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Showing results for tags 'Knocking'.
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A couple of days ago I picked up a 1998 Forester, the main issue I am concerned with is a knocking sound in the engine. I think the knocking sound is a lifter. It is a small hammer tapping type sound. If the car is idling in neutral and I increase the rpm's a bit, the tapping normally stops. But if I am driving around town, just normal easy driving, the tapping stays. Under load 20-25 on a steep hill, level ground 20-35+, going downhill, etc, it seems to stay pretty much the same other than the tempo changing with rpm's. I keep thinking it sounds like a sticky lifter. A rod bearing should get louder under load? and a wrist pin quieter under load? If I remember correctly. I have looked up videos and they show the timing belt tensioner gone bad making a rattle, but this is not a rattle, it is a definite tapping that is in tune with the rpm's of the engine. The engine has 246,000 miles on it. I am considering pulling it and rebuilding it. Any opinions appreciated, Thanks. -
98 ej22 in a Legacy L. ~141k I'm pretty stumped at this point and I appologize for a long post - bare with me here: After an oil change I start the engine with the knock sensor disconnected. I then reset the ECU or clear the code. Don't ask me why - it prevents the bogging issue - it works for me. After the latest oil change at 140k (Castrol 10w-40, FRAM filter), however, I have been getting the typical knock sensor bogging issue even after the tribal oil change dance. I moved the knock sensor to the location of a factory ground point (on bracket above starter), reset the ECU and drove for about 100 miles. Knocking? Yes. Hesitation, bogging BS? No. Corrosion was apparent on the mating surfaces so I sanded them back to clean metal. I then tried the old knock sensor in the factory location, reset ECU and got no joy. I do observe the ~15mile learning cycle by the ECU before it begins to bog. It is at this point I was confident a new knock sensor would fix my woes. I purchased a new Knock Sensor from Autozone and installed in correct location with about 15 ft-lbs making sure to orient the wire lead so that it was clear of block protrusions. Reset the ECU and got no joy. Now I started to suspect a bad connection so I cut the wire and hardwired the old knock sensor in sans connector. That resulted in no change of symptoms (see note 1 below). Now I was becoming befuddled and a bit ticked off. I can change the performance of the car by relocating the knock sensor but a new one won't fix the problem. I figured I didn't need a new knock sensor and, at this point, I started to march down the path of "Gee, maybe there's too much knock!" so I returned the new KS to Autozone. I drained/refilled and burped (to death) cooling system and installed a new thermostat (the bigger OEM type) and a new rad cap. Operates right around 180-190F according to OBDII data so it is not running hot. Then I went after the ignition system a bit: I installed $40 NGK wires and NGK Irridium plugs gapped to a tight 40 thou. I also installed 500 pounds of copper all over the place to enhance grounding. I cleaned the mating surfaces of the igniter and it's mounting plate, although the igniter is currently sitting on two ring terminals - one as a spacer only - the other with a lead directly to a ground point on same sheet metal platform igniter is mounted to. The coils are about 25k miles old and I have an older set which I have swapped out with no change in symptoms. The coil contacts are clean and I use dielectric grease on the plug wire boots. Then I filled up with high octane gas and reset the ECU. With the original KS installed in factory location I still got the bogging issue. When I move the KS to my off-the-block location the bogging goes away and there's no audible knock with high octane gas. So, at least I know that high octane gas really has a higher octane. After all this I went to the junkyard to source an OEM connector and soldered it in. There is a short section where the sheilding is soldered together but the rest is completely sheilded - see note 1 below. I then went back to Autozone to buy a new knock sensor. I did this with the hope that I would get another knock sensor (not the one I returned) but I got the same one. I'll ask and see if I can try another next time I'm by there. I purchased a BAFX Bluetooth OBDII adapter (cool tool) and tried to read engine parameters with Torque Lite. All I got was engine temp and load so an actual analysis of engine parameters was a dead end there. (If I buy Torque PRO will it give more engine data or is my car just too old-school?) At this point I'm thoroughly stumped. I will check the main harness connections but I don't expect anything to come of it. I saw some other threads on USMB with good info but it seems the threads just died without any real resolution - here, here, and here. I can't imagine it is anything other than knock sensor related. My next steps are to check the car's recall history and see if I can get a hold of a second new knock sensor to test the infant mortality theory. If a third knock sensor makes no change perhaps the ECU is to blame. All pointers/tips/ideas are welcome and appreciated! I have a degree in Electrical Engineering and can surmise that the real need for the sheilding on the knock sensor wire is when ignition parts begin to leak their current i.e. a leaky spark plug cable that is jumping to metal on the engine somewhere rather than fully to the plug. I can't imagine that there is any other source of electrical interference in the engine bay that could induce electric current in the wire - mine was a short, unsheilded piece which, I believe, means there has to be a LOT of unshielded current flowing somewhere else before any induction will take place in the short unsheilded wire to the knock sensor.