2JZ afr question

[dirtdiggler666]

Ok I am running a stock 2JZGTE VVTI with a small single turbo and everything else stock. I was running about 7LBS open wastegate and the afr was always right around 11.5 then I decided to recirculate the wg into the downpipe and now my afr is right around 10.5

Has this happened to anyone? anything I can do before I go standalone?

[Kingtal0n]

What probably happened is,

increased exhaust gas pressure = less efficient engine = less airflow through engine = richer air fuel ratio = less power

Another possibility is you created a boost leak somewhere by accident.

What can you do? You mean on stock injectors/maf/map?
-An SAFC can pull 10% fuel without any harm bring it back to 11's
-reduce fuel pressure slightly
-check for boost leaks
-raise the boost pressure (the higher you go, the leaner it gets... ah haha...)

[dirtdiggler666]

What probably happened is,

increased exhaust gas pressure = less efficient engine = less airflow through engine = richer air fuel ratio = less power

Another possibility is you created a boost leak somewhere by accident.

What can you do? You mean on stock injectors/maf/map?
-An SAFC can pull 10% fuel without any harm bring it back to 11's
-reduce fuel pressure slightly
-check for boost leaks
-raise the boost pressure (the higher you go, the leaner it gets... ah haha...)

All very good points.

I think first I will make a boost leak tester, I should have one anyways.
its on a maf and yes stock injectors so any piggy back worth a damn?

Its weird tho the higher I go on psi the fatter it gets? I would of thought it would have done the opposite thing.

If all else fails just to prove I'm not crazy I might just build another downpipe and vent the Wastegate to see if it goes right back to 11.5

[Janz99]

All very good points.

I think first I will make a boost leak tester, I should have one anyways.
its on a maf and yes stock injectors so any piggy back worth a damn?

Its weird tho the higher I go on psi the fatter it gets? I would of thought it would have done the opposite thing.

If all else fails just to prove I'm not crazy I might just build another downpipe and vent the Wastegate to see if it goes right back to 11.5

Id put a fresh set plug in at least one of the cylinders and make a pull. Then remove the plug and see if the plug looks appropriate for the A/F you are seeing.

Are you using a wideband? If yes, what brand/model. Its possible that your o2 sensor is starting to fail and its just a coincidence that it happened at the same time you did the WG recirc. Pulling a plug will either confirm or rule out an o2 sensor problem.

I also agree, check for boost leaks on the charge side.

-Ryan

[TheRealSy90]

Fix boost leaks, then raise the boost pressure until it leans out lol.

[dirtdiggler666]

Id put a fresh set plug in at least one of the cylinders and make a pull. Then remove the plug and see if the plug looks appropriate for the A/F you are seeing.

Are you using a wideband? If yes, what brand/model. Its possible that your o2 sensor is starting to fail and its just a coincidence that it happened at the same time you did the WG recirc. Pulling a plug will either confirm or rule out an o2 sensor problem.

I also agree, check for boost leaks on the charge side.

-Ryan

I have not had time to build a boost leak tester yet. but I raised the boost to 13 psi made a few pulls and it was right around 10.5 to 10.3 then I checked the plugs and they were very white and clean looking.

my AFR gauge is only a few hundred miles old and its a AEM X Series

Could the WG be causing turbulence in the downpipe and giving a faulty reading?

[Kingtal0n]

it goes

maf -> computer -> injectors

so,
its either the maf, computer, or injectors (and related)

->things that f#$*& with maf:
wrong maf
bad maf
bad maf wiring
bad maf grounding
poor maf placement (too close to turbo, turbulent tube, no recirculated bypass)
leaky maf plumbing (boost leaks and air leaks)
improper use of maf (boost leaks, blow off valves, poorly designed tubes, non recirculation bypass)

!>computer issues related to rich a/f ratio:
bad ecu grounding(corrosion), bad (maf/tps)sensor grounding
poorly tuned, improperly tuned
wrong maf
(unrelated note to check timing)

☼¶injectors issues general store for rich a/f ratio:
leaking injector O-rings
too much fuel pressure (rare)
Injector too large for idle speed/minimum pw (2000cc injectors)

[dirtdiggler666]

it goes

maf -> computer -> injectors

so,
its either the maf, computer, or injectors (and related)

->things that f#$*& with maf:
wrong maf
bad maf
bad maf wiring
bad maf grounding
poor maf placement (too close to turbo, turbulent tube, no recirculated bypass)
leaky maf plumbing (boost leaks and air leaks)
improper use of maf (boost leaks, blow off valves, poorly designed tubes, non recirculation bypass)

!>computer issues related to rich a/f ratio:
bad ecu grounding(corrosion), bad (maf/tps)sensor grounding
poorly tuned, improperly tuned
wrong maf
(unrelated note to check timing)

☼¶injectors issues general store for rich a/f ratio:
leaking injector O-rings
too much fuel pressure (rare)
Injector too large for idle speed/minimum pw (2000cc injectors)

Thanks for all the info

Hopefully I will figure it out soon