1996 Ford Ranger 4.0 V6 have codes P0306 and P0174 need some advice please

Thank you for suggesting I take another look at the wires. It paid off.

Ratz I broke the new sparkplug. I used a wobble extension to get the old plug off but I had a lapse and left it on to put the new plug on. Tomorrow I will use a straight extension. The old plug looked really rusty. It was a dbl Platinum too.

I had another plug so I put it in tonight. I am a little frustrated, the engine is obviously missing on I believe cyl 6. On a 10 mile hiway drive with 2 stops, no mil comes on. At idle in my yard the P0300 comes on regular, it starts flashing the mil then if I turn off the engine and restart it the p0300 is set. At idle the miss is noticable, at above 2000rpm the miss seems to disappear(no shaking)

A little background on when this cyl 6 miss first began to happen. I had a coolant leak in cyl3 for a couple years. Every 3-4 months I would change the spark plug and be good for another 3-4 months of no missing/codes. Then it happened that changing the plug did not help anymore. So I put in stopleak into the radiator, the kind you leave in without removing the thermostat. The code for cyl 3 went away with a new plug but now I had the miss in cyl 6. I put another bottle of the same stopleak thinking the head gasket sprung a leak in cyl 6, this had no effect. This is when the cyl 6 miss began. And I can't drive the truck since June 2012.

I put some Seafoam in tonite and 8 gallons of gas. I have driven about 30 miles since. I was hoping the wire was the cause of the miss and I just needed to run the engine for a while to clean out the gas that was six mos old. I really need help with troubleshooting this since I paid to register it again(plus insurance) and need to smog it soon, it was on a nonop. I was so sure the cracked boot and arc scoring on the manifold was the cause of the issue, I should have waited.

Please help me figure this out. Thanks

Also I should say the code that came up right after I changed the plug right now(before the latest test drive) was P0174. Thanks

Now that the obvious wire problem was resolved, how can I test the cyl 6 injector in a way I haven't yet: clogged injector, I don't know a test for this.

What are the steps to resolve the P0174 and P0300 codes? Why am I getting P0300 instead of P0306?

I removed the spark plug wire from the coil pack for cyl 6 and there was no change in engine sound. It was arcing as I removed it so it must be finding a ground.

Could the partially clogged injector trickle at idle then work better over 2000 rpm? Is there more pressure at higher rpm's? The missing seems smoother over 2000rpm.

Whew! I just came from the DMV and they will give me back the $104 registration less another $18 planned non op fee and my insurance is able to cancel the Ranger policy at no cost to me.

Now I can breathe and try to be methodical in testing the Ranger's misfire problem.

I replaced all 6 spark plugs about 10000 miles ago.

Could the egr be sticking at low rpm and smooth out above 2000 rpm?

Any steering you can give me to the best path to take. Will be great.

The current codes are P0300 repeating and P0174 once

Thanks

Injector balance test? At 2500 rpm?

After watching some Youtube videos, I can test the Cyl 6 injector by attching a fuel pressure gauge and powering the injector engine off. This will tell me if the injector is opening or not. I am afraid to use full battery voltage do you have a suggetion on how to power the injector without burning it out? Thanks

I ordered a AA battery holder and 9 volt connector to try and power the injector at 5V, 9V, or 12 volts I should get it in a couple days. Thanks

Compression on cyl 6 was 180 psi back in June. I removed the coil pack side of the wire for 6. Strong blue spark and then no change in idle when held aside. For a while I thought the problem was an intake manifold gasket leaking air to the cyl 6. How likely is this? Let's wait till I get the AA battery setup so I can open the injector with a fuel pressure gauge attached. I have looked for a Power Probe device to activate the injector but they are $40+. Can I just use a battery? What's your opinion about using full 12v battery power to test the injector? I am afraid of burning it out. Thanks

Hi, I just got an extra injector connector from the junkyard I will use to check the injector. I have to solder some wires to it and clips. I will rent the fuel pressure gauge at Autozone today. Thanks

When I checked the ohms back in June it was within specs. I will check it again. Thanks

Ohms are 16.1 ohms on Cyls 2 ad 6. Compression is 133psi on cyl 6 and 150 psi on cyl 4 cold cranking engine wot. Fuel pressure running is 31 psi, off 32 psi after 2 minutes 32 psi. From max of 36 psi fuel pressure each pulse of injectors 2 and 6 drops 3-4 psi fuel pressure per pulse (touching neg of battery momentarily) until exhausted. 2 and 6 are the same. Cyl 6 injector makes a good loud click. Please let me know your ideas. When running it is still rough missing at idle and smooths out above 2000rpm. I did not let it run much today. It was getting cool and dark so I stopped for today. Thanks

I just noticed you asked about inj pulse at inj 6. In june I used a noid light and it worked correctly. Flashed on and off.

Would a bad intake manifold gasket cause this problem? No firing on cyl 6? I wish I had a smoke machine, a mechanic here said it would cost $100 cash upfront to test with a smoke machine. That was why I was going to make one from a fog machine and air pump. Thanks