05 Tundra 4.0 rough random idle

been having issue with my 05 Tundra 4.0 (1GR-FE and 6MT). Sometimes the truck will idle Normally and then a couple seconds later it spunds and feels like engine RPMs will decrease and it will gradually start vibrating more and more, then it will go back to nroaml after some seconds. Also on cold starts the engine will be at cold idle and then it sounds like the engine stumble or wants to stall for a split second but then "catches" itself and returns idle. It feels like not all cylinders are firing when it shakes bad because if I give it more throttle, it will not smooth it out but you can still feel the shakin

Also, if I leave the truck in neutral and let it roll down a hill, the engine RPMs will increase as the truck picks up speed in neutral, not sure if normal? (6MT)


This is what I have done to try to fix.

- clean MAF
- clean throttle body
- replace engine air filter
-replace spark plugs
- replace ignition coils

Not sure what else it could be. Coolant level and color look normal and engine oil looks healthy.

Would appreciate any tips. Thanks guys!

 

Any codes? Maybe air fuel ratio sensors.

 

Check engine light won't come on. Except one time when the engine started shaking, I reved the engine a little bit and the MIL flashed a few times but wouldn't stay lit and hasn't come back since.

I bought the truck used. It has 151k Miles and I remember the engine air filter was extremely dirty when I checked it, probably never been changed once in its life until I got it.

 

Did you pull the negative battery terminal to let the ecu reset? Leave it disconnected for 4 hours or so, then go drive it around some

 

It's been disconnected several times. Runs mostly fine on the freeway, except sometimes I feel like the rear end clunks because the engine may be losing power for a split second and then suddenly regains power and applies torque. Usually though when I slow down for a stop and idle for a little while, half the time then engine will start vibrating, sometimes a little bit and other times pretty harshly. I'm not getting any codes and the motor mounts look fine to me. Sometimes when I refuel, the gas rushes back up the filler neck and spills out several times during a fuel up too.

 

Vehicle speed sensor will keep the revs up while moving in neutral. It's normal.

 

What is the purpose of this sensor? For smoother shifts? I'm thinking of replacing the injectors. I remember the engine air filter was so dirty, the filth looked like heavy grease almost. Every time after disconnecting the battery and replacing the spark plugs and ignition coils. The truck would feel much more lively and energized for a little while.

 

Are all the vacuum lines connected?

 

Yes. No codes for misfires are being stored either.

 

I'm not 100% other than informing the ecu how fast your going. If your air filter was that dirty, many other maintenance items may not have been done. How does it drive once moving? How does it accelerate? While poking around did you check your PCV valve?

 

Drives fine once moving. No engine vibes. Accelerates somewhat sluggish except for when disconnecting the battery and replacing the spark plugs/coils but then goes back to feeling sluggish.. The PCV valve had some oil residue but I did the shake test and left it as is. I'm thinking possibly the fuel injectors since it idles rough at idle but not at high speed. If the engine starts shaking bad and I try to accelerate, the CEL light will flash but will not stay lit and no codes get stored. Also, to clarify. It only idles rough sometimes, maybe 50% chance that I come to a stop and the engine will start to shake as if not all the cylinders were firing.


Also fuel mileage seems bad lately.

 

Run a can of SeaFoam Gas Treatment through. Might clean up the dirty injector theory. Cheap and easy.

 

CEL came on finally. P0301

Started the truck to go home. I let it idle for 3 min. It idled fine for about 30 secs, then it started vibrating slightly, then sputtered a few times and then shaking pretty hard. Before I left the parking lot, twice the truck bogged really hard as if I had hit slammed the brakes and it threw me forward in my seat. All the dash lights dimmed and then came on and flashed the MILs and the engine continued running. Then finally the CEL started flashing and remained lit.

 

Cylinder #1 misfire.
What brand coils did you use? Swap your coils around, delete codes, see if the code follows the coil.

 

Bought brand new older model DENSOs but they are compatible (90919-02248) All coils are new, not even a week in service. Will try to swap coils.

 

Where did you get them? I remember reading something about knock off Chinese shit on flea bay and Amazon. Labeled as denso, but not denso. @Professional Hand Model probably has more info than me. He removes and cleans them biweekly.

 

Got mine on Big Gurrl.

 

Got mine on eBay for a discount about $25 each. They look genuine to me and high quality/heavy. Came in Lexus/Toyota packaging. I still have the originals and they do the same thing. In fact, this problem has gradually become worse. When I bought the truck with 150k it did not have any issues besides the timing cover leak (1gr-fe). Then it started barely vibrating, then sputters on cold starts, then the engine started turning over weak when hot, now it misfires/shakes hard when it idles.

 

If they were $25 a piece they're knock offs. I cant remember where I read it but they come it Toyota packaging but it takes a keen eye to spot them. The chicoms are getting very good at faking parts.

 

Found it. Credit to @Trailscape.

https://forum.ih8mud.com/threads/ne...so-90919-02230-coil-packs-from-fakes.1031683/

 

The knock off market is absolutely insane!!! Identical parts, sneaky mother effers!!!!

 

Swap coils and see if it follows.

 

Stealership price divided by 2 equals AS LOW AS IT WILL GO.

 

Will try but problem as of now persists with the old and new coils.

 

I'm betting you got fake coils. Not your fault as they can seem legitimate.

 

Yeah. But trucks was misfiring even with old originals.

 

You probably had a bad coil. Wht we want you to try is keep the new coils, but swap #1 and #2 coil and see if it pops up with a #2 misfire code. That'll let you know if one of your new ones is bad.

 

I had this issue in my Tacoma with the 4.0L Only threw a code 1 time.Would drop to 500rpm at idle and really shake the truck. Replaced the coil pack and issue has gone away.

 

Copy that. Will do when I get home

 

Ok. I'm swapped the coils and am Techstream right now. It still is showing misfires on cylinder 1. (9 misfire count as of now). The engine acts like it stalls, all the dash lights come on and then the
engine resumes in a split second.

Also, I should add, this engine has the timing cover leak (rather bad). I've been checking the oil level because it leaks kind of bad and the oil level still looks the same despite the engine leaking as of now.

6:00pm PST (17 misfires cylinder 1) just now

6:01pm PST (4 misfires cylinder 1 plus 1 on cylinder 3)

6:02pm (4 misfires cylinder 1 again)

6:04pm (6 misfires cylinder 1)