Rough idle please help

2002 Tacoma 218k. Truck is only idling rough when stopped, drives fine. I have cleaned the mass air flow sensor, cleaned the throttle body, replaced spark plugs, replaced fuel filter, replaced air filter and added a bottle of Seafoam to fuel tank, it’s still idling rough. What next? Please help.

 

Not a lot of info to work with. No other symptoms?? Check engine light, low power, stumbles under load or heave acceleration, poor mileage?? Did you pull the throttle body to clean it, or just spray cleaned down her throat??

 

My 2.7 idles a little on the rough side. That's what they do once they accumulate many miles. Unless it's stalling I wouldn't worry about it. It's what 2.7's do once they get up close to 200,000 miles in my experience. Mine has been idling rough for 70,000 miles. Ignore it unless you want to buy a new throttle body as well as a new EGR valve, IAC valve and every other emissions gadget attached to the intake system. If it isn't stalling and runs great other than the idle ignore it. That's what I do and I just blip the throttle a little bit at idle to get it to idle a little bit better.

If you're REALLY pissed? Call the EPA.

 

Seafoam directly into the intake. Shut her down, wait 15min, then let her smoke! There are YouTube videos on this.

 

What are your short term and long term fuel trims?

 

OP are you saying that the idle is rough (as in a misfire) or the engine vibrates at idle? Can you post a video of the symptoms? My 2.7 automatic has 156,000 miles and it vibrates at idle, around 600-650 RPM when warm (in gear). It is noticeable but not severe, which others have said is normal for this engine and I'd have to say I agree. The vibration can be annoying sometimes, but there is no check engine light and it starts and runs great.

 

It could be a bad oxygen sensor, I had to replace one on a 1996 Taco or was it two? Anyway it fix the rough idle.

 

My 2016 2.7 auto has been vibrating in drive with foot on the brake at idle since new. You can even observe the tailpipe vibrate /shake. It’s almost like when the ac compressor is turning on / off like that.


There’s a normal idle vibration with 2.7s paired with auto transmissions. Unless you have a manual, and the way you describe it, maybe it’s something definitely wrong.

 

This just started happening to me, 9200 miles now. Either its been there the whole time and \I have never noticed or it just started and I noticed because I put a windshield mount phone holder recently and I can see it shaking when stopped in drive. I haven't decided if I should bring it to the dealer, they never want to do anything to help anyway.

 

Mine does it at idle too, but it's better now after I replace the spark plug coils. One of them was cracked pretty bad. Im suspicious that it may be a stretched timing chain on mine, or perhaps the air intake sensor. I haven't had time to poke at it.

 

That's pretty much been my experience with 4 cyl. tacos once they get over 125k or so. It never really seemed that rough until I bought a new one and had something to compare it to.

 

I've used SeaFoam a few times and it did nothing for my idle. I suspect it is caused by buildup in the IAC, EGR system and the throttle body. SeaFoam does nothing for the EGR or IAC.

 

I have a manual 2.7 vintage 2004 and it has a slightly uneven idle. I gave up worrying about it. Straight fours don't idle smooth which is why the 2.7 has two balance shafts in it. Once they get a lot of miles on them it could be anything that is causing it. The IAC, the EGR system, temp sensors, the MAF? Who knows? The coils, injectors, spark plug wires? EGR temp sensor? Coolant sensors?

If it runs fine I'm not going to worry about a slightly rough idle. I am going to take the throttle body off mine this summer and clean it as well as replace the IAC and EGR valve and maybe some other parts since mine is coming up on 200,000 miles. I might do spark plug wires and coils as well. Not that the truck runs bad but it could be that there are a few of these parts that just aren't working as well as they should. My 2.7 seems to be down on power (not that it really ever had any) from what it was 3 years ago.

Who knows what could be causing it?

 

My 2.7 at 75k miles started having a slightly rough idle. During some maintenance over the holidays, I cleaned the MAF and took off the throttle body and cleaned it up. Idle is a lot smoother now.

 

I'd bet a good TB cleaning is what mine needs.

 

I thought I had a rough idle and it was the air intake where it banks up to the fender. The foam wore out and created a nasty vibration in the cab. Only happened at <1500 rpm or about. Strongly recommend you take a look.

 

Thanks, I will do that. My truck is old enough that some type of "sealer" could very well be worn out. Thanks again!

 

It was easy to do on my 2.7. I also checked the air intake tubes for cracks.

 

Motor mounts... I have a 97 3rz Automatic 4x4 ( I am the original owner) and replace mine about every 60,000. Even though they look okay and the rubber has not severed from the metal mount, they go bad quickly on the 4 cylinders. I have 277,000 on my 97 and when it starts to shake badly at idle & in gear and the odometer has clocked another 60,000, I know it's time to replace and has become a scheduled maintenance item. This issue drove me crazy early on and I threw on all kinds of parts, went to several shops, the dealer said I had stuck rings in #2&3 cylinders... they were clueless. Finally replaced the motor mounts and smooth sailing... so it has become a scheduled maintenance item.

 

Interesting. I will have to look into that.