Texas_Ace

iTrader: (18)

Ok, this is REALLY starting to drive me batso.

So today i decided to check the injector pulse while i had the clips off anyways, and sure enough they are not firing anymore. Anythign above 3800 at WOT and the LED goes solid but no pulsing at all.

Now the injectors very well might be stuck open when it does this and that is causing the problems, i have noticed that it smokes some when the injectors are hooked up and i bounce it off the 3800 "redline" but didn't notice the smoke while doing it with the injectors disconnected.

So why are they not pulsing?

Tried grounding the pressure sensor, there were 2 wires that seemed to be grounds but only 1 was black so i tried that one. No change. Disconnecting the TPS/pressure sensor doesn't change a thing.

This is REALLY starting to bug me!

Texas_Ace

iTrader: (18)

Hmm, I am now 99% sure that the secondary injectors are indeed pegging open when it hits 3800.

I tried hooking the injectors back up and sure enough, rev it to 3800 and it smokes again, take the connectors off no smoke. So it dies 1 way due to lean condition and the other due ot rich.

So the injectors themselves seem to work fine, they are just not being told to pulse.

So what exactly does the ECU use to control the pulsing of them? What could cause this?

Any ideas?

ifryrice

If your wiring is fine, and you don't suspect the injector are locking, then it's probably the injector driving circuit in the ECU. It's more than likely fried, do you have another ECU to test with? Nothing as far as input sensors would cause that to happen.

Texas_Ace

iTrader: (18)

Thats what i was thinking but why did it do the same thing with the other ECU i tried?

I did find one for sale though that i am going ot pick up and another set of injectors just to make sure.

ifryrice

I didn't see that, it would probably eliminate the ECU. After reading through your posts, I'm a little unsure of a few things.

How were you checking the injector pulse? Was the led connected between both injector wires, or did you ground the one end of it and connect it to the signal from the ECU? Do you get +12V on both the secondary wires when they shouldn't be firing? What's odd is you should be able to rev it out of gear without the secondaries at all. I would verify that your pressure sensor readings are actually making it back to the ECU and are somewhat within range. I would probably start there, just backprobe the values at the ECU with the car off and at idle and compare to the FSM values. I would think if your injectors were really coming on full like that you'd stall or have some other serious issue.

I guess, check for +12V on both wires at the secondaries, check the pressure sensor at the ECU. My guess is the pressure sensor value isn't making it back to the ECU.

Texas_Ace

iTrader: (18)

I was checking the pulse by connecting the LED between the injector wires at the connector, thus showing any wiring issues. And below 3800 i get nothing, above it i get a soild light.

If i do the same thing with the primaries i get a nice pulse (well i back probed the ECU for them but same thing).

I will check the pressure sensor, anyone happen to know where that part is in the FSM? i am real bad at finding things in the FSM.

How would the pressure sensor cause the injectors to get soild voltage? and it does the same thing weather i have it connected, unplugged or anything. But i will still check it, i will try anything at this point.

satch

iTrader: (1)

Page 30-32.

http://www.teamfc3s.org/main/factory...SYSTEMS_NA.pdf

ifryrice

It controls if the secondaries come on at all, so I think it may be seeing a bad value or not working at all (which would cause the injectors to try to fire even with no load). Crap, it doesn't say what the value should be while running with it connected. But anyway, check the following.


At the ECU:


The sensor itself:

Texas_Ace

iTrader: (18)

Ok, checked it at the ECU.

I get no voltage there, wiring may be bad but it is also possible that the wires changed from 87 to 88 since the wire color is differnt on the ECU then the one leaving the sensor.

I checked the voltage at the sensor, i get a 5v with the key on on the signal wire (which is also the wire that has the spare wire tapped into it from the PO for some reason).

So it would appear that the pressure sensor may indeed be bad and possibly the wiring.

Could this cause the engine to "redline" at 3800? Anyone have a spare N326 sensor i can buy?

Could the resister pack be a problem?

ifryrice

I have an extra one laying around if you end up needing it. Are you getting a voltage coming out of the sensor at all? There should be the VREF (5v signal from the ECU), Gnd, (sometimes there were two) then the sensor reading. It's possible it got fried by whatever the previous owner did to it.

In any event, I suspect it could be part of your issues, I know it's used when determining if the ECU should engage the secondaries (which could explain why you can't even free rev).

The resistor pack shouldn't really fail in this way unless it's causing them to ground out, but that would happen all the time and not just at 3800rpm. I wouldn't worry about that. Let's start with the pressure sensor since that's where you had some 'effect' earlier from what I read.

Texas_Ace

iTrader: (18)

Actually i just did some more testing and i realized i was using the 5v refernce wire, after looking at it i realized i was testing the wrong wire. Tested the signal wire and it seems to work, falls into spec at the sensor.

Still don't get anything at the ECU, my guess is the wiring is differnt though. When i was giving the sensor vacume i ould hear some clicking as i moved the vacume up and down, the Bac valve i think, so it is getting a signal at the ECU in some form.

So back to square 1, i think i will put out the ECU and take it apart for the heck of it and see if anythign jumps out at me.

ifryrice

The pin position at the ECU didn't change between years, although the color may. Locate that wire and figure out why it's not reading as it should. I would check it by the pin position and not the color, although the color shouldn't change as it goes through the harness, since it doesn't change harnesses at all.

Texas_Ace

iTrader: (18)

Just pulled the ECU apart, nothing obious in there.

The wire at pin 2B is a differnt color then the wire at the sensor, at the sensor it is brown/white at the ECU it is yellow/red.

Have not looked for the same wire at the ECU yet.

I know it is getting some kind of signal fro the sensor though since it was clicking as i gave it vacume on the sensor.

Texas_Ace

iTrader: (18)

Ok, i just found the wire on the ECU, turns out i was reading the diagram wrong, getting too frustrated with this car to pay attention anymore lol.

The signal is fine from the pressure sensor.

ifryrice

Either someone replaced the wire, you're reading the pins wrong, or the wire's in a different location.

BR/R should go to 2B at the ecu (signal)
BR/W is 5V ref, comes from pin 2A
B/W is +12V
B is the GND

Doh, saw your edit.

Does the value change under vacuum? With that thing connected it should let you rev in idle just fine. I'm at a loss now since you've already replaced the ECU and it repeated. I'm unsure if faulty/bad grounds would cause them to stay in a grounded state like that. It's either the ECU, grounds, or the injectors at this point then.

Texas_Ace

iTrader: (18)

Yep, figured it out as you were typing. Was reading it wrong.

But this just makes things more complicated.

Could my temp sensor not working have anything to do with this? I also get this annoying BEEEEEEEEP anytime the key is on, might it have somthing to do with it?

Grasping at straws now.

Texas_Ace

iTrader: (18)

Yes, the voltage does change under vacume. So i am pretty sure it is working ok.

I have some injectors and ECU coming right now, so those will be put to rest soon.

Are there any other grounds that could be a problem? The only 1 i really had to mess with and made sure was ok other then the ECU grounds was the one under the intake.

satch

iTrader: (1)

The beeping sound "might" have to do with a "fourth" plug in the ignition switch which is supposed to sense whether the key has been left in the ignition and it might be malfunctioning. If this were the case then checking that aspect would be fairly easy for all you would have to do is remove the plug from the ignition switch. Of the four plugs connected to the ignition switch only one has four wires and this is the plug I speak about.

There are other possibilities such as a plug from the power steering feature being disconnected.

ifryrice

You said you have issues with your cluster, so it could be from there. Or, it could be one of many CPU related issues (the cpu is bolted down under the drivers kick panel). stick your ear around there and see where it's coming from. Either shouldn't cause this issue. Have you checked all the other sensors at the ECU per that FSM page just to see if something else was off? What you could try doing, is using a DMM with it set on 'volts' between the injectors (with them plugged in), and measure the voltage it reads when it hesitates like that. The voltage should start at 0 and increase, if it sticks at +12V that's worrysome. I would definitely think ECU in that case. I'm thining there's something wrong with the injectors themselves, or the ECU is having trouble firing them either from a faulty ground or something, but even that is hard for me to believe. Check the voltage with them plugged in when it hits the wall and see what it does.

Texas_Ace

iTrader: (18)

I will try that, that beeping is starting to melt my brain! lol


Actually i think i might have figured it out!!

Ok, so in desperation i just went through and sprayed down all the connectors with eletrical parts cleaner and cleaned everything. Put it all back together and tried starting it and see what happens.

Hooked up the LED's and saw they were pulsing! So hooked up the injectors again AND..... same thing as before, it would bog and change sound as soon as it hit 3800.

Then on a whim i decided to unplug 1 injector and see what happens, the front one made it start bouncing like a rev limiter again. Unplug the rear injector and nothing changes, i think the rear secondary injector could be the problem! We will know shortly once i get the replacements in.

I sure hope that is the problem, this is driving me crazy.

ifryrice

Have you checked the ohm's on the injector coils? That's pretty interesting though, so you get pulsing with the front secondary hooked up but not the rear?

Texas_Ace

iTrader: (18)

Kinda, i get pulsing on both now that i cleaned all the connectors on everything.

With both injectors hooked up the motor runs great till 3800 then the sound changes and it loses all power. I now think that is due to it running on 1 rotor.

If i disconnect the rear injector nothing changes, still does the same stuff. But if i disconnect the front injector it will no longer rev at all, it just hits a wall and acts like a rev limiter at 3800.

So i am pretty sure the rear injector is dead. I have some ordered so we will know for sure 1 way or the other soon but i sure hope this is he problem.

ifryrice

Interesting, I can't seem to figure out why your car uses staging even in neutral. Usually it doesn't from what I've seen. Check the Ohm's on the injector coils and see what they give you (if you haven't already). I guess if the person never drove it above 3.8k for a while they could be dirty/seized up or something. Very strange, reminds me of an old '86 I bought. Took about 5 cans of injector cleaner to finally get it revving above 3.8k in gear (it'd rev in neutral on the primaries).

Texas_Ace

iTrader: (18)

Well i am not that surprised by that, in ym old car i had to run without secondary injectors at all (had high impedence when i needed low) for a little while and it acted exactly the same as this car with the injectors unplugged, it would "redline" at 3800.

I have not checked the phm's on the injectors yet, i will check that out tomorrow for the heck of it.

The car was sitting in pieces for the last ~5- 6 years so it is not real surprising that an injector could be bad, it was 2 injectors going bad that surprised me.

I have 1 of every kind of injector cleaner walmart sells sitting in the garage right now, gonna dope up that fuel tank nce i get the new injectors in there and see what that does.

Texas_Ace

iTrader: (18)

Well in a strange turn of events, i thought i would update this thread with what fixed my problem.

Well today i was supposed to be at the dyno tuning my MR2 but ratehr then the RX7 being the car that randomly dies for no reason the MR2 just got a rod knock out of no where.

Then a few hours later i got the new injectors in and swapped the rear secondary out, started it up and all problems are fixed! Runs perfect now!

So all of this was indeed just the injector.

But i now need a new motor for my MR2 so the RX7 is also going up for sale before i even get to enjoy it to help pay for that ;-(

Only other problem with the RX7 is that annoying beep, i still can not figure out what it is. The lock tumbler is stuck like most RX7's, i can use my other cars key to start it, could that be the problem? How can i figure out what is causing the beep?

Thanks all of you for the help! Doubt i would have figured it out without you!