Fuel Pressure Question

Are you 100% stock?

 

While the numbers are below 10 they are a bit higher than desirable, usually I like to see below 4-5%+-... however, if you are not getting a lean code or a rich code I would actually point suspect to other dynamics which are causing the "low MPG" which you are concerned about. These computers have very fast reporting data and I have seen my numbers rise and fall in relatively quick succession in the past when at idle and at cruise situations. What I would like to know is what size an type of tires you are running, if you are lifted, and if you have armor. All are great contributing factors to low MPG which will make you think something else is wrong when it really is not.

Fuel pressure deadhead is not an accurate test, more a test to see if the pump is capable of doubling it's output if it is. If it is capable of doubling it's normal output when dead headed then you have a good fuel pump which is capable of building proper pressure needed to supply consistent fuel pressure when needed.

 

Tacoma gas millage sucks! Brand new, maybe 17 MPG! 15 MPG with 33's, on a good day with wind at my back 11MPG with 35's. Last weekend hauling heavy trailer with 35's I got 7 MPG.

Anyway....

Easiest way to test... Bring to an injector shop. Usually $10 each.

Before you spend money here is a pic of injectors from cyl 4 of a Tacoma, cyl 5 of same Tacoma and cyl 4 from an FJ. All 1GR-FE. Injector on cyl 5 on Tacoma was bad.


If it looks like either the injector on the left or right, most likely good. If it looks like the middle, I'd question it. At minimum, clean with carb cleaner. Or carb cleaner through it like next post.

 

To check at home, put a multi meter on the injector plug. Turn ignition on, test for which pin is positive, which is negative. Mark + and - on injector. Cut some 6" pieces of wire, crimp some female wire spade crimps at one end of each wire. Plug those into the pins on the injector. Strip the other end about 1/4 of an inch. Use a hose clamp and clamp about a 12" piece of rubber hose to one end of the injector in the pic. Get a bottle, maybe a clean old gear oil bottle or whatever spray a bunch of carb cleaner in it and use a hose clamp to secure the other end of the hose to the bottle. get a standard square 9v battery.
Squeeze the bottle, keep squeezing it, not hard, just keep pressure. nothing should squirt from the injector. Then touch the 9v battery to the + and - wires of your injector for a split second. Injector should click and spray even spray of fluid then stop.


If fluid dribbles through with no power to it, it's leaking. If fluid continues to leak out after you remove power it sticking. If no fluid goes through but you hear click, it's clogged, if no fluid goes through and you hear no click, injector is bad.

If it's sticking or clogged, just keep running carb cleaner through it, if it doesn't get better, replace. I got a whole set from a member for like $60! Don't pay dealer prices!

Easiest to have a shop test.

 

Are if you happen to pull lower oil pan when changing oil or whatever, use a flashlight, look into bottom of cyl 5 and 6, if you see a reddish looking drip line down the cylinder, injector is leaking fuel. When engine is turned off, pressure in the fuel line is pushing fuel through leaking injector into the cylinder and passing through the rings, dripping. Also getting into your oil. Another way to check that pretty easy, is pull oil dip stick, smell it. If it smells like you stuck your nose in a gas can, possible stuck/leaking injector.

 

Just for information the coils on those injectors should read about 12 ohms and will usually fall within plus or minus 1/2 ohm. They should read 11.5 ohms - 12.5 ohms.

Polarity should not matter when testing the injector, the coil does not care.

And as was noted above do not leave the coil energized for too long at a time a couple of seconds at most. If not it will overheat and damage the injector.

Keep them clean and do not drop the injector. It will damage it and it will cause it to leak or stick open or closed. If dropped, replace it. It could also bugger up the spray pattern.

I work with these devices every day. If there is an internal issue you can not clean it or disassemble it. Throw it away and get a new one. The needle valve inside is a metal on metal seal and cannot be fixed.

If it is sticking open do not install it in an engine it could hydro-lock the cylinder and bend a rod or break a piston.

 

Yes...

 

Tires: 265/75R16 AT's
No lift
No armor

It's just a stock truck.

Thanks for that confirmation.

 

While I am not expecting Prius level MPG... this truck has had a significant drop in MPG with no known change I made... so I feel something must be wrong.

I will take a look at the injectors when I have some time to work on the truck. Will probably be a few days.

 

I will smell the oil and see... don't have plans on dropping the oil pan anytime soon, but thanks for the suggestion and understanding of the possible symptoms of a leaking injector.

 

Can anyone comment / clarify this information set

MAF(lb/s): 0.00
SHRTFTB1S2(%): N/A
SHRTFTB2S2(%): .115 to .935

What does the acronym "SHRTFTB1S2" stand for?

I assume "B1" and "B2" mean "Bank One" and "Bank Two"... so these must be sensors. Shouldn't both be sending data?

Why does "SHRTFTB2S2" have a number and "SHRTFTB1S2" says N/A? Broken wire? Bad connection?

What is the range for MAF? I assume there should be some fluctuation of data there... isn't that the lb/s being pulled into the intake?

Thanks.

 

MAF range is 0-100 usually though I have seen a few vehicles exceed that and read 120 or so on occasion, if you see anything less than 80-85 gm/s your sensor is reading inaccurately. What are your gm/ s readings at idle?

These readings apply to N/A vehicles.

Oh and AT tires will net you a decent loss of MPG, but you are getting the same numbers I get, and I have a blower, mid armor, full suspension, and AT's as well. Something has to be wrong with yours.

 

Short term fuel trim (bank 1 / sensor 2)

The maf reading zero is strange, it may be a scan tool issue..

Any exhaust leaks near the o2 sensors?

 

I have another MAF sensor. I will swap that in and see if reading changes.

I replaced the exhaust gaskets just at headers. There were signs of leaking and the old ones were pretty toasted. So the answer should be no, now no leaks.

 

The MAF seemed to "wake up" a bit today.

I get .01 to .03 at idle. If I get on the gas under load I could get it up to .13 but just for a second or two.

These readings however are in lb/s not gm/s.

I assume my reader is "pounds per second" and you are asking "grams per second"... no?

 

So... I checked the dipstick and it does smell like gas.

The other thing this truck does is when it sits for an hour or so it has trouble starting. Turns over longer, then starts. But when cold (much longer sit time) it starts right up.

My theory is if I had a leaking injector (or several) maybe short sits the fuel leaks into the piston and drops pressure in the lines. Upon a hot restart all that extra fuel has to burn and pressure has to come back. But when sithing overnight, the fuel just leaks down into the oil.

Anyways... just guesses. But I think I will focus on testing / cleaning or replacing the injectors next.

 

Maybe one of those boroscopes from Amazon....ebay... Wireless, works with an app.
Pull the plugs after sitting a bit and compare what the cylinders look like.
Good luck in figuring it out.

 

Your assumption is correct. See if you can convert units to GM/ S instead of LB/ S.

If you have fuel leaking into your oil pan that is not good at all. Get to the bottom of it and quick because fuel is an excellent oil cutting agent.

Make sure you change your oil as soon as you repair the issue as well.

 

Those $20 eBay USB borescopes are well worth it. I keep a couple on hand with a hand full of on Android HTC M7 phones, so if I'm working on something and break them, new scope and phone, only $50 to replace, lol, phones and scopes do work when submurdged in oil, but only for like a couple mins, lol!

Joking aside, if you let it sit for at min a day or so and put a Cam in the cylinder, if cyl and piston head look normal, you see carbon build up and you look at the corners of the piston and see fluid puddles, that's fuel. Injector is leaking.

 

If you go the eBay USB endoscope route make sure it's a 'ridged', 5mm and has adapters included to fit the USB plug you need to use. I literally, I mean literally gave one of these and a phone to a tech at Hampton Toyota in Lafayette, LA to scope something deep in one of my engines that they could not reach with their scope.