Questionmy OBD2 reader keeps registering P0113 and P0300 from my wifes car. It is running worse all the time. Gets very low fuel mileage.
According to my maint. manual the P0300 is a randum misfire on multiple cylinders, but since it only has 4 and the manual says that the IDI or EI system uses a waste spark distibution method means that cylinders 1/4 and 2/3 fire at the same time. WHAT DOES THIS MEAN IF THE READER SAYS RANDOM MISFIRE and what is the fix for it? Next: the P0113 code is: intake air temp circuit High input--why and how do I fix it?
AnswerHi,Scott.
Yes a P0300 is a cyl missfire,the code is what as known as a generic fault for a cyl missfire,the PCM{powertrain computer}knows the engine has a missfire but is unable to determain which cyl has the missfire,later years have the capability to see what cyl is failing,now we'll fix the first problem which is the missfire,on your eng the quad 4 uses a coil over plug,they are located right on top of the eng under the plate that has the writing quad 4,there are 4 bolts that hold it in place on top,now GM has updated the ign componants for this same complaint,they are new plug boots,the coil cover,and the 2 ign coils,also new spark plugs,what is happening is that the old design boots coils and cover are causing excessive carbon tracking which leads to eng missfire in multiple cyls,the spark is tracking the carbon instead of firing the plug,you'll need to replace the above items to elliminate the missfire and the P0300.Parts are availible through GM parts dealers.
The P0113 is a high ckt fault at the intake air temp sensor,this means that the IAT sensor has either failed or the ckt is open,the sensor is located near the air cleaner box inline with the air intake tube,gray or black in color and has 2 wires and a connector,check the the connector is plugged into the sensor,also tug on the wires that go to that connector making sure the wire is not damaged,if the wires and the terminals in the connector are good then the sensor has failed and needs to be replaced,now i have never had to replace an IAT in the 21 years of being a GM tech,i have either found the wires damaged,the terminals bent back and not making a connection,or this is the best,never plugged in.Hope this helps,if you need more help drop me a line,let me know what you find out.Thanks
ED
