So I had my car tuned recently with a Dynojet 224x Dyno. While on the dyno and using the same bung that I use to normally run my PLX Wideband the AFRs on the Dynojet read between 11.5 and 11.7 almost the entire way in 4th gear from 3500RPM to redline on WOT. At least I think that's where he used it. He never compared it on the dyno to my PLX Wideband so we're unsure of their discrepancies. The PLX Wideband is only 2 months old and has not been damaged in anyway that I know of.

When I took the car to the street though my PLX Wideband continues to read anywhere from below 10 (saying RICH) at some points to running up to about 11.1.

Why the HUGE discrepancy?

On the Dynojet Dyno the car was making 355 rwhp. Took it to the track last night and the car ran a 14.4 @ 98 MPH with a 2.3 60', a 9.4 1/8th mile, and a 78mph 1/8th mile trap.

I have verified this PLX prior to this tuning with a Cipher cable and it reads almost dead on with the car's stock widebands.

The car does not bog or misfire and drives smoothly throughout the RPM range.

I'm not sure what the load settings on the dynojet dyno are but could this large discrepancy be due to a larger load on the dynojet than real world settings?

I have no idea what to think here b/c the numbers don't add up. I'll be taking my car back to my tuner but not for another month at which time I'll be back in town.

No cloud of black smoke billow out the back that I can see even when it runs "RICH" (AKA below the 10 AFR that the PLX wideband reads at which point it just outputs the word "Rich")

I'm confused, can anyone help?

 

14.4@98 sounds like a STOCK ET/Trap...

AFR on a dyno is typically read with an exhaust probe...

Do you have the dyno graphs?

 

it sure does.

this was read with a O2 sensor that went right into the location where my PLX O2 sensor goes so theoretically they're reading the exact same gases.

I'm wondering now if perhaps the final tune was not saved correctly on my unichip after the tuning was completed.

Here is the final tune's dyno sheet with AFR's

I don't have the actual data file so a photo of the screen is all I can do:

 

Is your gauge reading any boost?

You're running a "stock" time, but you're obviously FI. A severe boost leak could be the cause of this (although you'd see some soot/smoke from running so rich if you are indeed running that rich)

*edit*

This is a FD? Not a G? That boost graph looks more like a S/C graph rather than the TT curve of a FD, but the file name says RX-7...

 

That doesn't even look much like a supercharged G35 graph...seems way to linear.

+1 to what mike said...whats up with the RX-7 file?

-Sean

 

Its just a file name. It is my g35. A tt or st curve would look completely diff. Power and boost are very linear on an sc. This is not much diff than other sc vq35 dynos. You're reading too much into the file name.

 

So when are you going to bring it here for good set of injectors, a fuel pump, and a proper tune?

 

Like I said before, is your gauge/probe reading any boost?

 

I don't have a boost gauge. but it's been showing rich sine as soon as we took it off the dyno and plugged my wideband back in.

The only way to check is to put it back on the dyno and test again.

will check boost when I get back, thanks for the tip.

 

I think I figured it out that it's just the software didn't download it from the laptop during teh tune.

I'll verify with the tuner in a motnh when I get there.

 

maybe once I've exhusted this . I already got injectors and really just need a pump and your tune now.

but this tuner did a swell job and I'm confident we can get it working correctly. I think the tune just didn't get saved onto the unichip.

 

Are you using a single PLX gauge or the OLED display?

 

The graph only looks that linear because the power graph is by the 100's

 

I'm using the DM-5 single PLX gauge with the SM-AFR

 

Also afr guages have a tendency to be off compare to the much higher quality of the ones tuners use.