We had a local maxima dyno session today... Big thanks to BigDogJonx and SRT (the shop) for setting it up and organizing it... Anyhow, we all got our air/fuel ratios measured. It seemed that we were all running a bit lean since we all had AFRs in the 14-14.5 range. My AFR was flat throughout, but it was above 14... Any ideas as to why it could be lean? I used some fuel injector cleaner about 3000 miles ago, so injectors should be clean. The other thing I was thinking of was the fuel filter... sucks that ours is in the tank, or else I would have swapped that out. Any other suggestions?

Also, has anyone else get their AFR measured while on a dyno? BTW, this was on a 2k auto with midpipe/Apexi filter, Cattman y-pipe, RT cat, and UDP. Thanks!

 

Well if you go richer you will most likely loose power. Was it detonating?

 

no detonation/pinging as far as I could tell...

I was just thinking that I should be more around 13-14 rather than consistently above 14. Oh well... numbers were decent I guess....

180 hp
191 tq

 

IMHO, I think their oxygen sniffer is wrong. It's really hard for a N/A car with only the basic bolt-ons to run that lean. Plus, you said ALL OF YOU were running that lean. I think that's pretty unlikely. All the N/A Maxima dynoes I've seen are around 12.0-12.5:1

 

why do you think that between 14 and 14.5 is lean? That's perfect, IMHO.

 

hmmm... I always thought that around 12-13 was normal...

As for the sensor they were using, I don't think it was off. A stock auto Acura TL-S dyno'd as well and the AFR was dead on around 12.1 for the whole run. He pulled 199 hp and around 180 torque.

 

after looking at my AF plot carefully using the dynojet viewer, it is only above 14 between 3800 rpm and 5000 rpm. It is at 14 at 5000 rpm and decreases linearly down to around 13.5 at fuel cutoff. So it's not as high as I originally thought...

 

So SRT is building Dixit's turbo...

That's a good amount of torque you have.

 

I'll let Dixit tell you about the turbo setup he is going with...

SRT is Lexus only for now... we should try and get them to make Nissan parts... their stuff is top notch...

The torque was pretty good... more than I expected... but I need to understand this AFR...

 

The sensors could still be off. I know that Accord V6's run EXTREMELY RICH (10.x:1 range) at WOT. I'm not sure if the TL-S is the same, but if they usually run 10.0:1 but were being measured as 12.0:1 on the dyno - then 12:1 on a Maxima could have turned into 14:1.




But sounds fishy to me. Nice numbers, BTW

 

yeah... their wideband sensor may have been off.. but who knows

Numbers were not bad... I'll post the dyno in the dyno forum later today perhaps...

 

It is lean (per se) because cars normally do not run that close to stoich from the factory. They run a bit richer (mostly for safety's sake). Even though 14.0 is technically on the rich side, it is lean compared to most N/A cars.

Nevertheless, your power numbers are normal and decent. Don't worry about anything; you won't blow your motor.

 

thanks.

 

I thought I remember seeing it come from the factory with a 13.5 to 13.8 somewhere b4.

 

Well normally close to stoich is okay. But on the dyno, you are running WOT correct? If you are running that close to stoich at WOT, I "might" be worried. Becuase the ecu runs a closed loop program that is richer than the normal open loop ( 02 ) program.

Although, I think your car is running fine, I would look into your fuel pressures or maybe your fuel pressure regulator. If your fuel pressure is a low, it "might" cause a lean(er) condition.

 

yeah, dyno was at WOT...

I'll check out the fuel pressures and the fpr when the weather gets a little warmer. It's too cold to work on the car these days....