P0330 and other codes randomly coming up

Hi,

I have '02 3.4L quad cab that is throwing odd random codes. About 6 weeks ago, I had knock sensors codes, and the wiring harness was degraded, so had them and the harness replaced.

Was quiet for several weeks, and now, I am getting P0330 and alternately several EVAP codes. I clear them and they disappear for a while, but then one or the other comes back. I've checked the cabling for the knock sensors, and it looks fine, and no sign of rodents or anything that might cause the cabling to go bad this fast. I'm tending not to believe the codes are truly an issue, but that there's something else, and odd, that is happening.

Looking for thoughts or ideas, to see if anyone has come across this one before? I saw an old posting of someone over a year ago, but it went unanswered, so not ideas on what to check next.
Hoping someone has had experience with this.

 

Check cooling system is working properly. fuel filter Evap valves selinoids.

 

take a look at engine block grounds, I believe knock sensor cable is shielded and ground for shield goes to the ground lug near the diag port on intake mani. Inspect for broken wires and clean/tighten. Also check engine to body ground straps, one near oil filter and another on rear pass cyl head.

You got a genuine Toyota knock sensor cable? Those are critical, my new one had a test certificate come with it.

 

I’ll check these later today. Don’t know if it was genuine, had local shop do the work, cost plenty though.

 

Huge problem with replacement part quality these days and those parts are so deep in the engine...

I have heard of guys going to independent shops, telling them they want Toyota replacement parts then they ask for the box to verify - mechanic has some lame reply like "its equivalent". I think they make more profit on replacement parts or maybe their parts delivery service does not normally stop at the dealer - who knows but its a big issue. But only remedy is do the work yourself or take to dealer.

I think a few people here had issues with aftermarket knock sensors, the OE ones are about $100ea so its tempting. They are basically microphones so critical that specs match OE.

 

For tha evap check your gas cap gasket, mine is about to disintegrate. Also check all those hoses on all the evap comps near drivers side fender. There is a short plastic hard line that comes off on mine almost every time I work on the truck and that will throw code. Good chance mech knocked off a hose or broke something.

This is for 98 ( I have change vehicle to get 02, will check later). All of those hoses on right side are evap
related. The hard line is 17308.

I have learned not to lean on any of this or might break something but of course most mechanics won't know this.

 

Unfortunately we seem to get constant reports of mechanics screwing up jobs on the older Tacomas, not sure why. It may be because they are older trucks and so they assume customer won't want to spend top dollar for OEM parts which of course is nonsense - why do a repair that likely won't work. Also could be they are used to working on domestics where I think there are more choices for legit aftermarket.

I have heard that the foreign aftermarket is much worse in terms of poor quality because the foreign OEM has no reason to complain (why would they care) but for domestic the OEM and aftermarket supplier is often the same so the supplier cant let the quality get too bad.

An example is the carrier bearing - I let my guard down and bought an aftermarket made by a major domestic OEM supplier (forgot the name but they are major US bearing manufacturer). It was not even much cheaper than Toyota part. That part lasted exactly 1 year! In fact it turned out the noise I heard was not the carrier bearing so I put the original back! Since that domestic OEM is not a OEM supplier for Toyota they can turn out loads of crap and only complaints will be from consumer - and they dont really care about consumer.

 

Ok, so I got up and did a lot of looking and checking. Gas/evap hoses in general look in ok shape (frame was replaced in 2015, and some were replaced then), I checked grounds and battery connections, and battery connections were not good, fixed that. Did a couple other maintenance items, then went for a test drive, CEL came on when accelerating from a stop sign, same code P0330. Cleared and took for a second test drive, no CEL. I’m expecting it to come back on, and will try to note conditions when it does (rpm, speed, etc). By looking, I am -guessing- but I doubt it was a Oem replacement unit and cable.

 

NV

 

Here is diag procedure from FSM, looks like they cross connect the banks to isolate ECM vs sensor. If bank does not change its either wiring between connector and ECM or ECM. If bank does change its either wiring from conn to knock sensor or bad knock sensor.

Not sure if your mechanic is is sophisticated enough to do this, it appears few are. For DIY probably best way to get some spare connector pins (and ideally even connectors) and wire up as shown, I would be afraid to use any other method as it may damage the harness then your back to where you started.

Looks like you should be able to cause code by just running engine to 4k rpms in neutral.

 

Interesting, I’ll see about trying this tomorrow.

 

And of course you could take to an auto electric mechanic which in theory specialize in these kinds of problems.

 

finally came back on today about 3 minutes into first ride. Was taking off from stop at an intersecti9n and got the following freezer frame data.
Status P0330
Fuel system 1 status. CL
Fuel system 2 status —
Calculated load value 63.9%
Engine Coolant Temp 65C
Short term fuel trim bank 1 -2.3%
Long term fuel trim bank 1 3.1%
Engine RPM 2181
Vehicle Speed 52km/h
Intake air 18C

I will try seeing if I can swap wires next and see if it goes to P0325

 

Sorry, my bad, I misread your code and thought you were having a random misfire code p0300 among your issues.

 

So, was quiet for a couple days, then after filling up yesterday…3 codes popped P0440 P0441 and P0446, but no P0330…

 

Just want to make this thread thorough, so posting a couple pics. First one is new connector from harness of knock sensors. Second one is what they plugged into, and while not focused good, you can see they didn’t bother cleaning the connector, so plugged into a dirty old connector…possibly my issue? We’ll see in a few days.

 

Continuing to follow up for future readers. After getting a 0330 and 0446 again, Replaced gas cap, and canister purge valve. 100 miles later, so far no codes yet.

 

I spoke too soon….
After another couple hundred miles, have 2 codes, both are P0446. If anyone is still following, what is best guess at next evap component to look at?

 

You need to smoke test it.

 

That’s what I was thinking, just dreading what the shop wants to charge for smoke testing…. Maybe I should try one of those diy smoke testers.