Idle afrs lean, unless helped with AFC

[randomock]

New to the forums (duh post count)

My setup:
Cometic 1.4mm MHG
ARP head bolts
Stock IC and piping for now
Lexus AFM, screw about 1/2 way out
PTE 550cc injectors
Apexi NEO
AEM UEGO W/B
Walbro 255 w/12v mod
Aeromotive FPR
57 trim upgraded CT-26 (brand new)
Open 3" DDP (waiting for cat-back)
Fuel Pressure set at 42psi, vacuum off.

Problem:
At Idle with AFC correction turned off, AFRs are 16+, and Vf signal is 5V.
AFC correction set to +9 AFR hovers around 14.8-15.0, and Vf signal is 2.25

+9 seems like kind of a lot just for idle. I havent tried a higher FP yet.
Screwing in the AFM screw changes very little (tried all the way in and out)


Things checked:
Vacuum leaks - none
Boost leaks (with home made detector) - none
Exhaust leaks (possibly sucking air in before W/B, showing lean) - none
No leaks from AFM to turbo also.

Anything else I should try?
I haven't driven the car at all, kinda just want to get idle afr fixed first, and I still have to mount gauges, afc, glove box etc....etc...

 

[ihiryu]

have you tried adjusting the TPS. Check your codes first, even if it doesn't show a CEL, check it anyway. I couldn't figure out my problem, until I ended up checking and threw a code 51

 

[grimreaper]

also check timing, and id double check exhaust leaks again. the slightest bit of air will toss your wb02 reading out the window.
thats alot of fuel, i bet you pegg rich at wot with out the neo. im at 25 vac on around 32 or so with vac off.

 

[jdub]

have you tried adjusting the TPS. Check your codes first, even if it doesn't show a CEL, check it anyway. I couldn't figure out my problem, until I ended up checking and threw a code 51

Code 51 will not illuminate the CEL

 

[rumptis]

Something else is going on here. With your setup the stock ECU should be able adjust idle AFR to where it should be if you have no other problems. You shouldn't have to make any AFC correction.

You are running the stock O2 still right?

Also your fuel pressure seems a bit high, I would not expect this to cause it to run lean but this is going to cause other problems.

 

[suprafanatic]

my car has the same problem.. i have almost the same mods, i have lex and rc 550s and all the other mods.. my car idles at like 17+ afr and thats with the safc turned up to like +11 for just idle

 

[randomock]

Timing is dead on 10.
Double checked cps also, still within specs.
No codes stored.
Stock O2 sensor is still intact and hooked up.
Checked exhaust leaks using brakleen: sprayed around all fittings and had someone watch w/b, no movement.
Also tried checking exhaust with propane
(was told liquid might not get by a small enough hole and propane would)

 

[ihiryu]

that's what I said, the CEL won't illuminate. That's why I told him to check it anyway.....

Back to the topic, I checked mine with lex afm and I'm seeing 17:1 AFR's but the idle is steady. I'm also in TX so our climate may be a bit different

 

[randomock]

Update:

Been messing around with stuff some.

Took every exhaust component off, manifold-turbo-DP, no signs of leaks on the gaskets (black soot). Re-sealed with Hi-temp silicone + gaskets.

Replaced a couple of hoses: IAC, and PCV to accoridan tube (small cracks near ends)

Changed FP to 38 psi vac off.
+14 in NEO at idle for a 15.3-16.0 AFR at idle, with vac. on FPR (don't remember psi with vac.).
Vf reading 2.5v.
NEO reads MAF at 21Hz, warm idle.
NEO reads 650 rpm idle, warm.
MAF screw in 5/6ths (approx.) of the way


I finally drove it a little.

WOT, afr is roughly 10.3~ with fuel taken out, guessingly.
and crusing is around 15.0 +/- .3.

Only thing I can think of, is, possible vacuum leak?

Solid 18 in/hg vac at idle. Think that's normal for an EFI car.

 

[IwantMKIII]

this is not a concern that really needs to be addressed. You could run high 15's if you want and be fine, boost is when you should be worried

 

[jdub]

A 10.3 AFR at WOT is a bit rich, but that's better than lean

A 15.0 is a touch lean cruise AFR, but very acceptable...should help on fuel economy.

If you think you have a vac leak, block off the ISCV and PCV hoses with the car running. Assuming the TB plate is full closed, if the motor quits, you don't have a vac leak.

 

[V8hntr]

My problem is worse, I run stoich at idle, but when I am partial load off idle to around 3k rpm, the wbo2 shows 16, 17, 18 way lean. From 3-4k rpm it then engine hesitates alot and seems like there are dips in the torqure curve. At this point the turbo is on full boost and then the afr's come back to 12.xx and 11.xx. The car over heats if I drive even at partial load due to running lean. I dont have any codes, and my fuel pressure is within spec. I am thinking may be my ECU or CPS is bad.

Lex AFM, 550's, PlX wide band, Diamond pistons, shotpeened rods, HKS mhg, SP61 turbo 14psi.

 

[Rockola]

afc neo will not work nice with karmen..

afc 1 and 2 will work