SWAP Thread: '91 325i Sedan - S50b30us

[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]

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.

[Mr.SWISS]

o2 backfeed?

[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.

[Danny]

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

[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

[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.

[hwy84]

BAR Referee and SMOG (California)

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.

[hwy84]

So you want to post your thoughts of your current ix/e32 setup vs. stock? I think the bigger master makes it more touchy personally.

Will do. Booster is in a box on my desk as I type this... so I can't compare yet.

[Mr.SWISS]

So you want to post your thoughts of your current ix/e32 setup vs. stock? I think the bigger master makes it more touchy personally.

[R3Z3N]

Congrats!

[hwy84]

I sense a shift in the force of this thread....

Win?!?!?

Damn straight, win...


...Finally.:up:

[Mr.SWISS]

I sense a shift in the force of this thread....



Win?!?!? :weak:

[328ijunkie]

Good to hear you did the smart thing ;)

[hwy84]

Booster follow-up

So, it turns out that my BOOSTER wasn't binding at all.

However, the PIN in the clevis had enough sideways force on it, due to the angle of the clevis, that it created a ton of friction, and wouldn't allow the linkage to freely move. This friction was enough to a) make pedal drag, and b) prevent me from removing the pin without MAJOR force, fiddling, and swearing.

I finally got it all out. Without the pin, the whole assembly moved nice and smooth, and the pedal (and booster rod) returned just fine.

I therefore had a choice:

- Make the pin slightly less thick, so it wouldn't bind, and reassemble...

OR

- Do it right. http://www.r3vlimited.com/board/showthread.php?t=250474


In the meantime, I have the linkage half-assed, and it works fine, but I don't trust it for the track. However, I have been able to drive the car "with intent"... and holy shit... What a blast!!!