PO300 with PO302 & PO303

[ywgbandit]

So I am getting misfirin, but only when I'm using the engine for downhill breaking. I am just starting the break in on my new engine after a catastrophic piston failure. I have a brand new Ford long block and I have my TT S280 installed as well as a 180 thermostat, Mountune Radiator, Whoosh FMIC and intake & crossover pipes. I have a Dizzy base tune installed for the break in so I don't get any codes from using the TT S280. The base tune is limited in boost to the waste gate spring which is keeping the boost to under 14 psi. I also installed the one heat range colder NGK 6510 plugs. I'm wondering if the fact the engine is running 15 degrees cooler on limited boost and ambient air temp is about 55F that the plugs may be too cold for the conditions? They don't appear to be fouled and they are dry. Any ideas????

 

[SteveS]

I am sure you have already looked up the codes, but the P0300 means misfires. 0302 and 0303 indicate it's seeing them on cylinders 2 and 3, respectively. And the number one cause is faulty or worn spark plugs, number two is faulty plug wires or coils, and #3 is distributor failure. There are other causes, like fueling problems, vacuum leaks, timing problems, camshaft sensor off, etc.

Here's a diagnostic guide:
How To Diagnose P0300
Difficulty of Diagnosis and Repair – 2 out of 5

1. Use scanner to scan your vehicle to verify P0300 is the only code present. If other codes are present, they must be addressed first.
2. Check for loose connectors at the ignition coils or for damaged wiring. Look for loose engine ground wires as well. These can cause random misfire conditions. Tighten or connect where necessary.
3. Check the condition of your spark plugs and spark plug wires. Worn and old spark plug wires are common causes of random misfires. Replace spark plugs and wires if needed and recheck for misfires. (How to identify a fouled spark plug, How to test spark plug wires, How to gap spark plugs, How to replace spark plugs)
4. If you have determined that your ignition system is operating correctly, there may be a problem within your fuel system that is causing the random misfires. The following should be checked to ensure the engine is getting the proper amount of fuel.
5. Check fuel pressure. Low fuel pressure can cause intermittent misfires on multiple cylinders. When the pressure is below the specification, the engine does not receive the proper amount of fuel and will start to lean misfire. The fuel pump or fuel pressure regulator could be the source of the low fuel pressure. (How to check fuel pressure)
6. Check that the fuel injectors are functioning properly and activating. Random misfires can be a sign of faulty or clogged fuel injectors that need to be replaced. Also, check that the fuel injector wiring is not damaged and is connected properly. (How to check fuel injectors by ear, How to check fuel injectors with a digital multimeter)
7. If the ignition system and fuel system checks out, you may want to perform an engine compression test and leakdown test to see if there are any mechanical problems causing your misfire. Some common mechanical problems that cause misfire can be:
   • Leaking Head Gasket
   • Broken valve spring
   • Broken piston ring
   • Worn valve guides
   • Burned valve
   • Timing chain or belt skipped tooth and engine is off time.

 

[ywgbandit]

I tried new spark plugs tonight and same result..... car ran great and I was accelerating and when I let off the gas I got the engine light and the same codes. New engine, new plugs....same frustration!

 

[TyphoonFiST]

How many miles on your Ignition coils? Mine started to give up the ghost around 60k Miles. If they haven't been done it may be time...and do all 4 not just one. Rock auto sells them for Cheap in Fomoco and NGK and an economy brand usually.....$25-65 American dollars though*

 

[ywgbandit]

The engine is brand new and if they transferred the coils over from the old engine when they replaced it they will have 17,000 km (10,563 miles) on them. I'm pretty sure they transferred most of the externals, like turbo, intake, ignition harness, etc..

 

[ywgbandit]

Turns out my IAT sensor #2 is reading -40F all the time. I must have a faulty wire somewhere between the ECM and the MAP/IAT sensor on the cold side intercooler pipe. Tried a friends sensor and the reading stayed the same. My favorite thing to do is look for electrical issues.....NOT!

 

[ywgbandit]

I can't find the issue...keep getting the same codes and engine misfiring. Off to the dealer on Monday.

 

[ywgbandit]

So if anyone is still following this, it turns out that the ignition coil trigger circuit for cylinders 2 & 3 in my PCM was intermittent. I managed to get it to the dealer while it was happening and the tech was able to record the event. New PCM on order.

 

[ywgbandit]

I now have more than 5K miles on the new ECM without a single misfire or trouble code. The FiST is running better than ever and the TTS280 turbo is working perfectly. I added a Tsudo 2.75" turbo back exhaust that sounds amazing and flows much better than stock and doesn't drone! The 3" I had droned so bad on the highway I couldn't stand it and I sold it.

 

[NATYPE]

I now have more than 5K miles on the new ECM without a single misfire or trouble code. The FiST is running better than ever and the TTS280 turbo is working perfectly. I added a Tsudo 2.75" turbo back exhaust that sounds amazing and flows much better than stock and doesn't drone! The 3" I had droned so bad on the highway I couldn't stand it and I sold it.

Hell yeah. Seems like depending on your configuration the lower diameter exhaust options will put you in a nicer place sound and performance wise. I love the big single tip look of the Tsudo's I've seen. I really like the 'cannon' aesthetic.