About to give up on this car
Thread Starter
Teching In
Joined: May 2010
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About to give up on this car So ive been struggling to fix a knock sensor problem in my 98 WS6 for almost 8months now. I finished rebuilding the motor in january for the same knock sensor problem which i thought was for a spun rod bearing. Because I had to go on a detachment with my unit i took it to a shop in town close to base to finish up the loose ends. When i came back he was having trouble with the clutch. He recommended I change the slave cylinder and i did which fixed my clutch problem. Other then that and the fact that my knock sensor light was still on, something the mech said he was unable to figure out because the motor wasnt knocking, the car ran fine up until about a month ago. I started to feel vibrations and an random knocking in my shifter, the floorboard, and all three footpedals. At first everyone told me i was being paranoid and just to drive my car so i did. It been getting continuously worse. I drove it from my base in nc to panama city fl for leave and on the way here is the worst it has been thus far. There is a VERY nasty rattling coming from under the car, there is a grind noise when shifting to 3rd, 4th and 5th gear, and i cant downshift into 5th without shifting to 4th first. Im taking it to tick performance for a stg2 rebuild and hydraulic system swap once i get back to nc but what im wondering is can the transmission cause the knock sensors to go off and does anyone have any advice to back up my thoughts or if not steer me in the right direction
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Joined: Sep 2009
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From: PA/MD
The knock sensors only pickup a very narrow harmonics wave....but if your tranny is making the right noise in that harmonic range, then yes it could throw a code.
Sounds like you might have a synchronizer or two have are wiped out, and might be missing a tooth or two on one of your gears
Sounds like you might have a synchronizer or two have are wiped out, and might be missing a tooth or two on one of your gears
Thread Starter
Teching In
Joined: May 2010
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see thats what im thinking cause it sounds like something it rattling around in the tranny. I made it 812 miles and it still got close to 30 miles a gallon in 6th gear. If the motor was messed up i dont see it being able to do that. But im just worried i wont be able to make it back to nc with it like it is...but i really dont have a choice. Let me ask you this. I heard someone mention some kinda test you can do with your trans to determine problems...something about trying to pull the shifter into sixth whithout engaging the clutch and see if the car trys to move...i did that and it didnt move but up untill recently(due to what i think is something rattling around in the tranny case) when i would try that the clunking would go away along with a majority of the vibration....does that mean anything to you???
Start with the simplest part in the equation...your trans crossmember mount. It's a hunk of molded rubber and they are known to fail. When they do, the trans can bounce around and smack the floorboard.
Jack it up, crawl under there, grab the tailshaft housing, and give it a shake to see how much it moves. Visually inspect the trans mount for signs of failure, eg. cracks in the rubber or worn metal showing.
Jack it up, crawl under there, grab the tailshaft housing, and give it a shake to see how much it moves. Visually inspect the trans mount for signs of failure, eg. cracks in the rubber or worn metal showing.
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TECH Resident
Joined: Feb 2002
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From: Roseville, Ca.
All good advice above. There's more to check, although unlikely causes. If you do pull the trans out, you might as well check the U joints and have the driveshaft balanced. If you end up with a new clutch, have the flywheel and pressure plate balanced together as well. Make sure your crank pulley is intact and hasn't tossed a balancing weight. Make sure the rear suspension components and torque arm are intact and not letting the rear twist around. Overkill, but cheap peace of mind. When you rebuilt it, did you have the crank or rotating assembly balanced?
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A knock sensor is literally a microphone. It has certain frequency range that it can detect (sound). An engine knocking emits a certain narrow known band of frequency range. When the sensor picks up that range it will tell the computer that a knock is detected and then the ignition is retarded. Any sound that falls in the knock sensors detection range would trigger it to tell the engines computer that their is an engine knock. But just like any microphone, the knock sensor can only pick up sounds so far away from the sensor.
Grinding on any transmission calls for remove and find out where and why if the tranny mounts prove that they are not allowing the tranny to move around. But since you are having problems in various gears then i would say its safe to assume that your manual needs a rebuild.
Run a code scanner in realtime monitor mode and watch and see if your ignition is being retarded during your "very nasty rattling" events...that will tell you if the knock sensor is "hearing" your rattling noise.
Grinding on any transmission calls for remove and find out where and why if the tranny mounts prove that they are not allowing the tranny to move around. But since you are having problems in various gears then i would say its safe to assume that your manual needs a rebuild.
Run a code scanner in realtime monitor mode and watch and see if your ignition is being retarded during your "very nasty rattling" events...that will tell you if the knock sensor is "hearing" your rattling noise.
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Teching In
Joined: May 2010
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When i scanned it before the codes it pulled were a p0327 and a p0332. It said they were occuring at rpms ranging from 1500 to 2200. At higher rpms it wasnt detecting it. I had kinda already figured that out because when i would try to get the light to come back on i would open it up a few times and it would never come on but as soon as i brought it anywhere close to idle or shut the car off and started it back up the light would come on.
Those codes have nothing to do with engine knock. They are codes for voltage problems for the sensors themselves. You likely just need to replace the knock sensors and the harness.
The vibration and transmission noise has nothing to do with setting these codes. While by the sound of it you definitely need to have some tranny issues fixed I can assure you that it will not get rid of those trouble codes.
The vibration and transmission noise has nothing to do with setting these codes. While by the sound of it you definitely need to have some tranny issues fixed I can assure you that it will not get rid of those trouble codes.
