C Del

Did you buy from or sell the car to Carmax? How much was billed to the warranty? "Decarbon Procedure" may refer to a simple zoom-zoom decarbing, like I did with water, which they are probably more eager to cover, being that it can't be very expensive.

C Del

So, with an extreme amount of help from an awesome coworker (thanks, Mike!), I took the intake system apart enough to inspect the majority of the APVs. Without pulling the engine, I was able to get the intake manifold out far enough to see about 3/4 of each of the valves. Neither valve showed signs of carbon buildup which would, or could, cause the valve(s) to stick. In fact, I found the APVs to be much cleaner than I was expecting. Both valves rotated easily and smoothly via the APV motor gear, and the APV motor itself functioned properly when tested alone (having been removed from the engine). It was at this point that I decided to simply clean the accessible portions of the valves, lubricate them, and throw everything back together.

My new working hypothesis is that the connector for the No.2 APV position sensor is at fault, or that there is a wiring problem somewhere between the sensor and the PCM, causing the sensor signal to float intermittently.

As a note, we were attempting to remove the intake manifold without completely removing the engine from the vehicle. We found this to be either impossible or more involved than would have been prudent to undertake. To anyone reading this who may have seen posts elsewhere on this forum stating that this is possible: DO NOT attempt to remove the intake manifold without dropping the motor, or at least don't expect your attempts to succeed. Given time constraints and the fact that my APVs seemed quite clean, we did not drop the motor or remove the manifold, but we weren't far from it, and I firmly believe that dropping the engine, transmission, and front crossmember component as described in the service manual is the correct and easiest way to do this. I know I'm being wordy on this, but seriously, don't do what I did!

Here's a picture to look at - not particularly useful, but I'll thorw it in here to spice up the thread (click for full size):

Brettus

iTrader: (2)

Funny thing about you doing all that is that a simple log of g/s would have confirmed if the valves were working or not ...................

ASH8

As a note, you were advised not to attempt full LIM removal anyway without engine down or out...again, to completely remove APV's (LIM), this is the only way.

I hope you did not damage your APV's, did you read the 2011 TSB on removal of LIM?, how did you support the valves at 3/4 out?, you are meant to actually install two 9 inch long bolts into irons (each end of intake) so it supports the APV's, AFAIK this is not illustrated in any factory manuals as this instruction (installing the 2 x 9 inch support bolts) only came out in 2011 for all series 6 port RX-8's.

2 x Bolt purpose is not to damage the APV's (at their connection end) by LIM resting weight on them, this had occurred many times @ Mazda Dealer level requiring complete LIM replacement before Mazda made the 2 APV's and 2 single use mini Bolts available as a separate serviced part.

Anyway, what do you get when/if you unplug the # APV sensor, and leave it unplugged, does it still chuck a code.?

Only the US (only Series II's) has these silly APV position sensors installed...

Good luck...

TeamRX8

iTrader: (25)

Why did you even attempt to pull it before doing the proper analysis? Simply unbolting the drive motor and either noting the position or rotating the actuator gear will tell you if it stuck/sticking or not. Then there's performing a simple test on the position switch too. All that effort for naught. Wow.

Carbon8

iTrader: (4)

How is this not covered under the power train warranty.

Only a fool would pull the motor without doing anything else to verify, can't wait to see the result

EviLStewie

Honestly,
All I do is read posts on this darn forum and I've not seen anywhere in any post where anyone has even remotely suggested that you can remove the LIM without removing the motor.
Please link me to that post.

Now the UIM is totally possible.

Why in the name of all that's holy would you do all this work?
I don't see anything anywhere that indicates that the APV is the issue here.

TeamRX8

iTrader: (25)

I seem to recall that it has been done. You have to take the motor mounts/brackets off and push the engine as far over to the other side as possible. I believe it was OD who had done it this way?

ASH8

Just want to point out to a few here that...

1. This DTC has not been used before in RX-8, and is only used in USA S2's, not on any Series 1's or Series II's not for North America.
2. The OP has already renewed this Sensor @ APV #2 and is still getting the code (P2005).
This code is continuously monitored (so my suggestion of disconnecting sensor plug probably wont work)...this sensor only reports that the APV is stuck open.

Just throwing this around OP is there anything used on/in this car which is not OEM?
Are there any aftermarket LED lights used?, apart from the OEM.

BTW: If you are not going to assist this member stay out of thread.

Brettus

iTrader: (2)

Any idea why they bothered ?

ASH8

Hi M8..
I think was to comply with US Emission regs.. am happy that mine does not have AP Valve Sensors, really why would you want them, it is not like it has been an issue in any Series 1 .... APV Motor code has.

C Del

OK. I'm going to take a quick deep breath before continuing....

Done. Now, thank you for the constructive comments, however I don't particularly need to be told that I've been an idiot. I acknowledge fully that I was advised that removing the LIM without dropping the engine would not work, and I did not expect success in that attempt. Having seen it mentioned that the LIM could be removed by shifting the powertrain as described by TeamRX8 above, I decided it would be worthwhile, at least for the information of others if not myself, to test it out. I'm still not entirely convinced that it is impossible, however I do now believe strongly that dropping the motor is the best way to extract the LIM, and would probably be easier even if the same effect could be achieved by shifting the engine over. I feel it is important to note that I would have dropped the motor as prescribed had I felt that it would have been beneficial, however the amount we were able to get the LIM out gave us a good enough look at the APVs to convince us that carbon fouling was not the issue and that the APVs were rotating correctly. At that point, it seemed we had nothing to gain by continuing.

With respect to above comments regarding diagnostics performed prior to attempting to remove the LIM: I had replaced the sensor first (thanks, ASH8, for pointing this out) and I did manually actuate the APV motor gear prior to the teardown (the movement seemed quite smooth and unimpeded). I do have a few logs of mass airflow, and the thought did occur to me that this could indicate the state of the valves, but at the time I was skeptical that I could get much of a definitive answer from MAF readings, given that I don't have any readings from this vehicle prior to the problem surfacing. I will admit that I should've looked into this further, but I'm not sure that it would've prevented me from attempting to pull the LIM anyway.

I realize that I'm a noob here, and a noob with rotaries in general, but I'm not so sure this endeavor was quite as foolish as some of you seem to indicate. I could very well be wrong, but still, I became much more familiar with the vehicle, mechanically, through doing this, so I don't consider it a total loss (though it was a bitch).

I was aware of the issue of APV damage when removing the LIM, but I don't think I saw the TSB until after I had done this. When inspecting the APVs, I would pull the LIM away from the engine, do my best to support it by hand, and then mate it back up again if I was going to let go. I hope I didn't do any damage in doing that, and I was trying not to, but I regret that I didn't read that TSB until afterwards.

I will try disconnecting the wiring harness if I can get to it (this would be much easier if the No.1 sensor was complaining). I would expect to get P2007 then (APV No.2 stuck closed), depending on where the voltage wants to float to, but it might be interesting to see. It would be nice to have the MMDS right about now so I could see what the PCM is seeing. I've been meaning to get an oscilloscope - maybe I'll get one and hook it up on the PCM side and see what the signal coming from the sensor looks like. At this point, I'm not sure what else there is to test. Anything obvious that I've missed?

For TL;DR: Be nice. I'm posting all my mistakes here so people living in the future have a clear guide on what not to do.

Brettus

iTrader: (2)

If you posted a g/s and AFR log at WOT in 3rd gear from 2500 to 8500rpm I'm pretty sure I would be able to tell you if the APVs were working or not .

BTW : Good on you for taking all that and not getting too upset about it .


EDIT : actually a CSV file would be good . then I could overlay your result on a healthy engine ,and post it up, so you can see it for yourself .

ASH8

Just throwing this one out there...

IF you can not get this resolved and there is not any issues with wiring loom or plug, the only thing it can be is then PCM.

Would it be worthwhile trying a 1A in-line resistor which should report constant and stable 1A?
Series 2 (USA only) #2 APV Position Sensor wiring colours...
Lilac/White is constant voltage.
Black/Yellow is ground.
RED is reporting, so my thought is to install 1-Volt in-line resistor in red wire.....?

For reference only..
#1 APV Sensor wiring is Lilac/Green cv., Black/Orange ground., Red/Green report.

Just also throwing this one out there (clutching at straws) is there a possibility that the plug/wiring connections to the 2 separate but same APV Sensors has been reversed in error by someone?...and yes I know you 'should' get 2 sets of codes if they were.