So my car has recently started knocking moderately on me. I'd like to list out possible causes (considering it has run fine in the past).

I am getting a code 36, which refers to the burnoff, but I can't imagine this would cause knocking. Am I wrong? Also, the engine isn't running so smooth (this started at the same time the knocking started). It idles a bit rough (though not enough to shake the engine in the mounts, and doesn't run at RPM as smooth either. Almost like a weak or dead cylinder, but prelim tests seem to indicate all cyl's are firing.

Here's some possibilities -

1. Timing? (I checked this and it seems to be fine. The middle tooth on the bracket, pointing straight out, with the bypass unplugged. This represents 6 degrees, right? Regardless, its where it has been set in the past, and so it hasn't moved).

2. Knock sensor gone bad? (Come to find out, I didn't swap the knock sensor when i went from a 305 to a 350. However, like I stated, the engine ran fine just a few weeks ago).

3. Vacuum Leak? (I have investigated this and there doesn't seem to be one).

4. Oxygen Sensor? (I haven't looked into this. I'm not getting a code for it, though, and it was replaced when I swapped the engine).

5. MAF? (I am getting the code 36, and I will replace both the power and burnoff relays. But I'm not convinced this is causing the trouble. Any ideas?)


What else should I investigate? I really don't want to burn up a cylinder or cause any damage, so your help is GREATLY appreciated.

M



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'89 TA - 5.7 TPI (L05, was originally a 305TPI), T5-WC, 3.08 Posi (Drum)

 

As with any driveability symptom, you should investigate the system(s) responsible for trouble codes before you worry about anything else. Yes, if something is wrong with the MAF sensor or relays it can cause many different problems. It's probably leaning out the mixture too much and causing knock, but at any rate, I would check out the code 36 before anything.