Strange problem with idle and O2’s and knock


New Member
Dec 12, 2004
After driving for a while and then coming to a stop my O2’s show 820’s. BLM’s seem normal at 130-134, TPS is set at .44 with the car off and .46 with the car running and the IAC in park is 28-30 depending on the fan. If I let the car sit and idle the O2’s slowly go lower and lower. I have watched them over a 15 minute period of time go from 820’s to 590’s. Just seems strange. The car used to set in the low 800’s and stay there at idle. It is a open loop idle chip. The car is idling pretty ruff and seems to run ruff to. One other strange tid bit is, after the O2’s have started doing this if I idle the car up a little bit using the pedal the O2’s will go to 000 and might stay there for 4-5 seconds…. Strange


I had my alky chip installed, with no alky (long story), anyway I haven’t been pushing it at all because of that, just cursing lately. Well tonight I switched back to my street chip so I could at least run it through its paces to see if I had any other problems. I still have the same weird O2 readings. Also the boost is set around 15 PSI and I am getting crazy knock starting from say 7-10 PSI at any amount of throttle?

I don’t seem to find any vacuum leaks and BLM’s are where they should be any way. I checked the check valves, I checked the resistance on the coil pack and they all were in the 13’s, the wires where ok, I have put new plugs in recently, the MAF reads ok and the fuel pressure is set to 42 PSI with the vacuum line off.

Any suggestions?
Forget the idle, let's talk about the KNOCK problem you have. I just pulled a head on my car, massive piston damage that I'm going to have to fix ,due to detonation! I ran into a situation where I got stupid, stomped it, and paid the price, in spades! In my case, low fuel pressure killed me, what is your trouble?
I would suggest going though all the safety net procedures regarding detonation, including looking at piston hotspots. ANY damage to a combustion chamber piece will create a hotspot that could be the end of your motor.Also, lean mixtures,too much spark,and ANY amount of undue oil consumption(PCV?) can create problems. Good luck!