E32, the engine revs would rise and fall the engine shook like mad!

All explained here:

https://www.meeknet.co.uk/E32/PCV/Index.htm

...and more info here:

https://www.meeknet.co.uk/e31/BMW_M6...cuum_Leaks.htm

I was thinking the same thing, only now I suspect I either got a bad part (Meyle brand) or I forgot one of the little blanking caps, though I'm 99% sure I swapped them both over ($#@% aging brain... haha). I'm pretty certain I got the vent pipe set up correctly, because the connection between it and the old PCV was loose enough where the vent pipe would stay in place when removing the PCV. With the new PCV this connection was quite tight, to the point where I had to use the open end of a 17mm spanner wrench at the forward end of the vent pipe to slide it forward and over the new o-ring at the rear.

I'll be pulling it apart today and reporting back... dang.

[LysanderSpooner]

Nice quality control, Meyle... look at the diaphragm from about 11:00 to 2:00 in this pic:

Attachment 664932

A closer look:

Attachment 664933

It turned out that the lip of the diaphragm had not been seated squarely in that spot during assembly. I tried putting it back together with a little gasket sealer in that spot, but that didn't work. However, upon pulling it back apart I noticed that just reassembling it correctly had flattened out the lip of the diagphragm all the way around, so I ended up putting the new diaphragm into my OEM unit and she's idling much better now. Next time I won't be buying Meyle... ugh.

[Avec]

Coils are easy to disconnect without removing. Pull the coil covers and with engine running, pull the connector one one at a time. What you are looking for is NO change in idle to indicate a problem coil. Then, step 2 is to confirm coil is bad by swapping the bad with a known good to see if the issue follows the coil.

[LysanderSpooner]

Coils are easy to disconnect without removing. Pull the coil covers and with engine running, pull the connector one one at a time. What you are looking for is NO change in idle to indicate a problem coil. Then, step 2 is to confirm coil is bad by swapping the bad with a known good to see if the issue follows the coil.

Wouldn't NO change in idle indicate a worse case scenario of a coil that is completely dead? This would be the case if the idle is already quite lumpy, and it's a steady lumpiness that rocks the car rhythmically, particularly noticeable at the outer edge of the driver's door when it is wide open.

It seems more common that they start to fail intermittently (especially when hot), causing the idle to become more erratic, showing as just a slight irregular vibration at the edge of the door. Pulling the lead from one in this condition would have LESS effect on the idle (you would now have the same lumpiness as above if it's the only bad coil) than pulling one that is fully functional (giving you lumpy+erratic with an intermittent coil still in play).

Concur?

[theBMWbeast]

Grab the multimeter and just test them to be sure. If you want to pass smog, you have to start eliminating systems. High HC means unburned gas, so ignition problems seems likely. I believe m50 colds are interchangeable as well, so that could be a cheaper solution for replacement if necessary.

[shogun]

I copied that once from a Bosch site: Gas Analysis , Bosch Technologies Group - Three Reasons for Gas Analysis
* Identify engine performance and mechanical problems
* Test the running efficiency of the engine
* Test for exhaust emissions against state and federal standards

Combustion Chemistry and Gas Analysis.
* The combustion process releases the energy stored in the fuel
* Fuels consist basically of carbon(C) and hydrogen(H) referred to as hydrocarbons (HC).
* Under ideal conditions all of the HCs would be converted to H2O, CO2 and heat.

Combustion Chemistry and Gas Analysis.
* Unfortunately this complete combustion is rarely if ever achieved
* Short burn times, continuously changing mixture ratios and air temperatures, and combustion chamber quenching produce conditions which give rise to the formation of pollutants

Pollutants
* Incomplete combustion produces carbon monoxide (CO)
* Unburned fuel produces hydrocarbons (HC)
* High combustion temperatures produce oxides of nitrogen (NOX)

Other Exhaust Gases
* Carbon dioxide (CO2) is a product of complete combustion. Therefore the higher the level of CO2 the more efficient the engine is running.
* Oxygen (O2) level in the exhaust indicates the fuel-air mixture.

High O2 = lean
Low O2 = rich

Gas Analysis as a Diagnostic Tool

Gas analysis
* Is a quick and accurate way to determine the running conditions of an engine
* By observing the 5 gas readings and understanding their relationship to each other you can diagnose the 3 major engine areas:

Fuel delivery
Ignition
Engine Mechanics

High HC Only
Hydrocarbons are unburned fuel. This can be caused by:
Ignition Timing (base and advance)
Vacuum Leaks (hoses, brake booster, manifold, evap. etc.)
Ignition (misfires, coil breakdown, etc.)
Mechanical (low compression, bad cam, etc.)
Catalytic Converter Failures

High CO Only
* Carbon Monoxide is a result of incorrect fuel/air mixtures. Causes include:
* For Carburetors (float level, power circuit, choke circuit)
* For Injection (injectors, pressure regulator, temp sensor, MAP/MAF sensor)
* For Both Systems (air filter, PCV, Evap, O2 sensor, air injection

High Nox Only
* NOX is caused by high combustion chamber temperatures. Check:
* EGR (valve, controls, solenoids, passages, vacuum hoses)
* Ignition Timing ( base and advance)
* Engine Temperature (cooling system, fan restricted exhaust, Thermostat)
* Vacuum Leaks (hoses, booster, evap, etc)
* Mechanical (carbon deposits, converter, etc)

High CO and HC
* Normally, when HC and CO are high it is the result of a CO failure driving the HC high.
* Correct for high CO first (Excessive fuel, restricted air, Evap., etc.)
* If HC is still high, test as high HC (ignition, timing, mechanical, etc.)

High CO and Nox
* These problems are normally incompatible. If they occur on the same test they will most likely occur at different points on the drive cycle
* Correct CO failure first
Retest and locate NOX failure in drive cycle and correct as NOX failure only

HC and NoX
* High HC and NOX normally occur as the result of a lean misfire. Check for:
* Lean run (vacuum leaks, mixture problems, fuel delivery, etc.)
* Mechanical (oil burning can cause high combustion chamber temperatures)

CO, HC and NOX
* This is a complete breakdown of the emission systems or multiple failures.
Check:
* Catalytic Converter (missing, damaged)
* PCM (closed loop, wiring, etc.)
* Drive cycle ( if failures occur at different points diagnose each failure separately)

[LysanderSpooner]

Grab the multimeter and just test them to be sure. If you want to pass smog, you have to start eliminating systems. High HC means unburned gas, so ignition problems seems likely. I believe m50 colds are interchangeable as well, so that could be a cheaper solution for replacement if necessary.

I think I've got ignition system problems crossed off my list. My reply to Avec was rhetorical in nature. Since installing the OEM PCV valve with the diaphragm from the crap Meyle one she is idling really sweet. Now I just need to get tested again and see if I either pass or pull the cats for a citric acid bath.

[letank]

I think I've got ignition system problems crossed off my list. My reply to Avec was rhetorical in nature. Since installing the OEM PCV valve with the diaphragm from the crap Meyle one she is idling really sweet. Now I just need to get tested again and see if I either pass or pull the cats for a citric acid bath.

any success?

[LysanderSpooner]

any success?

Unfortunately, not yet. Some of the lumpiness at idle has returned and I failed the test again. I did try the lemon juice acid bath on the cats and that did help the NOX numbers. I have since done an engine swap and when that was done I replaced all intake gaskets and vacuum hoses but still I failed the test. I am going to have to do a really exhaustive search for any and all possible vacuum leaks.

[youngbimmer]

California requires emissions tests, but not safety inspections on their antiques?

[LysanderSpooner]

California requires emissions tests, but not safety inspections on their antiques?

If you mean brake and light inspections and whatnot, this ain't Germany. Unless you get a salvage title for some reason, then they are required.

[letank]

California requires emissions tests, but not safety inspections on their antiques?

yes, and it is getting really annoying because for the older cars, I mean the vintage collector ones, less and less smog test station have the equipment to do the tests because it take a lot longer than plugging the interface cable and waiting for the data to download...

We failed too on the high nox, but all the other numbers are very good. It is too lean, no vacuum leaks... I am going to try to work the INPA, I have not found version 3.01, but version 5.02 downloaded on that old XP pro laptop with the serial port, it even seems functional as well as on the win7 laptop... Now I need to build the cable interface, I have not found the right one already made.

from the software forum, the contributors have polished an easier version later on, otherwise from page 1
https://www.bimmerforums.com/forum/s...-ADS-interface