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87 T2, finally got it started for the first time in heavens know how long. Cranks over strong, starts in a hurry, sounds healthy.
Except it tends to die soon after starting. (and smokes like it's trying to get lung cancer, but that's probably the MMO I stuck in it. I'll worry about that later)
First time I started it, it lasted through 3 seconds of perfect idling before it shut itself off. No stumble or bog, just stopped dead like the key fell out.
Second time, I tried playing with the throttle to see if it would stay alive, and it revs nicely, but then it bogged down to 800RPM and then cut out completely.
The previous times, I had it in neutral, but the third time I started it clutched in, first gear. Idled a bit higher than the last two times, but it stayed strong the whole time and didn't die until I shut it off myself. I was moving the car back into the garage, and it seemed perfect: no stumbles, no bogging, didn't need any fancy foot play, sustained itself longer than the other two times, and kept its RPMs steady even when I eased out the clutch.
I'm curious to see how it would behave if I tried to drive it on the roads, but the family car was in the way and it was late. I think I'll try that tomorrow when I have the chance.
I read up a bit about potential causes, which basically narrowed the issue down to the fuel system being temperamental. Which is weird, since I went through and refreshed a lot of stuff. Injectors cleaned and serviced, rails cleaned, fresh hoses for everything, fresh filter, cleaned tank, fresh 87 gas with a little premix (half ounce to a gallon), a fresh pump sock, AFM cleaned (the flapper works no problem), etc.
I'm thinking it's electrical right now. Currently to get it started, I have the yellow connector in the boot by the passenger strut tower jumpered. If I don't, the pump doesn't prime or run at all, and the voltage drop across the black and blue wires at the pump is extremely intermittent (even though the red wire gets a steady voltage). I'm reading around 9.6 volts on both the red and blue wires when it's jumpered. I know I'll have to address the relays as a result, but for now, let's forget about that.
I need some clarification on how this jumper works. This bypasses just about everything in order to send voltage to the pump, correct? I doubt this was intended to sustain actual driving operation and just be used as a diagnostic tool. What's left in the fuel pump's circuit when the jumper is used? Is it basically just battery, pump, ground? If so, where on earth is the circuit crapping and cutting out? Is it even possible to get the car to drive normally while the jumper is in place, or I should go straight to addressing the fuel related relays?
I don't have video of the gauge cluster during start up. I'll try that tomorrow, but I will be uploading and posting the external shots of the three tries I mentioned above.
There is a fuel relay located within the AFM on the S4. When you start the car and the rpm rises above 500 rpm the fuel relay in the AFM takes over by sending a ground signal to the circuit opening relay and this keeps the relay from shutting off and cutting power to the Blue wire which powers the fuel pump circuit. Jumping the fuel check connector keeps a constant ground on the Brown wire in the relay that is necessary to keeping power on the Blue wire.
Your car is a turbo and you have an additional relay which varies voltage to the pump dependent upon how much load is on the car. The higher the load, the more voltage up to a point, is sent to the fuel pump.
so you did the fuel system overhaul 3 years ago? or before you tried to start it again?
The car has sat and been continuously fixed for a year and 3 months. I've done the whole fuel overhaul before I started the engine the first time since it went up on jackstands.
Originally Posted by satch
There is a fuel relay located within the AFM on the S4. When you start the car and the rpm rises above 500 rpm the fuel relay in the AFM takes over by sending a ground signal to the circuit opening relay and this keeps the relay from shutting off and cutting power to the Blue wire which powers the fuel pump circuit. Jumping the fuel check connector keeps a constant ground on the Brown wire in the relay that is necessary to keeping power on the Blue wire.
Your car is a turbo and you have an additional relay which varies voltage to the pump dependent upon how much load is on the car. The higher the load, the more voltage up to a point, is sent to the fuel pump.
So to clarify, the fuel pump check connector ultimately cannot bypass the switch/relay within the AFM once the car has started, correct? I've been fiddling with the car, and after prodding on the AFM wiring, it seemed to push up the connector enough to provide a secure connection, so I've managed to get the car to run without spontaneously dying on me. I'm guessing this was the problem and I'll have to figure out how to prevent that from happening again. The clip is engaging the catches and it snaps securely in place, but that doesn't seem to be enough and I need to force it up securely against the MAF for this to work.
As for weening the car off its dependence on the fuel check connector, I'll have to check that the circuit opening relay and the additional relay unique to the turbo are still working, correct? If I'm not mistaken, the second one is called the fuel pump resistor-relay and is the thing hiding under a bracket beneath the stock airbox, with a Nippondenso relay and a finned box with a heatsink. The other should be under the driver's side of the dash to the right of the steering column, right?
I'll check these this afternoon when I get back. I'm quite certain all of the fuses are good, so is there anything else I should look out for?
The AFM fuel switch is for "after" the car has started and not before. Again, once the car's rpm rises above 500 rpm the fuel switch is responsible for supplying the ground on the Brown wire to the circuit relay. W/o this ground the car would die after initially starting. So, the check connector does override the fuel switch in the AFM.
Alright, that makes sense. I did some more reading about how the RX7's fuel circuitry worked... And finally figured out that the S4s don't prime the pump when initially keyed to ON. So basically my concerns about the fuel pump resistor-relay and circuit opening relay having gone bad was wrong, and it started up just fine without the jumper on the fuel pump check connector.
Whoops.
Well anyways, I'll see if the AFM connector doesn't constantly wiggle out or if duct tape remedies it. If not, I should be fine to just jumper the wires that connect to the AFM's switch, right? I can't see any colossal issue with doing so, besides it possibly having a higher chance of flooding, which I'm not too concerned about at the moment.
Okay, problems are back again. Starts beautifully, then VERY QUICKLY dies. It's not that it settles into idle for a couple seconds then bogs out like earlier; it starts, hits 2k rpm, then gradually drops to zero. Fuel check connector doesn't do anything to help. Fuel pressure in rails, pump is working. I even tried jumpering the black and brown wires going to the AFM (which should be for the circuit opening relay), but it's still dying. It's not bogging, and will stay alive if you give it throttle, even if it's a tiny smidge to keep it above 1000 rpm, but the moment you let go, it starts dropping and dies. I already adjusted the TPS and the throttle cable mount. I also did a once over of all the vacuum hoses that I can see without pulling off the UIM.
Is this a vacuum leak issue? I just fixed a fuel leak issue and had to remove the UIM, and might have done a shoddy job of applying RTV as a gasket dresser where it mates to the LIM. That same fuel leak swelled a couple of the silicone vacuum hoses down where the LIM mates with the block, and they were kind of loose and fell off easily. If I remember correctly, one of the hoses affected was the one on the back of the rotor 2 secondary port OMP nozzle, the other one connected a nipple from the middle of the LIM to the rats nest. Could a leak in those areas even cause this? I'm starting to run out of ideas.
Found a vacuum hose I left off. Then found another vacuum hose I hadn't even plugged in the first few times I tried starting the vehicle (which is really confusing me as to how it idled so well earlier). I plugged both back in and resealed the UIM-LIM flange before firing it up again.
Same issues. Except now the vacuum leak is REALLY LOUD, and coming from the passenger side of the engine. To sustain the engine, the idle speed screw has been cranked all the way up to idle around 3k rpm, but it bogs and hunts the whole time. I feel like I could reduce the speed a bit and it'd scrape by, but I haven't run the vehicle long enough to figure it out. If I start it up again soon, I'll record its behavior and the noise.
I borrowed a friend's stethoscope and found a really loud hissing noise in the BACV, mostly where the idle screw itself is... Though, isn't that supposed to be normal to its operation? Outside of that, I didn't find much else with the scope. I'll pull it off to reseal its gasket, and do a few checks to see that the BACV works.
Before that, I'll also do both a boost leak and vacuum smoke test after the shops open to see if I can't hunt down the culprit of the leak. I have a sinking feeling it'll be somewhere under the UIM, so a smoke test won't really tell me much about where exactly the leak is.
Okay, okay. Found the vacuum leak, was the ACV, rather than the BACV like I initially thought.
I ran the car for 15 minutes yesterday, and the smoking came and went. There's a lot of smoke coming from the engine bay, but that's just the VHT Flameproof I used. The white smoke from the pipes cleared out when I fired her up today, and was utterly clean within a minute.
There was also the charge light, but it turns out my battery is just on its last legs. With the car off, it hovers at 11.8V, whereas the voltage stays around 13.3V. I'm sure a fresh battery will put the voltage above a healthy 13.6V. The light shuts up whenever the door is closed as well, so I don't think it's anything to worry about.
Yesterday, I only really shut it off because the cooling fan warning light popped up, so I assumed it hit 207*F or whatever temperature it triggers. Assuming this was because it actually was getting hot, it might have been from having the cap off since I wanted to burp the cooling system (thus no pressure). There's probably no cooling issue and that the cooling fan light triggered for other reasons, but more on this later.
At the time, I also figured that idling at 2.2-2.4kRPM while stationary isn't ideal for the cooling system, so I went to adjust down the idle first. After the whole vacuum leak episode, I forgot which way to turn the idle speed screw. It was pretty much all the way turned in the clockwise direction, which I thought was the direction I turned it to bump the idle speed, but spinning it counter-clockwise sounded like it increased the speed instead. I almost completely unscrewed it out of the BACV, but the idle speed didn't change.
I didn't figure out what was going on with the idle since the cooling fan warning light and buzzer came on, so I shut off the car first. Turned out that the fan itself suddenly stopped working, although I've no idea why. The fan itself works when 12V is put to it. At the connector, I can get battery voltage between the blue wire and the negative terminal of the battery. When the car is switched off, I get continuity between the black wire and ground. But whenever the key is switched to ON, the continuity breaks between black and ground, which is quite possibly the weirdest thing I've seen yet. Bypassing the black wire with a wire straight to ground runs the fan, but the cooling fan warning light stays on.
While I'd rather focus on core drivability issues, the cooling fan warning light is kind of my only instrumentation for gauging coolant temperature at the moment because the actual gauge in the main cluster doesn't work. It might have something to do with the fact that it's an NA gauge cluster shoved into a Turbo-II, but I've seen it intermittently work. In the next couple of days, I'll be picking up an aftermarket temperature gauge, but I also want to address the cooling fan warning before my sanity dries up.
tl;dr, how does the cooling fan warning light and associated cooling fan electrical system work? Specifically, the assist fan used for whenever the AC system runs or the system reads hot.
The cooling fan motor should have two wires, one is Yellow and the other Yellow/Black. The Yellow wire is powered by the cooling fan fuse in the interior fuse box w/key to on. Do you have voltage on this wire w/key to on? If you don't then look at the fuse. The rigger for the motor to turn on comes from the Y/B wire which will have a ground on it depending on what's going on at the electrical fan relay. When it has a ground it will turn the fan on given that the Yellow wire has power on it.
The cooling fan motor should have two wires, one is Yellow and the other Yellow/Black. The Yellow wire is powered by the cooling fan fuse in the interior fuse box w/key to on. Do you have voltage on this wire w/key to on? If you don't then look at the fuse. The rigger for the motor to turn on comes from the Y/B wire which will have a ground on it depending on what's going on at the electrical fan relay. When it has a ground it will turn the fan on given that the Yellow wire has power on it.
I checked the fuse, it's good. Yellow wire has full battery voltage with key to on when referenced to the negative terminal of the battery. Like I said, on the negative side of the fan's wiring (yellow/black), the continuity breaks whenever the key is switched to ON, but then regains continuity when the key is switched back to OFF or ACC. Bypassing the yellow/black wire straight to the negative on the battery runs the fan, but doesn't trigger the warning light to shut off. I checked the FSM and saw two relays associated with the circuit, but I've no idea how this works. Where are they?
I checked the fuse, it's good. Yellow wire has full battery voltage with key to on when referenced to the negative terminal of the battery. Like I said, on the negative side of the fan's wiring (yellow/black), the continuity breaks whenever the key is switched to ON, but then regains continuity when the key is switched back to OFF or ACC. Bypassing the yellow/black wire straight to the negative on the battery runs the fan, but doesn't trigger the warning light to shut off. I checked the FSM and saw two relays associated with the circuit, but I've no idea how this works. Where are they?
The electrical fan relay triggers the fan to come on because it allows a ground signal to reach the fan motor which in turn activates it to turn on. This relay, like all relays in your car, has a coil which gets voltage from the meter fuse w/key to on (since you haven't mentioned that your gauges are not working then I'll assume that fuse is good). If the relay does have voltage w/key to on at the Black/Yellow wire then the signal which activates the relay comes from a ground on the Green/Red wire. You can place a ground on the G/R wire w/key to on and if it causes the cooling fan to turn on then you know this relay is working properly and the problem resides elsewhere such as the sub relay or temp switch.
The G/R wire comes from the 2nd relay known as the "sub relay." For the sub relay to activate it needs to receive a ground signal at its coil on the Blue/Orange wire. This occurs w/the blower/fan motor on and the A/C on. The coil receives voltage from the fan fuse. When the coil receives its two proper signals (one ground and one voltage) the relay closes and allows a ground signal to pass through it on the G/R wire as it then runs to the other fan relay as previously noted. The thing is the sub relay gets a ground signal from the water temp switch. The switch senses temp,obviously, and it passes the ground signal to the sub relay. The switch has a single Green/Black wire and the switch is located by the thermostat housing. The sub relay is denoted as AC-05. Use the wiring diagram to locate this relay. Make sure its Yellow wire, powered by the fan fuse has power w/key to on. Verify that the Blue/Orange wire has a ground w/blower fan on and A/C on (ground voltage should be less than 2.5 volts). Verify that wire from the temp switch has a ground when the A/C is on and the heat of the engine builds thus activating the switch to send a ground to the relay via the Green/Blue wire which connects to the G/B wire from the temp switch. When all this comes into play the G/R wire at this relay should have a ground and the cooling fan motor should turn on given the other relay is acting properly. You could also just bypass the temp switch by placing a ground on the Green/Blue wire at the sub relay. If that gets the cooling fan to turn on then the issue likely resides w/the temp switch.
The electrical fan relay triggers the fan to come on because it allows a ground signal to reach the fan motor which in turn activates it to turn on. This relay, like all relays in your car, has a coil which gets voltage from the meter fuse w/key to on (since you haven't mentioned that your gauges are not working then I'll assume that fuse is good). If the relay does have voltage w/key to on at the Black/Yellow wire then the signal which activates the relay comes from a ground on the Green/Red wire. You can place a ground on the G/R wire w/key to on and if it causes the cooling fan to turn on then you know this relay is working properly and the problem resides elsewhere such as the sub relay or temp switch.
The G/R wire comes from the 2nd relay known as the "sub relay." For the sub relay to activate it needs to receive a ground signal at its coil on the Blue/Orange wire. This occurs w/the blower/fan motor on and the A/C on. The coil receives voltage from the fan fuse. When the coil receives its two proper signals (one ground and one voltage) the relay closes and allows a ground signal to pass through it on the G/R wire as it then runs to the other fan relay as previously noted. The thing is the sub relay gets a ground signal from the water temp switch. The switch senses temp,obviously, and it passes the ground signal to the sub relay. The switch has a single Green/Black wire and the switch is located by the thermostat housing. The sub relay is denoted as AC-05. Use the wiring diagram to locate this relay. Make sure its Yellow wire, powered by the fan fuse has power w/key to on. Verify that the Blue/Orange wire has a ground w/blower fan on and A/C on (ground voltage should be less than 2.5 volts). Verify that wire from the temp switch has a ground when the A/C is on and the heat of the engine builds thus activating the switch to send a ground to the relay via the Green/Blue wire which connects to the G/B wire from the temp switch. When all this comes into play the G/R wire at this relay should have a ground and the cooling fan motor should turn on given the other relay is acting properly. You could also just bypass the temp switch by placing a ground on the Green/Blue wire at the sub relay. If that gets the cooling fan to turn on then the issue likely resides w/the temp switch.
I'm going to try and find these relays tonight. Any hints on where the main relay is? I'm still drawing up a circuit diagram to see if I understand what you're saying about the way this subrelay is triggered.
Also, the meter fuse is good. All the fuses I've verified to be intact.
The wiring diagrams will show the location on the following page in the manual. When you say main relay I think you are referring to the two relays related to the cooling fan circuit and not the actual main relay powered by the engine fuse. And just look at the wiring diagram in concert w/the explanation provided of how the system works and it will become more obvious of how things work.
In looking at the page below the wiring diagram it shows both relays are grouped close together just to the left of the driver side headlight housing. The sub relay plug only has space for 4 wires with them being, Yellow, Blue/Orange, Green/Blue and Green/Red. The other relay has a plug for 6 wires but only 4 spots are used and the wires are, Green/Red, Black/Yellow, Yellow/Black and Black.
Hello, I'm back. I haven't been next to the car this whole time, so it's been difficult working on it. I only recently got to poke my head under the hood.
First off, I already don't think this is an issue of the subrelay. I got my battery charger back, and got it topped up. The battery charge light no longer comes on when the door is opened and the key is switched to OFF or ACC. It used to be at 12.1V, and now it's between 12.5V and 13.1V depending on the state of charge. However, whenever the key is switched to ON, the fan comes on and the voltage drops significantly. When it was at 13V, it dropped to 12.5V and within a couple seconds, the fan shut itself off and the warning light came on. When the battery is sitting at 12.7 or 12.8V, it will drop slowly, trickle down to 12.3V, then the fan will shut off again and the light will pop back on. If I leave the door open when the battery isn't topped up (which turns on the courtesy lights and drops the battery voltage to 12.4-5V), the voltage gradually comes down to 12.2V before shutting off. If the door is closed and I open it after I switch the key and get the fan running, the fan will shut off and the light will come on. If I trigger the fan to shut itself off before the car is switched off to ACC, then I can't immediately switch the key back to ON and have the fan come back on. The light will come on and the fan will stay off. If I let it sit for a few seconds before switching it back to ON, the fan will come back on before the voltage drops too much.
Sooo... basically not enough voltage.
I put the battery on a tester, and it says it's fine. I don't have another battery just lying around, so I can't just swap it out to see if that works. Currently the car's engine is partially disassembled so that I can find a vacuum leak, so I haven't tested whether the voltage will drop significantly and trigger the light again after the car is started and the alternator is charging the battery. That still wouldn't explain why the light would spontaneously trigger even when the car was running for only a couple minutes though. For reference, here's all the other times the warning light came on when the car was started:
-First time I idled it for an extended period of time. I think this was 9/30/15, which was the day before I first asked about the cooling fan. This time, I ran the car for 15 minutes and couldn't get the idle to go below 2kRPM, so I think the thermoswitch triggered it. The exterior of the thermostat neck read around 200*, so the coolant was likely right where it was supposed to.
-The day after, I tried turning down the idle, but within the first couple of minutes, the light came on and I shut off the engine. Not sure why it triggered then, as the temp at the neck was something like 150* whereas the pump was only 170*.
(in between the above start and the one below, the light would come on while the car was cold and not fired up yet, and sometimes it wouldn't. This was before I got around to charging the battery, so that might have explained it)
-A few days later, I tried the suggestion of shorting the relay's coil. When I had the key to ON, it wouldn't come on, but when I shorted it, it sparked and triggered the fan to come on. It kept coming on whenever I switched the key back and forth between ON and ACC, so I decided to take it for a test run around the neighborhood (the sparking probably blew out the meter fuse, which I had to replace before taking it around the block). I parked it, went to grab a friend to show him, and then the warning light popped up the moment I had it switched to ON again. I fired it up anyways, and the light stayed on while I ran it for a couple minutes.
-I tried running it again a couple days after, to try and figure out the idle issue again. The light came on after a few seconds of running, but I ignored it this time around. Fiddled with some stuff, and then shut it off again after 2 minutes.
And that was it. On that last run, I found out it had ANOTHER vacuum leak and took off some of the intake components (hence why I haven't done the voltage tests while the car was running). Then I got busy, and only now did I have time to do the tests mentioned at the top.
From here, I'm probably going to have to wait until I finish finding and fixing the vacuum leak (which will probably take a month given the nature of my damn car) before running more tests to see how it'd react when the car is started
08-10-15, 05:30 AM
