Hi
i don't know why its happening but most of the time my sensor's voltages are pretty much off. Whereas some days when I cold start in the morning it is completely fine. Alternator is good as my battery shows 14V all the time with engine start. What can be the issue? Ect map tps all the sensors are having weird fluctuation.

Thanks

 

Bad/loose engine harness ground at the thermostat housing would be a good start, and if that seems clean and tight, check all grounds between the engine and the chassis.

 

Do your headlights pulse/flicker?

 

No they don't
Even my idle is pretty stable whereas I know my iacv is in bad shape but its working fine

 

Battery ground to body ground and then from body ground I have a wire hooked up directly to thermostat housing. Is it a good approach? But the guage of that wire is not much.

 

 

JRCivic1 gave you solid direction. There usually is 3 main grounds in the engine bay. The one on the thermostat housing. The big one from the frame rail to the transmission. And then the front one that is from the radiator/hood frame crossmember to the power steering bracket usually. Some people try and put it on the valve cover but that is not a good spot for it being most all of it is insulated with rubber seals.

The negative battery cable from the tower to the battery isn't considered a ground per say even if it's the main negative of the grounding system.