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Discussion Starter · #1 · (Edited)
Help!!! I have a 08 evo x with about 40k on the clock and its my daily driver and I drive her with care. Early this week it started making a grinding/donkey moaning noise from the rear (almost like its coming from the diff) and it only happens when accelerating in 1st, 2nd, 3rd and when cornering at speed with a shift of weight.. I took it to the dealer and the tech could get it to doit in normal driving but when put on the lift they couldnt. Now that I have been thinking and doing some research I am thinking its the AYC. i have seen alot of issues with them online including them being burned up and I would like to solve this issue ASAP. I have 2 seperate videos where I have recorded the noise while driving.. Thanks in advance Brandon

video 1


video 2
 

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i doubt this will find the problem, but did you check under the car to make sure there's no debris stuck stuck around the drive shaft? I got a small stuck up there once that made a similar sound, only at certain speed/rpms. I doubt that's whats going on here, but its an easy check.

how fast are you losing AYC fluid? If you have to top it off more than once per year, then that's your problem. Any signs of leaks underneath?
 

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Discussion Starter · #3 ·
It was on the lift at Mitsubishi and I walked under it and saw nothing as well as the tech completely went around the car for like an hour shaking anything and everything to try and replicate the sound as if it was just a rattle... I know it's not, the circumstances under which the noise is heard, to me shows it's mechanical.. I had a tech ride with me and heard the noise but they put it in thr air and could not replicate the sound in the air.. My thinking is that it is the ayc because it had no load on the read dif so therefore it wasnt trying to transfer power around.. I took it to mitsubishi about 3 months ago because i was getting the service the awc light and the ran it and there was a tsb and they reprogramed it...But I recently filled it for the first time with about a quarter or a quart of mitsubishi Fluid... It was cold when I filled it to max and not running because I read that it is the way to do it.. I got frustrated today and with the car off but right after a hour long drive I topped it off to max again with about another quarter quart.. I will check it again tomorrow after my drive to nd from work and I also am getting a oil change tomorrow so I will inspect the drive train again tomorrow while it is in the air...Also I took the car yesterday to Mitsubishi and today I started the car and got a service engine soon light, it could be unrelated just the timing could be fluke but I will have my shop run the code tomorrow for sure
 

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That's a bizarre noise. Do you see it come on in conjunction with the SAWC graphic display (the one that shows you when the ACD and AYC is engaging)? The fluid use is way too much. Look around the rear diff at the back, there are two bleeder nipples. Any leakage there?

If the pump has air in it it could make a noise like that. Remember it is energizing the ACD and the AYC. The ACD clamps during accel at the times it makes those noises.

Another test you can do is put it into SNOW mode and accel in the same way. If the sound becomes more pronounced and lasts longer than in TARMAC and GRAVEL you will know it's the pump.
 

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Discussion Starter · #5 ·
So after driving to and from work, I checked the ayc fluid level when the car was off and cold and the fluid was below minimum again... Also the noise only happens when there is 3 bars that are displayed in the center of the s awc graphic display..
 

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Looks like you'll need the diff replaced or rebuilt. Is the car modded? If not, make mitsu replace it. If so, talk to IAG.
 

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have you had the rear diff fluids serviced? if so, who serviced it? when? some others had shops totally fuck up their rear diff and AYC when screwing up the fluid flush.
 

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Discussion Starter · #9 ·
No I haven't, I got the car like 10k miles ago... If the previous owner did can that void the warranty or anything?
 

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Did you buy it from a Mitsu dealership? Did they include a warranty? If so, then you're good. Otherwise, if the warranty was voided, then you're screwed.
 

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Discussion Starter · #11 ·
No I didn't buy it from them but my 5 year warranty is still good... Had them do some other warranty work before... And I just had my shop run the ecu and it came up with a dtc p1320
 

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Discussion Starter · #12 ·
Also I checked the entire under carriage and no sticks or debris or anything...also I inspected the rear diff and ayc pump and no signs of leaks
 

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P1320? Can't find any code like that, is this a typo?

Don't concentrate on the rear diff until you can rule out the pump. The pump activates the ACD in the T-Case as well as the AYC clutches in the rear diff. Did you try the different mode tests?

The ACD comes on briefly in low speed accel all the time, if the noise is associated with it then things can become more clear. If you have air in the system it can make this noise.
 

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First thing to do is to keep accelerating and making videos... Don't bother going to a service center, that is overrated! :whipping:
 

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Ah, P1320 was changed to P050B in the 2010 manual. Sounds like timing is heavily retarded. Just like the linked thread it suggests to look at the thermostat.

Not sure if this is related to your noise, however.

 

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Did you ever find the cause of this? My car is making the exact same noise as yours. Other than the noise it drives just fine.
 

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Nope 100% stock!!! Was waiting till my warranty was up thank god!!
Good move that paid off for you!
Did you buy it from a Mitsu dealership? Did they include a warranty? If so, then you're good. Otherwise, if the warranty was voided, then you're screwed.
Basically. Good luck and let us know how it goes.
 

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I've had this noise a couple times when it was very cold out. It sounds like it comes right from the S-AWC pump area. My guess is that it's the valves actuating making those noises. Here's what you can try (and no this won't hurt anything). Disconnect the solenoid valves on the S-AWC pump and see if it still makes the noise. I bet it doesn't.
 
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