UCON Flex Advanced Engine Management System

If you do a hard reset of the ECU/UCon for more than 3 minutes, does the problem return immediately? I am wondering if this is a problem caused by some values that UCon has learned/adapted to

This is personally where i would start troubleshooting

 

Yeah... as good as the UCon is, sometimes it does seem to confuse itself and needs to be given a timeout and disconnected for 15 minutes so it can think about what it's done.

 

I've logged it and discussed with Scott. You can clearly see the event and the vehicle pulling throttle despite command. He feels like there's an issue outside of the UCON, but I haven't been able to confirm this.

From Scott:
"Regarding the unexpected decel:
I do see the throttle pulling back from 21 to 8.79 when the pedal is firm increasing (plot 2).
Mass airflow is spiking high then low (toggle) around the event (plot 3, point 2536)
The CAMs are both falling from 16 to 6’ around the same point.
AFR control is nominal – no lean spikes.
Engine acceleration does not decrease until 300ms later.
Spark angle is being driven by torque control mode…

So the MAF toggle presents like a physical issue.
It occurs before the throttle drop.
And you mention that this only happens more when turning.
I would examine your air induction pipes.
Make sure there are no vacuum leaks and all pipes are moving when the vehicle flexes during turning…
It could also be related to bad wheel speed sensor going into the traction control computer (UCon does not access).
Try keeping traction control off and see if the unexpected decel disappears…"

Here's a screen shot of the event.


I still am a bit confused by the whole situation. Since this occurred, I have installed the Nomad Valve body, and I feel like this happens "less frequently". I do feel like this very well could be connected to the traction control/ VSC system. Sometimes when I'm accelerating in a straight line, the engine will pull the throttle back repeatedly during the same acceleration run. I won't get a traction control light, which is weird! This throttle oscillation (full to no throttle) can happen 10 times on the same acceleration event. However this doesn't always happen, it's usually if I've gone over a bump in the road or some sort of uneven traction event.

In an unrelated event yesterday, during a light sweeping turn to the right while under firmer acceleration, the traction control light kicked on and lightly modulated the throttle at around 45mph. This event was a great application of the traction control system, and not what I'm describing above.

I do wonder if this could be related to my VSC system. I think this was the first year for it. Do you guys have VSC? I think it was mandated only for the suv's during the 2007 year?

 

Lol, my thoughts exactly.

Id personally recommend resetting it and then try driving easy to let it relearn that part of your driving style.

 

I have VSC on my truck, yes

Since this is such an intermittent thing, i am wondering if this is a bad connection somewhere. During my UCon troubleshooting, i took my ECU and UCon apart several times and cleaned both the truck harness, the ECU, and the UCon's connectors with a couple cans of contact cleaner. This might be a good starting point. I also cleaned grounds on the valve covers, and the main one near the negative battery terminal. Just thinking out loud here

 

I want to add to this that ever since I've gone to 315's, I can clearly tell that I have a much higher center of gravity. The change from 295's to 315's was significant. I also am currently running without a front sway bar (testing) and I intend to revert back to the sway bar. My body roll is significant and I wonder if this in any way can contribute to an over active VSC. Usually, if VSC kicks in it does so with an audible alert and flashing lights on the dash. Its quite the moment really. However, like I've said earlier, I'm not seeing any of this when I feel the throttle cut issues. I'm curious if the vehicle is utilizing the data and quietly making calls for brief throttle augmentations among other parameters as a means to straighten up the vehicle.

 

Interesting. I don't have VSC on my truck any more. When I put the after-market steering wheel in 7 years ago, traction control and VSC just gave up and hasn't worked since. I prefer it that way, I never found those systems useful or comfortable. And I live where the roads get like skating rinks.

 

I would say it definitely can, as i have a 3" lift, no sway bar, and 295s on my other taco. My vsc cuts my power if i go into a corner too fast and sometimes in other stupid situations where it's not needed(even after resetting it using this thread) but it always blinks the lights and chirps at me when it does this, so i am not sure thats whats happening in your case.

 

Thank you for the info. I will make sure to put my ECU in time out tonight and see if it happens right away. There is one particular corner it seems to always do it on. It is an uphill right had corner. But on that note, my truck does not have VSC or traction control. It is an '06 and never had it. But I do know that my clock spring is bad as I have not had cruise control in over 5 years and have put a new switch in it and that didn't fix it. But have no airbag light yet and the horn still works. But since the 4.88's no cruise is bugging my wife because I always seem to slow down giving the the sound of the engine screaming at 2900RPM. Maybe I will fix that and see if that might be something that is causing the ECU and Ucon's relationship to not like this corner. And to second guess my plan to reset the ECU/Ucon, do you think I should do that now given that I only put about 6 miles a day on the truck and am planning on towing the camper 130 miles Friday night. Or wait until I get back from camping?

 

Do it NOW. UCon takes about 200 miles to relearn everything from what ive come to find out.. Mine runs all kinds of wonky until it has about 150 miles on it, then it's all smooth sailing. Truck will also make a good bit more power if you let it relearn since it can figure out the fueling and adjust timing advance appropriately. After resetting UCon it retards timing a good bit until it relearns. I can tell a noticeable difference driving the truck after i let the UCon learn for about 150 miles

 

I would also do it now since you tow often, you can use that towing for the UCon to learn that aspect of driving as well

 

But is it going to be good for it to re-learn while being loaded up to 6500lbs and towing 7800lbs? Or hell if it learns that, it might just take a breathe of air and run like a raped ape when not loaded down! LOL

 

Doesn't the FJ have a yaw sensor, like the 4Runner? Is so, disconnect the ABS plug on the master cylinder(assuming the same as the 4Runner) or pull that fuse. Then try the same driving styles.

This, or set a gas cap CEL.

This is what we have to do on Lucario Runner's 4Runner, when he races.

 

Yeah, this is the next step for me.

A lot of FJ guys just throw in a vsc cancel switch on the purple blue with yellow tracer wire that goes from the master cylinder to the driver’s side kick panel. Pin 26 on connector A4.

edit: The blue wire mod may only work on vehicles with the factory e locker. Others have also thrown a switch on the purple wire that goes to the plug you mentioned. I think with the blue and yellow tracer wire, you may not need a restart to return to normal.....

 

I think itll be fine learning while towing. Might be better for it to learn that way actually since those are the loads the motor is put under regularly

 

Well I reset my ECU/Ucon last night and also sealed off my snorkel to intake and vented the lid of the AFE airbox with some diff drop spacers to lift the front edge when I boost so the airbox doesn't cavitate like it did when it was all sealed up. Noticed that with it sealed up and the snorkel head turned backwards it is not cooling off the IAT nearly as fast as when the box was sealed but drew air from the fender and the snorkel. Thinking I will turn the head around for the ram air effect and any excess pressure should be lost due to the lid being open a bit now. That will hopefully not cause chaos with the MAF sensor. But I am really having a hard time believing that the snorkel is causing crazy turbulence on MAF given I run the Dondaldson air filter and the distance from the air box and filter of the MAF. But we will see. It drives smoother already though. But that is with the head facing backwards. I know pretty much everyone with a snorkel runs the head forward and I did for a very long time. But before the Ucon.

 

Finishing my 7th install tonight. Got everythign wired up just need to add the tee to my fuel rail tap and hook up my fuel pressure sensor. Hoping i can get it flashed with the stage 3 tune in the next few days

 

Gday I’m interested in getting the ucon-ems, cam gear and thermostat kit and wondering if anyone has any recent experience with it all and if it will work with a 2004 1gr-fe prado 120 cheers

 

That is a really good question. Not sure if the plugs on that OEM ECU are the same as the '05-08 Tacoma, same for the 4Runners, and 07-09 FJ Cruisers?

Find that out, and you'll be one step closer.

 

Looks like it doesn't start coverage until 2005 MY. Just reach out to Gadget and see what he has to say.
https://www.urdusa.com/ucon-ems-advanced-engine-management-for-toyota-1gr-fe-4-0l-v6/