Knock retard on cyl 4 only...with very light load.

[1FastCSX289]

OK....another beauty of a problem on my CSX. It just keeps going and going and going. This thing is obviously posessed. Ive come to the realization that whatever I fix doesnt matter; it will only be followed by something else.

Anyways.....check engine light is flashing at me constantly because of knock on cyl 4. I would imagine its been this way since I converted back to stock electronics, but its only been within the past week that I finally got all the codes cleared and fixed so the CEL is normally out now. The thing is that I kinda doubt its actual knock. The only thing that leads me to believe that it might be is that the #4 plug is the only one that is spotless clean....all others have a chocolate color to the ceramics. The light comes on under boost at part throttle, WOT, low rpm, high rpm, low boost, higher boost, cold engine, warm engine.....it usually happens just as the turbo starts to spool, before the motor really starts to pull, which leads me to think its not really knock. Im also only running 15 PSI and spraying alky at it with very tame timing. I doubt its knock. I swapped the #4 injector to the #2 and vice versa just in case it wasnt getting fuel. Same problem......knock on 4.

The only idea I have at this point is that the turbo is SUPER close to the #4 intake runner; in fact I had to grind the runner to get the turbo to fit on the back of the motor. Perhaps, the sound of the turbo is traveling down the intake runner triggering the knock sensor? Any other ideas?

How does the computer determine which cylinder is knocking? Also, how does the computer pull timing on only one cylinder? Any ideas on diagnosing this problem?

[black86glhs]

Try swapping inj harnesses to rule out a bad harness. Otherwise, wrist pin noise or a bad knock sensor?

[1FastCSX289]

Try swapping inj harnesses to rule out a bad harness. Otherwise, wrist pin noise or a bad knock sensor?

UNfortunately, its a VNT harness, so its an oddball. Ill try testing continuity, power and ground. Swapping the sensor is probably not a bad idea either.

Thanks, anyone else have any ideas?

[Pat]

UNfortunately, its a VNT harness, so its an oddball. Ill try testing continuity, power and ground. Swapping the sensor is probably not a bad idea either.

Thanks, anyone else have any ideas?

Are you sure the '89 VNT harness is unique to VNT's? I would think it would be the same as a '90-'91 T-I SBEC harness. Don't hold me to that though...

[Stratman]

How does the computer determine which cylinder is knocking? Also, how does the computer pull timing on only one cylinder? Any ideas on diagnosing this problem?

This knock battle between real knock and mechanical noise will drive a man crazy and can make you retard the timing such a ridulous amount trying to get rid of it. The 2.2 common block in my 89 Daytona has set of the knock ce light since it was re-born. There are 2 problems I have noticed that will make mine go crazy. My problem seems to point toward possible large clearances between the cylinder walls using the forged Venolia pistons, and at times a specific lifter I rarely hear around cylinder 3.

[1FastCSX289]

Are you sure the '89 VNT harness is unique to VNT's? I would think it would be the same as a '90-'91 T-I SBEC harness. Don't hold me to that though...

Its a hybrid of the 89 and 90 injector harness.......its SBEC electronics in an 89 car.......the CSX-VNT was the first.

This knock battle between real knock and mechanical noise will drive a man crazy and can make you retard the timing such a ridulous amount trying to get rid of it. The 2.2 common block in my 89 Daytona has set of the knock ce light since it was re-born. There are 2 problems I have noticed that will make mine go crazy. My problem seems to point toward possible large clearances between the cylinder walls using the forged Venolia pistons, and at times a specific lifter I rarely hear around cylinder 3.

I have venolia also, but I havent heard of this problem.......what do you do?

[slasky]

Did you try some Teflon tape around the knock sensor threads before installing it?

[R/Tony]

Had the same problem, and I went away when I changed the pistons (killed one forged JE) and installed forged Venolias with the correct wall clearance... aparently the piston was making noise or something like that.

[Aries_Turbo]

did you try different knock sensors?

if you use a scanner you can see how much timing is being pulled in each cylinder.

i doubt the turbo noise is traveling through and setting off the sensor. its not the right frequency.

6000-6300hz sets of the knock sensor.

if your pistons are noisy, it can set off the sensor. you can retune it though by datalogging a scanner under load with no knock. (run racegas, less timing etc) i can help you retune that table to account for noisy pistons.

putting in racegas will tell you if you have real knock or not.

Brian

[1FastCSX289]

Did you try some Teflon tape around the knock sensor threads before installing it?

No....do you tape your sensor?

Had the same problem, and I went away when I changed the pistons (killed one forged JE) and installed forged Venolias with the correct wall clearance... aparently the piston was making noise or something like that.

I JUST put these venolias in. They are very quiet for venolias. I dont hear any noise from them at all.....ive heard venolias that sound like a diesel engine.

did you try different knock sensors?

putting in racegas will tell you if you have real knock or not.

Brian

I just grabbed a sensor from the bin at school, so ill throw that in with some tape on it and see what happens. If its the same, ill put some race fuel in......if its not real knock, ill have to swing out to Warsaw some night and have you help me out.

[Aries_Turbo]

warsaw has good tuning roads.

ill be at the track tomorrow if you have time to swing out in the early afternoon.

[1FastCSX289]

warsaw has good tuning roads.

ill be at the track tomorrow if you have time to swing out in the early afternoon.

Tomorrow is no good. Ill catch up with you at some point soon. I gotta get some time with this thing.....needs an axle shaft also.......started to shake violently under acceleration. Freakin thing.