2001 toyota tundra v6

i have a 2001 toyota tundra that is throwing a knock sensor code. the symptoms of the truck are when i crank it it , when it hasnt been driven in a while, it runs like a top. i will drive into town, cut the engine off, then crank it back up it runs rough. then sometimes, not always, halfway home it stops running rough and is fine. my question is if it is the knock sensors or the wiring harness, would it only be doing this sometimes? vacumm leak?

 

Any set or pending CEL codes?

If it starts, runs well then a while after shutdown struggles, it could be the fuel pump. While the pump itself is fine, the anti-flowback valve is failing allowing fuel to drain back into tank.

But I would want to know of CEL codes first, could also be a fuel injector leaking, so check for that also. Let us know what you find.

 

the code it is throwing is p0330. this morning i cranked it up and drove it for 45 minutes. ran perfect. stopped at home depot and when i cranked it back up it was running rough. got on the interstate and going up inclines it was losing power. after 10 minutes of driving it quit, had power back, when i got home i turned it off, waited a minute and cranked it up , ran fine. after 10 minutes , cranked it up, started running rough again. after then engine completely cools, it will run fine until i cut it off and re-crank it. last week it also coded for catalytic converter but i had them replaced, no more codes for that.

 

408000 miles on truck, change oil every 3000 miles.

 

looking at codes it threw 2 codes.p0330 and p0325

 

Knock sensors rarely go bad, so I'm wondering if a rodent didn't get in your valley and nibble on some wires. Take a flashlight and see if you can look in there and see anything.

 

This man speaks from direct experience, too.

 

problem solved. toyota dealership told me i needed a new wiring harness. all they did was read the codes. no problem solving. took the truck to the guy that always works on my vehicles, found that the wiring harness was unplugged behind the plastic cover in the front. no more codes. question, do you think the dealership would have told me that or just replaced it and taken my 900.00? you were right, not the knock sensors, was the wiring harness, only not mice, just unplugged. thanks

 

They'd have taken your money. And not even replaced the part. That's one of many reasons some of us refer to them as the "stealership".

Glad to hear you got it sorted out. Now stick around, dammit.

 

Knock sensor code was fixed by plugging the wiring in. Still have a misfire on cylinder three, not the ignition core, swapped them and it was still on cylinder three. Possibly fuel injector or wiring. If it is the fuel injector, can I just replace one or do I have to replace all six.

 

On the injector, the computer should be able to monitor and adjust for flow, so theoretically you could swap in a new or used one and be done, if new, the computer should be able to monitor for fuel flow and adjust. However, I think most guys would take this as an opportunity to upgrade to Dirty Deeds or possible OEM injectors from another engine.

If it were me, I'd attempt to do an injector flush. i.e. get a can of SeaFoam, run my engine down to a little less than a quarter tank, and dump a whole can of SeaFoam into the tank, then run to nearly empty. SeaFoam is just highly refined petrol and they say it won't damage anything used this way even at 50/50 concentration or more.

If that doesn't manage to do it, and I were on a budget, I'd probably pull the injector in question, then rig up a 9v battery with alligator clips to power the injector, pour some SeaFoam into a reservoir, and run a tube from the reservoir to the back of the injector, and do a 100% flush of the injector, both to test and clean it up.

Sample of what you can expect:

https://www.youtube.com/watch?v=XYp4OeNQpnc

 

Oh, and obviously, make sure you check your wiring. Unclip/reclip the coil and injector for the cylinder in question. You wouldn't be the 1st person to forget to, or to bump loose one of these two cylinder wiring harnesses while working on something. This just bit someone in the ass within the last couple months, actually. The heat and environment around the engine can lead to the connectors getting brittle, coming loose (supposedly).

 

I read where if the injector is working OK it makes a loud clicking noise when you’re using a stethoscope. I went to Harbor freight and bought one for five dollars and put the stethoscope on it and it is making a loud clicking noise yet there’s still a misfire in cylinder three. I’m baffled if the injector is ok, and the ignition Coil is ok, what else could be causing the misfire? If you don’t think I know anything about trucks, well, you’re right, I lay ceramic tile for a living. A little bit out of my league here. This morning I cranked the truck up and drove in town to Harbor freight, purred like a kitten and ran great. As usual when I got back in the truck and cranked it up it was misfiring. Sometimes it will stop misfiring before I get all the way home and run fine.If I had any hair, this is where I would be pulling it out!

 

Think I’m going to go into town in a minute and get some seafoam and try that.

 

So you're saying it's often fine from a cold start, but gives you grief on warm starts? Or am I mis-reading that?

It's important to think bigger picture. A lot of stuff has to happen for a cylinder to fire. To over-simplify it, all the engine needs for it to fire is air, fuel, and spark. If we want to think more deeply about how that works in our truck:

• Engine needs to pull correct amount of air into the cylinder
• Engine needs to spray correct amount of fuel to mix with that amount of air in the cylinder
• Coil pack for that cylinder needs power and correct timing to send a spark at the perfect time
• Spark plug must receive spark from the coil, spark plug must be properly gapped and free of crap so it gives a clean fire

If anything goes wrong ... like, timing is off by miliseconds, can't measure the exact volume of air, spark isn't strong enough from one cylinder, one injector isn't spraying the necessary amount of fuel into the cylinder, you can misfire.

So, say you replaced a coil it with a cheap, Chinese-made coil with low quality control, or the tube on your coil is cracked, or the boot at the end of the coil tube is missing, or you're running mis-matched spark plugs, any of these things can lead to issues. Cracked coil tube or missing coil tube boot could cause failure in spark delivery, for example, arcing.

A lot of people have come to this forum because (A) they replaced their coil with some cheep non-OEM/non-Toyota brand coil or (B) they bought their parts on Amazon which has a really crappy reputation of allowing vendors to sell counterfeit parts.

My big take-away here is this:

1. The misfire code is only for one cylinder, not ALL cylinders
2. That limits the number of things you need to diagnose and rules out bigger system-wide things like the MAF, catalytic converters, fuel pump, major grounding/power lines, vacuum leaks, etc.
3. You know the condition tends to happen only when the engine is warm (if I'm reading your 1st post right) so heat could be playing a role here

If you're hearing clicking out of the injector, that's not a 100% "it's working" sign, but ... that would be enough for me to start focusing on the other stuff:

- Check spark plug on cylinder 3
- Check coil on cylinder 3

I suspect you'll find one or the other may not be working correctly, or has cracked bits. If you need to replace a coil, trust me, you want to replace with OEM. If you find the spark plug is fouled to hell, I'd recommend replacing all of them with Toyota's recommended NGK iridium plug, unless you recently had all of them changed (last 40-50k miles if they were long-life plugs)

 

Thanks, i’ll pull the plugs. On cold starts it never misfires. And it doesn’t misfire until i get where im going, cut it off for a bit then start it back up.i always try to get oem parts .i’ll get the ngk iridium plugs and swap those out. See what happens. Thanks

 

put seafoam in the tank, need to drive it around ,then im going to do it again. here's something funny i noticed before. when its cold, near freezing all day, in the 30's like today, it doesn't mis at all. go figure.

 

Suggests whatever's up is being exacerbated by heat. Definitely a symptom that may toss a red flag for someone here.

I've heard of no-start conditions caused by heat; pretty sure that was the fuel pump relay getting stupid, though, and that was a straight-up NO START situation, not a "runs poorly" or "limp mode" thing.

 

Just a follow up. Still have not solved the misfire on cylinder three. Put OEM spark plugs in it, swapped the ignition coils around, put new spark plug wires on it. Does not miss when I crank it up in the morning, and I can drive it for however long and it’s fine. It’s only when I turn it off and come back and crank it up again it misses.Even during the day if I cut the truck off and wait a couple hours and then crank it, it doesn’t miss. Only when it heats up. I’m wondering if it could be the wiring connection that comes from the harness and connects to the ignition core. I know that you can buy those separately. Sooner or later I’m going to have to take it to the shop I guess. If I had any hair this is where I would be pulling it out.Around the seafoam in it, and have been putting that in regularly. But it doesn’t change anything. I’m thinking maybe it’s not the injector.