Slow crank and low oil pressure

I have a 2004 Tundra 4.7 and just changed my oil this past Friday and everything was fine until Saturday afternoon. That’s when I had the slow cranks and unusually low oil pressure all of a sudden. I know the gauge usually reads low on our trucks, but this is lower than normal. I’ve had my battery load tested and the battery is good. I’m almost positive it’s not the starter. Monday the engine started running hotter than normal so I pulled over and let it cool down and it hasn’t run hot since. When the engine is cold and I start it, it makes a whirring noise right when it starts and when it’s hot and I start it, it knocks when I first start it. It hasn’t stalled on me yet and I’ve had no other issues with it but any help would be appreciated. I can’t seem to find anything else online with this exact problem.

 

Did you check the oil level on the dipstick after you completed the oil change?

 

All questions:

1) You have proper oil level and spec 5w-30?

2) Proper size oil filter (not cheapy)?

3) You possibly hack any sensors/hoses/wires when removing oil filter?

4) Check coolant levels for grins?

 

Yes I put 7 full quarts of Mobil1 high mileage full synthetic 5w-30 and I used a Napa filter. Oil level is perfect at the top notch on the dip stick. The coolant level is fine from what it shows in the overflow reservoir.

 

Its coincidental that this happened right after an oil change. Sounds like the basics are eliminated other than our trucks 4.7L are spec’d at 6.5 quarts and NOT 7 quarts as you stated. The extra .5 quart shouldn’t matter?

 

No check engine lights I'm guessing..?

 

I have had a CEL due to a bad O2 sensor but I’m going to take it to autozone soon to get them to check it. I added another .5 quarts because it wasn’t at the full mark yet. I was assuming my oil pump going out but I still have pressure, just not as much as normal. When I hit about 3,500 rpm it only goes to the quarter mark. It sits right at the low mark on idle.

 

The o2 sensor could be making your truck run lean, thus running it hotter than normal.

 

True but it’s also been like that since December and hasn’t cause an issue yet. I guess I should stop being cheap and just get a new O2 sensor but this issue seems pretty serious and I don’t want to blow up my engine

 

Yep. Won’t hurt since you know the initial CEL was for the o2 sensor. You might have had another code pop up since then and not know it.

 

I wouldn't keep adding oil if you already started with 7 quarts which is more than spec'd. Unless you're losing it somewhere?

 

I had 6.5 quarts in it and then checked the dip stick and it wasn’t full so I added another half a quart which equals 7 quarts

 

You are fine. I think your problem is the o2 now that we determined your CEL has been on for months.

 

I guess I misunderstood your earlier post when you said you put 7 quarts in. Then later you said you added another half quart. My mistake.

 

While technically the bottles are filled up with exactly a quart, you'll never get all of that out of it. It's very common to have to add a half quart or so extra to compensate. I believe the oil companies skim some off the top LOL. I've never had a car that didn't take an extra 1/4 to 1/2 quart after I dumped exactly the amount it called for out of a bottle.

First we would need to know which O2 sensor it was. Most cars have 4. Bank 1 sensor 1, Bank 2 sensor 1, Bank 1 sensor 2, Bank 2 sensor 2. Sensor 2's only real job is to make sure the cats are working properly. The sensor 1's are narrow band sensors that verify the AFR when the vehicle is not in power enrichment mode (WOT for example.) This is when the computer commands an AFR that the narrow band sensors can't really see which is why almost all tuners use a wide band O2 sensor. I said all that to say this, even if the up stream O2 sensors were out of wack, the computer will command 14.7 (ish) and because of how well these things are tuned from the factory, its pretty accurate and RARELY results in a super rich/lean condition. There would have to be multiple other factors that would cause that and it would run like crap in general. My money is on a downstream sensor behind the cat.

OP- we need a video of the cold start whirring noise and knock. The best way to find out what is going on is to cut open an oil filter or send an oil sample off for testing. This way they can read what metals are in the oil and can tell you what its from. If you cut open the oil filter, you need to look for lots of shiny flakes or pieces of metal or post a good picture on here and I can take a look for you.

Lets not rule out that the oil pressure sending unit could be bad. You could check this with a manual gauge or if you just want to throw money at it, you could just install a new sending unit and see if it returns to normal.

The hard start has me thinking its a head gasket issue and there may be water in the oil that COULD possibly be causing the low pressure. That's just an internet guess as I'm not there to verify anything in person.

When you go to autozone, get the code number and post it on here. Don't accept "you need an O2 sensor." The code will tell us which sensor it is specifically. Some of those parts store guys will try to sell all 4.

Post a video of the whirring and knocking noise on cold start too please.

Good luck and I hope this has helped you.

 

The factory o2 sensors will only give you a snap shot of how far off the air fuel ratio is based on what the sensor is seeing. Looking at the voltage is a help but its not going to help him because he does not have that equipment and would most likely have to pay someone more than the cost of the o2 sensor to get that info. He may be able to find a shop that has a scanner that could read that (Snap-On Solus for example) and any tuner would need money for labor with something like HPtuners.

The computer is programmed to shoot for a commanded AFR. The computer reads voltage and through an algorithm it determines if the voltage it is seeing equates to the AFR it is commanding. Then the computer runs another algorithm and pulls data from the MAF, MAP and uses LTFT and STFT to correct the fuel mixture to achieve the desired AFR and the process repeats many times per second. MOST tuners are unable to look at factory o2 sensors and tune off of them. They use the voltage they see coming from that sensor to 1) determine a problem and 2) to verify what the tuners wide band is displaying if the vehicle is equipped from the factory with a wideband which I believe tundras are (not sure which year they started but I doubt 2004) but not like a wideband a tuner uses. The computer also monitors what each upstream and downstream sensor is seeing and compares the two. If it seeing a large variance, it will throw a code. It will be able to tell you which sensor is bad based on the data it receives.

If the oil pressure sensor is bad, it will give bad data. The computer gets its data from the oil pressure sensor. AFAIK, the tundra only has one oil pressure sensor. If the oil pressure reading is questionable, the only way to verify it is by installing a new sensor or verifying what the computer is seeing with a manual gauge.

Codes DO tell you things. Depending on the code. The computer is smart enough to tell you which O2 sensor is malfunctioning but its not going to tell you where exactly a vacuum leak is for example. Since he has had it checked and he knows that its an O2 sensor, he just needs to know which one which a simple code will tell him. If the computer were to find a bad O2 sensor, it will pull data from a good sensor and use it to help command an AFR that is within spec so to speak. Because of how well the computers are tuned from the factory, it will not run crazy lean or rich to the point that the vehicle will run like crap, worst case is that it will go to open loop and just command everything and hope for the best and usually the computers are pretty damn good at this.

The whirring and knocking noise and low oil pressure is not caused by an air filter, or a cracked/pinholed air tube. Even if the air tube was cracked and had pinholes, the computer would revert to the VE table and turn the MAF off (assuming the crack was behind the MAF) and it would throw a code for a lean condition or a MAF code etc. The computer would see variance in data and give you the code and since it doesn't monitor the integrity of the air hose, the code will, as you said, lead you down a path to find the problem. He doesn't have a problem like this.

The best bet is to send an oil sample off and/or cut an oil filter open and inspect.

 

Or he can go to autozone, have them pull the code for free since the computer has already done the work, buy the correct o2 sensor and not have to spend money on that code reader. I didn't really look through that thing but the only one I saw that read all that extra data was like $75 so I'm not understanding why youre wanting him to spend money so he can spend money?

 

So you just posted a link to buy a scanner to show that they exist?

I'm all for advice but you gotta be on point and make sure you aren't wasting his time. He is here with a knocking issue, oil pressure and an overheating problem.

You said "you need a scanner to show live data" when he already has had the code pulled and just needs to go get an o2 sensor, which I don't think is his issue anyway.

You told him it would show true oil pressure too which doesn't help since he hasn't eliminated the possibility of a bad sensor.

You told him codes don't tell him anything when they in fact do tell you things.

And then you asked about an air filter and an intake hose being cracked and pinholed. Neither of which would cause a knocking noise, overheating or low oil pressure.

I don't want OP to spend any more time or money than he has to to get the problem fixed so he can carry on with his daily life ASAP.

Everything extra I posted was to help other people understand how these systems function just because I felt like people would want to know.

 

If it were mine and all I did was change the oil and filter I would try another filter. I say this because I got a bad Motorcraft filter once and if not for the bypass I would have damaged a good engine because of a 6 dollar filter

 

Yeah I agree with that.

 

A bad O2 sensor that has triggered a CEL reverts back to programmed tables, making it run rich, not lean.


OP, I’d try install a new oil filter. That would be my first guess, unless you coincidentally had some other failure.

 

Do you have a Toyota link to this information concerning o2 sensor? I’d like to study it.

 

I don't, that's just how the systems are designed. an gasoline engine running lean will overheat and blow up. a gasoline engine running rich will have poor fuel consumption and lower power. Pretty easy to see which side of the equaision you'd want to stay.


Diesels on the other hand, are the opposite. they love a lean burn, but put too much fuel in there and EGTs get too hot and they go kaboom.

 

well, sorta. It's why turbos do so well on diesels for sure, but it's less for cooling and more for power still.

 

This simply is not accurate. Reason being is that the computer isn't set at just one table for all temperatures and conditions. The computer will go into open loop but that doesn't mean it loses all ability to perform self tuning tasks. You need to read up on how modern computers work.

Without an input for AFR, the computer will revert to a set of tables programmed into the computer. When you start the vehicle up, it is on a startup table which is different from the table that it reverts to at operating temperature. So you see, just because it is in "open loop" doesn't mean that it is brain dead. It still adjusts based on engine temp, IAT, etc. So to say that when you turn the key on, it just stays the same and that it just runs pig rich is just not accurate. While it is missing a piece of information, it will still be pretty close to stoichiometric because it has a number of tables at its disposal and can make adjustments based off of the information it has available. These motors undergo THOUSANDS of hours of tuning based on every imaginable scenario.

Diesels have large turbos based on a number of factors. The number one factor is displacement and the second factor is desired cyl pressure. Any time you compress air (turbo or supercharger), it will generate heat. Its physics. Diesels have the ability to perform efficiently with larger turbos because they operate at such high cyl pressures and additionally, in general, are larger displacement engines. Diesels don't have throttle bodies and instead use fuel to regulate engine speed. Shut off the fuel, shut off the power. The term lean and rich in a diesel cant really be compared to gasoline engines because of the nature of the design of a diesel engine. A gasoline engine will typically shoot for 14.7 AFR while cruising and idle and 12.0 - 13.0 under a load. 15.1 being lean and 12.1 being rich. A diesel will operate as rich as 15.1 and as lean as 60.1. Its not uncommon to see a diesel engine idling at around 50.1 AFR. Diesel engines will burn up due to high combustion temperatures the same as gasoline engines. BUT the temperatures are generated differently in a diesel engine. More fuel + more load = higher combustion temperatures which is why you see all the performance diesel guys riding around with EGT gauges. So the way to cool a diesel engine down is to reduce the commanded power output with fuel. At no point in the history of engines that I'm aware of has a forced induction component ever been used to cool an engine. Compressing air causes molecules to become closer together which leads to friction which generates heat. The intercoolers you see in almost all forced induction engines, gasoline and diesel alike, is to cool the air charge to create more dense air and to keep combustion temperatures down. Remove the intercooler and you will not be able to generate the same power. Remove the turbo and the engine power output goes down. The turbos job is to generate boost which forces more air into the combustion chamber and when added with more fuel, more power is generated. Thats its only job. Turbos are not designed to cool anything.

 

Well now, there is no need to get upset. I'm just trying to educate you so that the next thread you get into, you don't spread false information and waste peoples time.

Your diesel may be overheating because it isn't running efficiently due to a massive boost leak. What are your EGTs?

My intent was to help you understand, not make you mad.

 

@ ATCinfantry is it possible for our Tundra 4.7L engines to run lean? Does a bad o2 sensor cause this?

I double checked some sites this morning after being corrected here this morning and sure enough read that bad o2 sensors can cause rich or lean conditions. I can post the two links but won’t to eliminate confusion.

 

Well it would depend on various conditions. Short answer is yes it is possible. The tendency is for one to run rich to eliminate the risk of pre ignition and high combustion temperatures.

It works like this. There is a base table in your computer. Its full of pre set values so basically X amount of air + X amount of load should = X amount of fuel. If everything is functioning, it will run algorithms that factor in intake air temperature, engine coolant temperature, o2, and what the MAP sensor is seeing etc. and make corrections based on this info. If something is missing, it will, simply put, take the info it has, look at the base table and make an "educated guess" as to what it should be putting in for fuel.

So it is possible that it could run lean but more often than not, factory computers are rich from the factory. I usually clean up factory tunes before I do performance tuning of any kind.

 

Thanks for this. I have read and heard these 4.7L engines run rich just in normal mode when everything is operating as normal with no CEL. What is your recco on going about doing a tune on these engines? Or, just to begin an initial clean up pre-tune before the main tune?