2020 Toyota Tundra Rough Start Sometimes...

Hey guys,
Was looking, could not find a specific thread about this, so if it was answered sorry. On my 2020 Tundra, sometimes after the truck sits over night I will start it and it starts rough. Almost like it is sucking up something. It will idle a little rough for about 3-5 seconds, then go the the usual high idle that the 5.7 is known for until it warms up a bit and calms down. I asked the dealer last time I had it serviced, he said they plugged it in and no codes or anything. Thought I may have gotten water in the fuel somehow. I have put premium in at good gas stations (like the dealer suggested) for the last 1000 miles. (always go to good gas stations anyway) It still does it, only after the truck sits overnight or all day. Also, one time when it did the rough start it died half way through the start and had to restart it, did the rough start and started after that.

Not sure if any of you guys have this problem but would love to hear what you think. Only reason I am a little concerned is this is happening in the summer. If I go into the winter season in NJ and go skiing, it gets cold. Afraid it might not start at all when it gets below freezing. If there is an issue. Thanks!

 

I would drop it off at the dealership on Friday afternoon and let it sit to Monday morning. This way they can see what you are talking about.

 

There have been some reports on here with issues with new trucks. Like something was missed at the factory.

Try to unhook your battery for over 15 min to reset the ecu and let it relearn. Maybe it’s confused or something.

Did you check your vin for the fuel pump recall? I assume they would’ve done that when you went in, but never know.

 

It was only about a month ago that I took it in. When I told him about the issue he checked for recalled, lol only recall he found for my truck was with the turn signals. I will double check with my vin for recalls on the fuel pump, haven't seen anything yet about it for my truck though. I will try the unhooking the battery to reset the system.

 

Thank you, going to try timsp8 first, if it does not work I will call the dealer and schedule something. Cause clearly it is not normal

 

Under warranty, it should be looked at by the stealership... If the one you're using isn't finding anything, then its time to take it to another stealership. Nothing worse than getting brushed aside until the warranty expires and then you have to fork out some dough to repair it.

 

Is your truck a flex fuel?

 

Sorry then, I am of no help. Symptoms lined up with mine a few years ago. Needed a reflash for the ethanol algorithm.

 

No my truck is not flex fuel. Thanks though!

 

Are we supposed to be putting premium in it? I thought it was actually worse to put a higher grade fuel if the truck didn't have the fuel/air ratio for premium

 

No manual says to put regular, dealer told me to put premium in it because they thought I got water in the fuel somehow and that was what is causing the rough start. But ive done it for 1000 miles and it is still doing the rough start etc. Putting premium in will never hurt, it just does not do anything for the truck. Other than premium is less likely to have water in it, and it has more cleaning aids and stuff.

The truck will adjust to the correct fuel/air ratio within seconds, never hurts it.

 

Manual does say research higher octane, I'm sure lexus requires premium on the LX570, at least mine stated it in the 5.7l. Any chance you live in higher altitude?? I had to get my ECU reflashed for altitude as I purchased my truck in LA and moved to Reno, NV and at times it had issues with rough idle due to altitude, or so they said.

 

When my 2019 sits for a few days, sometimes a week (not my daily driver), It takes a couple extra seconds to crank over and runs rough for a sec. Kind of concerning. I'm due for the fuel pump recall, maybe that will fix it.

 

And no ethanol in the premium around where I live.

 

I'd figure out a way to put a fuel pressure guage on the fuel rail and see how quickly it bleeds down.

Sounds to me like possibly a leaky injector dropping fuel into a cylinder overnight.

That said... the only fuel I've put in my truck since day 1 has been 93 octane.

 

Not sure if it’s of any help but the batteries in these trucks have been known to fail prematurely. Get a multimeter and give it a check.

https://youtu.be/COJr7OB23Hw

 

This has happened to my '20 twice. It was odd, but has happened 2x's in the span of a few months.
Is yours pretty consistent w this rough start?

 

My 2017 does this. If it sits overnight or over 8 hours, it'll start up pretty weak. Its also not a flex fuel. Just for precautionary measures since they weren't super expensive or hard to do, I've done spark plugs and fuel pressure regulator. Today, I replaced the battery, not because it was bad, but because I used the old battery for a bed mounted winch and figured I'd take the opportunity to replace the 4 year old battery to be safe. I've been running thr truck on premium fuel the past several months and it hasn't helped, may have actually gotten worst. So, today I filled up with regular and will check to see how things go when I leave work in the morning. Side note, the battery replacement likely reset the short term fuel trims, so if it was fuel related, it may come back after a few cycles. So, be interesting to see how this goes.

 

Your symptoms sound like a leaking fuel injector, that drips a bit into the combustion chamber overnight. The result is one cylinder has a richer mixture than the others resulting the rough idle. How to verify this is another issue. You could try pulling spark plugs after the vehicle sits for awhile and see if one of them is wet with fuel. Dealers have a bad habit of only checking for codes, so the answer often is "no code, no problem" which is complete BS. All that said I may be wrong as I am new to Tundras and Toyotas in general. As others have said try resetting the computer.

 

I have a 2020 and it doesn't cold start like it used to. Now it starts up "slowly" as opposed to the loud and "instant" jump to cold start rpm's. The tach slowly climbs to cold start rpm's.

 

I have similar issues on my 2020, but shows p0300 and p0301, p0302 and couple more. Then 2 or 3 restarts gers it working again.

 

Try two bottles of this, it has worked wonders for used cars with bad fuel.

 

My 3 month old, 2300 mile 2021 did this last night. Instead of roaring to life was like a giant burp and then everything was normal. It had sat for 24 hours following a simple turn the truck around in the driveway. I wondered if the shut down the night before allowed a little extra fuel in the system for the startup. 2 hours later after soccer it started fine and I just checked after sitting 16 hours and it started fine. Not sure if that helps or if this is an area of concern for me yet.

 

There seems to be something faulty coming out of the factory. Please post back with what I assume your warranty work will cover please.

 

Sure seems to be alot of rough start issues with 2020 and 2021s...

I have a 2019 and have never had start issues and it sits plenty long between runs.

 

You wanna swap?

 

Ok some more testing, and the CEL comes on even without hard acceleration as this morning, now just trundling along in the neighbourhood, but only registers the P0019, not the p0302 which I assume is a consequence under hard acceleration with the p0019. Again reset the codes, and switch off the car, and all ok.

Now that it is p0019, which states the following "P0019 Deviation in crankshaft position sensor signal and VVT sensor (for Exhaust Side of Bank 2) signal",

I can deduce that if only this bank, and the Exhaust side, then it can not be the crankshaft sensor, as it should cause issues with both banks, and possibly on both intake and exhaust.

So I have taken the exhaust side camshaft sensor out, and register 1.136K ohms, which seems to be in spec, although I dont have a workshop manual, if anyone can confirm. It's night here now, tomorrow morning, Ill take a look at the VVT exhaust solenoid valve and give it a clean with carb cleaner. Anyone know where the VVT oil valve filter is.

And I think I am the cause of this, as the Tundra calls to 0w-20 oil, which I did not follow, and have put 2 oil changes of 5w-40, which could be causing this, I did this because i I live in the Dubai, and we get 2 months of 125F for most of the day time, and our lowest temp during this period is 95F, that is at 3am in the night. I was thinking Toyota have changed to a lower weight to meet emissions criteria, which in turn is not great for our engines, as the dealers here have all of sudden changed even the FJ engine, which for the longest time they were using 5w-40, but maybe Toyota japan is asking to use a lower weight oil, which is probably lower emissions by 1% per annum per vehicle, but when you have millions on the road, that will make a difference.

Your thoughts on my analysis, and use of 5W-40, should i change to 0w-20, as maybe the VVT solenoids need this.

 

Rough starts may be related to oil viscosity. Try 5w20 given the ambient temps where you are at.

 

VVT systems are generally oil driven and viscosity matters. I do believe these engines were originally intended to run 5w30 but now run 0w20. If it were me I would switch back to 0w20 and see if the problem resolves.

 

So did some trouble shooting. I swapped the VVT exhaust solenoids, and still got a p0019 code, then I swapped the VVT sensors on the exhaust, there are 4 in total 2 for intake, and 2 for exhaust. Then took it for a test drive, and no more p0019s recorded, but still get the p0302 code, which is misfire on cylinder 2, and ofcourse the radar and trailer brake malfunctions as part of the safety procedure. Reset the codes via scangauge, and then swith the car on and off, leaving a gap of 30secs, sometimes takes 2 engine on/offs to get the radar to work again.

Now consistently I am not getting a P0019, which maybe due to a loose plug on the VVT exhaust sensor bank 2, swapping them, i also cleaned with contacts cleaner.

Now to address the p0302, i have swapped the coils with cylinders, but just noted that i swapped the wrong clinders, I will swap the right ones and see where i get.

Quite easy to do, just 10mm socket thus far, and very easy to get too, also have a relatively new car, all the plugs come off easy, and there is no crude to fight.