2010 TRD having issues

Hi, I’m hoping to get some help and input on my truck. I got a po304 #4 cylinder misfire the other day. I have changed the plugs, coils, injectors, and injector harness and still keep getting the cel and same code regardless of what I do. I did a compression test and all cylinders were really close. The thing that throws me off and makes me think that the ecu is bad is I can reset the cel and the truck runs good for a day or so. As long as a light isn’t on the truck will run fine. I hope someone can help or has some knowledge about this issue. Thanks!

 

It might help if you had the freeze frame data when it happens.
See what RPM / Engine load it is happening at.
Also see what the run time was when it was set.

 

It seems to always trip on startup, either first thing in the morning or at 6pm when I leave work.

 

assuming quality parts
doesn’t hurt to borescope and leakdown while you’re at it
Maybe pull a valve cover and inspect top end

at this point given the age I wonder if the FPR or better yet fuel pump is dying and if there is any other codes. Or check fuel pressure and delivery rate to make sure pump is working.

I would hope in such a case the ECU would be sensitive to pick up on that and throw a code for low pressure or running lean from not enough fuel sent up to the engine.

but the diagnostic capability and ECU of these trucks does not seem to be as revealing as other cars in terms of telling on itself.
ie saying something like “no signal” or “open circuit” in a fault pointing towards break in the wiring which it seems you’ve ruled out.

Maybe there’s a place for tech stream, or reading live data as it happens.

If it was my truck doing that at this age I’d probably throw a fuel pump at it and re evaluate but that’s just me.

an ECU dying seems pretty rare and doesn’t change other parts of the system still in there being old like pump that on top of that from factory doesn’t have a replaceable filter like it should.

In general fuel pumps can act up on cold start due to no longer holding pressure and struggling to keep up with the increased demand of cold start after sitting, such as if they use a check valve forward that is no longer working. You may also be able to check that such as fuel pressure test, delivery rate test.
I threw a new regulator at mine because why not. It’s cheap and old one is old.

 

I’ve had 2 other mechanics look at it with diagnostic testers hooked up while running and that’s the only code that is showing up. They think it’s the ecu only because it doesn’t seem to be a mechanical problem ie: I can reset the cel and everything runs fine.

 

That kind of suggests you may be getting coolant in the cylinder from a slightly leaking headgasket.

I'd pull the plug on that cylinder, put some pressure on the cooling system with a pressure tester, let it sit for a few hours or overnight, and look in the cylinder for coolant.

 

Anything. Fuel leak down. Oil leaking in. Coolant leaking in.

Yes you can pressurize it overnight and look inside with a borescope. $30 camera on Amazon connects to your phone.

hopefully not the case since it’s a 2010.

water converting from liquid to gas has the effect of knocking loose and cleaning carbon. Some people inject it into their engine for this reason, while careful of a small amount to not hydrolock.
Coolant leaks do the same thing. Long enough time coolant leaking into a cylinder will steam clean it looking cleaner almost new compared to other cylinders.

cold long term test would be better for it to not burn off or evaporate
black oily tailpipe can point to things too but isn’t necessarily a 100% confirmation.
(Such as burning oil)
Which if your oil level is fine it’s probably not.

who knows maybe ECU is cheap. Idk if it needs crazy extra work like lock unlock match to vehicle make immobilizer work etc

 

I’ll try that on Friday when I’m off. I haven’t had any drop in my coolant level since this problem started because I thought it was a

 

I will pull the plug and boroscope it and see what it looks like inside. I think one of the guys I took it to did this. It won’t hurt to do it again though. I haven’t looked at the tailpipe yet but will do that before leaving work today.