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The car does not need to be running. If you press the throttle while looking at the commander the VTA1 should run up and down from ".51" to "1.25" (*) to show the throttle valve axis turning.
((*) I am not sure about the 1.25. The upper reading might be higher. Perhaps check the forum threads.)
If it does not react smoothly to your throttle pressure it may indicate the throttle is sticking, or the TPS, is sticking and confusing your ecu.
The positioning of the TPS is a bit tricky. If it is not mounted just right, it could throuw those readings off.
You can also get the commander to show graphs. When the car is running, show just the graph of the rpm and boost.
In my car the graph lines moved opposite of each other (up and down) for about 20 cycles, then the ecu settled at a fixed 1000 rpm and the boost straightlined as well.
This pattern went away when I corrected a vacuum leak (or two).
My understanding is the Power FC does not depend on the 02 sensor reading.
Looking at a video of my VTA1 and VTA2 test. The VTA1 ranges from 0.53 up to 4.95. The VTA2 ranges from about 2.5 to 4.95. Both in response to the throttle movement.
All this you just posted is extremely helpful research information. As for the O2 I don’t think it matters if it’s malfunctioning because most people just disable it anyway since it’s air pump and ACV related both of which are disabled in my car. I disabled mine and still doesn’t make a difference. I was thinking of resetting the apexi base map and letting it relearn with O2 disabled. Also it never had a base map before just in case you’re wondering. The TPS sticking might be it. It’s just so weird that it ran totally smooth and fine 2-3 weeks ago (even with O2 feedback enabled) and now it’s idle doesn’t seem to stabilize and it stalls when I try to go into first gear and drive
The car does not need to be running. If you press the throttle while looking at the commander the VTA1 should run up and down from ".51" to "1.25" (*) to show the throttle valve axis turning.
((*) I am not sure about the 1.25. The upper reading might be higher. Perhaps check the forum threads.)
If it does not react smoothly to your throttle pressure it may indicate the throttle is sticking, or the TPS, is sticking and confusing your ecu.
The positioning of the TPS is a bit tricky. If it is not mounted just right, it could throuw those readings off.
The FSM will also show the proper ranges.
according to Mazda 1.25 is within the limit so that’s weird and rules it out at least
. VTA1: closed 0.10 to 0.70. open 4.2 to 4.6. VTA2: closed 0.75 to 1.25. open 4.8 to 5.0.
are the official ranges.
do you think it could be because the car isn’t fully warmed up? Like maybe I have to let it relearn idle when the car is fully warmed up? Because it took awfully long today to warm up and I don’t think it got to learn with the car fully warmed up. Will try to let it. I think something with water temp levels that the ecu reads and idle go hand in hand.
also does cutting the 4 wires to ecu matter? I have a USDM Cali 93 FD. I mean it ran great before without cutting the wires 2-3 weeks ago so I doubt it but still food for thought.
1. warm up first to 84C
2. reset pfc and let it relearn
3. see if it improves after learning while car is warmed
really appreciate you for helping me man. You go out of your way to get your own stats and that means a lot. Thank you
Perhaps check your vacuum hoses again. One might have popped off or cracked.
If your Power FC came with a tune, that tune may be out of sync with the current state of your set-up.
But I don't know about resetting base maps.
If the PFC is not getting a reading it is looking for it may assume a range and run with that.
hmmm I just did a whole silicone vaccum line replacement job with zip ties at the end to hold them extra secure so I don’t think that would have happened but doesn’t hurt to try to check again.
the pfc did come with a tune but I reset it long ago. I know how to reset via the re init all in the etc section of the apexi. It ran great the first time I had started the car up 2-3 weeks ago. Really great actually and it didn’t have a tune just learned off of idling but I reset it again after that. Going to try to reset it again tomorrow after it’s warmed up and in warmer weather. Actually today I did the idle learning procedure with the crossover tube popped off on the turbo inlet end so maybe that effected it since it throws off air ratios? Tomorrow will tell
In the mode of checking the simple things first:
There's a good chance that all that idling, especially if the mixture was a bit rich, has fouled the plugs. On a rotary, once fouled, plugs are almost impossible to clear up w/o hard running.
So, if it were me, I'd replace with new plugs and try again.
I wonder if your thermostat is stuck open causing the long warm up.
I'd be concerned about snipping any wires to the ecu.
I am not sure how much the Power FC can learn by itself, I get mixed information from my tuning shop.
I would leave adjusting the Power FC tune to the shop.
If you don't have a wideband AFR gauge, and you are not ready to spend $800 or so to have one rigged in, I have seen techs rig an afr sensor to the tailpipe and run the wires externally to a hand held gauge in the cockpit (so they can read the gauge when working the throttle.)
Guys I feel like it might be my spark plugs although they’re brand new maybe 8 miles or so on them max.
I just reset my pfc on this hot morning and started the car to let it idle and it shut off mid idle. It started up with super low rpm’s too and eventually after 5 minutes or so just turned off. It also sounded like it was running like ****. Going to take out plugs, clean them, throw them back in and see if that makes a difference
Guys I feel like it might be my spark plugs although they’re brand new maybe 8 miles or so on them max.
I just reset my pfc on this hot morning and started the car to let it idle and it shut off mid idle. It started up with super low rpm’s too and eventually after 5 minutes or so just turned off. It also sounded like it was running like ****. Going to take out plugs, clean them, throw them back in and see if that makes a difference
I often "clean" plugs using a "Bernzomatic" type torch because I have several small engines that foul plugs. I get the center electrode almost red hot to burn off the carbon. Works like a charm.
Well she’s flooded again and I’m trying to do the gas pedal trick again to start her
here are some pics of my spark plugs fresh out of their ports. After I wiped them with shop rags and a wire brush they looked almost brand new (no carbon on surface at least)
Well she’s flooded again and I’m trying to do the gas pedal trick again to start her
here are some pics of my spark plugs fresh out of their ports. After I wiped them with shop rags and a wire brush they looked almost brand new (no carbon on surface at least)
Make sure you got all the carbon off the center electrode and as much of its insulator as you can. That's what bleeds off the voltage and causes the plug to not fire. The outer electrode isn't important since it's the ground and contacts the housing. What you can easily see is the least important portion.
So guys it doesn’t start, not even with the gas pedal down. Might have to deflood it by taking out bottom 2 spark plugs and cranking.
however, it died again just idling the way it did the first time 2-3 weeks ago which I believe causes it to flood when it dies like this. Why does it do that? What causes the car to just idle really low until it shuts off on its own?
Idling too low could be from either not enough air into the engine, or wrong air/fuel mixture, or a problem in the ignition system. Not enough air could happen due to aftermarket ECU settings not being tuned properly to match your car, or it could be from the idle valve not working properly, or the idle bypass set screw not set correctly. Wrong air/fuel mixture could be a sensor not reading correctly, or aftermarket ECU not tuned properly to match your car. I agree with the others that a fresh set of spark plugs is a good idea to try. If fresh spark plugs don't solve the problem, you can keep the old spark plugs as spares.
If the ecu is not getting a signal it needs, it might default to a range. You may be able to look at what ranges the ecu defaults to in any particular situation.
A clue might be the ranges the stock ecu defualts to.
The Power FC may mimick some of those ranges.
Although I have been told the Power FC does not rely on the o2 sensor.
Here is a table of ecu inputs and outputs. The ecu will analyse the inputs and send signals to the output devises to make the motor run the best way it thinks.
At this stage, you may want to take a step back and read through all the major threads talkoing about troubleshooting the Power FC,.
Something obvious might become apparent to you.
Likely it is best thing to do is to find a shop that is experienced tuning rotaries.
Otherwise, you have to expect that trying on your own, its going to be hit and miss, with frequently going back to square one and working through all the possible permiatations contributing to your troubles.
Here is the table showing how the many functions interact with each other. You can imagine once you start making changes to the set up, by deleting emission stuff for instance, how those interactions can be messed up.
This page discusses how the TPS and ECU interact. The bottom paragraph talks about the default ranges the ecu assumes. The Power FC may also incorporate such default ranges.
02-21-24, 11:08 PM
