A/F lean at idle and cruising with VPC/SAFC

[kikdurazz]

So the car has been completed with installs of new parts.
Gone to a GT35R on T4 setup
With HKS VPC/safc combo

Previous setup was a Lexus afm/ safc
Ct26 60-1 with 10 degree clip

Mods on the car:
550 injectors
walbro 255lph pump few years old now
AFPR(have to check what pressure is at)
J tube block off
no egr
3 inch exhaust
2.5 intercooler pipes
Spearco intercooler
GT35R
T4 manifold
with external gate
Aem uego WB

Now we got the car running and want to get it out to the dyno for tuning but to do that I have to drive about 1 hr outta town.

When I drove the car home from the shop yesterday the car idled at around 14.5 up to 15 on the WB when it was warmed up.
Cruising home in light traffic the A/F were hovering around 15-17 with light load. Alot of times it would just go to the extreme lean and no numbers reading.

when I got on the hwy at 23-2500rpm it was 15 and beyond generally not reading just the 2 lines on the wb in the red. This is with 10% throttle applied reading off the safc to keep a steady RPM. If you give it a steady tromp on the gas more then 30% throttle it starts to go richer between 12-13.

Obviously this had me worried on the way home. Should the cruisng A/F not be closer to 14-15 as the ECU is doing all the correcting?

1. First time with a WB in the car so I have no idea what is normal to see on a WB while driving in traffic and on the HWY/
2. All the settings on the safc are from the last setup and the vpc is newly added.

So should I:


A: set the safc to 0 correction on lo/hi throttle and vpc to 1200 on all nobs and see what it does at idle
check fuel pressure and make sure it is set to base(checked tonight with vac line on FP is at 32-34psi)
B: just leave things as is and drive out to tuners
C: tow the fucker out there (which would cost a fortune)

If you guys need more info let me know I just wanna get this thing running right before doing power runs.

 

[speedgilligan]

ummm, pick one? you have two conflicting piggybacks going on here...

correct me if im wrong, but the VPC completely negates you needing an AFM by providing the ECU with a signal from a MAP sensor, and the SAFC interrupts the AFM signal. So your ECU is a little confused.

 

[Devin LeBlanc]

And you should never touch the low throttle map in the SAFC as it will screw up the VF.. Only adjust the high throttle.. Set the throttle points for 80% so correction only comes in passed that point..

 

[91Supra313]

I talked to Carma Performance in Nashville TN ( a few miles from me ) and they said that the SAFC and the VPC need to be wired a certain way together in order to not conflict signals. Once I get some light mods done this winter, I will be taking my car out there and having them install my NEO. I also have the HKS F-Con on mine so I really have conflicting signals. My AFRs are messed up too. Normal highway driving around 3000 with light throttle, I am around 14.5-15. Sometimes it dips into the 2 line mode that you are talking about. So it tends to be WAY too lean. But in my eyes, if I am going to have a messed up AFR, I would much rather be too lean then too rich.

 

[kikdurazz]

ummm, pick one? you have two conflicting piggybacks going on here...

correct me if im wrong, but the VPC completely negates you needing an AFM by providing the ECU with a signal from a MAP sensor, and the SAFC interrupts the AFM signal. So your ECU is a little confused.

I'm not sure I understand your response. The Lex AFM is gone, the vpc replaces that. The safc is wired in between the VPC and the ECU to clean up the signal that the VPC is outputting. The safc will allow for fuel tuning for when I start doing wide open runs.

What I want to know is How do I fix this cruising A/F mixture that seems to be going way to lean. I believe the ECU should be taking care of everything in closed loop regardless. Adjusting the knobs on the VPC or adjusting the throttle settings on the safc make differences in the A/F but I shouldn't have to do that.

So it should be something else causing the problem just want to know where I should start looking at what needs to be fixed.

 

[89supra7mgte]

i just installed the gt40 on my setup i in the 16s at idle, no load, cruising i am in the 14-15 no boost and low vac. but sometimes it will go way rich no load. have the safc2 no lo throttle settings. Need to wire in my lc1 with the factory o2 cause it is not installed (factory o2) and think that is fucking my ecu off. but not sure if disconnecting the oe o2 will create problems or help?

 

[QWIKSTRIKE]

cruisng at 14-16 is ok.....this is a good fuel economy setting. Going 12-13 WOT isnt bad but a lil to lean for a piggy back for my taste

 

[89supra7mgte]

i dip down into the 10 full boost but made good power=bad mpg. has anyone ever installed a wideband and no 02 with any problems? i just ran my factory o2 into the lc1 so that i can eliminate o2 for now. still sends a narrowband signal to ecu. when i check the vf at diag block it is at 4.9? if i remember right that means the ecu is seein lean so it will adjust right? the wideband reads 14.4-15.3 at idle. when i check the o2 reading at diag it is fluctuating from .110 to .720 (that reading is coming from lc1 to ecu)

 

[kikdurazz]

cruisng at 14-16 is ok.....this is a good fuel economy setting. Going 12-13 WOT isnt bad but a lil to lean for a piggy back for my taste

I would be happy if it was between 14-16 but the A/F are going off the scale at light throttle. On the hwy it is basically 90% of the time at 15 and beyond alot of the time not even registering on the WB. I thought at cruise at a steady RPM it should be as close to 14.7 as possible.

If I adjust the vpc to 12 o'clock on all settings and the lo throttle on the safc to 0 then the car goes lean to 16-17 now at idle. Something is messed up because the ecu should be managing the idle a/f.

Where should I start to see what is messing with the A/F ratio's. Kinda frustrated as I just got the car back and basically can't even drive it and now it will be heading into storage for winter soon. Would like to get this sorted out before snow flies so next spring can get on the Dyno and start making pulls.

The WB is new so this probably could have been there before I went to VPC/SAFC combo. I have no idea who messed with the lo-throttle map must have been from previous tune (not regular tuner) for when I went to the track that adjusted it.

So maybe there was an A/F ratio problem at idle and low range that they didn't tell me about. Is there a process to go through to check and see what could be causing the lean idle and lean cruising scenario's?

It also take along time for the car to fire on initial start up. 20-30 seconds of cranking, runs real rough and then the idle smooths out. Could it be fuel pump? cold start injector? I don't wanna be replacing needless parts on a hunch.

And strike I haven't given it A WOT run as I don't want to pop something but the car does go richer at 50% throttle 70% I was seeing 11's on A/F

 

[kikdurazz]

So I just did a jumper between Te1 and E1 to check codes and get a code 43,
Starter signal.
<No STA signal to ecu until engine speed reaches 800rpm with vehicle not moving> Check ignition switch circuit, ignition switch or ecu

I can't see this as being the problem for me running lean at idle and cruise, although this probably explains my horrendous cranking time.

I zero'd everything out on the safc lo-throttle settings and put the VPC to 1200.
At idle the car is sitting 16.2-17. A/F and idle is low 550-600rpm(this car was auto to manual swap years ago does have a manual ecu in it idle was never this low prior to the work)
I notice my vac on the boost guage seems alot lower as well. 13-14inhg when I was sitting 16-18inhg prior to the work.
Give it a stab of gas it hesitates wants to stall and then will pick up the RPM and the wide band will go to 14-15. then immediately back to lean.
If you give a steady throttle at say 2500rpm for 5-10secs it goes unreadable lean and the exhaust gives a gurgle and pop as you let off.

FP is reading 34psi with the vac line, give it throttle and the fuel pressure does react to throttle movement. When you shut the car off FP only stays in the gauge for 30-60secs and then slowly drops off the 0. that doesn't seem right.

Any ideas on where to start guys? Car is going back to the shop on Wednesday to try and figure this out they think most likely vac leaks, but if not that kinda wanna know where to look next.

 

[kikdurazz]

So I just pulled the EFI to let the ECU reset and turned the VPC knobs all to 1200 and zero'd everything on the safc.

Took the car for a drive and with this setting the A/F at idle was 16-17 and running rough like it wanted to die. idle was 500-550 give it gas and the rpms would drop like it was gonna die and then it would respond and increase.

I then adjusted the Gain to the 5 o'clock position and the RPM's picked up to 650 and was idling at 14.2 -14.7 a/f took it for a drive and in 5th gear at 35mph and 1800 rpm it is around 15.5 a/f

on the hwy at 60mph 2400rpm the A/F is still going 17.0 with 10-13% throttle.

Could this just be a tps issue?
When I down shift the car exhaust is popping.

Guys with VPC/SAFC setup's have you had to adjust the gain or idle at all? I thought everything just gets left at the 1200 position and you need to tune the hi-throttle points on the safc for WOT runs.

 

[mk3tattoos]

sound like a vac leak, plus exhaust leak. go through and check all the lines and zip tie them to be sure there not leaking, while the car is in cold start check with your hand around all the areas were the gaskets are on the exhaust . what is your vf reading, did you hook up your safc to read vf? if not it might be a good idea to do that.

 

[kikdurazz]

Someone just pointed this out to me in my build thread. How should the IACV be run with speed density.
It appears the shop T'd it into the PCV system.

Should the IAC go to the intake or just a filter put on it? Something is backwards here, car is in the shop now so I can phone them on friday to correct it.

Hopefully this solves some or all of the problem.

 

[TRG22]

Someone just pointed this out to me in my build thread. How should the IACV be run with speed density.
It appears the shop T'd it into the PCV system.

Should the IAC go to the intake or just a filter put on it? Something is backwards here, car is in the shop now so I can phone them on friday to correct it.

Hopefully this solves some or all of the problem.

Mine just has a filter on it, not sure this would effect your idle or A/F ratio though...

 

[kikdurazz]

So got the car back from the shop and this is what they have checked.
Vac lines tight and secure no leaks. Vac at idle(my guage was incorrect) is at 17-18inhg
No boost leaks.
No exhaust leaks.
Timing checked and is at 10degrees BTDC at idle
TPS checked and is within spec
Checked injectors and wiring with in spec
Checked coolant temp sensor and wiring with in spec
Checked map sensor within spec
Went over wiring to VPC and safc.

Checked VF and it is reading .03-.1 volts at idle. Although I'm not sure he did this test at Te1 and E1 in the diagnostic :/

Idle A/F is closer to 14.7 with the idle knob up 2 clicks on the vpc but cruise A/F on the hwy remains 18+

The car has been put away for winter now so i'll have to regroup in the spring but any ideas on where to look next when we get back to it?
He's wondering if even with the coolant sensor reading within spec at cold and warmed up if it is taking a dump during driving giving the ecu an improper reading.

 

[Kristian_Wraae]

Did you ever figure this out?