well ive been having tremendous issues with my current motor (98 b20b4 with 108,000 miles and an intake. all stock otherwise).

tons of background info and pictures in this thread here

https://honda-tech.com/forums/all-motor-naturally-aspirated-44/b20-tune-issue-my-maps-off-3107976/

i put a wideband on to make sure afr is good. originally it was very lean at idle on the oem p75 ecu, like 18:1 till it warmed up, so i swapped in an extra neptune rtp. i got the idle afr in control but really noticed the damn thing had speckles all over the plugs. i tried using 6 heat range plugs, 93 octane and even disabling ignition corrections

nothing really helped. keep in mind i dont rev the thing out and never go wot so my issue was in the low to midrange load below 5000 rpm or so.

recently put on an adjustable fpr to get afr to normal on cold start and at high load so i could run the factory ecu and 02 sensors to get inspected (obd2) . still no dice, heres the plug i just took out. holy crap i never had plugs look so bad


currently i have the distributor retarded 3-4 degrees and am using 93 octane.
imo this is absurd and there is no reason i should be detonating. something has to be up with a bad sensor or something idk. what do you guys think?

 

It would be interesting to see what the piston tops and combustion chambers look like. It might be possible that you have excessive carbon built up that is creating hot spots. It is also possible that there are casting irregularities that are creating hot spots.

Another something I've run into (it's rare but), weak pick-up coils can cause scrambled signals to the ECU. If you have a HO stereo, there might be some interference there as well. You might check to see if there are any EMF type wires near the harness feeding your RPM signals to the ECU. Like I said, it's not common, but it does happen.

Mike

 

Specs on a plug are not always detonation, when its shiny aluminum, then you need to inspect further.

Do you HEAR the detonation? Could just be deposits from something, maybe the fuel you use...try putting in a new brand of fuel, let it go through an entire tank, and fill up with the new fuel again, and then change to brand new plugs and check again.

 

Might be a stupid question, but have you actually sync'd the distributor timing with an actual timing light? The belt could be off a tooth.

 

I have definitely used the timing light. I used to have it at 16 degrees and since i went back to stock from my neptune I used the timing light again to retard at the distributor between 3 and 4 degrees, just outside the red marks. I put an obd2 ls intake cam in a few weeks ago to try and get the engine to flow better. All mechanical timing marks line up.

xenocron, I really consider it being other stuff that's burning, though then motor lost about 8ish psi compression in the process. For the most part, them spots look like little white fluffy flakes...

 

if you ever wanted to rent dyno time, im more than willing to give you a little input as you do so

 

thanks man i do appreciate the offer. its definitely in the back of my mind. im not too far either just up by poughkeepsie