2.7L engine knock

When i start my truck in the morning and pull out of the driveway there is an engine knock. it lasts for a few minutes or about a mile or two. If i start it and just let it sit and warm up and then drive off it is minimal or non existant. It is a knock more than a ping. i am not a mechanic but it sounds like what i would consider to be sticky valve lifters, but that is a pure guess as my mechanical knowledge is minimal.

Another annoying problem is the accelerator difficult to push down. you almost have to punch it to get it to engage if you take your foot off of it for more than a 5-10 seconds. It has been a lot worse with the cold weather. seems like the throttle cable is sticky, but again I don't have much knowledge. If you are driving and remove your foot from the accelerator and then engage it makes a real jerky motion when it finally engages. the only way around it is to engage the clutch, punch it, let out the clutch, then you can get a smooth engage out of the accelerator.

Any help/ideas would be appreciated.

2002 2.7 4x4 168K

Thanks

 

Mine does the same thing. Not 100% sure but i think its something with the oil pressure. idk? it seems when i do my oil change and add some slick 50 in there with it, it helps that. i just let it warm up for a good min and go. after all its a toyota.

 

is it cold where you are?
its been hovering in the -20's (Celsius) for the past few weeks now... mine knocks like a hammer when i dont plug it in. and its only 2 years old, 44000km. i'm also running amsoil 0w20. but i guess either way this is kinda comparing apples to oranges.

 

Mine does the same thing. Worse when the weather is cold. I read somewhere on here that many 1st Gen 2.7 experience the knocking but never had any problem with it.

 

Thanks for the responses. I might try switching to synthetic oil and putting in a block heater. My father swares by synthetic and block heaters, seems his autos always go over 250K miles.

It is cold here in Maine. 5degF this AM. I started the truck and let it run for a few min. No knock when I left the driveway. It started it near the end of the summer I would say, starting it in the mornings and taking off, noticed it.....so it wasn't cold outside, but the engine was obviously cold.

 

I run royal purple synthetic and it wasnt enough to make i difference. i run my synthetic and slick 50 and that seems to help.

 

Cold engine piston slap, mine does it also. Not much you can do about it but let it warm up for a few minutes. A bit of clearance between tbe piston skirt and cylinder from the mileage,,,,just dont rev it hard when cold,,you could snap a skirt off.

 

Mine does it too, but i took it to a trusted family mechanic who is a very good mechanic, works for the local power company. He said mine was something in the Catalyic converter that pings when it cold , but once it heats up and expands it doesnt do it anymore. He said not to worry about it unless it gets worse.

 

http://www.tacomaworld.com/forum/1st-gen-tacomas/59940-knocking-when-cold.html
This. I think the majority thinks its piston slap or something to that effect.

 

As for the sticky throttle.... pull the air intake pipe off the throttle body and clean the throttle plate and around it with spray carb cleaner. I usually open the throttle plate and use the spray and an old toothbrush. Try not to spray excessive amounts inside the intake. It will be hard to start afterwards, but should clear out rather quickly.

 

you should all way run what the factory recommends you to use.

 

My 85 22R had the same noise, engine was torn down and noise was proven to be piston slap by the machinist. Had the piston skirts knurled, reassembled motor, noise was gone for awhile until the knurling was worn off the skirt, then the noise reappeared. The machinist was always adamant about not revving when cold if it is slapping due to the fact that those frequencys can snap a skirt off, or crack one, Piston knurling or not. I haven't seen a piston out of a 2.7 so I don't know how much skirt is there.

Cheap gas really makes them bang when cold.

I was a starving college kid, so I had them knurled. The proper fix is a rebore and new pistons., which eventually it did get with TRD pistons.

It will live for miles with that noise, just have to be careful when the engine is cold and use good oil.

Take it FWIW.

 

My 2010 will do it when its cold, I just let it warm up until it comes off the cold mark.

 

synthetics will flow easier at low temps and will also cling better to prevent a dry start (5w 30 would be a good choice), my 04 would knock a little when cold if you did not let it warm up before taking off. a block heater will also help where you are

 

basically the piston is made out of round from the factory it well become perfectly round when warm.
Mine does it to and I'm not worried about it. Friends silverado does it as well. No biggy.

 

That knock on startup is more likely to be ignition timing being too advanced. Reset the timing and it should go away.

 

Slick 50 maybe can of restore. wd40 Carb cleaner. check the butterfly area it might be all crapped up with the sticky throttle black stuff. if so wipe it out and then spray it while running. run a tank or 2 of super.

 

If his 2002 is anything like my 2004 than you can not adjust the timing.
When the engine first starts the metal is cold. When the fuel is sprayed into the combustion chamber as a mist it will condense and form droplets. Thus the EMC has to run rich. This applies to all engines.
I don't think it's "pinging" and needs it's timing adjusted.
Basically all manufacturers produce their pistons oval shaped. The long sides are the opposite from the wrist pins. The thrust plate is also located there. The piston is also tapered. All of this is because the engine will warm up and the piston needs to be designed for heat not cold. So when the engine is cold you will get some sounds. all perfected normal so long as his oil system is good.
You can connect a gauge to the main oil galley to check if the pump is strong. Should be 10 psi for every 1000 RPM's. many things can cause low oil pressure and it will take too long to cover them and I doubt it's an issue anyhow but since I do not know your maintenance routine....
in short this is a common issue with the 2.7 you are fine.

 

Found this: One way to check for piston slap: Remove three spark plugs, leaving number one in place. Crank the engine over until you feel the resistance of number one piston coming up on compression. Crank against compression until the piston is about half way up the cylinder. Now rock the crankshaft back and forth and listen for a metallic knocking sound. If you hear a knock, you have piston slap and the only way out is to rebuild the engine.