Rough idle with P0300, P0304, P0305, P0306

[MZAMPINI]

If anyone can help with this it would be greatly appreciated. I have a 1998 Explorer with the 4.0 SOHC and about 98K miles. Everything was fine when I left it for about two weeks in the driveway. When I came back the MIL was on, running rough and a moderate to loud ticking noise. It was a great massage on the way to hockey practice. When I returned I read codes P0304, P0305 and P0306 misfire on cylinders 4, 5, 6 respectively. The MIL is now blinking. After resetting the codes I get the following error code, P0300 which is the error code for random / multiple Cylinder missing. The spectrum of solutions range from replacing spark plugs to replace the engine, yikes. Replacing the engine will cost more then the value of the car. If engine replacement is needed, I hope to find a ‘minimum for your trade’ and get a new car. Thanks in advance for your help and advice. What a great way to start 2009!

The freeze frame data is below:

Fuel System 1 Status – Closed loop … Normal
Calculated load – 32.9%
Coolant Temp – 183 F.
Short Term Fuel Trim Bank 1 – 2.34% Rich(+)
Long Term Fuel Trim Band 1 – 24.22% Rich (+)
Short Term Fuel Trim Bank 2 – 2.34% Rich(+)
Long Term Fuel Trim Band 2 – 18.75 % Rich (-)
Engine Speed – 1314.75 RPM.

 

[dynamite196]

How full was the tank before you let the car sit? I'm willing to bet it's water in your gas tank. Fill up the tank and add a can of seafoam, that should solve the problem.

 

[MZAMPINI]

Thanks for the tip, the tank was full. Also, I noticed that it runs okay for the first 5 or so minutes until it warms up, after resetting the codes it starts with P0300, followed by P0304, P0305 and finally P0306. The engine sounds like the old days with extensive engine knock on acceleration. I also noticed the fuel trims were at 100% lean. Once in a while the MIL flashes for a few seconds, typically at a long light. The local shop was out of SeaFoam so I tried two cans of the ChemTool B-12 without any changes in operation after 20 or so miles. Any other ideas?

Thanks again for your help.

 

[BaroquenHorse]

Vacuum Lines

Try running the vacuum lines for a collapsed line. esp the larger diameter hoses.

 

[jfrenzel]

Did you have any luck with this? I have a 99 Sport SOHC that does the same thing. I cleaned the MAF and it seems to be bit better.

 

[team]

Obviously it is running lean because the fuel trims are adding a lot of fuel. So i would clean the maf sensor first then see what happens. You could also check the resistance of the plugs and plug wires to see if any one of them stands out before just buying parts. If after you clean the maf and check the plugs and wires you are still getting a lot of fuel trim added you may have the SOHC's famous intake o ring gasket leak.

 

[BaroquenHorse]

JFrenzel,
If your question was to me, the answer was yes. I changed the maf and wasted 125 bucks. Then bought a 5 dollar hose at the parts store and Voom. Then the same thing happened to my daughters 01 Focus. Ran the hose and bingo, clam shelled right by the back of the engine. My 2001 Explorer collapsed on a large diamater hose located under the large intake duct. I coudn't see it in either case. Since it costs nothing to check for a collapsed or loose leaky hose, just give it a try. (engine off!!!) Good luck!

 

[zukman]

Check your heater hoses! My '98 Exped just thru a code 0304 -misfire in #4
Turns out the heater hoses are routed directly above, they drip and or leak causing a short between the boot and the plug. It can tale other cylinders with it. Worth looking at.

 

[fdte320]

This is my first post in this forum. Got a 96 Explorer XLT 4-door. Just pulled out a P0306 DTC. Did my search & it ranges from spark plug, wire, coil & possibly the CAT. Has anybody experience a P0306 and how it was fixed? Thanks for any advice.

 

[team]

This is my first post in this forum. Got a 96 Explorer XLT 4-door. Just pulled out a P0306 DTC. Did my search & it ranges from spark plug, wire, coil & possibly the CAT. Has anybody experience a P0306 and how it was fixed? Thanks for any advice.

Your number 6 cylinder is misfiring. Check the wire and spark plug first for problems.

 

[fdte320]

Thanks for the reply. I believe cylinder 6 is the one closer to the firewall, driver side? Any particular signs I have to look for in the spark plug & wires? I I have read also that the coil can also trigger this problem. Can a shot cat converter trigger this DTC? Thanks again.

 

[92eddie4x4]

I just wanted to let you guys know of my experience with P0300. I pulled this code after work one day in the 5.0L V8, 1997 Explorer. It started up fine, but the idle was quite rough, certainly a misfire. I went to drive home and on the way the CEL came on and started flashing at me. I decided to investigate after I got home and found the #2 cylinder spark plug wire had been rubbing against the hot exhaust manifold and burnt through. I changed out the wire and the engine runs fine again. I cleared the CEL and it hasn't come on since.

5.0L V8 Cylinder Diagram
FIREWALL
4 - 8
3 - 7
2 - 6
1 - 5
FRONT