7AFE knocking on 91 RON

[SRA]

Hello Everyone,

I decided to publish this issue after I just replaced many parts ,ran out of ideas and about to give up.

Three years ago I've purchased an auto AE112 with 150K on the odometer, shortly after I've noticed that idle would dip below 700 rpm only when in Drive or Reverse, in N or P it just sits at 700 rpm and it's nice and smooth.

Additionally the car felt a bit weak on low-end torque and I just think that fuel economy could also be better, however it has been driven or long and short trips and it didn't miss a beat.

Starting to troubleshoot that, beside doing normal services, I replaced O2 sensor, PCV valve, thermostat and its gasket (car wouldn't warm up in cold weather), all the parts are genuine Toyota.

I also checked and tested parts like Knock sensor, ISV, spark plugs, TPS, O2 output and MAP sensor, Distributor pickups, cam timing, valve clearance and all were fine.

I purchased a timing light from a local store and went to check ignition timing, it was set at 2-3 BTDC (with TE1 and E1 jumped) so I changed it to 10 BTDC as the sticker on the engine cover says, the idle issue has almost gone but it pings a lot on that setting so I decided to retard it back to where it was, I've tried 4 BTDC and it would ping slightly for a split of a second when taking off in hot weather so retarded it again to where it came originally.

I even doubted the timing light and bought another one of a different brand but they both showed exactly the same thing.

The only case when it won't ping on 10 BTDC was using 98 RON but I need to figure out what is wrong with it.

I have a feeling that the ECU is not retarding timing as it should but I'm trying to find out why.

If anyone can share their thoughts that will be appreciated.

Cheers

 

 

 

[SRA]

I forgot to add I also checked carefully all vacuum hoses for any leaks but they're all in good condition, engine doesn't consume any oil and coolant is clean and at steady level.