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So the story goes, The other day I noticed when I started my car, a bunch of dash lights would come on (ABS, TCS, Brake, Battery, Power Steering, etc.) as well as the power steering not working. A free diagnosis proved that the alternator was dead so I just replaced my alternator, and when I started the car, everything was running fine, the battery was charging, and all seemed well. I let the car warm up and charge the battery a little bit, and decided to take it for a drive. I was easy on it for a good 15 minutes, but then decided to open it up in first gear. I revved up to around 8k or so, and pushed in the clutch so I could coast to a stop. As soon as I pushed in the clutch and let go of the gas, the engine revved itself all the way to redline, but fell down to about 3k RPM where it sat and jumped up and down by itself (was not idling). When I tried to push the gas, nothing happened. It did not respond to the gas pedal. I eventually coasted to the side of the road and cut the ignition. After I cut the gas off, I tried to start the car again, but it wouldn't turn over (edit: the starter would spin, but the engine would not ignite). The battery had plenty of charge to start it, so that is not the issue. As soon as it started revving itself, I got a CEL. Haven't had a chance to get the code read yet. I posted a video here (note that the TCS light is only on because this was the first driving cycle after reinstalling the battery):
A failed alternator is not good news. It is rare, but when it happens it can fry a lot of expensive electronics.
Can you confirm that when you attempted to restart it would not turn over? As in the did nothing, or the starter spun but the engine did not? Or do you mean "turned over but would not fire" Many people use "turn over" incorrectly, despite it meaning exactly as it says, so I want to be sure I understand you right.
A failed alternator is not good news. It is rare, but when it happens it can fry a lot of expensive electronics.
Can you confirm that when you attempted to restart it would not turn over? As in the did nothing, or the starter spun but the engine did not? Or do you mean "turned over but would not fire" Many people use "turn over" incorrectly, despite it meaning exactly as it says, so I want to be sure I understand you right.
My bad, by turned over I meant the starter would spin, but the engine would not ignite.
Ok, there are a bunch of possibilities, and this probably isn't going to end up being cheap. However, some free stuff to start with, a couple that J already mentioned.
- Unplug the battery for several minutes
- unplug the maf at the same time for several minutes
- clean the ESS while you are waiting (you are about to clear it's profile, might as well make sure it's a good one)
- after reconnecting, reset the ESS profile
I'm suggesting this because the ESS drives both the tach and the fuel/ignition. If there is an ESS problem, then it would cause the tach to have problems easily, and could also cause the engine to not fire when cranking. IF the problem is just in a profile problem, then this will clear it, along with any residual configurations that the ECU has stored. Rebooting it all so to speak.
If no change, then either replace the ESS or swap yours with someone else's known good one, to see if you get a change.
If still no luck, you will probably need a dealer to test the ECU for problems/errors, and almost certainly deeper than just 'checking codes'. The ECU can and will fry rather quickly with an alternator over-voltage. It rarely just goes dead, resistors inside the ECU will burn out and allow far too much current through whatever circuit was involved with it, causing all sorts of problems. Which circuit it happens with is virtually random.
Ok, there are a bunch of possibilities, and this probably isn't going to end up being cheap. However, some free stuff to start with, a couple that J already mentioned.
- Unplug the battery for several minutes
- unplug the maf at the same time for several minutes
- clean the ESS while you are waiting (you are about to clear it's profile, might as well make sure it's a good one)
- after reconnecting, reset the ESS profile
I'm suggesting this because the ESS drives both the tach and the fuel/ignition. If there is an ESS problem, then it would cause the tach to have problems easily, and could also cause the engine to not fire when cranking. IF the problem is just in a profile problem, then this will clear it, along with any residual configurations that the ECU has stored. Rebooting it all so to speak.
If no change, then either replace the ESS or swap yours with someone else's known good one, to see if you get a change.
If still no luck, you will probably need a dealer to test the ECU for problems/errors, and almost certainly deeper than just 'checking codes'. The ECU can and will fry rather quickly with an alternator over-voltage. It rarely just goes dead, resistors inside the ECU will burn out and allow far too much current through whatever circuit was involved with it, causing all sorts of problems. Which circuit it happens with is virtually random.
Now that you mentioned the ESS, a while back (maybe a month ago), I was having a hard time starting the engine, and eventually it threw a code (P0366), which was related to the crank sensor? Eventuall the code went away, and it was starting up instantly again, so I didn't worry about it. Maybe that's related? Then again, it did just start happening after the whole alternator issue, so maybe the ECU is fried?
Generic code readers will show "crank sensor" codes for the ESS, only Mazda specific code readers will show "eccentric shaft sensor" or "ess" or "e-shaft sensor". Same function, same sensor design, same trigger method.
Generic code readers will show "crank sensor" codes for the ESS, only Mazda specific code readers will show "eccentric shaft sensor" or "ess" or "e-shaft sensor". Same function, same sensor design, same trigger method.
I will start with the above suggestions then. My house doesn't have a garage or a safe place to work on a car, so I towed it to my parents house while I figure this out. I will go over there later and disconnect the battery/MAF/ESS. How would one diagnose a bad ESS?
There are 2 images missing that don't copy paste into text. See the Mazda service manual (foxed.ca) for the full article and the images showing the pinnout.
2005 - RX8 - Workshop Manual - Engine
ECCENTRIC SHAFT POSITION SENSOR INSPECTION
NOTE:
Before performing the following inspection, make sure to follow the troubleshooting flowchart. (See FOREWORD.)
Visual Inspection
1. Remove the eccentric shaft position sensor.
2. Verify that there are no metal shavings on the sensor.
If the monitor item condition (reference) is not within the specification even though there is no malfunction, perform the “Circuit Open/Short Inspection”.
Resistance Inspection
1. Disconnect the eccentric shaft position sensor connector.
2. Measure the coil resistance between eccentric shaft position sensor terminals A and B.
If not within the specification, replace the eccentric shaft position sensor.
If the monitor item condition/specification (reference) is not within the specification, even though the eccentric shaft position sensor resistance is within the specification, perform the “Circuit Open/Short Inspection” and repair or replace the malfunctioning part.
Eccentric shaft position sensor resistance
950—1,250 ohms (at room temperature)
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Disconnect the eccentric shaft position sensor connector.
3. Inspect the following wiring harnesses for open or short circuit. (Continuity inspection)
Open circuit
If there is no continuity in the following wiring harnesses, there is an open circuit. Repair or replace the wiring harness.
Eccentric shaft position sensor terminal A and PCM terminal 2U
Eccentric shaft position sensor terminal B and PCM terminal 2X
Short circuit
If there is continuity in the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
Eccentric shaft position sensor terminal A and body ground
Eccentric shaft position sensor terminal A and power supply
Eccentric shaft position sensor terminal B and body ground
Eccentric shaft position sensor terminal B and power supply
There are 2 images missing that don't copy paste into text. See the Mazda service manual (foxed.ca) for the full article and the images showing the pinnout.
So should I remove the ESS entirely, or just clean it? Many of those inspections are over my head. The visual inspection I can do, but from there I'm not sure. Unfortuantely, there aren't many 8's in my area, so swapping with a friend's wouldn't be an option. And as far as resetting the ESS profile, does that just happen with unpplugging the battery/MAF, or is there something else I'd need to do?
Are you familiar with the "20 brake pedal stomp"? That clears the ESS. It's Key to ON position from off, and then 20 brake pedal presses (just enough to trigger the brake lights is fine) within 8 seconds. If you have a 2005 or later, or a 2004 with the later flashes, the oil pressure gauge will sweep full right to indicate that it was successful.
If you aren't able to test the ESS, then swapping it with someone else's known good one, or ordering a new one, would be how you would 'test' it. Removal would happen in either case if the reset doesn't fix anything.
Are you familiar with the "20 brake pedal stomp"? That clears the ESS. It's Key to ON position from off, and then 20 brake pedal presses (just enough to trigger the brake lights is fine) within 8 seconds. If you have a 2005 or later, or a 2004 with the later flashes, the oil pressure gauge will sweep full right to indicate that it was successful.
If you aren't able to test the ESS, then swapping it with someone else's known good one, or ordering a new one, would be how you would 'test' it. Removal would happen in either case if the reset doesn't fix anything.
Yes, I'm familiar with it. I'll take a look at it tomorrow, and try disconnecting the battery/MAF and clean the ESS and reset the profile. I am not yet going to spend $140 on a new ESS unless I know I will need to.
At first it sounded like it went into limp mode like an OMP issue, but you still have some limited throttle then. The other limp mode feature though is e-throttle safety related. The fact that the engine revs shot up when you lifted and then it had no throttle at all seems to suggest an e-throttle issue. I'm not familiar enough it to know if engine starting/idling might be affected.
I have some spare ESS if you would like me to mail one to you to check against. There typically would be ESS related codes though so unless you have those that's probably not it.
Did you check all your fuses in both the engine bay and driver foot panel? A blown fuel/ignition/room fuse will prevent start up. There may be more ...
Also don't understand why people are suggesting to unplug the MAF along with the battery?
At first it sounded like it went into limp mode like an OMP issue, but you still have some limited throttle then. The other limp mode feature though is e-throttle safety related. The fact that the engine revs shot up when you lifted and then it had no throttle at all seems to suggest an e-throttle issue. I'm not familiar enough it to know if engine starting/idling might be affected.
I have some spare ESS if you would like me to mail one to you to check against. There typically would be ESS related codes though so unless you have those that's probably not it.
Did you check all your fuses in both the engine bay and driver foot panel? A blown fuel/ignition/room fuse will prevent start up. There may be more ...
Also don't understand why people are suggesting to unplug the MAF along with the battery?
.
I am about to drive over to my parent's house to check these things. If you would be willing to mail me a spare ESS for testing purposes, I would gladly accept. I unfortunately don't have a way of borrowing one any other way.
Also, it did throw a code, I just haven't been able to get it checked yet. That's another thing I will be looking at today while I'm over there.
I'll keep you guys posted, and appreciate the responses.
Checked codes and got P0638 and P2109, both throttle body related. I took apart my AEM intake near the throttle body and found this little guy hanging out.
Now that's not supposed to be there, is it? Nope. Removed it, cleared codes; she started right up.
When I hit around 8k RPM at WOT, the intake sucked up the screen that was inside the intake tubing, and caused the throttle body to be stuck open. That's why the RPM's were jumping, and the car wouldn't start because the codes it threw disabled ignition. As soon as the codes were cleared, it started fine.
*Thanks Obama/AEM*
Last edited by thomthoms3; 02-14-2015 at 02:33 PM.
No, it was all bent up, and would not fit back in the intake. I'm not entirely sure it was necessary to have anyway. It looks like it might just be there as a backup to catch leaves or something. I ordered a new one just incase, but I don't want that to happen again.
Emphasizes the point that we're all e-guessing prior to the codes being pulled and pointing you in a possible direction to go. Had this happen locally to WTBRotary, though his screen didn't get that far into the TB, so it wasn't as extreme as yours. You should be able to straighten and re-use the screen. It's fairly common on the AEM intake, which I don't really care for much. It's important to push the coupling and pipe togegher and get the screen squeezed in tight between them while tightening the coupling hose clamp to get it all held tight in place.
That screen does have a job. It is not a debris catcher. It helps even out the air flow for the MAF. I suggest following through and getting it, or a replacement, back in there. The fact that it was sucked out, confirms it was doing something to the air flow.
Yes, restricting airflow. The AEM screen with the thick rubber donut perimeter is not as good of a
design as OE in this regard. The screen has larger ooenings, but the donut design results in a less-than-OE inside diameter flow path. There is another section that is also smaller ID than the factory MAF tube.
02-13-2015, 07:12 PM
Nope. Removed it, cleared codes; she started right up. 
