Weird noise under load and only in 4th and 5th gear

[4x4mike]

We're out of town right now and the 4Runner is experiencing some weird noises. There doesn't seem to be a decrease in power but the noise comes while on the freeway while in 4th or 5th gear and around 2500 rpm. Speed wise its probably around 60 mph but again only in 4th or 5th. Idle is fine and when under the hood with the transmission in neutral while moving the throttle cable there is nothing out of the ordinary.

Starting from a stop from first, second and third there is no noise even around the suspect rpm range. My Ultra Gauge doesn't show a code or a pending code.


For S&G's I put the deck plate in but it made no difference. It kind of sounds like knocking but more of a rumbling noise. I have an extra coil pack but haven't messed with rotating those. I was thinking maybe it's some bad fuel but I'm not too sure becuase it's only while in gear. Motor oil is brand new and at the proper level.



Any thoughts? Right now I don't feel like I'll be stranded but I also wouldn't be surprised if it threw a rod.

[Seanz0rz]

Does it kind of feel like a stumble? Almost like a misfire but never a check engine light or any other indication. Almost a cough like running out of gas? I had that after I bought mine and solved it with new plugs and wires. Might be a place to look. Seems like plugs and wires on these engines don't last a long time, at least they don't for me.

Also look for more wind related items, like flapping body-frame gap covers and wheel well liners.

[4x4mike]

No stumble but I know what you're talking about. This kind of sounds like a metal coffee can knocking around under the hood. I'm getting just shy of 20 mpg and still have the power.

I can slightly increase the throttle and it will start. Not all the time but most.

Plugs and wires have about 50,000 miles on them. The ones before we're stock and new from 1999.

On possibly a related note the chirping noise started again but not during the rumbling.

[Seanz0rz]

Mine typically die after 40k now.

I would start looking at loose things, especially the accessories. Check skid plates too and exhaust.

[4x4mike]

I'll take a look. Any harm on driving with it doing this? I've got about 300 miles before I get home. I guess in the mean time I could inspect the wires and see if anything pops up.

If the plugs or wires are the problem would timing, or something else I could monitor, be off?

[Seanz0rz]

I'm not sure how the ecu adjusts timing from knock input. I think that if the problem is in the ignition system, you should be OK to drive as long as it isn't misfiring constantly.

Got auto club? Lol

[4x4mike]

I've read a bit more online and I don't think Ive got a misfire. I plan to find a squirt bottle and go outside now that it's dark to look for sparks.

Mileage wise I think I'm due for new plugs, wires and a fuel filter. I'm also going to fill up with premium and toss in a bottle of injector cleaner. Thanks for the tips Sean.

[4x4mike]

Just sprayed... No sparks. I also inspected the air intake tube and it's fine. Plug wires have a born on date of 2009.

[slomatt]

That is odd that it only happens in 4th and 5th gears, which makes me think it is either engine load or possible speed related. If it was load related it could be detonation, but your check engine light would be on if your knock sensor detected anything.

Does your exhaust smell like gas? If a plug or a wire was going out I'd think you'd be missing and would notice a loss of power, mpg, and raw gas smell in the exhaust.

Since it is speed related, it could be a loose plastic or metal piece on the body, like a plastic panel or a heat shield.

It is definitely odd that it started and your unexplained chirping came back at the same time. Could it be something related to the York air compressor?

- Matt

[4x4mike]

It's not the York. I ran without that belt for about a month while trying to figure it out last time. It doesn't really sound like anything loose. All my plastic and fender flares are intact.

I'm going to hope it makes it home then check the plugs and order some new ones when I get home.

[paddlenbike]

I got a tank of bad fuel one time in the desert out of Barstow and that's pretty much what it was doing--pinging at low rpms in the higher gears, but would go away in lower gears at higher RPMs. (This was on my 3.0L truck)

Keep in mind the knock sensors are not active below 3000 RPMs, so if you think it's pinging/knocking, it's better to downshift a gear and keep the RPMs in a range where the knock sensors can retard the timing.

[4x4mike]

Good to know, thanks. 3000+ rpm should be great for mileage.

[DHC6twinotter]

Is it pinging? My MAF sensor went bad on me several years ago, and it pinged while under load. No CEL either.



Keep in mind the knock sensors are not active below 3000 RPMs, so if you think it's pinging/knocking, it's better to downshift a gear and keep the RPMs in a range where the knock sensors can retard the timing.

I never knew that. Good info!

[4x4mike]

Well I made it home last night. I was a bit nervous because I wasn't sure what the problem was, we had my niece with us and we had a good drive ahead of us so that added to the excitement. Before leaving towards home I topped off the tank with premium fuel and it took about 12 gallons. I wanted premium because I was concerned I had a bad tank of fuel or that I was experiencing detonation and wanted the higher octane to minimize it.

Well the drive went buttery smooth, the 4Runner that is. A rear seat with 3 kids is a different story. I drove the speed limit and didn't try to test my luck in passing or going over the grades. I had the cruise control and the AC on most of the way and all was good. The Ultra Gauge reported 20.4 mpg for the drive home and no trouble codes or pending codes.

Dan I'll have to check the MAF. Mines been beat up through the years with dust and dirt. I keep it pretty clean and drive with a spare but I'll see if I can look into it. The UG displays two parameters in relation to the MAF so maybe I can take notes with each one and see if they operate the same.

I'll also order a fuel filter and pull the plugs to give them a look. Thanks for the help guys.