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Discussion Starter #1
Is this normal?

Outside temp is 34c degrees (Celsius not Fahrenheit).

The vibration is noisy and causes my coins to make sound.

After about a few minutes, and stepping a bit on the throttle (just a little not allway down) it goes away.

It wasn't like this previously.

Its a 2010 model.

Oh and I usually have the car engine running at idle to keep the ac on while I work from my car for about 6 hours almost every day. Does this hint you about a possible cause?

Do FJs have common causes if this issue?

Any protocol that you suggest for me to do by myself to identify the actual cause instead of exhaustively bruteforcing the space of all solutions?

Note: I don't trust maintenance shops here.
 

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Discussion Starter #3
First thought is spark plugs or dirty injectors....
When's the last time you changed the spark plugs?
Try running some injector cleaner through the system too...

Red Line Synthetic Oil - Gasoline Fuel Additives - SI-1 Complete Fuel System Cleaner
But will a dirty or damaged sparkplug cause engine vibrations only in the 1st few minutes when the engine is relatively cold (34c), and then get back to normal?

I sort of feel (just feeling) that if it was damaged/dirty spark plugs then I'd have the variations all the time (not just in the 1st few minutes)
 

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Clean and regap the plugs and check their color for a warm toasty brown... Can't hurt and it will give you an idea of what's going on with the combustion.
Sounds like you let it idle for quite some time frequently so taking it out for a road trip and opening it up on the highway to blow it out and burn off the fuel deposits in the oil and catalytic wouldn't hurt too... Again, how old are the plugs? I buck and vibrate in the morning when I'm cold too fwiw... :lol: Hot = better combustion... Cold = sputter and buck... The color of the plugs is going to say a lot about what's going on with the combustion... Hell, you could have an open thermostat and never reach operating temp which would load it up but good. Eyeballing the sparkplugs is a quick and easy check to gauge which direction to take or you could just wait until it's really bad and then go looking. Do they have fuel additives that clean deposits standard in the fuel you purchase in the UAE? A miss when cold could be many things from a bad injector to an ignition coil that has a thermal window when bad so I touched on the easy steps you can take that won't cost a lot.
 

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Discussion Starter #5
The 29th day of the 10th month of the 2013th year, since Jesus was presumably born, was the last day I replaced the spark plugs.

Today I had a vibration-free cold start by simply doing nothing. Which is annoying cause my FJ is becoming like a human (hard to know what it wants). This reminds me of something on computerised cars that cars may one day need to be sent to a psychologist that is also another computer.

As for cold, I mean 34 Celsius degrees which i guess is considered hot by most Americans or Europeans. Dunno what you mean by cold, probably you mean fridge like cold? Which i guess is normal in your part of the world.
 

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Six hours of idling every day at high ambient temperature???

That would be considered very severe, if not brutal, operating conditions for an automotive engine.

You mention that after running for a few minutes, AND increasing the engine speed slightly with the accelerator pedal, the roughness disappears.

Questions:

a) Will the roughness eventually disappear even if you don't touch the accelerator, or is that an essential part of achieving a smooth idle?

b) How frequently does the vehicle get driven at highway speed, and what's the duration of the high-speed running?

c) How frequently do you change the engine oil?


I'd suggest the following:

1. Check for any stored codes in the emission control monitoring system.

2. Replace the spark plugs, even if they were replaced in 2013. Carefully examine the old plugs, looking at the uniformity of color of the ceramic insulator, and the amount and type of any deposits on the insulator. Are the plugs all very similar as to color and quantity of deposits? Do they have a "fluffy" black or hard white deposit? Do any plugs look distinctly different from the others?

2. Thoroughly clean the throttle body.

3. Thoroughly (but carefully) clean the MAF sensor in the air intake system.

4. Replace the PCV valve, and make sure that the PCV hose is not kinked or blocked with deposits.

5. Replace the oil, as it's likely contaminated with fuel and condensed water.

(Please provide a response on questions a through c.)
 

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Discussion Starter #7
My response is inline in blue:
Six hours of idling every day at high ambient temperature???

That would be considered very severe, if not brutal, operating conditions for an automotive engine.

I did know it's bad but didn't know that it's that bad. I thought of turning the engine off and then run the AC and my laptop from some external power generator but couldn't conclude anything convenient yet.

You mention that after running for a few minutes, AND increasing the engine speed slightly with the accelerator pedal, the roughness disappears.

Questions:

a) Will the roughness eventually disappear even if you don't touch the accelerator, or is that an essential part of achieving a smooth idle?

b) How frequently does the vehicle get driven at highway speed, and what's the duration of the high-speed running?

Rarely. Like maybe once every 3 months I cross a highway at a speed around 120 kilo meters per hour (+/- 20km/h). Usually I use non-highway roads at a speed between 40km/h and 100km/h.

c) How frequently do you change the engine oil?

Last time I did a full service was when the ODO meter was at 40,000, and now it's around 52,000. We use the metric system here. Usually this happens about once every year.


I'd suggest the following:

1. Check for any stored codes in the emission control monitoring system.

2. Replace the spark plugs, even if they were replaced in 2013. Carefully examine the old plugs, looking at the uniformity of color of the ceramic insulator, and the amount and type of any deposits on the insulator. Are the plugs all very similar as to color and quantity of deposits? Do they have a "fluffy" black or hard white deposit? Do any plugs look distinctly different from the others?

2. Thoroughly clean the throttle body.

3. Thoroughly (but carefully) clean the MAF sensor in the air intake system.

For the record I use a K&N air filter (if that means something special).

4. Replace the PCV valve, and make sure that the PCV hose is not kinked or blocked with deposits.

5. Replace the oil, as it's likely contaminated with fuel and condensed water.

(Please provide a response on questions a through c.)
 

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I think that's normal for older vehicles. I've had that problem myself - and I live in the south where winters really aren't that cold. I suggest cleaning and regapping the plugs, which should help..
 
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