P0304 misfire code

Hey guys,

A few weeks ago I went to turn on the heat on my truck and the engine got louder groaning noise. I was going on vacation so I left it parked for three weeks.

today when I started the truck it was misfiring and I pulled 0304 and if I turned on the heat or ac the engine got very loud.

Anywhere I should start looking? Could spark plugs?

 

Might want to provide some more details about your truck. Engine, miles, mods, etc..

Without much to go on, I'd suggest checking your coolant level and monitoring that pretty closely. If you haven't replaced the plugs or wires, it would be a good start. Label the plugs as they come out. Pay attention to cylinder #4. Then move on to compression and leak down tests.

 

The truck is a 2004 double cab, it has 475,000 km, no mods just maintenance items. The plugs were done around 60,000 km ago. My coolant levels are good I keep a constant watch on that. I’m going to start looking at things this weekend

 

Again, you might also want to provide what engine you have so that suggestions are more accurate between the v6 and i4.

Cross your fingers for something easy, but be ready for a head gasket or worse.

 

It’s the v6 4x4, yeah that’s what I’m getting from previous threads. If it is the head gasket? Better to put a new engine in it? I just redid all the suspension, ball joints, tires etc. it’s a clean truck no rust on the frame.

 

Depends if it’s a head gasket could just take time if your capable of doing it your self be under $1000usa with gasket, valve seals, knock sensor, water pump timing belt.. all that recommended services while your in there. If it’s a head you could get an eBay one for around $

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500usa but it’s a gamble could get a junkyard pull for $1800usa also a gamble. Or a head from Toyota for around $1000. Think jdm imports are around $1500. Depends on the gamble you want to take I think with head from Toyota which takes a little more work being the best odds. A gasket is cheaper in parts if you need any more work done like engine swap it’s all a gamble with different odds on the life left need to find out in your area about the company’s doing the work selling the parts.

 

Being it’s on cylinder 4 I’d replace the spark plug looking into the cylinder if you don’t find anything odd. Then coils and wires. If it’s not those I’d check the injectors 1st. Is there a reason you watch coolant levels regularly? No milk shake oil no loss of coolant no steam from exhaust?