Hey Buds,

03 Max, getting misfire code.

HOWEVER, i noticed that the car doesn't hardly misfire when i have the AC off....it basically misfires when the AC is ON and i'm sitting idle at a Stop Light.

ANYONE know why this happens?

Thanks!

 

If there is a misfire, it will happen whether the compressor is engaged or not, but with the A/C on
there is an additional load on the engine that may make it more noticeable.
CEL on?

 

Yes --the CEL is on.

I'm wondering if its the #3 plug and coil, as these cars are known for bad head gaskets in rear.

Perhaps, oil is leaking from back gasket in rear?

 

Since the check engine light is on, why don't you stop by an auto parts store and have them read the codes for you? This will help to eliminate an awful lot of guessing.

 

Pull the codes so you know exactly what's going on versus guessing and throwing random parts at it

 

Sorry....forgot to add that. Had the Store run codes a few days ago.

It threw codes
-p0300, Multiple Misfire Random
-p0154, oxygen circuit mem activity
-p1800, VIAS
-p1168, Closed Loop Vent 2
-p1448, Vent Control

The VIAS controller works. I took it off and tested it. Not sure what to make of the other codes. Upon reading, looks like the O2 sensor could be bad, but i don't know. Trying to figure this stuff out...(sigh).

Like i said, the car idles fine, but when i put on the AC, it misfires (but not all the time---usually takes a 10-15mins of driving).

Anyone ? ? ?


Thanks!

 

P0300 is your misfire problem

 

The vent control code is evap, the purge canister remains open to environment. Under a load this will create a certain form of vacuum "leak" called ported vacuum, i believe this is why you get a VIAS CEL as well.. im aiming torwards a vac leak bud

 

Evaporator Leak...

Interesting...now how would i solve that?

Would that issue give you a MIS-FIRE ?

 

Id say start by replacing the EVAP canister vent control valve if its cheap or try to home remedy with some cleaning and such

 

You can test the evap vent control valve by removing it and applying a current to one of the prong connectors. You'll hear a click and you should be able to blow air into it, then when you remove the current you can try to blow through and it will block the air (disclaimer, this might be the other way around). Just something to try before buying a new one. If it's working it could be an issue with the wiring leading to the valve itself, but it appears your codes are specifying the valve... so you might just have to buy a new one anyway.

 

I had that same Evap code and went to pull it out and noticed the connection was just severed. Maybe you'll get lucky like me.

 

Ok..I'm still trying to figure HOW a Evap Canister will trigger a Misfire???

Anyone???

 

Next time if you wouldn't make your question a riddle it would be greatly appreciated. Then others who browse the forum can read what is interesting or what they feel they can help someone with by the question terminology.....Not a riddle.....just sayin.

Thanks.

 

The evap canister code has nothing to do with the misfire. It is separate and not involved with a misfire situation.

Misfire problems are mostly the ignition coils, fuel injectors, spark plugs. Timing problems caused by the crankshaft sensor or a damaged flywheel could cause misfires also, so could an intake air leak or a bad fuel pressure regulator.

The P0300 code says that you have more than 2 cylinders, otherwise you you get specific cylinder numbers. Start by checking the spark plugs. Take them out an see that they are not worn out. Check the rubber coupler between the MAF and the throttle valve that it is not split. Check all the vacuum hoses that none have split of fallen off.

 

Thanks Dennis. I'll check those connections and plugs.

 

How long time ago did you do the spark plugs? I agree with Dennis about that, you could also test out the coils with a voltmeter, there is a procedure described on forums if you search for it.

 

Most times a multiple misfire is not plug related. The ecu knows the RPM's and the
amount the engine should move forward after each fire, but when it doesn't advance as
expected, the CEL come on, so one would look into all items that are common to all cylinders.