It's like Christmas on the dash

I have a 2008 5.7 that won't stop surging, and goes into limp mode at 45 to 50 mph. I've changed out the coil packs and plugs. Found a double leak on the pressure regulator valve and changed it out. Nothing changed.

 

get the codes read that it is throwing. Either get a scan tool so you can read them or maybe hit up an auto parts store, many of them have a code reader they can hook up so you will know the errors identified.

 

Done that says it's misfiring but the cylinder keeps changing

 

Do a google or other search of the specific number codes being thrown and Tundra, and you will get hits were you can look and see what others have done to address the issue when they experienced the same error codes.

 

Do the cylinders keep changing or is it a multiple misfire? I would swap your old coils back in and reevaluate the situation... if it still shows a misfire pick out the coil and swap it with another one and see if it continues or changes. I have 240k miles on my original coils.

 

What are the code numbers?

If you dont already own a code reader, you need to buy one. A cheap hand held one is $30.

 

Welcome to the forum

 

Ok so I changed out the MAF and it won't even start.

 

Why did you do that? Why would you do that?

You are not diagnosing the issue, you're shot gunning parts. This will make more problems than the one you started with. With a $100 scan tool you could figure out if the MAF was reading properly. If you put a junk MAF in from the local auto parts store, that's not helpful.

Put all your old parts back, start the truck, then read the codes and report them here.

 

Yeah been there done that. Must be the code reader then I'm doing what it says is wrong

 

So the code reader said "Change the MAF sensor"? I've never seen that engine code.

 

Ok it said multiple misfire, MAF.

 

What are the actual codes though? What was the code related to the MAF?

A situation like this could be related to something extremely simple like a vacuum leak or a damaged wire, but when you start just throwing parts at it you will make more problems and you will then have to deal with what you've made and the original problem.

 

P0300 and p0430

 

What do your misfire counts look like? Those two codes would not at all be a reason to replace the MAF. If you have your old one, I would put it back.

This could just be a vacuum leak, bad gas, or possibly a failing coil. You'd want to look at the misfire counters to see if one cylinder is piling up the misfire counts or if it's half the engine. It would also help to know that the misfires and the catalyst inefficiency are happening on the same side of the engine.

 

I put the old one back in.

 

Are the misfire counters all piled up on one side?

What flow is being metered by your MAF at idle?

To check for vacuum leaks, you can listen for a sucking sound while the engine is running, or take an unlit propane torch and let propane leak out around your vacuum lines. If the engine RPMS change when the leaking propane passes over a certain spot, then you know to look for a cracked or disconnected hose. You can also pop the hose off the air box and tape over it temporarily with packing tape, then blow smoke into the intake tract to see if it leaks out anywhere as another way to look for vacuum leaks.

 

Spraying intake cleaner in short bursts along the vacuum lines will do the same thing as the unlit propane torch.

 

The abundance of warning lights on the dash can also be cause by a bad ground. Mine did that when the transmission grounding strap finally corroded through from road salt. It's on the passenger side of the transmission, but there other grounding straps in the engine bay as well.