Kevin Doe
March 26th, 2008, 10:18 AM
I'm having an issue that I can't seem to sort out. A little background.
I have my VE tuned in to within 1% over nearly every single reachable cell. I spent a LOT of time on this. That said, if look in the log and see the commanded AFR, the acutal will match (with the BBL I'm using there is a bug so I can't log AFR, but i know its fine).
I have been getting knock at low speeds (usually between 10-20 mph) wiht light throttle, maybe 20% TPS. The knock ranges from 0.5 tapering off, and sometimes as much as 4 or 5 degrees then tapering off. Its always when I start driving from a dead stop.
Again, on the log I have attached I could not log DYNCYLAIR_DMA due to a BBL limitation, so I logged the non-DMA parameter and assume its fairly close. I've looked at the data in several ways. In doing so I've noticed that at a particular rpm and gram/cylinder combination there are many vehicle speeds that it could be at depending on what gear I'm in. That said I looked at the data and I only get the knock at the low speeds. Same location on the timing map, yet I only get knock at the low speeds. I looked at the fueling at both high and low speeds when in the same condition, and thats equal as well.
Looks like the spark on high-octane map and the fueling maps would put it at the same condition, but yet it knocks. I'm pretty much baffled.
Now my question. What in the control logic is dependent on VSS that could cause this issue? Any ideas on fixes. I've lowered my High-Octane spark talbe a few times in the problem area, but it does not have any effect on the problem.
I have my VE tuned in to within 1% over nearly every single reachable cell. I spent a LOT of time on this. That said, if look in the log and see the commanded AFR, the acutal will match (with the BBL I'm using there is a bug so I can't log AFR, but i know its fine).
I have been getting knock at low speeds (usually between 10-20 mph) wiht light throttle, maybe 20% TPS. The knock ranges from 0.5 tapering off, and sometimes as much as 4 or 5 degrees then tapering off. Its always when I start driving from a dead stop.
Again, on the log I have attached I could not log DYNCYLAIR_DMA due to a BBL limitation, so I logged the non-DMA parameter and assume its fairly close. I've looked at the data in several ways. In doing so I've noticed that at a particular rpm and gram/cylinder combination there are many vehicle speeds that it could be at depending on what gear I'm in. That said I looked at the data and I only get the knock at the low speeds. Same location on the timing map, yet I only get knock at the low speeds. I looked at the fueling at both high and low speeds when in the same condition, and thats equal as well.
Looks like the spark on high-octane map and the fueling maps would put it at the same condition, but yet it knocks. I'm pretty much baffled.
Now my question. What in the control logic is dependent on VSS that could cause this issue? Any ideas on fixes. I've lowered my High-Octane spark talbe a few times in the problem area, but it does not have any effect on the problem.