Hey I have an 89 22re. It has ~60K on a rebuilt engine. I am going to put as much info as I can to give a good picture.
I have had an intermittent code 52 (knock sensor) for a few months, usually comes on around 2nd to 4th gears, and more when engine is cold. I can kill the engine and start it back up (even while driving), and it sometimes stays off and sometimes comes back on. Replaced the knock sensor (expensive and didn't work!) and increased the shielding on the connecting wire. Checked the resistance and ok. So unless is the computer, don't know. Related to other engine probs?
Also, the idle is a little rough (loping a bit).
And...blowing white smoke. Used to just be occasionally in traffic or starting from stop at a light, and when cold. Recently has seemed to increase to more often. Exhaust smells sweet, but I have had no noticable drop in coolant level.
I have a newer Flowmaster 50 series muffler and high flow cat. Just fixed a exhaust manifold gasket leak. Still have a very small leak between header and connector pipe to cat. Have new distributor cap/rotor, spark plug wires, plugs look ok and gap is correct. K&N air filter is clean. Mechanic buddy did a fuel injector clean little while back.
Could it be bad head gasket so soon after rebuild? I guess I plan to recheck the compression, but was ok 6 months or so ago. Leak-down test? I read about checking the coolant for CO2, is that correct and something I should try?
Sensors? Which ones? Anything else?
Thanks for any help or direction.

 

When your light comes on is there a sudden drop in engine power?

 

yep. feels like less power in general then there should be, and then even less when the knock sensor light comes on.

 

Have you done a compression test yet? Have you adjusted your timing? If you are loosing power when the light comes on and it's not the sensor, then it's sensing a knock. Smoke tells me no good things. Is the engine making any noises, rattle, pinging under a load ect?

 

Carefully check your timing. If you don't have a timing light, next time you get gas, put in some high octane and see if the light goes away.

I'm going to guess that your engine is pinging at speed, which is generally caused by one of three things:

1. improper timing
2. excessive compression (due to modified engine or carbon buildup, etc)
3. piston slap

- Timing is easy to check and rectify.

- Higher compression is generally a good thing, either run higher octane fuel, or back off your timing by a couple degrees

- piston slap is generally caused by worn out pistons, and usually is most apparent when the engine is cold, before the pistons expand to operating temperature.

 

Timing is correct. Just checked it. I am going to do a compression test by this weekend. I don't think engine is making any strange noises, now that the exhaust manifold leaks are fixed. I've never actually heard a pinging engine, so I'm not sure what it sounds like. Would it be really obvious? Engine seems to sound fine at idle and load, just no power.

Thanks a lot for throwing out ideas. I'll check on compression and get back. Also, could a fairly dirty intake manifold explain any of this. Also, is it weird that after revving the engine and it is revving down, it sounds like air pressure is getting pushed back toward the air filter. Sounds like a throaty growl coming from the air box...Strange.
THanks again.