1JZ Lean Spot

[bhg4life]

Under light - moderate load (200-300 mm/Hg) and roughly between 3500-4000 RPM my 1JZ goes very lean. On my WB display it goes from 14.x - 16.x during this spot. I run 440 injectors, BC cams, an AEM FPR and a S-AFC to trim the fuel. It was doing this prior to all of these mods, so I don't think they are a direct cause.

I can make it a little better by adding about 20% fuel on the S-AFC, but that really seems like a hack solution at best.

I found a couple of similar issues to mine doing a search but it didn't seem like there were any real satisfactory solutions or reasons so I figured I'd try again...

Thanks
Chris

 

[supra1008]

Yea I'm having this problem too. I have the same mods but with stock injectors. I'm about to upgrade to 550's. The only difference is it never ran this way before. Before I was running on a mines tuned ecu w a neo to tune. This time I'm running on a stock ecu and an safc 2 until I can get a standalone. Any ideas?

 

[supra1008]

nobody else had this problem?

 

[johnd]

I've had this problem for years. I notice almost everyone with this prop is running 440's, afpr, with a single turbo.
I raised my fuel pressure to 50psi also running 440's and my lean spot disappeard, so i'm pritty sure those 550's will solve it.

 

[GotTurbos?]

I've had this problem for years. I notice almost everyone with this prop is running 440's, afpr, with a single turbo.
I raised my fuel pressure to 50psi also running 440's and my lean spot disappeard, so i'm pritty sure those 550's will solve it.

Yup I ran into the problem under the same circumstances (but with 550's). Problem was running lower than stock fuel pressure on the stock ECU. Raised it back up to ~43-45 and with super minimal adjustments on the neo it was smooth all the way up!

 

[zoppii]

Yep, what Johnd and gotturbos said, I have a turbonetics 60 series, HKS 264's, tial44, HKS AFPR, 440's, walbro, SAFC II, DM FMIC and I have the same lean spot but more at 2800 to 3000 rpm. I doubt the 550's will take it all away but it might help some.
You can use your AFPR and Piggyback to get it flattened out pretty well. If you have a throttle point settings you may want to mess with that a little as it seems to be more prevalent at certain throttle opening percentages. If you can't get it straightened out, then you'll have to start saving pennies for a standalone.