Misfire: '02 Taurus 3.0L Persistant CEL P0302 - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

HomerSimpson · 09-06-2009, 21:43

Title says it all. Idles rough, minor surging when cold. CEL after running ~half hour. CEL flashes when accelerating uphill @ freeway speed.

Changed fuel & air filters, tried injector cleaner & mid-grade gas for 3 tanks.

Replaced plugs, wires - No change = P0302

Replaced injectors - No Change = P0302

Swapped #2 & #5 plugs - No Change = P0302

Swapped #2 & #5 injectors - No Change = P0302

Swapped #1 & #1 wires - No Change = P0302

Replaced crank sensor - No Change = P0302

Guy @ AutoZone suggested that because the upper radiator hose was hard when engine is warm, air trapped in system and maybe marginal thermostat operation. Replaced thermostat/coolant. Ran 3-4 hours longer before CEL. (Still seems to have air in the system, but I have been unable to get it purged.) This seems promising, but CEL/P0302 persists.

I'm stumped! Consistently gets a P0302 code, sometimes P0316 code. It never shows a misfire on any other cylinder. Coil pack? Would that be consistent with the cold idle problem?

**Bert** · 09-07-2009, 09:06

I think you hit on it with the coil pack. They can do the same thing as plugs and wires.. As far as the cold surge, I'd fix the miss and the surge may straighten out. The PCM tries to make changes to the system to correct other problems and when you correct the miss, it will probably correct that too.

**tbird100636** · 09-07-2009, 17:39

P0316- Misfire Occured in the first 1000 engine revolutions
This sets with cylinder Misfire codes that are present at startup. Ignore this. Spray the coil pack with water and see if it runs worse. If it does, definetely a bad coil pack. You will also see an electrical light show around the coil.

Ratman516 · 09-07-2009, 19:03

The 2000 3.0 coil pack is known for cracking.
They were mounted on the valve cover and have since moved them and in the process have cured the problem. The coil remains the same. Not to say this can still fail.
Having swapped everything else with a known good item, try swapping the coil.
Good luck!

HomerSimpson · 09-26-2009, 11:32

No Joy!!!

Installed a new OEM coil pack, reset codes. Started it, P0302 & P0316!

I borrowed a compression guage and all cylinders seem low (65-75 psi), but they are all within 5-10 psi.

I am out of ideas. It is very rough when cold.

**tbird100636** · 09-26-2009, 14:32

Quote:

Originally Posted by HomerSimpson

No Joy!!!

Installed a new OEM coil pack, reset codes. Started it, P0302 & P0316!

I borrowed a compression guage and all cylinders seem low (65-75 psi), but they are all within 5-10 psi.

I am out of ideas. It is very rough when cold.

You need to do a leakdown test on cylinder #2 (middle cylinder, rear bank). This will tell you if you have a leaking intake or exhaust valve, a ring sealing issue, or something else. Where you've done everything else to diagnose, this is the last thing you can do. Piston has to be a TDC of the compression stroke before testing. You may have to hold the crank from turning with a breaker bar and socket on the crank pulley bolt. The leakdown tester uses compressed air for the test. Any more than 15-20% percent leakage is too much. Listen through the tailpipe, intake tube, and the oil filler to determine where it's leaking from.

HomerSimpson · 10-06-2009, 20:07

Tbird was right on. I need heads, #2 leaks past exhaust valve badly.

So, any opinions on new vs. reman heads?

Anybody recommend a good source for heads?

**tbird100636** · 10-09-2009, 20:06

Quote:

Originally Posted by HomerSimpson

Tbird was right on. I need heads, #2 leaks past exhaust valve badly.

So, any opinions on new vs. reman heads?

Anybody recommend a good source for heads?

New heads are typically from the dealer only, and are bare, no valves or anything else. Remans come complete, either from the dealer or other sources. You don't have to mess with installing the valves and springs. Haven't had any problems with reman heads I've installed.

HomerSimpson · 08-05-2010, 21:17

Update: Spent the last 3 evenings pulling the heads. Examined cylinder combustion chamber and cylinder 2 did not look obviously different. The exhaust valve was slightly different in color and there appeared some difference in the deposits adjacent to the exhaust valve, but not a whole lot different. Called my mechanic friend to see if I could take it by for him to look at. While loading them in the back of my truck, noticed a broken exhaust valve spring on cylinder #2.

Man, I wish I had looked more closely before I pulled the manifold and heads.

Now the question is should I replace the head with a reman unit, or just replace the spring? The idea of a do-over really sucks, I'd hate to put it back together and then have to change the head.

**tbird100636** · 08-05-2010, 22:08

Quote:

Originally Posted by HomerSimpson

Update: Spent the last 3 evenings pulling the heads. Examined cylinder combustion chamber and cylinder 2 did not look obviously different. The exhaust valve was slightly different in color and there appeared some difference in the deposits adjacent to the exhaust valve, but not a whole lot different. Called my mechanic friend to see if I could take it by for him to look at. While loading them in the back of my truck, noticed a broken exhaust valve spring on cylinder #2.

Man, I wish I had looked more closely before I pulled the manifold and heads.

Now the question is should I replace the head with a reman unit, or just replace the spring? The idea of a do-over really sucks, I'd hate to put it back together and then have to change the head.

Swap a spring from another cylinder. Fill the exhaust port with water and observe around the exhaust valve. If you see water gradually trickling from around the edge of the valve then you have a burned valve, and most likely a burned seat. Do the same test with the intake valve and do every other cylinder. More economical to do a reman head then having to ship the head to a machine shop to get the seat repaired or replaced. If the seat on the head were ok and just the valve burned just replace the valve, and lap it in the head with the correct lapping compound.

If when you swapped the spring and filled the port there is no leakage past the exhaust valve or any other valve on the head then just replace the spring and reassmble.