Helllpppppp

I have a 01 tundra 4.7 sr5 2wd it’s a great truck and motor but I have a problem that no one can seem to figure out why it runs normal when I first start it in the morning as soon as the temp gauge moves the tiniest bit to warm up it immediately starts running almost like it only on 4 cylinders I changed the mass air flow sensor and temp sensor still no difference someone please help

 

Check engine light on?? Can you check codes??

 

Yea it scanned and said that the crank position sensor and cam sensor but I replaced both since I did the mass air flow I just noticed that it’s running slightly better but still a lack of power and once it hits close to 3 on the rpm gauge it breaks up real bad and like falls on its face

 

I got the truck about 4 months ago it ran normal for about 2 weeks and ever since I’ve been chasing the issue

 

All codes are clear now?

Sounds like a possible fuel issue.

 

I replaced fuel pump and fuel filter being that was my first thought Lol

 

Almost sounds like the timing belt slipped if your getting cam to crank correlation codes then the timing is off

 

I thought so but my thing is it runs perfectly normal until it heats up the slightest then it starts running bad

 

Coil pack? Recently new spark plugs?

 

If you would do us all a favor and answer whether or not the truck is currently throwing any codes that'd be the most helpful thing to get out of the way.

What are you using to check the codes?
Do you have access to a scan gauge or OBD reader that can also measure temp AND more importantly tell you when you truck goes from open loop to closed loop?

You said you changed the MAF and "temp sensor". Did you install a used MAF from another Tundra? Did you buy a AutoZone sensor? What temp sensor did you replace and why? With what part? Usually on a "dummy" OEM temp gauge when the needle starts to move the truck has already warmed up quite a bit.

You're generally going to be in one of the following states:
A0 open loop due to insufficient engine temp
A1 Closed loop using O2 sensor feedback to determine fuel mixture
A2 open loop due to engine load or fuel cut due to deceleration
A3 open loop due to system failure
A4 closed loop using using at least one o2 sensor but there is a fault in the feedback system.

If when you're warmed up a bit and the truck goes into closed loop, you have any issue with part of the feedback system - be that a shitty off brand MAF, fault CTS...etc - your truck will start to run like dooky and you'll generally trigger a code shortly thereafter.

 

Did you replace the crank sensor and cam sensor with OEM ones? i had a tacoma come in a few years ago with an aftermarket crank sensor that it ran great, till it hit 3k RPM and it just basically hit a rev limiter.

at 3k RPM the sensor would start reading 2200 rpm on the data log. so basically it had no clue where the engine was. New OE crank sensor and she ran like a top.

there was no codes.

 

I would suspect a bad head gasket.

 

Yes it’s throwing codes I haven’t scanned it since I did the sensors but it’s still on and the temp and maf sensors were just autozone sensors nothing oem atleast I don’t think but it does that as well once it hits 3000 on rpm it breaks up real bad and doesent produce any power

 

What’s the open and closed loop part I’m enclosed but not that much

 

Close loop is when the vehicle is below operating temp it uses preset perimeters to run the vehicle, once it's at engine operating temp it now will feed off the sensors. So if a sensor is bad it will now run bad, or like an O2 just run rich but still drives. Whatever code you had is most likely the sensor that is bad. there's always that 1% WTF something else triggered it. I have so far had no problems with aftermarket sensors, try not to blame. Not saying a New Puppy can't Die either. If your timing belt slips you will have a multiple misfire code. It will either be misfire on 2,4,6,8 or misfire on 1,3,5,7. It wont cause a Cam or Crank code. If you have both those symptoms, then yea, you have a slipped belt AND a bad cam or crank sensor. But always look for that 1% WTF that could be causing it. Stay to the basics until that arises.

 

How old is the timing belt? Really sounds like a timing issue. Codes were crank and Cam sensor. Not sure why the MAF and Temp sensor were replaced? or if the crank and cam sensor were replaced? I would think there was a crank and cam problem. Not a bad sensor. Idle and run are two different phases of engine operation and require different timing adjustments. Idling normal is not an indicator that the timing is correct. I would start with a true timing belt and timing inspection. Interference motor, if its a timing belt issue, could cause major damage if the belt fails and the valve train and pistons come in contact with each other. Best of luck and keep us updated if you find the solution.

 

pay close attention to inside of crank and cam sensor connectors for corrosion seen it many times

 

Are any of you guys located in nj that you could see in person idk much about the page or anyone on here I was just looking for help but the thing that makes me think it’s not timing is it runs perfectly normal I can drive about 5 blocks close to before the tempature gauge moves but the minute it moves it runs like it’s on 4 cylinders you can even hear the difference in it when it warms up and the idle it sounds like it’s barley running but like I said when it’s cold it runs perfectly fine just the minute that temp gauge moves the slightest it runs like shit

 

When I bought it motor and trans were replaced it had 150000 on both but timing belt was replaced I pulled the covers off to check the belt and it seemed okay

 

all the timing marks line up?

 

your description of it does make it sound sensor related. I would check the connections at the sensors and also second the motion to put Toyota OEM sensors on there. Also, not that anyone wants to hear it, but it sounds like you've purchased someone else's problem. Motor replacement at 150k? what caused that failure? how many miles on the new motor?

 

That’s exactly what it is it was someone else’s problem it ran good and is clean I paid 3300 for it and it’s been nothing but a headache but yes timing marks all line up I just can’t figure out what else it could be but the Toyota oem sensor where do I get that and is that what it’s called cause the dealership is crazy expensive obviously so I try to do it thru auto zone and stuff

 

That’s how many were on it when I got it he showed me the paper of the replacement and the papers of the new frame that was done by Toyota he claims the guy before him was original owner he only drove it back and forth from Florida to nj then this guy bought it and he claimed after the frame got done it sat for 3 months because he had a diff car that was better on gas bla bla bla but it all makes sense unfortunately

 

I didn’t know if this was just a Toyota problem that was common on this model so I figured I’d see if anyone knew about it

 

Have you done a compression check and a cylinder leak down test both easy to do and you can rent the tools at Autozone or Orileys well in my city I’m sure Yours has to be similar

 

No is that just one tool I can ask for and how does it work

 

A compression test reveals the condition of your engine's valves, its valve seats, and piston rings and whether these parts are wearing evenly. Healthy engines should have compression over 100 psi per cylinder, with no more than 10 percent variation between the highest and lowest readings.

Leak-down testing is a static test. Leak-down tests cylinder leakage paths. Leak-down primarily tests pistons and rings, seated valve sealing, and the head gasket. Leak-down will not show valve timing and movement problems, or piston movement related sealing problems.

 

Okay I’ll give it a try

 

Here's a thought that's kind of out there, but what is the level and condition of the coolant? A low coolant level could allow the engine to start to seize as it warms up, creating the general scenario of running well cold, but getting rough as it warms up.

 

I’ve checked it and double checked it to be sure cause that was one of my first thoughts but it’s good its at the fill line