Hello!

Let me start by saying I've had a lot of vehicles that ticked. Mainly Subarus and 22r's. What I'm hearing doesn't sound normal.

I have a bone stock 3vze 5spd with 150k. At idle and on flat ground the engine is smooth and quiet. When going uphill, trying to maintain speed and or accelerate (engine under load) I start to hear a ticking that doesn't have a uniform pattern. It's a very high pitch tick if that makes sense. The ticking goes away if I let up on the throttle. For example, if I'm going 65 in 5th on flat ground, then come to a hill and keep on the gas, the ticking will start and get louder with more load. I downshift to 4th, ticking goes away. I attempt to give more throttle to maintain around 60 (3k rpm) and the ticking comes back. I'm forced to let up little by little to keep the ticks away until I'm eventually going about 50 and the hill ends.

Now I understand I can't always leave it in 5th going up hill, but it ticks even in 4th at 3k rpm. It really depends on engine load.

Without throwing out my own theories, does anyone have an idea of what it might be? Have you experienced this behavior?

Thanks in advance

 

Well the 3.0 is belt driven iirc so no timing chain.
its not the sound of a vsv opening and closing rapidly or something loose in the engine bay?

If its engine internal, it probably exists all the time at a lower volume. Try getting a mechanics stethoscope and giving a listen.

 

Sounds like the symptoms of an exhaust leak at the manifold of first pipe. Check for loose studs at the heads or feel for puffing with your hand around the manifold on a cold start.

 

Pre-ignition, aka ping under load.

Easy to check out, put a tank full of premium in it and it will delay the noise to a higher rpm under the same load..

Which of course is really hard on bearings and turns into rod knock if you keep on the same course.

Free things you can do is ensure your exhaust is all sealed tight. Downshift before the hill pick up speed and keep the rpms in the power band before the ECU starts to pull the timing advance down.

Low cost, you want to run some injector cleaner. (This one is cheap enough you might as well do it regardless) This will help with soluble clogs but not actual debris like rust or other solid particles in the filters.

After that it gets abit more extensive and expensive. If you don't know when the oxygen sensors were replaced, and you can get them off without snapping the studs, it's not a bad investment..


The ignition trim is cyclical here, engine detects ping and reduces timing advance, retarded timing produces less power and now you have a loaded engine which starts to ping and you start back at the beginning which brings the engine eventually to a practical stop.

 

Good call. I wasnt thinking detonation.
So youre saying its the computer adjusting for bad fuel trim?

 

Thanks for the input everyone! 94_pu I think you hit the nail on the head. I looked up videos of engines pinging and it sounds just like it. I feel bad I let this go on for so long (1500mi) so hopefully there isn't long term damage already. I always backed off when I heard it though. Makes me sick to my stomach.

Obligatory pic of the old beast:



I'm going to follow your advice and start with injector cleaner and exhaust. It isn't loud but I have been suspecting a leak. I also have a new fuel filter I've been meaning to fit. It probably hasn't been replaced in 10+ years.

 

I agree with Co_94_PU; sounds like pinging. Back before knock sensors, that was common when running at full throttle and low rpm. Good reason to learn not to do that.
Normally the ECU and knock sensor should keep it from audible pinging, but a couple of things could prevent the ECU from retarding spark enough.
- excessively advanced base timing
- really crappy gas
- clogged or defective fuel injector causing a lean mixture
- carbon build-up in one or more cylinders resulting in hotspots causing preignition. The carbon acts like a glow plug. (I once blew a hole in an aircraft piston because of that. interesting day.)
- lugging the engine excessively at low rpm

Trying premium gas is a good idea. Also, if you haven't already, adjust your driving habits such that you never operate under full load below 3000 rpm. Your engine will thank you. It's ok to idle along in traffic at 1500-2000 rpm, but when you want to accelerate or go uphill, try to keep rpm between 3000 and 4500.

 

Thanks for the advice RJR, I'll adjust my habits. I've been trying to keep it between 2.5-3k under load. The previous owner said not to go much over 3k but he's not a mechanic.

 

No not exactly a lean fuel condition due to trim, but it (lean) will make it (pre-ignition) worse or more notable.

Once you've identified it as PING by adding a higher octane fuel and noting a shift in the rpm or load range it happens in, you'll wind up going thru a bunch of voltage tests of sensor data at the ECU.

​​​​​Its very much helpful if you've got a low traffic hill you are familiar with that you can reproduce this testing on.. If you can start at a RPM and speed range and either go farther before it happens or add a larger throttle plate angle before it starts to make the noise after upping your octane it's likely pre-ignition.

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[Q]Thanks for the advice RJR, I'll adjust my habits. I've been trying to keep it between 2.5-3k under load. The previous owner said not to go much over 3k but he's not a mechanic.[\Q]

It's a common misconception that running at low rpm is somehow easier on the engine. Not so. Cylinder pressures are higher at low rpm and full throttle than at higher rpm, because the piston can't move away from the expanding gases as quickly. Higher cylinder pressures mean higher rod bearing stresses, and more importantly for the 3vze, higher head gasket stresses.Not what you want.

Obviously running continuously at redline isn't a good idea, but at anything under 4500 rpm, the rod bearing stresses due to piston acceleration are considerably less than the stresses due to cylinder pressures.