Spark Knock

[00 Expy Police]

Hello All, I got a 00 Expy that i bought with a blown eng and had a hole in the side of the block the size of ur head,,I bought a motor minus intake timing cover and pan,,basicly i had to put all my stuff on,,well the motor i got is an 03 and after getting it all in,i changed all plugs and coil wires,ran fine for 2 days and detected misfire in cyl 1, that new coil was bad and I put old one back on and its fine,,now when i start up and leave for work in the morning soon as i get out and moving it will start spark knocking right off the rip,i throw it in nuetral and restart and its fine,,soon as i come to red light and restart moving or try to pass on eway it will spark knock and no eng light or codes,whats the prob here never seen something like this,,i even ran 93 octane and injector cleaner thinking injectors were dirty,pulling my hair out trying to get past all this other than that shes got some power

Thanks

 

[JUST4FUN]

possable egr problem ports are clogged??

 

[JUST4FUN]

are you running a 3 valve motor in a 00

 

[00 Expy Police]

are you running a 3 valve motor in a 00

no its a 2v

 

[00 Expy Police]

the guy i got the motor from said it came out of an 03,also valve cover said 03

 

[00 Expy Police]

possable egr problem ports are clogged??

could it be that i got the wrong plugs in it,,auto zone says i need platinum plugs i put copper plugs in it?

 

[designit]

is a spark knock different than a general misfire?

 

[panda24619]

go with, what are they, motorcraft? plugs. thats what these motors like. switch them out and that should help.

 

[toms89]

Spark knock to which I believe the op is refering to is pre-ignition. Not the same as misfire.

I believe the reluctor wheel is different on post 2000 expys and possibly the sensor?? Maybe this can cause issues on earlier processors... doubt it buy maybe. Other than that I would say maybe one of the sensors the computer uses to adjust timing and fuel. I know... thats most of em. IAT sensor, coolant temp sensor, mass air, 02 sensor... etc.

I would say maybe bad fuel but it sounds like you put new fuel in. Check for vacuum leaks.

 

[toms89]

Oh yea..... too hot a spark plug range could cause pre-ignition or if it protudes into the combustion chamber differently that stock. Type of plug should not matter as long as it is correct for the application.

Forgot to mention fuel pressure...... maybe its low due to fuel filter or pump problems.

After rereading your post a few times I think you said it did not start to ping until a few days after you got it running. If this is the case my best guess would be the o2 sensors. The computer readjust the spark and fuel tables based on input from many sensors and this is adjusted based on o2 sensor readings. So over a few days as the computer adjust from the base program it may have it running too lean. You can easily test this theory by reseting the computer.