Our Community is 940,000 Strong. Join Us.


305 V8 Spark Knock !


Bob1942
05-19-2006, 07:08 AM
It is not a CAMARO But I now have a rebuilt 305 TBI roller lifter engine from a 1991 Camaro in my 1988 Chevy van ...It has new Clevite OEM type .060 recess dished top pistons This engine looks identical to the original and bolted right in with the same sensors as the original in the same places . Runs great BUT I have a short duration Spark Knock when the engine is lugging a little like when you go up a slight hill and give it a little more throttle at about 40 mph it will Spark Knock for just a second ! ping ping ping ! then quit ...then the "Check Engine Light " will SOMETIMES come on ! I get a 43 trouble code (spark Knock ) ...When I use the cruise control to accelerate it does the same thing ... I have reset the timing ...several times ... If I retard the timing far enough the knock goes away BUT the engine loses a lot of power and sometimes backfires ! ... I went out and filled up with fresh regular gas at a different gas station also I installed a NEW distributor assembly new plugs ,new distributor cap and rotor ... Does the 91 Camaro TBI engine require premium gas ? What is the timing specs on the 91 Camaro engine ?
How do you time the engine when you have replaced the timing cover with a pretty new one that does not have a timing pointer on it ?
...FRUSTRATED BOB :frown:

Bob1942
05-22-2006, 04:40 PM
It is not a CAMARO But I now have a rebuilt 305 TBI roller lifter engine from a 1991 Camaro in my 1988 Chevy van ...It has new Clevite OEM type .060 recess dished top pistons This engine looks identical to the original and bolted right in with the same sensors as the original in the same places . Runs great BUT I have a short duration Spark Knock when the engine is lugging a little like when you go up a slight hill and give it a little more throttle at about 40 mph it will Spark Knock for just a second ! ping ping ping ! then quit ...then the "Check Engine Light " will SOMETIMES come on ! I get a 43 trouble code (spark Knock ) ...When I use the cruise control to accelerate it does the same thing ... I have reset the timing ...several times ... If I retard the timing far enough the knock goes away BUT the engine loses a lot of power and sometimes backfires ! ... I went out and filled up with fresh regular gas at a different gas station also I installed a NEW distributor assembly new plugs ,new distributor cap and rotor ... Does the 91 Camaro TBI engine require premium gas ? What is the timing specs on the 91 Camaro engine ?
How do you time the engine when you have replaced the timing cover with a pretty new one that does not have a timing pointer on it ?
...FRUSTRATED BOB :frown:




OH BOY ! I FOUND THE PROBLEM ! IT WAS THE KNOCK SENSOR !!! ...The old knock sensor checked good with the ohmmeter per the Haynes manual ... After trying several other things I figured maybe a knock sensor might check good but still not work properly so I connected the NEW one I had to my old oscilloscope to try and see any voltage spike when I hit the sensor ...YEP !
I got a nice big spike on the scope with the new sensor ...I had thought that I would need some voltage on the sensor to make it work or a circuit made up to test it but NO it worked fine hooked directly to the scope ...I then tried the old sensor and it had a much smaller spike ! it was working but not as good as the new one ! I was sure I had found the problem ... I installed the new sensor in the engine got antifreeze all over me again ! UGH ! Then I took the van out for a test drive NO KNOCK ! I could not make it knock no matter how I drove it ...

Now about that unknown sensor I called the Chevy garage and got a guy who knew a lot about Chevy stuff and he said to me "You got a dash mounted temperature gauge on that thing " "yes " I said then he said "well you gotta have a separate sender for that gauge and it looks just like a knock sensor but it has a different connector " Holy cow ! that unknown sensor is the sender for the dash mounted engine temperature gauge ! DUH ! :rolleyes:

Anyway I am so happy to have my knocking problem solved in my new engine
THANK YOU Wright Z28 for your ideas and advice I really appreciate it ...
HAPPY BOB :iceslolan in Michigan

Add your comment to this topic!