When Boost Rises, 02 Readings Fall.

[ZGN]

When rpms near 4000+ and boost starts to rise, car stumbles out and has no power. on the PFC O2 is reading .02 when this happens.
As long as there is no boost, the car runs perfect. I have a few ideas but thought I would post here to kick off the forum!

What do ya think?

My setup is as follows:
Apexi Power FC + Commander
Profec Type S Boost Controler
BNR stage 3 Non Sequential
Streetport
850/Bosch 1600cc Top Feed Injector
MSD6A
Nippondenso Fuel Pump (known as the Supra TT pump)
3" downpipe, Midpipe, No Cat, PFS exhaust
PFS Intercooler / Airbox
ACT / 9.5 flywheel
Fuel filter 10k miles on it 3 years old.
Tuned by Steve a few months ago.

Thanks,
Kevin

[Brent]

Given your narrowband O2 Sensor is by no means the most accurate, .02 means you are running very lean. On a stock O2 Sensor if I remember correctly, the "ideal" voltage is .45... which means it is at an optimal air/fuel mixture. Anything below that is lean, anything above that is rich... relatively... based on the number. I'm sure you already know that, I just wanted to throw that in there for anyone in the future that may experience the same problem as you that is searching.

Does it always lean out at 4000rpm's or only when under heavy acceleration?

[ZGN]

It only runs lean when under boost, I can gradually accelerate the car to 6000+ and it reads .84 to .89

[Herblenny]

I agree with Brent... narrow band is useless.

First of all, Check your ground. Make sure the ground to your engine is good.

If your car was running fine before, it shouldn't be anything to do with the tune.

Also, since you are non-seq, there shouldn't be much troubleshooting regarding vac lines.. Check those just incase..

[ZGN]

Checked for vacuum leaks and found none. I pressurized the intake with 5psi useing my air compressor.
I bet it is related to my leading coil pack or msd6a
or it could be a drop in fuel pressure but i don't know because my gauge is under the hood, Hard to read while driving. :)

[ZGN]

Even though it seems ass backwards in my mind, a bad coil or a fouled sparkplug that is not firing on one chamber, will cause an o2 sensor to read lean. I would expect it to read rich, due to all the unburned fuel coming through the exhaust from the non-firing chamber. But I have seen it a few times on my own car with a wideband when i was running 10.5 race plugs that foul at idle easily.

That said, i wouldnt rely on that stock sensor for jack shit. You can get a wideband with display for as little as $250 these days. Hell, if for no other reason, it will teach you to drive the car more efficiently for MPG when you're not on the throttle. You'll find out a couple of surprising things about when your engine is most efficient.


That is what I am suspecting also, I cleaned the plugs. but still same results.
I am useing a 2nd gen leading coil pack with a MSD6A. This weekend I'll desolder it all and reconnect it to reassure me it's not a loose wire. how do I verify the MSD6A is working properly? Or maybe my leading coil pack is going out again. I had previously blown a stock leading coil pack with this setup. It literary blew it apart.
http://www.rotarycarclub.com/attachment.php?attachmentid=38&stc=1&d=1203608411

[Herblenny]

Kevin,

I've seen so many issues with MSD6A.. If you had problems in the past and now similar problems now, I think its time for you to get something else. I've heard very few people having issues with HKS twin power.. and I think the amounts of time you replace your coil and time, it might be worth the investment to just pick up a twinpower..

[ZGN]

Anyone have one for sale? vendors speak up!

I'll put the twin on my FD and save the MSD6A for my 240z :)

[Chadwick]

I have never had any issues with a 6a, but I have not run very many. BUt this has been the standard ignition box for the race crowd for a long time, so I dont think you have anything to worry about.

From what I understand, the twin power simply increases dwell time on the spark, without increasing intensity, while the 6a leaves dwell time the same and increases the spark itself. I could be wrong, though.


That is a pretty close description Kevin, the twin power uses a double spark which does increase dwell time, it does not amplify the spark like the MSD or Jacobs.

Dan

[ZGN]

That is a pretty close description Kevin, the twin power uses a double spark which does increase dwell time, it does not amplify the spark like the MSD or Jacobs.

Dan

Which is better? to increase dwell time?
Or with the msd to increase the spark?
Should I have to be replaceing my coil every few thousand miles or so due to the MSD?

Thanks,

Kevin

[Chadwick]

I'm kind of old school so I like the increased spark amplification, but many have said good things about the Twin Power.

Dan

[Bryan@BNR]

Hey ZGN Kevin,

I'll buy your 6a if you purchase something else. My 323 needs some more spark!

Bryan