the other day my engine supposedly overheated. after removing the thermostat with my bare hand(it wasn't hot cause i had only drove 2mi) and my engine still running "hot", it stumbled all over itself. the ECT ended up being bad along with my radiator cap( it wasn't holding pressure). i ended up realizing that the stumbling was from the ECT telling the ECU that the engine was hotter than it really was and with it being cold just threw the timing all out of whack. now, with the ECT replaced i am still having an intermittent misfire/stumble when the engine is warming up. i've looked through the manual, both then one posted here and hayne's. i know it has to be a timing issue cause by a sensor during the warm-up period, either its going through a dead zone or its just enough out of spec to not throw a code( its not cause that was probably the first question you asked ). i just replaced all the O2 sensors, ECT of course, IAT (thinking about trying a newer one), spark plugs are good ( champion copper, very nice...yes?!). im thinking either the MAP or the IAC, but the IAC seems to run fine since i can see the pintle valve move in and out. the IAC does provide a loud hissing noise usually in the morning, but thats a lot of air through a little hole. the TPS isn't out of rule but i've checked it and its flux on my fluke is a nice smooth transition.

i guess my question is, during warm-up and idle mode, what really adjusts the timing. i can understand timing through the coil cause either the cylinder is firing or its not, but what sensors aside from the ECU are telling it what to do?
i apologize for being so long winded but im stumped. any ideas or suggestions or whatever would be appreciated. thanks

 

well you have the basic crank shaft sensor that allows the timing of the injectors per cyl. pulse. this could have been thrown out of wack, but that needs to be set at the dealer.

 

you've got a very good point, i was hoping to avoid taking it to the dealer until last resort. each day i know im just getting closer and closer and would save some headache if i just took it in. but i'll keep playin with it for the next week or to. thanks for the reply.