engine knock under heavy load and low RPMs
engine knock under heavy load and low RPMs
(OP)
I have an 09 impreza with a naturaly aspirated stock 2.5l SOHC engine with 10:1 compression. Engine is rated at 170hp at 6000rpm and requires only regular 87 octane. I have been noticing hesitations with this engine at around 2500 rpm under load. After some data logging i noticed severe knock corrections at those RPMs. I personally don't hear any pinging or detonations (i have excellent hearing). Above 3000 rpm car pulls fine with no reported knocks. Enriching the mixture and using 94 octane gas hasn't solved the knocking issue. I'm wondering how i can go about and figuring if this is a knock sensor issue (false knock) or just a bad engine. Engine has 50k miles.
Logs:
testing temprature 70f, humidty 60%, altitude 700ft, 91 octane gas
https://docs.google.com/file/d/0B3d0m8bScGepQnk5Qm...
https://docs.google.com/file/d/0B3d0m8bScGepWHdWS3...

Logs:
testing temprature 70f, humidty 60%, altitude 700ft, 91 octane gas
https://docs.google.com/file/d/0B3d0m8bScGepQnk5Qm...
https://docs.google.com/file/d/0B3d0m8bScGepWHdWS3...






RE: engine knock under heavy load and low RPMs
I think you're losing an exhaust valve.
Mike Halloran
Pembroke Pines, FL, USA
RE: engine knock under heavy load and low RPMs
I unexpectedly picked up what felt like 20 HP after removing a barely rattling heat shield on a '85 Volvo 240 that had a crude non synchronized knock sensor in its Bosch motronic system. I assumed the rattle was annoying the knock sensor, even though I would never have expected the sensor to feel it.
RE: engine knock under heavy load and low RPMs
I do have a noisy heatshield. The dealership is supposed to fix that this coming tuesday. A rattling heatshield only causes knock noises under load? Engine is quiet in idle or revving it at idle.
RE: engine knock under heavy load and low RPMs