AEM FIC help

[shawnitz]

Hi Yaris world I'm new here and need some help.

Short version of the issue:

Terrible hesitation and stumbling when flooring it. When going from closed loop to open loop with AEM FIC plugged in.

Issue is not there with the the stock ECU (AEM FIC bypassed). Vehicle completely drivable with stock ecu besides the leaner than desirable a/f ratio - so no stuttering when attempting to accelerate.

Long version of the issue:

When attempting to accelerate (change in throttle at any rate ending at the bottom of the pedal travel), there is a terrible stuttering which causes the vehicle to nose dive then back up and then back down for 4-5 seconds until 5k rpm. It is completely undriveable.

I have a 2008 yaris, boosted with zage kit, 250cc green corolla injectors. AEM FIC with Boomslang harness.

Things Ive tried:
1. Every version of the AEM firmware
2. Many hours of acceleration enrichment setting - sensitivity 2% to 50% (max) and all other settings swept
3. Unplugged O2
4. Unplugged coolant temp sensor
5. Response time from 300us to 900us (in 50us steps)
6. Calling AEM tech support which suggested to try different firmware
7. Unplugging (bypassing) AEM FIC which is the only fix for the stuttering during transient from open loop to closed loop.

Asking you guys is the last thing I will be doing before dialing the boost to minimum and completely giving up on this car.

[06YarisRS]

Originally Posted by shawnitz

Hi Yaris world I'm new here and need some help.

Short version of the issue:

Terrible hesitation and stumbling when flooring it. When going from closed loop to open loop with AEM FIC plugged in.

Issue is not there with the the stock ECU (AEM FIC bypassed). Vehicle completely drivable with stock ecu besides the leaner than desirable a/f ratio - so no stuttering when attempting to accelerate.

Long version of the issue:

When attempting to accelerate (change in throttle at any rate ending at the bottom of the pedal travel), there is a terrible stuttering which causes the vehicle to nose dive then back up and then back down for 4-5 seconds until 5k rpm. It is completely undriveable.

I have a 2008 yaris, boosted with zage kit, 250cc green corolla injectors. AEM FIC with Boomslang harness.

Things Ive tried:
1. Every version of the AEM firmware
2. Many hours of acceleration enrichment setting - sensitivity 2% to 50% (max) and all other settings swept
3. Unplugged O2
4. Unplugged coolant temp sensor
5. Response time from 300us to 900us (in 50us steps)
6. Calling AEM tech support which suggested to try different firmware
7. Unplugging (bypassing) AEM FIC which is the only fix for the stuttering during transient from open loop to closed loop.

Asking you guys is the last thing I will be doing before dialing the boost to minimum and completely giving up on this car.

Hey. I assume you have a wideband gauge? Are you getting extreme fluctuations in AFR in the transition from vacuum to boost? What are your fuel trims doing when you get the issues? I had to smooth my fuel map out a lot as I was getting bucking. I have it dialed in pretty good now. When I did have issues, pressing the throttle a little harder always stopped the bucking. I'm also assuming you've clamped your MAF. Some of the Scion guys had to add a 2.2Kohm resistor between the F'IC - and + crank sensor wires. I did this too and it helped with some bucking as well as improved my idle.

I am going to go standalone eventually, as the F/IC is a little too finicky for my liking.

Have you made any adjustments to your 02 map?

Jeff (desircustoms) also has the F/IC. Maybe between a bunch of us, we can get this thing perfectly dialed in.

[shawnitz]

Hi, thank you for the reply!

Yes I have a wideband gauge. I saw your post after search and put the fuel adjustment to 0 between 12 to 15 psia - did not help.

No mater how much I press against the firewall it does not smooth out at all. Completely undriveable unless around 4k rpm when accelerating and even then there is a noticeable hick up - the issues not present with the FIC bypassed.

I did not do any wiring work on this car so not sure about the resistor mod you refer to. Not sure how that would help with stuttering. Going by the data from PC logging, MAF in and out seem good and stable. Also idle is completely fine.

Have made adjustment to the O2 map for getting the part throttle a/f ratio corrected because with closed loop the ECU just ignore any other input in fuel adjustment from FIC.

Long trim is 0-3 in most of the CL area with the FIC plugged in as I used the injector wizard to set the base-map. Without FIC it sits around negative 17-20 in almost all areas. This is all expected and nothing unusual given the larger injectors.

I have a Link G4+ Fury for a different project but the ECU costs more than my Yaris so I would not be installing it. This is supposed to be my daily car and not my project car.

Bought the vehicle with the AEM FIC and tubo kit already installed. Out of the scope of this thread but given the choice I would have went with Greddy Em Ultimate. I have used it before with a different vehicle with great results and found it to be a much better piggyback in every aspect such as capability, logging, tuneability, and ease of use. The only drawback with Greddy is after sale support.

[06YarisRS]

Originally Posted by shawnitz

Hi, thank you for the reply!

Yes I have a wideband gauge. I saw your post after search and put the fuel adjustment to 0 between 12 to 15 psia - did not help.

No mater how much I press against the firewall it does not smooth out at all. Completely undriveable unless around 4k rpm when accelerating and even then there is a noticeable hick up - the issues not present with the FIC bypassed.

I did not do any wiring work on this car so not sure about the resistor mod you refer to. Not sure how that would help with stuttering. Going by the data from PC logging, MAF in and out seem good and stable. Also idle is completely fine.

Have made adjustment to the O2 map for getting the part throttle a/f ratio corrected because with closed loop the ECU just ignore any other input in fuel adjustment from FIC.

Long trim is 0-3 in most of the CL area with the FIC plugged in as I used the injector wizard to set the base-map. Without FIC it sits around negative 17-20 in almost all areas. This is all expected and nothing unusual given the larger injectors.

I have a Link G4+ Fury for a different project but the ECU costs more than my Yaris so I would not be installing it. This is supposed to be my daily car and not my project car.

Bought the vehicle with the AEM FIC and tubo kit already installed. Out of the scope of this thread but given the choice I would have went with Greddy Em Ultimate. I have used it before with a different vehicle with great results and found it to be a much better piggyback in every aspect such as capability, logging, tuneability, and ease of use. The only drawback with Greddy is after sale support.

I believe the resistor mod was to clean up the supposedly 'dirty' signal from the crankshaft position sensor. Some Scion folks apparently put resistors on the camshafts as well. I read that the F/IC is overly sensitive to noise in that/those circuit(s). Not sure if this is true or not, but some claimed a complete 'cure', while others said it did nothing. Maybe it was coincidence, but it seemed to have completely fixed my idle stall that I initially suffered.

Are you confident in the wiring that was done on the car?

I still get some hesitation - with AFR fluctuations - at around 3 psi if I maintain steady throttle pressure. The slightest blip of the throttle smooths things out. I've found that if I slowly and continually depress the throttle through acceleration, things are completely smooth, with no hesitation. If I put the car in cruise, hit a long hill, the car will hesitate (feels like a slight misfire, not bucking or harsh at all) when it reaches between 2 and 3 psi. Either slightly advancing the throttle or letting off a touch eliminates the hesitation. I have learned to drive my car completely smoothly but I am going to pursue a standalone computer or investigate further the ECUMaster DET3, which can apparently do a batchfire fueling strategy which apparently removes the stock ECU from fueling altogether. I believe my AFRs are safe but I installed a water injection system for extra security. I can notice a subtle difference in power (a very minor) drop with the water injection system engaged but it's not enough for me to run the car with it disengaged.

You said that the car was wired when you bought it. Is the busking and hesitation a new development and did it run ok when you test drove it?

[shawnitz]

Thank you for the reply! Much appreciate the support!

I have tried various rates of acceleration change (pedal pressing rate), from smooth to fast and car always becomes undrivable when the pedal reach around 90% of travel. Pressing more does not help either. And this is true at any rpm below 4-5k rpm.

I think the issue is FIC fueling strategy. Its just slow to respond to change as fueling goes from sequential to batch fire in open loop wide open throttle. I say this because the car drove completely fine without coolant temp and O2 sensor during warmup. Due to the fault (ECU OL-Fault), it spray in batch fire the entire time. Yet it switches to sequential when the engine gets hot even without any coolant temp input!

Im not sure if Boomslang harness has the mod already.

Could you share a map you are using with 1NZ please?

[06YarisRS]

Originally Posted by shawnitz

Thank you for the reply! Much appreciate the support!

I have tried various rates of acceleration change (pedal pressing rate), from smooth to fast and car always becomes undrivable when the pedal reach around 90% of travel. Pressing more does not help either. And this is true at any rpm below 4-5k rpm.

I think the issue is FIC fueling strategy. Its just slow to respond to change as fueling goes from sequential to batch fire in open loop wide open throttle. I say this because the car drove completely fine without coolant temp and O2 sensor during warmup. Due to the fault (ECU OL-Fault), it spray in batch fire the entire time. Yet it switches to sequential when the engine gets hot even without any coolant temp input!

Im not sure if Boomslang harness has the mod already.

Could you share a map you are using with 1NZ please?

Interesting. Where did you get the info on the sequential and batch fire sequences for the 1NZ? I briefly toyed with the idea of disconnecting the wideband to see if the car would stay in open loop. Then I could just adjust my fuel map to get my desired AFRs without the ECU trying to trim out the added fuel. I guess it doesn't work that way, though. I'd be happy to share my map, but I have the 2ZR engine and 440cc injectors.

[Desircustoms]

Try playing around with the "maf map". I've had stuttering issues around 3-3.5k rpm at 120km/h, I smooth out the voltage on the maf map around 3-4k rpm and it stopped stuttering.
I wish I had the stock maf voltage data, so I could build the map accordingly.

[06YarisRS]

Originally Posted by Desircustoms

Try playing around with the "maf map". I've had stuttering issues around 3-3.5k rpm at 120km/h, I smooth out the voltage on the maf map around 3-4k rpm and it stopped stuttering.
I wish I had the stock maf voltage data, so I could build the map accordingly.

Interesting! When you say smoothed out the voltages, did you just make the values between adjacent cells closer together?

Here is my current maf map.

[Desircustoms]

Originally Posted by 06YarisRS

Interesting! When you say smoothed out the voltages, did you just make the values between adjacent cells closer together?

Here is my current maf map.

Yes, exactly... I 1st tried something similar to yours, but had some issues, now its starts from 1v to 3.8v... Will post a screenshot later.

[06YarisRS]

Originally Posted by Desircustoms

Yes, exactly... I 1st tried something similar to yours, but had some issues, now its starts from 1v to 3.8v... Will post a screenshot later.

Awesome! I look forward to a pic of your MAF map. Thanks!

[Desircustoms]

Originally Posted by 06YarisRS

Awesome! I look forward to a pic of your MAF map. Thanks!

I actually think I might have a leak somewhere, maybe that's why I have to crank the voltage higher than you. And we also have different engines.

My car is always stalling when idling ever since the cold started... Will post more on my thread whenever I figure it out.

[06YarisRS]

Originally Posted by Desircustoms

I actually think I might have a leak somewhere, maybe that's why I have to crank the voltage higher than you. And we also have different engines.

My car is always stalling when idling ever since the cold started... Will post more on my thread whenever I figure it out.

Sorry to hear that man. Do you have leak testing stuff? I had idle stalling before I installed a resistor on the crankshaft sensor wiring, but my stalling occurred when the engine was at operating temp.

[Desircustoms]

Originally Posted by 06YarisRS

Sorry to hear that man. Do you have leak testing stuff? I had idle stalling before I installed a resistor on the crankshaft sensor wiring, but my stalling occurred when the engine was at operating temp.

Thanks I will try the resistor soon, it might be the culprit, as I had crank sensor code came up once or twice throughout the summer.
I double checked and tighten all the clamps. I tried swapping spark plugs, shortened the gap to .03" and it still dies at operating temps. It must be fic related because it still does it after I zero'd all the maps, and the car was running fine before I wired the fic.

[06YarisRS]

Originally Posted by Desircustoms

Thanks I will try the resistor soon, it might be the culprit, as I had crank sensor code came up once or twice throughout the summer.
I double checked and tighten all the clamps. I tried swapping spark plugs, shortened the gap to .03" and it still dies at operating temps. It must be fic related because it still does it after I zero'd all the maps, and the car was running fine before I wired the fic.

Yeah, I found out about this fix on the Scion forums. The theory is that the F/IC is overly sensitive to the somewhat 'dirty' signal from the stock sensor. Apparently, the 2.2Kohm resistor bridging the crank sensor + and - wires cured problems for many, but not for everyone. I think that the experimentation that resulted in a cure was designed to address mid range RPM bucking, but a side effect was improved idling. Unless, it was purely a coincidence, my car's idle issues completely disappeared when I installed the resistor. I can't remember the wattage rating of the resistor, but I think it was 1/4 watt or something like that. I actually bought a pack of 8 or 10. I could mail you a couple, free of charge of course, but it would probably be easier and quicker for you to pop into an electronics store and grab a few.

[Desircustoms]

I found a 2.2k resistor in my electronic stuff, soldered between crank magi- and +. It fired up, got to temperature, and it stalled while idling, a bit after i revved it a couple times.

I read somewhere that you didn't wire the cam magi?

[06YarisRS]

Originally Posted by Desircustoms

I found a 2.2k resistor in my electronic stuff, soldered between crank magi- and +. It fired up, got to temperature, and it stalled while idling, a bit after i revved it a couple times.

I read somewhere that you didn't wire the cam magi?

Sorry to hear that it stalled. Dang. No, I did not put a resistor on the cams. I didn't even wire the cams into the F/IC. Did you wire your VVTi into the F/IC? I see you're running PVC tubing for your vacuum lines. I don't suppose that's collapsing under high vacuum at idle? Probably not, as it would likely cause problems right away as opposed to only when at temperature. Could the tubing be getting softer at operating temps? Not sure if vacuum itself is related to temp or not. I know that when I installed my catch can, I used rubber transmission hose or similar and it sucked flat under vacuum. I had to replace it with hydraulic hose, probably because I used a larger - more likely to collapse - diameter tubing. Just a thought.