rough idle since service
 

I have a 2017 4runner limited. Has 32000 kilometres (19900 miles). Took it in for its's 3rd oil change and was told upon dropping it off it is up for it's 3rd scheduled maintenance which will include the following:

- Check installation of driver's floor mat.
- Reset Maintenance Reminder Light or system.
- Inspect all lights and horn for proper operation.
- Inspect wiper blades, linkage and washers for proper operation. 1
- Visually inspect drive belts adjust tension if required.
- Replace engine oil & filter (synthetic).
- Lubricate locks, latches and hinges.
- Inspect and adjust level - engine oil, brake fluid, engine coolant, power steering fluid, transmission fluid, differential fluid, and washer fluid.
- Remove & inspect engine air filter. 2
- Remove wheels & visually inspect brake pads, calipers, rotors, brake lines and hoses.
- Remove brake calipers and/or brake drums. Inspect and measure brake rotors, drums, pads and shoes.
- Check and record tire tread depth. Examine tires for damage and uneven wear.
- Rotate tires (applicable to same size wheels, front & rear) or alternatively perform seasonal tire change-over. 3
- Perform 12 Volt battery service and comprehensive electrical charging system evaluation.
- Inspect valve clearance (audibly).
- Check steering gear, linkage and shock absorbers for looseness, damage or leakage.
- Inspect ball joints and dust covers, driveshafts, chassis nuts & bolts for looseness or damage.
- Inspect fuel system for leaks or damage, inspect condition of fuel tank band, fuel tank cap gasket, fuel tank vapour vent system hoses, fuel lines and connections.
- Inspect engine oil cooler lines and automatic transmission cooler lines if equipped for leakage, looseness or damage.
- Inspect exhaust system for leaks, damage or broken hangers.
- Record inspection results, measurements and component condition on inspection form and/or repair order.
- Remove & inspect cabin air filter.

Upon picking it up and starting, the idle is off. Feels like a mild shake throughout the vehicle. Problem is, it is not consistent. Rougher at start than other times. Do not notice it while driving, but at every light, there is a 50/50 it is noticeable. In neutral, I rev the engine a bit and once it revs down, sometimes the rough idle is there and sometimes it is not.

I few days later, this is really bothering me so I start looking at the service paper from the dealer with the full list of everything that was checked on the vehicle and cannot make heads or tails of what may be causing this. I pop the hood, and see both battery terminals have some blue stuff covering them, but do not think anything of it.

Again, a few days later (today), I pop the hood and for some reason, no idea what lead me to it, but I reach over to the positive battery terminal and give them a wiggle, solid. I grab the negative battery terminal and it is very loose, taking 12 or so turns on the ratchet to tighten it properly.

I fire up the vehicle and it seems the rough idle is gone. Take it for a short drive and it seems to run like it did prior to the service. Is this a normal symptom for a loose negative battery terminal, to cause the rough idle?

I will be able to drive the vehicle more tomorrow, and will see if it is really gone.

Thoughts?

Yes a bad ground can often have negative affects on both fuel and spark, so the rough idle can be a possibility.

Yes, I'd be 98% sure you just found your problem and fixed it.

Anytime i see "inspect" in paperwork it means done nothing to me. Next time tell them to change oil and filter and leave everything else heck alone! Do not let them disconnect stuff if they can't connect it properly.

Precisely why I told those idiots at the dealership not to do anything except change oil.
They always look flabbergasted that I don’t want them touching my aftermarket wheels for a rotation or that I don’t want a fuel injector service


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Sounds like shop was banking on you returning... Charge you a diagnostic fee and re-tighten battery cables. Find another dealer.

Issue resolved.

So after I tightened the negative battery cable to the battery post, the vibration seemed to be less, gone at times but present at others. I took the runner back to Toyota, had the service manager come for a ride and again, at times preset and other times not. Like the vehicle was struggling, and then all of a sudden fine. I felt like he was down playing the vibration, trying to tell me it was because it is cold outside (-7 Celcius or 16 Fahrenheit). Not really all that cold at all, especially as the engine temperature was 1/4 between cold and hot, so the engine was warmed up. Then the tech tells me he really doesn't feel anything most of the time. I discuss the issue with him further on the way back to the dealer and he decides to have it booked back in.

The vehicle goes back in a week later, they scan the vehicle, run diagnostics and I get a call. They think it is one of the injectors. Now an injector, coil and something else is on order.

Vehicle went back in today, the injector, coil and whatever else was changed in cylinder #1.

Poor ground... Negative effect. I see what you did there.

UPDATE: 11-Jul-2020
 

Ok, so I had written the issue was resolved. Turns out that later that same day it was back.

So I'll jump back with on December 18, 2019 my 2017 limited went in for it's 32000km servicing (oil change). Afterwards a shake in the vehicle could be Flt when the vehicle was not in motion, but either in Drive (foot on brake), Neutral (foot on brake - or sitting on level ground no foot on brake), and Park (no foot on brake). The shimmy/vibration would pop up intermittently and go for 5 seconds to several minutes and stop.

Had the runner back in on 2-Jul-2020 for it's 40000 km servicing (oil change). I had spoken to Toyota prior to the drop off and explained this issue has not gone away and needs be fixed, and I will need a vehicle from them until it is resolved.

I drop it off at 7:30 am. I get a call at 4 pm, the service guy says he will talk to me when I get there.

They had a new tech guy looking it over, cleaned the throttle body, redid something to the ECM, and nothing. For some reason this new guy decided to check my oil level on the dipstick... WAY high!

He does the oil change, put in the PROPER amount of oil. Starts it up... shimmy/vibration totally GONE.

ISSUE RESOLVED!

Glad you got it resolved. Not that I let anyone change oil in any of the 4 cars we have, but if I did, I'd check the level either in the lot before I leave or first thing when I get home. I'll also retorque my wheels if anyone has touched them.

How many miles did you put on the car with the overfilled oil?

Make sure you keep the documentation because the excess oil could cause issues down the road.

Why let them change the oil?

There are plenty of little steps they won't do.

New washer for the drain nut? Valvoline doesn't change em.

Things like that.

I'm surprised a loose battery cable didn't result in more symptoms or throw a CEL and some codes. Glad you got it resolved.

A good automotive tech is like a good doctor all of them are certified but if you find one you are comfortable with' stick with him. Find out who the new guy is and may be write a few words to the dealership owner or manager 'online letting them know. I request two mechanics at my dealership and it has caused some issues between me and the dealership in the past but they do honor my request begrudingly.

It's not unheard of for lube techs to forget to drain the oil in the first place.
I would not be surprised if your engine had double the amt. of required oil after it left the shop when the oil was changed.

As mentioned above, all of that "check check check" stuff never happens.

Your lucky if they actually change the oil filter and refill with the correct amt. of oil + tire rotation. Many shops only have ONE wt. of oil in the service area. Whatever that wt. is - you get. Don't be surprised after a dealer visit to find the pressure in your tires to be all over the place and lug nut torque whacky as well.

While it may seem like a small thing, you may be charged for the oil pan gasket - part # 90430-12031 and never actually get it. Old gasket reused.

I know people live in places that don't allow owner servicing, but if you don't, change your own oil.