Knock Retard, a little long, need help!!
12-25-2008, 05:43 PM
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Knock Retard, a little long, need help!! I am having a problem tracking down the cause of my knock retard, I don't know what to check next. My car woes started when I was messing with my shift points and all of a sudden my car started to miss and hesitate. I thought I may have over-revved it so I took it to a shop.
At the shop they did a compression and leakdown test, pulled the pushrods and checked them, checked the springs, and it turned out that it was a cracked spark plug (I did a plug change 2 weeks prior). I drove the car home, everything seemed to be fine. Next day I installed bolt-on subframe connectors and took it for a test drive. That is when I noticed I was having a knock retard problem.
The computer has been pulling up to 16 degrees at part throttle (50% throttle or so). On throttle tip in I am getting up to 4 degrees, and part throttle (40-60%) I am experiencing 5-16 degrees. The problem is intermittent (not always present). Wot is mostly fine, occasionally I will see 1 degree or less of KR. I have been through 3 tanks of gas since the problem started so I don't think it is bad gas. Here's what has been suggested to me so far:
1)- Subframe connectors need to be welded? I have poly motor and trans mounts, along with all poly suspension parts. The subframes may be transmitting vibration to the floor pan and it is being picked up as knock. It was suggested that I get the subframes welded in.
2)- Bad knock sensor? I did hose the engine compartment down about a month ago. I did replace both knock sensors about 15K miles ago. I did not replace wire harness, and I did over-torque them (didn't know they needed to be torqued). It was suggested that I replace both knock sensors and wire harness.
3)- I have a lean condition, perhaps the fuel pressure regulator?
So, what's your take on it? I did order knock sensors and wire harness, I am pulling the intake tomorrow and replacing them. I will torque them to 13ft/lbs and put teflon tape on the threads.
Thanks for the help!
At the shop they did a compression and leakdown test, pulled the pushrods and checked them, checked the springs, and it turned out that it was a cracked spark plug (I did a plug change 2 weeks prior). I drove the car home, everything seemed to be fine. Next day I installed bolt-on subframe connectors and took it for a test drive. That is when I noticed I was having a knock retard problem.
The computer has been pulling up to 16 degrees at part throttle (50% throttle or so). On throttle tip in I am getting up to 4 degrees, and part throttle (40-60%) I am experiencing 5-16 degrees. The problem is intermittent (not always present). Wot is mostly fine, occasionally I will see 1 degree or less of KR. I have been through 3 tanks of gas since the problem started so I don't think it is bad gas. Here's what has been suggested to me so far:
1)- Subframe connectors need to be welded? I have poly motor and trans mounts, along with all poly suspension parts. The subframes may be transmitting vibration to the floor pan and it is being picked up as knock. It was suggested that I get the subframes welded in.
2)- Bad knock sensor? I did hose the engine compartment down about a month ago. I did replace both knock sensors about 15K miles ago. I did not replace wire harness, and I did over-torque them (didn't know they needed to be torqued). It was suggested that I replace both knock sensors and wire harness.
3)- I have a lean condition, perhaps the fuel pressure regulator?
So, what's your take on it? I did order knock sensors and wire harness, I am pulling the intake tomorrow and replacing them. I will torque them to 13ft/lbs and put teflon tape on the threads.
Thanks for the help!
