Hello EVeryone on MonteCarloforums.I need some help i just came came from Autozone and plugged the OBD scanner into my 2000 Monte carlo LS 3.4. with 125,000. I had two issues pop up

1. Random/Multiple Cylinder misfire.
2. Manufactuerer Control Auxillary Emmissions control

I have no idea what this means, and i hope its not a huge problem...i can only guess i need a gas cap, and maybe need to change some plugs or something. if you guys can give me any ideas i would highly appreiciate it. i was also told maybe my cylinders are bad.

I am also looking to change my oil to Mobile 1 extended performance Synthetic oil....is this a good idea? let me know soon cause the Hoopty is due for a oil change like today.

 

i think mobile 1 makes an excellent oil, i would certainly use it. i do'nt know about your problems.... distributor, or whatever these cars have with the 3 pack things?

 

I don't know about switching to synthetic with that many miles. Mine has 110K, and my son and a few others told me not to change now because I could end up with leaks. We disgusted this not long ago on here too but I can't remember which thread it's in.

 

DO NOT SWITCH TO SYNTHETIC OIL UNLESS YOU HAVE BEEN RUNNIGN IT FOR THE LIFE OF THE CAR!!!!!

If you have had fossil oil and you change it to sysnthetic now after a 125,000 then it could devlop leaks in your car that might not be there now.

As far the multipal misfire.
means that one or more syslinders is misfireing while the car is running. and due to it being random it is just that random.

Mine turned out to be a coil pack on it's way out and it caused it to miss several times while driving . even to work that is 15miles it would drive me nuts feeling a loss of power and also studdering etc..

hope this help ya some .
as far as oil i would go with the extended life but not the Synthetic version.

 

I agree too.. do not switch to full synthetic. if you want the extra protection they make a mixblend. 50/50 are good... i used that when i first switched at 82k miles. the most important thing on an oil change is actually not the oil... it is the filter... its better to buy the cheepest oil and the best filter then buying the very best oil and a cheep filter!

as far as the misfires... could be any number of things...
bad gas, clogged air filter, rapid temp/humidity/pressure changes, even corrosion on the spark plug wire terminals. all these can play a factor in misfires.

as far as the emission control failure... it would help to know the actual code. GM has some particular codes in the OBD system arent universal. think it is any code above 1400 i think

 

do you know what the actual code numbers were?

as for the misfire, might start by checking the coil terminals for corrosion. if your plugs and wires are original, this might be a good time to replace them anyway.

 

coil pack? how can i go about fixing that? can i fix it myself? so def a no with synthetic huh? so what brand of oil would you recommend?

 

i have the codes for the multiple cylinder misfire the code is p0300 and then for the manufacture control auxillary emissions control its p1404

 

i also would like to know if its the thermostat that went bad on my car if it only blows cool air now and how hard is it to fix i just bought a thermostat from autosone its a duralast brand.

 

how to change the T-stat is actually easy. Follow th top hose from the Radiator to the T-Stat housing . take out the bolts. and then remove the old one and make sure the surface is clean. then replace it with the new one MAKING SURE that you watch out for the direction of flow on the T-stat. Then just put the housing back on to th manifold. Then tighten the bolts up so they are tight but not so tight that they break anything. Makes sure there are not leaks by letting the motor come up to temp and allow it to circulate. this will also make sure that it is working correctly and bring the pressure up some.

remove air in the system by loosening the small nut on top of the T-Stat housing . CAREFUL NOT TO GET BURNED BY HOT FLUIDS AND DO NOT TAKE THE SCREW OUT COMPLETELY!!

If it is only blowing cold air make sure that when you select it from hot to cold that it is changeing .

What year is your car and what kind of heater controlls do you have?
if they are the dials make sure the cabel is being moved.
IF I TIS NOT!! for a temp fix to turn on the heat is find out the cabel and follow it to where it switches the flow of water in tot he heater core. then make sure it moves if it dose not then you can manually move it also.