Low Idle and Vibration

Hi, I tried searching but never found anything that really answered my question.

I have 2009 4.0L with 55K miles on it. When in "D" and at a full stop the truck idles around 550 RPM which causes vibration to be felt through the steering wheel. When in neutral, park or in motion the RPM's increase and no vibration.

Any suggestions? I know it wasn't always like this. Thanks for the help.

 

One possibility - there are others:

https://www.youtube.com/watch?v=-P22feMUdJ8

 

Thanks, I watched the video and a few others on engine mounts and I don't think its the culprit but I'll check them out.

 

Clean the MAF Sensor and the Throttle Body.

 

Hello, I'm having a similar issue on my 2008 2.7L 4cyl Tacoma and it has since developed into a misfire P0302. Took it in for oil change at first CEL (Toyota dealer actually a sweet deal here, particularly with their shuttle service-and they dealt with recall issue); they switched the coil packs from 1 to 2 and 2 to 1. Said spark plugs OK but a little dirty. If CEL comes back recommended replace spark plugs and coils. CEL came back still P0302. I replaced spark plugs myself (all 4). I'm about to go out and double check my install for connections and even gap, but CEL has since returned still P0302. I have not cleaned MAF sensor or TB yet. I've never done either of those before. I'm wondering if I should use Seafoam or a fuel additive. Oh and it's 68k miles mostly city driving with some longer trips in summer, a lot of cold COLD starts in winter. What other info can I provide for assistance in diagnosing this vibration and now P0302? I understand 3 elements to running cylinders: spark, fuel, and air, but I do not have much DIY experience except a bit of troubleshooting on an old VW Bug.

Any guidance appreciated, and/or developments in OP's idle issue?

 

Cleaning the MAF is super easy, just unscrew it and pop if off, delicately...they are fragile. Be sure not to touch the sensor itself.

ONLY use MAF cleaner specifically to clean the sensor, a lot of places (including autozone) will tell you their electronic parts cleaner will work but don't do it. MAF cleaner is like 6 bucks. Spray the sensor several times, let it dry then plug it back in. Super easy, took me less than 10 minutes.

As for the throttle body, seafoam works great, I've used it before.

Not sure if a dirty MAF or TB is what's causing your code, usually a bad MAF sensor pops up as a P0171 code (at least it did for me), but its such an easy DIY repair that you should just give it a shot to at least eliminate the possibility.

 

All of my encounters with P030x - x=cyl # - have been due to a defective coil in the X cyl. Doc on this issue says it could also be O2 sensors, but those usually have their own code(s).

If you replace the coil, buy OEM. The aftermarket stuff is flaky.

My 2 cents.

 

I agree with Lester ^^^^^^^^^

 

I reset the codes this morning at auto store and just now I finished double checking my gaps and install on NGK iridium plugs. They gapped between 0.040 and 0.044. (NGK website says you don't have to adjust iridium plugs, so I didn't.) I double checked all connectors to plugs. I made sure all hoses secured again. I'm headed to auto store for MAF cleaner to see if that will help. I'm hoping the CEL will not return. I'm afraid of an expensive round of trouble shooting at a shop and up here in AK the coils are $63/each! I didn't want to start throwing parts at it until I tried the simple stuff first. Still open to thoughts and suggestions as I continue, and if I figure it out, I will update here. Thanks again.

Also,since you mention OEM, I took Denso plugs out, should I have bought Denso and not NGK?

 

MAF codes are usually one or more of the following:

P0171/P0172/P0174/P0175

Clean the MAF anyway.

New NGK plugs will not be the reason the P017x sticks around.

$63 for coils - are those dealer coils? If they are, that's a heck of a price. I have a feeling though you've quoted an aftermarket coil price.

 

You're right, 'cause I just doubled checked at auto store and Densos are $109 plus shipping since they have to order them. (quote one auto store) Anywho, threw a code on the way to auto store but bought MAF anyway. Doing that now. Store said I should disconnect battery after I do it or it will run rough...? That's not on the instructions.

 

Did you buy a MAF or MAF cleaner? Either way, pulling battery cable is not needed unless you are trying to clear the code. On many OBD-II vehicles, pulling the battery cable and letting it sit may not clear the code; on some it might.

One way or the other, the codes set will have to be reset and again, if they come back, it's likely not the MAF.

Have whoever reads the codes(if they occur again) and record the value(s). P030x codes are going to point to a bad coil. x = the bad cyl #

 

Sorry, typo-bought the spray not the part. Except for the 1st time the CEL came on I'm the one reading and resetting the codes. The codes have been P0302 except 1 time when it was P0300 along with P0302. Today was P0302 every time and I reset it at the parts store before coming home with the MAF cleaner. They sold me a bottle without a straw so I had to go back. Just finished the MAF cleaning and giving a full 10 minutes before I start her up to be sure was dry. (I disconnected the battery before starting in case it was a fire issue, though I doubted it.) The first start after MAF cleaning and the idle dropped to about 500rpm, definitely feel a shake, but she isn't dying. I probably need to drive a few cycles to see what happens. I have to p/u my daughter from daycare soon, and then I will wait to see if another code comes back.

Would it still be the same cylinder P0302 if Toyota service dept had already swapped the coil as they said they did and only after a returned CEL I changed the spark plugs (but no coils and did not swap them back)? Maybe Toyota already swapped them back after their test runs? I have not tried switching all the coils 1 at a time, yet.

I don't run the best gasoline and was a little delinquent on an oil change, but I don't drive the hell out of her. So a bad coil makes sense, but Toyota says they switched it, and I'm still getting P0302.

I'll update soon as I can.

 

Mine has the same issue. It started about a year ago. Let me know if the cleaning works

 

P0302 indicates a misfire on cylinder # 2.
P0300 indicates random misfires.

If it continues getting P0302 Codes I would swap coil packs myself between cylinder # 2 and another cylinder as I don't trust anyone's say so when it comes to troubleshooting....

 

You're right. I nearly went down a worst-case-scenario fret until I remembered I need to start simple. I almost did that coil swap myself while I was in there the last time. Ultimately, I decided not to confuse variables and wait 'til after I verified my spark plug install. Tonight after the MAF cleaning and a couple of short trips including some highway merges I haven't had a returned CEL. That doesn't mean anything to me yet, though. It's my everyday vehicle, so I should know in about a week if the CEL doesn't come back that the MAF was actually helpful. I expect a return of CEL=P0302. When that happens I will begin swapping 1 coil at a time to see if it changes the P030X.

I think I will still clean the TB soon, too because it appeared to have some black buildup on the butterfly plate. Should I run the Seafoam if I do the TB cleaning? Is it better to do TB cleaning before the Seafoam or vice versa? One parts store guy said if I do the exhaust clean I should also clean the catalytic converter. Is that because of debris knocked loose in the cleaning puts strain on the catalytic converter? I don't even know yet where my catalytic converter is. I don't own a service manual.

You're also right, that the codes I'm getting are specific to misfire P030X and not any of the MAF specific codes above.

I need sleep now. Thanks again for your input.

 

I know a lot of people dump Seafoam through a vacuum line straight into the intake. I for one do not recommend that method as there is a chance of cylinder damage if done improperly.

If you want to use Seafoam put it in the gasoline tank where it belongs.

 

Oh Lord, now what have I done? So the CEL came back on today and when I went to parts store expecting to see P0302 again, instead see P2441 and P2445! Did I knock something loose? Or is this a pump going bad that contributed to the misfire? I think I'll probably take it to Toyota. I'm not so good with air leak issues.

 

That sounds like the Air Injection Pump Valves are sticking open.

https://www.tacomaworld.com/search/1951487/?q=AIP+Bypass&t=post&o=date

 

My engine hasn't gone into limp mode at all. (Yet?) Once warmed up it actually almost seems to purr now. Except for the shimmy I still see in the gear shift and vibration in the steering wheel at idle, I don't smell, hear, or feel anything wrong...especially once warmed up. But then I see the CEL still illuminated. For the most part, I haven't felt any loss of power, except when driving before fully warmed up. It was like that before I ever saw a CEL, but the shimmy was new as of about 7-10 months ago. CEL first appeared 1 week before taking to Toyota for oil change--along with recall inspection 1.5 months ago, they read and cleared the codes etc...

The only difference I notice from before the new spark plugs and after the MAF cleaning is that overall my rpm is lower. Like, now I find I can get all the way to 35mph before rpm sounds like I should gear up from 2nd to 3rd. I used to switch from 2nd to 3rd at about 23mph, because it sounded like I would be pushing the rpm too high if I didn't gear up. 4th gear now gets me comfortably up to 65 mph and the rpm never reaches all the way up to 3000. It just seems somehow more responsive, but almost imperceptibly so. (It's a lot more pleasant drive in traffic when you don't have to shift as much.)

On cold start this morning, before the new instance of a CEL, the idle was back to 750-800rpm. Nothing funny except the small vibration/shimmy. The CEL came on right before I got to work. At lunch there WAS something a little funny at first start: the engine seemed to race for a moment after initial idling period of about 2 minutes. The rpm did not shoot up the way I would have expected with that kind of engine revving sound, but it was over almost before it started...then during lunch driving the idle never dropped down below 900 and hovered closer to 1000rpm, definitely higher at idle than I've seen in a while.

I suspect I still have a bad coil or 2 possibly, maybe an injector needs cleaning? I'm pretty hesitant at this point to swap things around and be in and out of the engine compartment in light of the new codes. Sadly, I really probably will take it to Toyota to see what they say now. I don't know how soon, but I will try to stay tuned here, too. If Toyota won't repair it under warranty or they want my daughter's retirement to pay for it, is it really the better option to bypass the system? Makes me a little nervous on top of being a little uncertain about trying DIY auto repair stuff anyway.

Thank you thank you and thank you all. Mostly at this point I am just glad to have a place to document my troubleshooting both for myself and any other who might come along behind me with similar issues. I still really appreciate any who contribute to these sites and try to address my questions/concerns, or allow me to hijack their thread... I take more than I give. I DO wish I had a repair manual for my truck, and a better understanding of the parts in a vehicle that has neither a distributor nor a carburetor.