Trying to tune car with SAFC II and Zeitronix Wideband, can't get AFR low enough...

[teedoff00]

Hey Guys,

I hope this will all make sense to everyone other than myself. Car is an 86.5 Turbo Swap (rebuilt motor with mls head gasket), I am running a Aeromotive AFPR, 550's, Lexus AFM, SAFC II, AEM Tru-boost, and a Zeitronix Wideband for data logging. If anything else is relevant let me know.

I recently installed my rebuilt turbo due to excessive deceleration smoke (thought blown turbo seals) the turbo did have quite a bit a shaft play. They were able to rebuild it (I believe it may be the dreaded 60 trim CT-26 forgot to have them measure it, but it came with the turbo motor when I did my swap, wish it were a 57 trim...)

After the install, I decided to try and get her "tuned" a bit with my AFPR, SAFC II and Zeitronix Wideband. I have always ran with my fuel pressure at around 25 psi with the vacuum line connected. There was about 5 months between the car getting parked and the turbo getting rebuilt because of Utah Winters, so I am kind of just getting the car out of the garage for Spring/Summer.

After the turbo install, I had to raise my fuel pressure to 29 to get my AFR's closer to 11 so I wouldn't be running too lean. Even at 29 psi (vac connected) I can't seem to get my AFRs any lower then about 13. I have the boost set at about 10 psi (according to the Kalvico Zeitronix sensor). With boost controller off and about 6 psi of boost I dip into the low 12's, but I can't seem to get it to enrich. This was with almost 20% correction from about 4000 rpms to 6000 rpms on the SAFC II !!!

Something has to be wrong, according to TSRM fuel pressure with the vac connected should be 23 to 30 psi, I am at 30, and have added lots of fuel (more than I consider safe with the SAFC) and I am still running lean. I have visibly inspected the vac line connected to the afpr and it seems fine, I will be checking that tomorrow.

What could I check? There are no codes, and everything else looks and runs fine, just can't run high boost for fear of running lean. Could the injectors be clogged? I run premium chevron, but haven't run any fuel system cleaner in a while, I did however replace the fuel filter around when I installed the turbo.

To boot, I still getting huge amounts of deceleration smoke, when I let off the gas after boost, it doesn't seem to be oil (and the turbo has no shaft play) could this be related?

Sorry it's long, any help or advice would be greatly appreciated. I would love to get it figured out so I can run the same pressure I was running before the rebuild. (around 14)

Thanks again!

 

[isnms]

You don't list a fuel pump.
Turn your AFM screw all the way in.

 

[teedoff00]

Thanks for the reply. I did forget the fuel pump. Its a fairly new walbro. I didn't think of the screw, I will turn it in as soon as I get off work and give it a go. I try resetting the the SAFC back to zero correction and see what I get.

Thanks!

 

[teedoff00]

Ok, this is confusing the hell out of me! I don't know what I have screwed up, or where to begin.

I turned the screw in (most of the way, however I didn't bottom it out) on my AFM, I set the pressure back to 25 psi and I zeroed out the correction on the SAFC II. I set my boost controller to about 12 psi, which on the Kalvico map sensor reads at 10 psi (there is quite a difference between the two...).

I am still running way lean! I tried adding correction on the SAFC, up to about 15% and saw a drop in AFRs at the end of gears while boosting to about 13 to 1.

According to the Zeitronix, the vf signal is also always 5.0V during cruise, and 0.0V under vacuum (downshift). I thought that in closed loop I was to be seeing near 3V, meaning the ecu was content with the narrowband switching point. (set to the default 14.7)

Where should I start, I don't see how to get even close without uping the fuel pressure back up to 30psi.

Any help would be greatly appreciated!

Thanks again...

P.S. I have a new odd symptom. When the car is started (cold) it runs like crap, and the AFRs are 18+, it feels like it is starved for fuel and it doesn't go away for about 10, then it acts normal. The car is already warmed up (per dummy temp sensor) around 5 minutes.

 

[TurboStreetCar]

In my experience with VF upon initial startup, boosting moderately to heavy, and deceleration the VF signal would drop to roughly 0 volts.

In my experience any time the engine was in open loop for the above conditions or in fuel cut operation for decel i saw zero volts. Im stating in my experience as i have herd of others having different results.

Any time the engine is running under normal conditions such as idle, cruise or regular off boost, sub 4000rpm operation the VF signal is a direct visual of the real time fuel trim.

2.5 volts or something in that area is neutral. This means the base fuel map the TCCS created, combined with long and short term fuel trim is achieving a correct air/fuel ratio.

When the voltage is higher then that it is adding fuel. The higher the voltage the more fuel it is adding.

When the voltage is lower then that it is pulling fuel. The lower the voltage (aside from open loop operation in my experience) the more fuel it is pulling.

You need to tune the SAFC to maintain 2.5 volts on the VF signal at all times. When i was running the MAFT GEN2 i was running stock injectors and a stock AFM so i made ZERO correction until my load point (based upon TPS) of 90% was reached.

I set the load point so high as i knew if i ever was at that throttle position i knew it would be in open loop and my corrections would go unnoticed by the TCCS.

If you make correction in closed loop the TCCS will see the correction based upon feedback from the 02 sensor and it will RE-correct, undoing whatever you did. Not only does this effect closed loop operation but the correction factor is written to the open loop fuel map as well. This means at WOT it will not run as desired because the tuning was ruined by the closed loop feedback.

If i were you i would first set the fuel pressure to 40psi with no vacuum, zero out the SAFC and pull the EFI fuel to reset the TCCS.

Start the car and see what the air fuel ratio and the VF is telling you. Since its the stock TCCS and there is no changes made to the tune, adjust fuel pressure to obtain a 14.7 ratio and 2.5V VF signal and make note of that fuel pressure with no vacuum.

You need to get a baseline of what the car needs before trying to make changes. Since the AFM and injectors would make a "main scale" like change to the entire tune as a whole, adjusting fuel pressure would make the same change and should be able to equal out whatever effect the AFM and injectors are having on the tune.

 

[teedoff00]

Thanks for the help NoseChunks. I know I still have a lot to learn when it comes to the TCCS. I appriciate the help all the same. I don't think I really understan how to use the SAFC, so today I am going to try and read up on it. I will most likely post again with more questions
Thanks again guys!

 

[NashMan]

what wrong with 30 psi


if you play with that little toy and nothing is happening i would go over the wiring and then make sure the unit works right

 

[teedoff00]

OK. I plan on doing what you suggested right after work Nosechunks. I do have a question (after reading the SAFC literature again) regarding the operation of the SAFC. I have heard in the past, and I could be mistaken, that closed loop adjustment with the SAFC was pointless because the TCCS will basically throw it out like you said, so does that mean that the Lo-Throttle setting in the SAFC should be zeroed out? I would guess that Lo-Throttle will only affect the closed loop operation. As to the switching points for Lo and Hi Throttle, where should I be looking to make adjustments? I originally started with 10% for Lo, because it was zeroed out, and about 25% for Hi. I figured if I start building boost at around 25% throttle (usually at the earliest, but it is more of a concern when doing highway speeds in 5 gear and building boost up hills at fairly low throttle %'s) then I would be safer because of the correction that the SAFC would make after 25% throttle.

Is this the correct thinking?

I plan on turning the AFM screw all the way in, resetting the TCCS (pull EFI fuse), starting the car, and setting the fuel pressure at 40 psi off vacuum. I will then see if I can get that vf signal at 2.5V, my trouble has been in the past, and some have said it may be because of the bigger AFM, that I really get high AFR's at idle due to stalling of the sensor. Most of the time after the cold start injector kicks off, my car idles at about 17:1. So I guess I will just tune to get that 2.5V.

Hopefully this will put my open loop map closer to where it should be (in the past I have had no problems achieving low 11's and high 10's at 14+ psi of boost), and then I can make *fine* adjustments to the SAFC to get it "perfect" instead of the +20% I have been having to make to get it closer.

Nashman- Thanks for helping, I think 30 psi would be a little high on vacuum, would it not? I guess the TSRM specifies 23-30, so I am definitely at the high point. The problem I am having, is that I am currently at 10 psi of boost, 30 psi of fuel pressure with vacuum, and about 20% correction added on the SAFC between 4000-6000 rpms, and I still am having trouble getting lower that high 12:1's. So hopefully my closed loop map has screwed with my open loop map, and resetting it and starting over will fix it. Thanks!

Thanks again for the help, I will be reporting back soon.

 

[TurboStreetCar]

That is correct, any correction in closed loop will be undone based on feed back from the o2 sensor.

Set everything to zero so your starting from scratch. It should be relatively close with 40psi of fuel pressure with no vacuum.

Note the air fuel ratio and VF at idle after warmed up.

 

[teedoff00]

Ok, I tried to get it close and I can't see a significant change in pressure on my AFPR when on vacuum and off. When I set it to 40 off vacuum, it only drops to about 36 psi on vacuum.

I get suction from the vacuum line connected to the AFPR, but it doesn't seem to be working as I figured it would. Does it mean that my Aeromotive has taken a shit on me?

Thanks again.

 

[TurboStreetCar]

The fuel pressure should drop the same as manifold vacuum. Inhg is inches of mercury. That is usually what vacuum is measured in. to convert it to PSI it is pretty close 2:1. 2 INHG is about equal to 1 PSI. You should have approx 18-20INHG of vacuum at idle, that is roughly 9-10PSI of vacuum. MY motor sees 9.6PSI Vac at hot idle.

Fuel pressure should change that amount when switching from on to off vacuum with the engine running.

What is the air fuel ratio at that time? If the motor is struggling to run manifold vacuum will be lower. For instance if the mixture is verry rich or very lean, or if the timing is very retarted the engine wont be running efficiently. The engine will be working harder to maintain an idle and that will reflect in manifold vacuum. The low change between off and on vacuum could be because manifold vacuum is only ~4PSI or ~8inhg.

 

[teedoff00]

The car is definately having a hard time idling. The weird thing is, it mostly started having problems about 2 weeks ago, the two weeks prior to that it was running great, save for the leanish mixture under boost (I was able to get into the low 12's high 11's with quite a bit of SAFC adjustment and 30 psi of fuel pressure)
Now when I start it cold it struggles to run, and when driven won't accelerate even when throttle is +50%. It chugs and shows a lean mixture (infact feels like a huge maf leak, except for lean mixtue recorded not super rich like with a MAF leak). These symptoms stay even after the engine warms up (per dummy sensor) until I turn the car off and restart it. Then it idles fine and drives fine, but I am still lean under boost.
If I set the AFPR. To 40 psi off vac and then turn it off, pull the efi, put efi fuse in, restart it and make a pass with zero correction on my SAFC and have my AFM screw all the way in. Should I be rich (theoretically) under boost? I thought I had the vf fairly constant at idle and cruise at around 2.3V. But then I drove it for a while and it changed to ~3.5V at idle and cruise.

I am so confused, I am not really sure what could be causing this.

Thanks again for the help!