jjcobm

iTrader: (18)

I'm not 100% sure, but I'm pretty positive they are referring to the AFM, air flow meter.....

RotaryRocket88

iTrader: (7)

That would be the measuring plate / door in the AFM on an S4. On an S5 is what, a little cone? This would be to switch the fuel pump on.

Edit: jjcobm beat me to it

Amur_

Got it. Thanks. I'll physically open it, to do it properly.

Amur_

So close!


Fuel Pump Resistor Relay

a-b should be 0, reading bounced around then settled on 3.0

c-d should be 60-92, got 70.7

e-f should be 0.70-0.94, got 2.7

So that's not too healthy.


PRC - passed both tests


Circuit Opening Relay (here's where the action started)

When backprobing and then cranking Fp, Fe and E1 the car started and then stalled (those are the ones I marked down as having started, it may have also started on the others.) It ran like crap and would stall out within 5 seconds. I tried revving to keep it going but it would stall out every time. I didn't persist in trying to keep her running - the goal was to complete the testing, and I didn't want to sit there revving her too much while she was running so poorly.

**bold indicates out of spec reading

-----------Fp------Fc------B------STA------E1
ON-------0--------0------12------0--------12
AFM------0--------0------12------0--------12
START---12-------0------12-----12-------0.3

E1 is supposed to be 0 in all tests. The other two 0s should be 12s.


Fuel Pump

fuel pump connector, a-b continuity - OK

L/G with key On - 0v
L/G with key Start - 12v and engine started.

And it was a normal sounding and feeling start, not the ugliness of the FPR starts. She started smoothly, ran smoothly, revved smoothly and I was able to get out and walk up to and watch the engine bay. I didn't notice any oddities. She didn't do the 3k start-up and the idle was up around 2.5k. As time passed that slowly dropped, until at about 3 minutes she stalled out. No sputtering, just died. I got back in and cranked it (without disturbing the multimeter) but she just spun.

After all of this, I then jumpered the pump and listened around the manifolds. No sound of fuel moving. What I am hearing is the sound of a small motor running somewhere close to the firewall between the wiper motor and the middle of the car. I wasn't able to localize it more than that. I really need to hit the local army surplus and pick up a stethoscope when all this is done.

Time for a break to thaw my toes and make some food.

ifryrice

EDIT: Whoops, i made a mistake, the FP relay is closed by default, not open. Corrected.

Well, I'll start with the COR.

Fc is the ECU's signal to trigger the pump, it also has the test connector attatched to it. If i was showing 0v (or ground), it could mean either the connector was jumpered, the ECU wasn't sending any signal at all (apparently it sends +12V when it's not supposed to be on), or the ECU was trying to turn it on.

Fp is the power output to the FP relay/resistor. The S5 FP signal is triggered by the ECU depending upon the AFM's position, and I think that it doesn't open that if the cars not running, but I could be wrong. It should see +12V from the ECU whenever the ECU triggers it... That one's kind of unusual and worries me.

E1 is supposed to be straght to ground. This circuit is what's used to turn the pump on during cranking. The test results show that this works, though why there is +12V on the other side is beyond me and is somewhat suspect, but I don't think it's your problem just yet.


Now, onto the FP resistor/relay.

A-B is interesting, but could just be from corrosion/etc. Clean the connectors.
C-D is the relay's coil, which looks good meaning it should pull the relay closed.
E-F is the resistor to drop the FP voltage under certain conditions... with a reading like that I'm thinking it could be dropping your cranking voltage too much, as during cranking the power comes throgh that resistor directly to the FP.

I'm starting to think your FP relay/resistor is wet/connector have coolant/etc. The fact that it started at all after playing around with those connectors just goes to further provide evidence for that. I'd take them apart, clean them out, spray them out, wire brush em(I'm thorough!), and reassemble and see what happens. It's also possible your AFM has some water or something in it that's causing the Fp AFM test not to work. Clean that one out too.


Edit: Oh, for the AFM Fp test, you can jumper the fuel pump test connector and it should be effectively the same as if the ECU were doing it, which would allow you to verify that it's sending out +12V to the FP relay/resistor from the COR if the ECU triggers it, which would then lead you back to the FP relay/resistor (where you should probably do some voltage checking).

So, to test voltage at the FP/R do the following (make sure to backprobe these, and not disconnect the harness, with the car ON and the FP connector jumpered). This should cause the COR to turn the FP on, but on the low voltage setting.

Check voltage of A, C, and E pins (All are L/R color, same pin layout as on the resistance checking you already did), all should be +12V with FP connector jumpered/key to start/during running.

D (G/R color) could be 0v or 12v, depending upon what the ECU is doing.... If it's turning the FP onto full power, this will be ground, otherwise it'll probably be +12V, you can tell if this is being used by the outputs below.

F (L/G color) should be +12v, UNLESS the ECU is turning on low power mode, then it should read a value less than you read on the A,C,E pins, this is the power output from the resistor to the fuel pump itself.

B (L/G color, sucks they're the same?) should be +12V unless the ECU is trying to turn on the low power output, in which case it should read 0v.

Amur_

The jumper was not used during this these tests.


What I could see of the connectors was spotless. And the entirety of both connectors was dry.


Except I expected them to be shielded by the airbox, and this has proven to be correct. There is no visible trace of coolant on the FPR, its connectors nor its general vicinity.


Okie.


Battery at 10.5 (recharge time again)

Without anything being cleaned or otherwise altered from earlier:

a - 9.7
c - 9.9
e - 9.88

d - 6.65
f - 9.7
b - 9.79

ifryrice

It's interesting that D's down at 6.6, that's about the drop I'd expect when the ECU is dropping voltage, but since it backfeeds (the wires are connected later on after the relay prior to the FP), I figure it would've gone up.

I realize I didn't account for this on the B pin either, it'd read the lower voltage as well.

In any case, it doesn't make much sense since everything checks out as far as relays/etc go (except possibly the voltage drop being too much, or the COR not doing it's purpose all of the time). I think you're down to the FP itself and watching the voltage at the pump itself. This is definitely a pain in the ***. It would seem that it had something to do with wiring as it went from not firing at all to starting just from backprobing/etc.

At this point.... I would do the absolute simplest thing and run a battery fed +12V straight to the pump. Bypassing the COR/FPR completely and seeing if the car will start/idle without stalling afterwards. It'll get the fuel pump/sock/pressure regulator/fuel filter/lines all off the board. If it refuses to start even still, then I'd suspect something from the group I just mentioned.

Amur_

Ran a line from batt + to L/G and cranked. She fired up and idled. Stalled after 10 seconds. But I think I know why that's happening.

The gas is low. Just a bit above E. Not a big deal except... the car is parked perpendicular on a slope and the pump/intake are on the high side. I think I should put some more gas in there before I try again.

ifryrice

Well, I guess it's a good sign that it at least fired in that condition. I'd still try again with more fuel/etc eventually. After that I'd start from the beginning again. (If, it turns out the pump is fine).

Go back to the COR, jumper pin B to pin Fp, test that the car starts/runs just fine. If not, the issues either in the wiring, or the FP/R and you can skip everything below.

If that checks out, ground Fc and repeat the above steps. If that fails the relay likely is having issues and should be replaced.

If that works then I would try grounding the EV1 pin and checking to verify that the car starts. If it stalls shortly afterwards it would indicate some issue between the ECU wiring and the COR. If it starts/stays running, then the issue could be a faulty ground (EV1 should always be grounded).

If that doesn't work, jumper B to STA and try again. This would indicate a power failure from the IGN switch starting position and the COR.

That should help identify/eliminate the wiring to or the COR itself completely. If the COR stuff doesn't work at all, then it's got to be at the FP/R, and that looked good from the voltage tests. All you would need to do there is jumper any of the L/R to either of the L/G's and see what happens. Either one of them should get power back to the FP.

Amur_

Sounds good. Thanks for staying abreast and offering the guidance. Electrical is not my strong suit.

misterstyx69

iTrader: (142)

just an Observation..but the AFM connector is about where the Upper rad hose is..
my Thinking is that when the Rad exploded,it Could have got the connections wet,or even screwed up the AFM.have you tried another AFM?

Amur_

The AFM plug was and still is 180 degrees away from the rad. It was sheltered by the entire snorkel. I have also repeatedly disconnected the plug without noticing any liquid nor dampness.

ifryrice

Even if the AFM wasn't sending a valid signal back to the ECU, the COR would power the fuel pump during cranking, so it would start then stall almost immediately. It's something to check into though later because his Fc value wasn't showing up right, but for now I don't think it's the primary issue.

When I can't work on my own car, pretending I can work on others serves to cure that craving.

misterstyx69

iTrader: (142)

My car is under snow,so i can't work on it..or help with hands ON..sort of thing.
I am just Throwin a suggestion or two out there..I hope it isnt Too "far out"..
..I am gonna Love to see WTF it was or is though..
Good Luck Amur..STYX!~

Amur_

Dumped in 2 gallons and cranked. Nothing, she just spun for about 4 seconds. This was without reconnecting +batt to the fuel pump. I paused for a moment, then pushed the accelerator to the floor and cranked again (which I had been doing during the Start part of the COR tests, when the car first began starting again.)

She fired up. And stayed running. Again, no 3k start-up but she did sit comfortably a bit below 2.5k. I sat and looked at the gauges and waited. Everything seemed normal. I popped the hood and got out. Like yesterday, all seemed normal.

But there was one thing yesterday that I didn't report, that occurred again. There is some kind of smoke or steam coming from somewhere around the BAC/secondaries/under the snorkel. There's no colour to it and no smell that I can identify. Definitely not gas nor coolant. It's becoming a genuine concern because it hasn't lessened at all. I was looking around as much as I could but there's a mess of wiring and piping in there and I couldn't see anything that looked like a source.

I think it may be smoke rather than steam. I stuck my face right into a cloud of it (it's coming out of there in a steady stream) and it stung my eyes, something steam doesn't do. Or maybe it's contaminated steam. :shrug: I don't want to move the car 5 feet until I figure it out or it goes away.

So at least she's running again. I think I'm going to run a switched 12v from the +batt to the pump.

I'm going to do ifryrice's COR tests tomorrow. It's too cold and dark out there now - I was out there for maybe 15 minutes with light cotton gloves on and all of my fingers were numb when I came back in.

ifryrice

Did you check those coolant lines that run from under the manifolds? They like to burst/fail quite a bit, especially when overheated. I can't think of any way exhaust would be getting up to that area, or what else could be burning off. There's only coolant/fuel around that area. Either is worth checking into though.

So it stayed running just after you pumped the throttle and didn't stall out/etc again? It'll suck if it doesn't come back again soon because you won't really be able to identify exactly what it was, and if it comes back later (while driving) it'd suck even more.

Running a switched 12V has it's negatives, such as if the car flips/crashes/etc, it'll never turn off. You could remove the use of the resistor/FP relay, and install a replacement for the CoR, but that gets tricky because the signal from the 'Start' position to turn on the pump is +12V and the ecu signal is GND. You'd either need two relays, or another relay like the COR that has two coils. (Or just replace the COR with another good one, and bypass the FPR/run your own wires from the COR back).

Good luck!

Amur_

I think the long-term solution is replacement of both the FPR and COR with known-working units ASAP. The +batt would be an interim 'insurance' move.

This looks rather like the fuel system/pressure problem was just a coincidence. We haven't found a cause yet, have we? This car has a helluva sense of timing.

ifryrice

Nothing in particular, unless something got wet and caused some kind of voltage drop to any of the power/gnd's the relays would require. It's stupid things like this that drive me nuts though, I hate when problems aren't consistent. Makes them so much more difficult to resolve properly. At least the good news is the motor/etc's fine after the overheat, that's rare in and of itself!

MazdaMike02

iTrader: (4)

The fuel pump relay makes the difference of sending either 9 or 12 volts to the fuel pump. If it failed in one position it could probably be only sending that 9 volts which would probably not be enough fuel to start. Since your running a constant hot 12v to the pump thats bypassing the problem. Sounds like the fuel pump relay has an internal short or maybe the contacts are just worn right out from use.

ifryrice

He's already verified that it was putting out the proper power, and the car should start with the pump running on the 9v too. (probably not the 6v he got when he tested it with a near dead battery). The problem seems to either be the COR, or the wiring between the COR->FPR->FP.

Amur_

Mmmmm... something we'll have to disagree on. I think people are a little too fast to jump on the Zomg It Overheated Rebuild Time Oh Noes bandwagon.

https://www.rx7club.com/showpost.php...3&postcount=32

(rather than re-type it)


Could be. The sooner I get a replacement in there, the sooner I can stop worrying about it.

Anyone know offhand if the s4 and s5 CORs are identical? I'll compare the FSM tests for them when I get a chance.

MazdaMike02

iTrader: (4)

Well depending on his compression numbers and fuel injector condition 9v may not be enough to run the engine.

I know on my 7 I had proper fuel pressure and It still wouldn't run properly, I swapped the pump out for the exact same type from another s5 and it solved my problem..That and I discovered when you don't have the bolts in to hold the pump the pressure escapes through those holes and it wont hold pressure.

Amur_

Missed two.

I didn't inspect them closely (I was focused on other things and didn't think of it,) but there was no coolant present in that area at all to suggest that they might have failed.


I premix and use a high-flow cat. If the smoke was at all exhaust related I'd know immediately. And then when I regained consciousness I'd probably post about it.

ifryrice

I know what you mean, so it's either fuel/water/coolant, or plastic/something else? Most of the time if it's a small dribble/etc, you won't notice any coolant, but you can often find the white powdery residue it leaves behind from the area it burns off of. Just something to check for later (if it doesn't go away on it's own at least).

We've already verified the FP/R seems to be working properly. I don't understand the second part you said though, if you had proper fuel pressure, swapping to another pump wouldn't make any difference at all unless it was exceeding the volume capacity of the original FPR, in which case it'd rise the fuel pressure above what you had considered proper already. Unless you tested the pressure at key 'ON', and the pressure dropped significantly when the injectors opened or something.

Amur_

I'm familiar with the white powdery trail bit from water pump failures. I'm confident I would have noticed one had it been visible up there.

Right now the only explanation is water, b/c of the odourless aspect. Everything else has a distinct smell to it. After the engine snuffed and I had her off the road and stopped, I did try to pour water into the system by disconnecting the upper rad hose from the elbow above the pump and then pouring water into the hose. I doubt I would have made a great mess of it, but it's likely that was at least a little spillage. If some of that spillage found places to pool and freeze, I may be witnessing vaporization and sublimation... But it sure is taking its time.