[stuner494]

i have a 2002 sec-v that's throwing a p0300. the only thing is that the car run great intell i turn the heater on. then the cars rpm's will start to go up and down. anyone know what could be causing this

 

[i68k]

did it give you any other ses code? did you check your coolant level? did you fix the misfire?

 

[stuner494]

no just the p0300 and coolant is good. is there any vacuum line that is involved with the heat/ac.

 

[i68k]

im not sure actually, does the heater actually work, or blow cool air? did you check out the fsm for this one? also, are you turning the heater on? or are you turning the defroster on? your specv comes with automatic ac, when you select a defrost position and turn the blower on. its possible you have something wrong with your ac if you have it on defrost. ever notice any coolant leaks? does the ac blow cold air or warm air? when was the last time your serviced the ac system?

 

[stuner494]

the heater works great but im in cali so its not on much, but thats the only sign of anything wrong with the p0300 as the car runs great with steady rpms in tell the heater is turned on. which leads me to the question if there is any vacuum hoses that are needed for the heater, which could indicate a leak in a hose.

is there any index for the fsm as i dont have a fast internet speed to open every one

 

[i68k]

normally in compliations, the fwd mean Front Working Directory. this should be your table of contents, probably named fwd.pdf or something. i believe you can access the index from the fwd, ive never used the index. remember, you need to download all those pdf files, the fwd will just link to them. once youve opened them, just save them to your computer, for future access. they will be your best friend.

there is no vacuum going to the heater? its an electrical connection, and the heater core uses coolant. this is why im trying to isolate the problem, its unlikely that your heater will cause a loss of idle, unless your charging system is very poor, and that little voltage is causing a drop. however, if youre using the ac, or defrost, there is a large voltage drop, also tension added to the pulley when the ac clutch engages/disengages, which should change your idle, but not lose idle. the tension added could be extreme if your ac system needs servicing, and could possibly outwit your ecu to lose idle.

 

[JudoJohn]

p0300 is a general misfire code. first and easiest thing to check is the spark plugs and the connections to the coil packs.