[hotrod182]

Just got done putting the 2.5" UR downpipes on again! A slight increase in mph this time perhaps. This time I weighed each downpipe. So compared to the stock units, a savings of about 10lbs. As some of you may already know, my lean misfires went away when I reinstalled the factory downpipes. I had no idea why, but the problem definitely went away. I believe the 02 sensors in the UR DPs were somehow causing my lean misfires. So I paid a lot of attention to cleaning the downpipe flanges and 02 sensor bungs, etc. Even though I had some pretty impressive performance on the stock DPs, I thought I would try the UR 2.5 CL downpipes one more time, just in case cleaning the 02 sensor threads, etc, helped.

Did 4 back to back 0-150 runs, no 20:1 lean spikes!

This also included two back to back runs of 125.3 mph in the qtr.
Level runs, no wind. 47F, and 30% humidity.
I think this confirms our cars really love cool dry air!

I think a vbox reading of 125.3mph is probably some kind of record for a stock turbo, stock catback, stock intercooler, 335i BMW. I did it before, but that was when I was running straight downpipes.

Looks like my little sedan is running strong again.

If further testing goes well, I am about 90% sure I am going to Sacramento next weekend. Hope some other tuned N54s can make it out there too!

[blisstik]

Awesome. What did you clean the o2 sensors with? Alcohol?

[JamesM3M5]

Just the bung holes.

Interesting how the DPs possibly caused your issues. ECUs are now extremely sensitive to O2 sensor placement.

[cn555ic]

Glad u got it working. It's a Christmas present to yourself getting your car working!! Lol. Did you try nitrous again? Curious to see if cleaning totally clean up the lean spikes on nitrous.

[hotrod182]

Originally Posted by blisstik

Awesome. What did you clean the o2 sensors with? Alcohol?

No, it was quite an extensive job. I took a battery terminal cleaner and cleaned inside the DP threads as best possible. On the O2 sensor flange on the DPs I used a right angle air grinder with a scotch brite disc. On the O2 sensors, I scraped the threads with a wire brush, and tried to sand between the 02 sensor washer and the 02 sensor with a piece of sand paper. Some of it was just a half ass job, but I wanted to at least make sure there was some clean metal-metal contact. You can see how rusty the 02 sensor bung hole threads were. Although this was mainly on the after cat 02 sensors which wouldn't be suspect in causing DME mixture problems. I also ran the grinder along the DP/Turbo flange.

Originally Posted by JamesM3M5

Just the bung holes.

Interesting how the DPs possibly caused your issues. ECUs are now extremely sensitive to O2 sensor placement.

I never would have thought about this except for fact that I noticed the problem went away with the factory downpipes. So therefore I tried to focus on what a DP swap would affect. I knew the DPs worked fine before, so I then focused on the 02 sensor feedback system. I already changed plugs and tried new coils with no improvement. Never would have found this if I didn't personally wrench on my own car, and without the constant before/after testing. I'm still not 100% sure the problem is fixed, but four 0-150 runs without the spikes is a pretty strong indication that things are okay.

[JamesM3M5]

Always helps to have a very sharp M18x1.5 tap to clean the threads, especially if the old sensor trades metal with the hole (happens more often than I'd like). McMaster.com has a great selection.

Those holes were pretty rusty. Corrosion could cause some odd voltage signal disruption. Nice catch. Check grounds and other connections if these problems persist.

[Lulz_M3]

Call me immature but I chuckled every time I saw bung hole used.


Glad to see this worked out, these types of threads are priceless for forum members.

[Lulz_M3]

Call me immature but I chuckled every time I saw bung hole used.


Glad to see this worked out, these types of threads are priceless for forum members.

[Lulz_M3]

Call me immature but I chuckled every time I saw bung hole used.


Glad to see this worked out, these types of threads are priceless for forum members.

[hotrod182]

Just to give you an idea of how strong a 125.3mph run is. This was a 11.7 with a 2.0 sec 60'. If I could have a 1.8 instead of the 2.0 this would be well under 11.5 seconds!

[The Ghost]

Originally Posted by Lulz_M3

Call me immature but I chuckled every time I saw bung hole used.

ditto, I LOL'd

Hotrod, your car runs very strong. It's kind of discouraging. Perhaps you're vehicle is just 8 STD Dev out there. Nice

[hotrod182]

Originally Posted by The Ghost

ditto, I LOL'd

Hotrod, your car runs very strong. It's kind of discouraging. Perhaps you're vehicle is just 8 STD Dev out there. Nice

Thanks. And this is on 91 pump/meth.. at reasonable boost levels as you can tell by the logs.
Im really hoping some other tuned 335i BMWs can make it to Sac next Saturday!

[woodga16]

You're running CM10&cm7 @100% methanol correct?

[hotrod182]

Originally Posted by woodga16

You're running CM10&cm7 @100% methanol correct?

Used to. For the last month or so i replaced the CM7 with a devils own DO12. Didnt really notice any increase in traps.

[cn555ic]

Originally Posted by hotrod182

Used to. For the last month or so i replaced the CM7 with a devils own DO12. Didnt really notice any increase in traps.

So you using a CM10 and a DO12 at the same time! Thats alot of meth but I guess it has to do with the nitrous...More fueling for larger jet size your using.

[hotrod182]

Originally Posted by cn555ic

So you using a CM10 and a DO12 at the same time! Thats alot of meth but I guess it has to do with the nitrous...More fueling for larger jet size your using.

All the runs in this thread are with the nitrous bottle out of the car. You can see in the logs these runs are to 150 with good timing. I usually don't run nitrous past the qtr mile mark. Plus on nitrous, I was still getting a AFR spike in the shift into 5th gear. But regardless, I run the same meth nozzles on/off the bottle.

[dbjb]

Originally Posted by hotrod182

Thanks. And this is on 91 pump/meth.. at reasonable boost levels as you can tell by the logs.
Im really hoping some other tuned 335i BMWs can make it to Sac next Saturday!

New years eve? Several of us are going to Laguna Seca instead.

[the332i]

Impressive. Very nice, man.

[datbimmerdoe]

good shit!

[hotrod182]

Originally Posted by dsbj

New years eve? Several of us are going to Laguna Seca instead.

Yup...Sac has a special New Years Eve race weekend scheduled with test and tune on Saturday.

[Sneeze]

I wish i can go down with you in sac. I just finished installing my nitrous jb4 intergration. I hope we have a private rental in famoso soon. But im goin to test it in mexico when i get some time off.

[cn555ic]

Originally Posted by hotrod182

All the runs in this thread are with the nitrous bottle out of the car. You can see in the logs these runs are to 150 with good timing. I usually don't run nitrous past the qtr mile mark. Plus on nitrous, I was still getting a AFR spike in the shift into 5th gear. But regardless, I run the same meth nozzles on/off the bottle.

I know you run the same nozzles on or off the bottle, what I was stating is that's the most meth I have seen anyone use. Mostly see 2 CM10 nozzles but you trump it by adding DO12. That's a shit load of meth! Glad you found your problem as it will help others pay more attention to their O2 sensors.