Another FD start issue
 

So here’s the story guys.

after months of work, I got my FD running, went and got it fresh gas, came home and let it idle. It idled and then stalled out. I tried to start it again but it would just try to catch on like making ignition noises but it would never catch and start. I looked under the UIM and found puddles of gasoline on top of the rotor housings so I thought, oh fuel pressure probably went low due to a leak and it shut off.

anyway I fixed that leak today, attempted to start, and the same issue. Now I’m dumbfounded because it ran great before. Here’s another variable, when I fixed the leak, I touched the alternator wire with my wrench for a split second and a few sparks flew. I checked all the fuses under the steering column and they’re fine. I checked my main 120amp fuse and it’s fine. I even tested the fuel pump by jumping gnd and f/p and fuel pump runs. All interior lights and even headlights turn signals etc work.

so what could it be guys? If it’s trying to make ignition sounds right now but doesn’t start that means I have fuel and spark and I know I have compression since it just recently ran great. It’s also getting air for sure. Tomorrow I plan to start by checking the fuel pressure by plumbing a gauge at the firewall fuel line. Let me know if you guys have ideas. Trying to get her running this week to impress my woman! (She hasn’t seen this damn car run in months but I’m close :lol:)


forgot to add I had a no start issue before but I fixed it by cleaning the injectors (they got stuck from sitting after being sent out to clean). This time I ran the car right after they were cleaned again to flush the cleaning fluid out of them so I don’t think they’re stuck again. Also the car makes rumbles like it’s trying to start which should be a sign of injectors firing and spraying fuel into the compartment

Might just be flooded again, deflood before anything else, check the plugs like before and get any fuel out of the housings

Pull off the intake prior to the elbow and see if it will run briefly on starting fluid. If it catches, runs, and then dies you probably have a fuel delivery issue with the pump.

You mentioned the car sat, how long did it sit and have you had a look inside the fuel tank at all?

Perhaps provide a link to your prior thread, so folk can know what you already know.

As you may recall I was dealing with a similar flooding/non-starting issue as you.

The final things that contributed to the getting the motor to run were:

1. Changed out the gas.
2. Replaced the coils.
3. Took off the ISC and let the intake suck in a ton of air (while regulating the flow by partially covering the hole by hand.)

Once the car starting running and continued to start and run, I went looking for the possible root cause of the flooding. Things I did were:

1. Changed the fuel filter.
2. Discovered the FPR was not getting vacuum.
3. Removed and had the injectors refurbished (replaced the FPR and FPD with new).There was some evidence the injectors had been leaking.

With the clean injectors the car is running quite rich, but so far no additional flooding events. (I still start the car by applying no gas pedal.)

Current assumption is the tune on the Power FC was done based on the weakened flows from the dirty injectors. So I will be going for a tune refresh soon.

So that might be one of your issues: that your tune was done based on weak injectors, and now you are flooding.

(Note: We were hampered by my AFR gauge not working. I replaced that as well and thereby can see the rich running pattern, including a brief very rich running moment on decel.)

Ok guys first of all thank you all so much for the feedback. It really means a lot to me when you guys take your precious time to respond to me.

So before I test the fuel gauge I just wanted to let you know I attempted to start it and it made ignition sounds but didn’t start. I put starting fluid in it and now it doesn’t make ignition sounds. Currently sitting in the car with EGI out and cranking to see if I can get an easy deflood this way without pulling out plugs first. Hopefully it’s just flooded.

also later today I’ll link my previous thread. Currently this car has half a tank of fresh week old gas and the other half is since last fall.

Ok so after I did the egi unflood procedure, maybe this is just coincidence or not but I tried to start again and it’s back to making ignition sounds but that’s it. I guess next step is to check the fuel pressure that’s going to the feed line. I can verify pump works for sure because when I jump it I can hear it

edit: tried to start again but this time by mashing the gas pedal while trying to start and it kept making ignition sounds for a solid 30 seconds straight. Never has been able to been this close to starting before. Maybe that means fuel pressure is low because it doesn’t have enough constant flow to run?

I may have the answer. Several years ago, I also touched the alternator hot for a split second. The car would not restart no matter what I did after the incident. The car made some ignition noise but no go. After days and days of troubleshooting I finally found the problem. When I grounded the hot lead on the alternator it partially melted the main fuse but not completely. There was a little current still passing through but not enough to start the car. Pull your main fuse and look at it closely under a magnifying glass to see if it is partially melted. You could also check the resistance across the poles or leads once it is out to see if the resistance is almost zero, which it should be. If it's bad, you can get one at Autozone for $15-20 and it hopefully starts after deflooding again.
Mike

hey Mike,
I actually already replaced the 120 main fuse as a preemptive measure. Still no luck

Also I want to make this note.

I took out EGI and cranked and it was still making some ignition sounds. That means there is fuel in the compartments and it’s flooded?

Want to make a correction.

first time I pulled the egi RELAY not fuse.

I just pulled the fuse and it no longer made any ignition sounds. It just cranked and cranked and when I checked the exhaust some little bit of smoke was coming out.

put battery on charge and will try again with egi FUSE in this time and see if she starts

Our theory on my car was that it was instantly flooding after every deflood.

That is why we pulled the ISC valve to give the intake a lot of air, after the TB, to offset the flooding.

I still don't trust the old gas.

If you are checking in your tank for corrosion sediment, check the debris sock.

It can clog up, but then the debris floats off until the next time the pump sucks it into the sock.

Although we tested the coils for spark, we suspected the spark might have been weak. Changing the coils might have been one of the things that helped me.

I don't know if your alternator short could have damaged one, or more, of your coils.

For reference:

https://buyee.jp/item/yahoo/auction/...age_watch_list

I don't know what this does but it is part of the fuel pump circuit and the wires have to run a long way back and forth to it through the Front harness


https://buyee.jp/item/yahoo/auction/...uggest_history

Pulling the EGI relay and/or EGI fuse may not cut the fuel pump. It seems there may be redundant circuits to the fuel pump.

To make sure the pump would not run, we undid the wiring harness at the fuel pump end.

Make sure you plug the fuel pump wire back in before trying to start.

Mikejokich makes a great point. I've had that problem before but with the battery. After bad contact with things it shouldn't touch, my battery would read 12V but would have nothing in terms of amperage. I've also seen a bunch of fuses that were "closed" but didn't allow enough current to be of use.

The FD has its own deflood procedure where you don't need to pull anything. Hold the gas to the floor and then start cranking, keep the pedal down, don't pump it. This disables the injectors. As it cranks it should slowly start making more and more "starting sounds" and eventually catch and die. Only then release the pedal and fire it up normally.

IF that doesn't work then start troubleshooting deeper. Looking at the plugs, checking fuel pressure, checking the fuel sock, current to the pump, alternator (maybe the regulator went during the arc). After all that then deeper still: coils, coil wires, injectors (sticking open?), igniter, pressure regulator.

Thinking back to your other thread, I don't think it has anything to do with your timing wheel and plugs, maybe just hit the NE and G sensors with some brakleen to ensure they're nice and clean. It may be a longshot but the tune may have flipped a bit - but that's prob the final thing after all the others have been checked.

It's the fuel pump resistor located in the engine bay under the igniter. It reduces fuel pump speed (via resistance) until the ECU closes a relay bypassing it and allowing the fuel pump to operate at its true speed.

ok I’ll do this tomorrow. I’ll attempt to deflood by holding the pedal to the ground and cranking until it catches and dies. Does this mean keep the starter spinning (cranking) until I feel it catch and die? Or crank for 15 seconds, pause and wait 15 seconds, and repeat?

You can do 15 seconds and pause, just keep the pedal down.

dude you are a genius. Car started and not too long after I held it down. It burped a bit and I kept holding it down and then it caught on and I let off gas and it kept running. Weird I was convinced it wasn’t flooded because it’s never flooded before but maybe after me messing around the fuel system it did.

runs great now and I don’t know if this is related to my fuel leak before and it possibly seeping into some unseen compartment but I had smoke come out of the turbo area for a little bit. It would smoke for 10 min straight. Stop for a few min, continue, stop and now maybe for 20 min or so it hasn’t smoked so maybe just leftover gas that was on top of the motor burnt off? Btw this is it just idling, I haven’t driven it as I was letting apexi adjust

fyi before you think it’s oil or coolant it’s not. I completely refreshed those systems and put stainless steel oil lines. It’s bulletproof so it’s either gas or exhaust leak.

I’ll attach a pic of where it’s coming from with the area circled.
https://cimg8.ibsrv.net/gimg/www.rx7...97ced4c74.jpeg

Still hasn’t smoked so I’m assuming it’s fine. I checked the places where it used to leak on top of the motor and they’re dry. Also if there’s wetness in that picture it was raining lol

Update so it no longer smokes but it stalls out very easily if I try to drive it. Maybe apexi still needs to learn? I’ve idled it for way more than 30 minutes though. For example when I put clutch in and first gear and try to let off clutch and give it gas, idle drops considerably until it stalls almost or straight up stalls. I was thinking maybe because it has half a tank of 6 month old fuel and half a tank of 2 week old fuel but I drove it 2 weeks ago to get gas on just 6 month old gas and it drove great. Hmmmmm


edit: some notes: I have emissions deleted I blocked off ACV and replaced air pump with pulley. Just tried to turn off o2 feedback in my FD. Attached will be a picture of my sensors on the apexi as the car is running. My idle keeps dipping to ~600 rpm range at times too

https://cimg0.ibsrv.net/gimg/www.rx7...0e4ed3a3c.jpeg

I was going to ask if the "pedal to the floor method" still worked with the power fc. Has not worked for me. But it did not quite follow the exact steps suggested above.

We also, at one point, suspected leaky injectors.

And we found some evidence of that later.

Take another look at your TPS readings.

where can I see this?

VTA1 and VTA2.

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.


https://cimg0.ibsrv.net/gimg/www.rx7...0e4ed3a3c.jpeg

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.

The MAP sensor is more important.

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.

Here is a screen shot of my commander. Note the reading for the O2 sensor. Your signal seems weak. I don't know how this would affect things.

Perhaps check the FSM for the o2 sensor ranges.

https://cimg6.ibsrv.net/gimg/www.rx7...8bc2ab1ebf.jpg

mm

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

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 shit. 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


https://cimg6.ibsrv.net/gimg/www.rx7...49eba92a4.jpeg
https://cimg9.ibsrv.net/gimg/www.rx7...491f313ac.jpeg
https://cimg1.ibsrv.net/gimg/www.rx7...afb80868b.jpeg
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.

Those are pretty horrible!

Replace with new.

remove any doubt.

Also.

To eliminate the crap gas risk.

Drain it all and replace.

Are you putting in too much pre-mix btw?

You can always add the suspect gas back to the tank a little bit at a time.

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.

Maybe hook that back up anyway.

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.


https://cimg7.ibsrv.net/gimg/www.rx7...28254bbe09.jpg

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.

https://cimg5.ibsrv.net/gimg/www.rx7...ed04d90aae.jpg

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.

https://cimg9.ibsrv.net/gimg/www.rx7...3a0e3a835d.jpg

The fact that you plugs are fowling so badly is a very big clue.

What is causing that?

Although my car was flooding badly, tne worse the plugs looked like was a light black smudge on the uppers.

Somewhere there is an analysis table that identifies what your burnt up plugs are trying to tell you.

Was that fill up six months ago contaminated by deisel?


https://www.reddit.com/r/Justrolledi...estimate_your/


Deisel or not, if the octane level of that old gas was very low, it could be (still) part of your trouble.