http://www.badassperformance.com/misc-vid/knock.wmv
(2.8megs)
First:
I realize there are a lot of threads about knocking problems and I have searched and read them all (I think). Everyone describes the sounds differently and I’m not sure if the problems are the same as mine. Because of this, I uploaded a video of the engine with the sound. Hopefully, someone who has solved this problem before will have an extra minute for me!
History:
The car is a 1987 Rx7 with a 2000 Camaro SS w/T56 engine transplant. It has been running poorly for about a year until I found out I plumbed the fuel incorrectly and was getting too much fuel. I installed a corvette fuel filter/regulator and the car ran great for three days. Then after filling up the fuel tank and getting hard on the throttle, the knock showed up.
Problem:
Engine knock sounds like a higher pitched Diesel sound. It is RPM dependant and louder at certain spots. I can’t tell if it is every, or every other RPM that it knocks.
Things I have done, or know about:
Oil pressure is 40psi when cold, goes down to 30 when hot and gets to 60 with higher RPM. I have EFIlive scan tool at my disposal. I have not noticed anything out of the ordinary. No knocking detected, LT fuel trims around -5 to -8%. I think my fuel pressure is a few psi low at 54. I am new to the software and willing to run more logs if it could help. I ran the balance test and all cylinders seem the same, but each time I run it, some cylinders are left out. They are different each time. I don’t know if this is normal. I’m still trying to fix the VSS sensor. Spark plugs and wires are new. I also put in a bottle of NOS octane booster when someone suggested bad gas (I got the gas at a newer and popular BP station). People suggested the engine was hitting something. I don’t think the engine shakes at a high enough frequency to make that noise. There are some close fits, but I haven’t found anything hitting. With a homemade stethoscope, I think the noise is most evident when I touch and front of the oil pan or the water pump. The knock is still there with the main belt removed. The car feels fine power-wise, but I’m afraid to really drive it much. I don’t want to do more damage.
My only theories:
Get the fuel pressure up to 58psi with a booster pump.
Bad main or cam bearing?
Bad timing chain?
The engine has 40-50k miles on it. It ran great for three days. What could cause this?
Please help, thanks!
Tom