Since the 7th gens in Pakistan do not come with an O2 sensor and the mixture is almost preprogrammed based on TPS, MAP & MAF. The question is how do we know we are running lean or rich?
2 months ago i accidentally replaced my spark plugs from OEM NGK coppers HR 6 to NGK copper HR 5. (heat range). I found out after the plugs had already been installed. The older ones were used for about 33K km so it was time to replace them. Even with the non recommended HR, i decided to give them a go. I noticed loosing acceleration but some improvement in the mileage. Lost the smooth touch and sometimes felt idle to be a little rough. Anyways i continued to ignore and kept driving until yesterday i found the engine to idling rougher and felt loosing power after a 45 minutes rush hour drive.
I quickly hooked my OBD reader and looked for logged codes. Found AIT code (voltage too high). I cleared the code and moved to replace the plugs in the morning. Replaced the heat range 5 NGK with Denso IK20 iridiums. Found the car to be pulling better and revving smoother.
The old plugs i pulled out were rust coloured. Now i am not an expert on reading plugs and thats where i need help.
I feel like i was running too lean ... ? a little hotter? there is some glazing on the ceramic park...
I replaced them with these
I am hoping they are the right choice.
If i am indeed running lean how can i shift the mixture to the richer side of the scale?
My current IAT reads about 15-20 Degrees over ambient temperature. Is it normal ??
I am hoping this thread to serve as a guide to reading plugs and interpreting sensor readings.