SWAP Thread: '91 325i Sedan - S50b30us

[Mr.SWISS]

For California People:

I took the car to the BAR Referee today. I went to the Evergreen Valley College location in San Jose.

Short version: Passed visual, failed sniffer. Questions at end of post.

Long version:

The guy there was pretty "by the book" and did the entire visual inspection and smog test without saying a word. It was clear that I wasn't going to get a chance to discuss any mods, tweaks or stories with him during the inspection.

I have a fairly stock S50, with a stock 95 M3 center section, including cats. The only potential worries were:

- S52 Manifolds
- K&N Cone Air Filter
- Dinan Chip
- Lightened Flywheel (Machined M20)
- M20 Evap Cannister (Not S50)

Before the inspection, I discussed the Cone Air filter with the guy, and he said that as long as the MAF and intake BEHIND the filter were stock, he had no problems with it.

I passed "visual" - and he took his time. Mirrors, flashlights, the whole nine. He probably spent 15 minutes poking around the car.

Then he did the SMOG test. I am fortunate to live in a rural part of the bay area (yes, they still exist) so I don't have to pass on the rollers - just the old school idle and 2500 RPM test, and only tests HC and CO. (No specific NOx test).

I failed the test, on HC at idle. Everything else passed fine.

Idle: HC MAX = 100, HC MEASURED 110
2500: HC MAC 120, HC MEASURED 14

I need to make sure my TPS is actually registering closed when the throttle is closed, check my ICV, and run out some old gas still left in the tank. I am also going to run some fuel injector cleaner through the next tank of gas, in case my unknown injectors were sticky and leaky... though the clean-ass 2500 RPM number seems to indicate that isn't the problem.

My idle is a little "lopey" with the light fly... is it possible that the ECU is adding fuel to try to smooth out the dips at idle? Seems unlikely, but possible.

Thoughts are welcome. Overall, I am pretty happy with the results, since now I just need to focus on SMOG, and not worry about the equipment.

I had my idle bumped up to 900 and that would help tremendously just to pass the test if all you failed by was 10ppm.

[cmybimmer]

Damn, do all BAR tech's run the car on the sniffer? I plan on getting my car BAR'd in the near future and thought it was just a visual thing...

Wish you luck on fixing the problem! Congrats on getting her driveable though

[Danny]

Some BAR stations are refering people to a smog shop due to budget cuts but its very uncommon.

[hwy84]

More SMOG details

Got the car on a sniffer today.

At idle, the HC cycles from about 60 ppm, to 250 ppm every few seconds. Car is lean across the board (15.2) and o2 is low (.1).

I'm thinking vac leak, and the fluctuations are the ecu trying ro fix it...

Gonna chase down any leaks tomorrow and see what I find. Again, thoughts are welcome.

[Mr.SWISS]

o2 backfeed?

[hwy84]

Possible...

o2 backfeed?

Isn't the classic sign of 02 backfeed a varying idle rpm?

My idle is pretty damn smooth at about 750 rpm. When I pop on the aux fan, it gets a little rough, but the idle never moves more than a needle's width on the tach.

[hwy84]

Got the car on a sniffer today.

At idle, the HC cycles from about 60 ppm, to 250 ppm every few seconds. Car is lean across the board (15.2) and o2 is low (.1).

I'm thinking vac leak, and the fluctuations are the ecu trying ro fix it...

Gonna chase down any leaks tomorrow and see what I find. Again, thoughts are welcome.

Update:

That ^ was a result of a bad O2 sensor. Not bad enough to cause a code, but apparently "lazy" enough to respond too slowly to over-rich or over-lean conditions.

Replaced the 02 and now fail for HIGHER HC, thanks to a fairly pronounced miss at idle. I think this has been there all along, but the bad O2 was masking it.

I have replaced a ton of crap, and tested everything - except the MAF, which is indicated as the problem in this thread: http://www.r3vlimited.com/BOARD/showthread.php?t=214790

I'll get that fixed and report back, hopefully to close out this build! It's been long-ass time coming!

[hwy84]

Nope.

Update.

MAF didn't fix it.

Random, frequent misfire at idle only. Mostly just popping/burbling, with occasional hard miss where the engine stumbles and almost dies.

Smooth power delivery all all throttle applications otherwise, and great power, with NO misfires under load.

Have replaced or swapped out the following with no change:

• Injectors (swapped out)
• DME (swapped out)
• Chips (Ebay, Turner, Dinan - no change)
• FPR (swapped out)
• Coils (new)
• Plug boots (new)
• Plugs (NGK OEM)
• MAF (swapped out with known good)
• 02 sensor (new)

I have checked for vacuum leaks and found none.

Continuity on grounds from coils to head to chassis is good.

Cleaned ICV.

Verified O2 sensor is working fine at idle on GT-1.

Compression is even, and high, across all cylinders.

What have I missed? :(

This is all that's standing between me and California legality. I am to the point that I might register my car in a more SMOG stringent zone, so I have to do a roller test instead of 2-stage idle, because the misfire isn't present under load...

...but I'd much rather fix it right.

[hwy84]

In case it helps for searches...

Update

Leakdown test showed 8-9% across all cylinders (incredibly good, in fact).

Fuel pressure test was a-ok.

I did find a valve cover vacuum leak with the smoke machine (damn you Victor Reinz!) and fixed it.

...No change in idle. :/

So... I went to pop boys, and bought the chepest, hottest plugs that would fit the car. What do you know? Smooth ass idle. Pings like a bastard under load between 4500 and 5500 rpm, but that doesn't matter for the SMOG test.

Gonna test it with these plugs, then swap them back to the NGK bkr6 when i'm done...

[hwy84]

Passed!!

Just to close this out:

I passed the BAR smog test at Evergreen Valley College today (finally).

In case you haven't read the whole thread, I passed the visual no problem, but I had a misfire at idle that made high HC numbers.

After replacing all the stuff listed in the post above, I finally bought rebuilt injectors from OK Injectors on ebay (Their website http://www.okinjectors.com/) and cheap, copper, single electrode Autolite plugs.

The stupid plugs alone seemed to help a lot - smoothing out the idle in a big way - but the new injectors made the most difference. My car ran PIG RICH (like blowing plumes of smoke out the exhaust rich) for about 3 minutes after I installed them - indicating to me that the old injectors had been so clogged up that the ECU was calling for WAY long duty cycles to get the right amount of fuel in the mixture, and the new ones flowed so much better that they were open WAY too long until the ECU adapted.

In any case - I passed, and I am so damned happy I want to drive from here to New York.

Fellow Californians - it IS possible, just make sure you have a clean running motor. The visual part was the easiest part of the BAR process. The dudes at Evergreen are super chill, and as long as you have the right cats, a legal intake (I had a K&N cone with the EO sticker on the strut tower), and a charcoal canister, they won't hassle you. If anything, they WANTED me to pass - Gary at Evergreen is a real car guy at heart, and was super nice to deal with the whole time.

Word up. Thanks for all the help along the way R3v!

[M3PO]

Do you think I can pass with the aftermarket cat that is on my car now? The car AND the drivetrain are old enough and have enough miles that aftermarket cats should be okay right? What about eBay headers?

[hwy84]

Do you think I can pass with the aftermarket cat that is on my car now? The car AND the drivetrain are old enough and have enough miles that aftermarket cats should be okay right? What about eBay headers?

Are the aftermarket cats approved (with an EO number) for the engine you are running? They will ask.

Pretty sure ebay headers won't fly. But the good news (I guess) is that I am living proof that you can go back again and again and again without issue - so you might as well try. The worst the can do is fail you, and you have to go back again with the changes made.

[cmybimmer]

Congrats man! Im super jealous!

Failed BAR twice so far. passed visual from the gates, but emissions is where the problem is. Im pretty certain i need a new cat, so im on the hunt for a good one :(

[hwy84]

Congrats man! Im super jealous!

Failed BAR twice so far. passed visual from the gates, but emissions is where the problem is. Im pretty certain i need a new cat, so im on the hunt for a good one :(

Thanks! You already did the hard part by passing viz - now it's just a matter of time.

I'll keep my eyes out for a cat in the bay - are you OBDI or II?

[cmybimmer]

Yeah, only thing is time is not on my side ..

Smog is due on June 10th! lol not good

And thanks man! Its OBD1, just have the plain ol' m50 for now :)