servo-motor?

[mn_sled_head_87]

Hey everyone, i'm having an issue with my '05 M7, and i'm guessing it's the servo-motor, but it's so sporadic that i'm not sure if it's the servo itself, or if it's some other problem. but, when i fire it up, it runs fine and everything goes as it should, but when i get on the gas and pin it, it'll jump up to peak rpm's, but then fall flat on it's face. took me 3 pulls to get back up daisy to get back to cooke last wednesday, and even 3 pulls was cutting it close. it did the same thing a couple times on the way back. the next morning, i fired it up, let it warm & started going down the road, and it started throwing 6 flashes of the check engine light, servo-motor, i know. so i shut 'er down for a few minutes, fired it up again, and headed down to the parking lot, and it didn't throw any codes, and it only dogged down once out of 10 or so WOT pulls on the road (testing to see if it kept acting up). anyone know what would do this? bad servo-motor? messed up wiring? i'm kinda at a loss for ideas at this point.

sorry if that was sort of long-winded or confusing, but any help would be greatly appreciated!

 

[catmechanic]

start out easy. i had the exact same problem 2 years ago with an 07 M8. check the free length on your powervalve cables. if they are a mil or 2 out of tolerance, it will throw that code. if that doesn't fix it, then you are looking at the servo motor. keep the valves clean(once or twice a year), and check and set the free length on the cable every time.

don't quote me on this, but i want to say the length is 34.1mm??? sounds familiar i guess. im sure somebody on here will chime in if im right or wrong. also, measure from the inside of the ball on the end of the cable to the edge of the cable housing. don't measure to the outside of the ball.

 

[mn_sled_head_87]

awesome. thanks for the help! i'll check that out when i get home on friday. one more quick question (probably kinda stupid, but i've never worked with the cable lengths or the servo motor before): if the length is off by a bit, how do i adjust them?

 

[mn_sled_head_87]

can anyone verify the correct length for the APV cables at the servo-motor? i can't seem to find it with the search feature, nor how to adjust them (which makes me feel kind of foolish. lol)

 

[Mjunkie]

The correct length is 34.5mm plus or minus 1mm. You want to adjust them on the short side since the cables do stretch with time. To adjust them there is a cable adjust nut with a locking nut to hold the adjustment. Pull the cables off the motor and check the length like was said above, then to adjust it you first loosen the locking nut and turn the adjuster nut. Just look at the cables and you'll see what I'm talking about. If you haven't cleaned the powervalves they could be sticking, so I'd do that also like said above.

 

[mn_sled_head_87]

i actually just cleaned the powervalves at the beginning of december, so i'm pretty sure that the cable lengths must be off by a bit. i'll be sure to check that out when i get home this afternoon. thanks for all the help!