Dyno'd my stock 2003 350Z on a Dynojet today. A/F came back pegged at 18 [edit]with no detonation whatsoever[/edit]. What do I need to do to fix this problem?

Atmospheric conditions today; 69.68 F in the shop, 29.86 in-Hg, 7% Humidity.

Cars directly before and after my run returned normal A/F ratios. Both tailpipes tested the same.

 

Please scan and post the chart. Thanks.

 

You might want to check that humidity. I don't think 7% could be right for Michigan. Here in Ca. it gets in the 30's but thats pretty dry maybe 20's in the summer.

 

Dyno was performed in Missouri, outside temperature was around 49 F at the time and relative humidity now is 58% @ 6:45 pm central time. The first pull was in 4th gear and 2nd and 3rd pulls were in 5th gear. I continued to run the car because I did not notice any detonation.

 

what mods do you have? Post the chart? Thats abnormally lean... Even if it wasn't detonating (u might have super gas), it might cause a lot of heat in the engine bay. You sure the a/f guage at the shop wasn't broken? where was it placed? Do you have an air leak in the exhaust??..

 

93 octane here in MO. I think yeperra hit it on the nose with the Humidity factor. I'll wait to hear more.

plumpzz, I have a completely stock 2003 350Z.

 

Oh boy. If u can go back to the dyno, or go to another dyno.. Reset the ECU? If u had 18a/f ratio ur car should explode from the heat.

 

When the filter gets dirty on the wideband on dynojets they read lean. I would bet $100 the filter was dirty and the worthless shop didnt even bother to think of that or check it...your numbers are fine for a stock Z.

 

Alberto,

I would think the same, especially because they bought the dyno from another shop. But the cars that ran immediately before and after mine read normally.

Do you think the Humidity reading could have screwed everything up?

 

No not a/f wise. The A/F wire could have blown out of the tailpipe for that run. I HIGHLY doubt your running that lean, you'd be putting down REALLY low #'s and hearing detonation, and you didnt do either.

 

Got it. All three pulls were very smooth without any hesitation. The first run, the A/F tube was placed in the driver's side exhaust outlet. For the 2nd and 3rd runs, they were in the passenger side tailpipe. The car before me was an older body style Supra that spit out dark exhaust. Maybe that gummed up the A/F tube.