Man...I am cursed with the ol' CEL PO400 syndrome. (AKA Misfire 4). I have done just about everything I have taken from the previous posts (thanks everyone) but the light still keeps coming on and blinking at me. I am thinking it might be the EGR Solenoid Valve but I am not sure. I am not really sure I know what it does. Does anyone know?

 

This is what I have done so far:

Plugs (autolite), Wires (Belden - NAPA), Coil Pack (OEM), Fuel Injector @ 4 (OEM), MAF (Junk Yard- OEM), Cleaned the throttle body and all the tubes,& Cleaned the EGR Valve.

 

These are the symptoms now (before it was idling rough):

Idles better but not all the way normal

Feels like it is going to stall out when approaching a stop

Engine temp rises abnormally when sitting in traffic or at

steady speed (45 mph).

Otherwise, it drives great. Oh yeah one more thing. I have very leaky valve cover gaskets. They need changing bad but I need to get this CEL to stop coding the computer so I can get it smogged. I am two months w/o tags.

Thanks for any help -Brett

Hey! I am having the same problem. Well almost the same, my idle is ok. I have misfire on cyl 4 but it hasnt been as much of a problem lately and Im also using 89 instead of regular gas and it has helped a little. I replaced plugs, wires, and coil pack. I also cleaned out egr system and hoses but im still getting misfire and I also get a erg cel too(I dont remember what it was) I havent checked into the egr stuff yet b/c all the parts are expensive and I dont hav the cash right now to fix it.

P0400= EGR Flow malfunction

P0304 = Cylinder 4 misfire.

 

Which one do you have?

 

If it P0400, good news, obviously you need to focus on EGR components. If P0304, causes can be various...

P0400= EGR Flow malfunction

P0304 = Cylinder 4 misfire.

 

Which one do you have?

 

If it P0400, good news, obviously you need to focus on EGR components. If P0304, causes can be various...

 

Woops...your'e right. I am getting PO304. I was looking @ ALLDATA before I posted and read about the EGR system. I would have thought if anything was wrong with the EGR, the system would code it specifically (i.e. PO400)

 

A mechanic buddy of mine told me to pull the EGR off and close off the system by making a seal gasket from a coke can. He said to drive it around a day or so and see if anything changes. He said it would probably drive better by bypassing the system. Well see.

Could be EGR...cars are strange.

Other things to check - overheat - hope it's not head gasket...check for exhaust in coolant overflow...search for dollar bill test on this forum for sticky valves...

I would do a compression test before doing much else. Make sure that there is not something wrong with the engineesp on the cylinder that is giving you the code.