Can a VVT-i problem sound like an engine knock?

Will that throw a code?

 

Yes but it will run decent, you just won't have the VVT working. You can run it long enough to see if your noise is still there.

 

Thanks.

OK, next question: where are they?

 

In the valley pretty much directly under the throttle body.

 

Thanks!

 

At what engine RPM does VVT-i kick in?

Thanks.

 

It's not really a vvt-i like Honda has where there's a "kick-in". It varies the valve timing based on hydraulic pressure from the oil control valve to the intake cam phaser on the 1gr-fe in the Tacoma. I believe the 4.0 in the 4Runner and FJ have dual vvt-i, varying the timing of the exhaust as well.

 

It varies cam timing based on engine load & RPM, here is the stock base cam timing table (0 would be no VVT operation), if you have a tune the table will likely be different.

 

Ah, that would certainly make sense based on its name.

Thanks.

I'm hearing a rattlecan sound at 1800-2000 RPM under moderate load and wondering if it's related to VVT-i.

The sound is distinctly different than the one I talk about in my OP.

 

I was chasing down the same issue up until I got the OTT done. It would lessen with higher octane fuel leading me to believe that it was a timing issue causing pre-ignition or "spark-knock".
At this point I'm contemplating just replacing the OCVs. I cleaned and tested them with 12v and it didn't seem to help.

 

I'm going to pull the plugs on my OCVs and see if the noise goes away.

It'll also be interesting to see what kind of hit to performance occurs with VVT-i disabled.

 

Keep us posted!

 

Well, I pulled the two OCV cables. Broke the trigger/latch on the left side. Is that easily replaceable, or do I have to pull a mile of cable out of the truck?

Anyway, doing so threw a CEL and the "traction control disabled" lamp illuminated as well, which I thought was interesting.

The rattlecan noise is still present.

At least I now know what it isn't.

 

Oh man, sorry to hear the clip broke. Not sure if that's something you can splice a new pigtail on or not. Might be easier to try to find an alternative fastening method to keep it from coming loose.

Mines still rattling away around 2k right before shifting and I'm still scratching my head. I'm almost wondering if there's a leaky injector that's causing the ECU to run the fuels trims leaner in an attempt to compensate. I don't have the time to tear into it until Sunday which is of course Superbowl.

 

I might be able to somehow wire tie it on.

Something else interesting that I meant to report: I've noticed no perceptible difference in performance whatsoever with VVT-i disabled.

Is VVT-i supposed to be a performance thing, or an MPG and emissions thing?

 

I logged some OBD-II data with VCM Scanner.

(aside: the latest version of VCM Suite has a "mark" feature. Press the "C" key to bookmark the log trace. This is a great feature that was in older versions but disappeared for a bit).

I'm unable to correlate the rattle to any specific sensor data.

I did determine simply by spying the tac while driving that the rattle is happening at a very specific RPM: 1750. It happens while passing 1750 on the way up and on the way down while under at least a moderate load.

I wonder if I'm dealing with a bearing that's not long for this world?

Or maybe something as simple as an exhaust shield? I did replace both cat heat shields so I know it's not them.

 

I'm back! I am still having that same issue. Tuner told me that noise is normal, that it's the vvt kicking in sooner, but I'm having a hard time believing that. It's such a loud harsh noise. He also said the when they revised your first tune, you were having spark knock due to carbon build up and the adjusted your timing. Now it seem we are having the exact same issue. I replaced both my vvt solenoids and oil filters with no luck. Have u had any other discoveries? I don't have the issue with the stock tune, but would hate to have to go back to that slow pig tune.

 

I don't think what I'm experiencing now is tune-related. I think it's a mechanical vibration somewhere outside of the engine core. It's just a real b__ch to find.

 

Just to answer the title of this thread yes it can sound like an engine knock. The vvti on my 2JZ when I had my Lexus would sometimes do it on cold start before it pumped up with oil

 

Might be a long shot, but I had a metallic noise under the driver's side at a specific RPM when accelerating/decelerating. I was pretty certain it was a heat shield, I just couldn't isolate which one.

One day I heard a few clanks under the truck and spotted something in the mirror bouncing along the street behind me. I turned around and found it: obvious heat shield about the size of my hand: Rattle gone. I looked under the truck to see where it might belong, but no signs or hints on where it lived, and no fires or hot spots in the 15,000 miles since it took flight. I have fluid film all over everything up front except the exhaust pipes and cats and see no signs of heat stress in it.