P0171 (system too lean)..!!!!

[herry2405]

So I already changed the plug and a new coils for my celica due to the P0171 code problem (system too lean bank 1). But when I scan the car again, it still appear the code P0171, even tho I already put the new coils in. I also got some other codes like P0301, P0100, and P0110. The problem seem to be getting worse when I drive on highway (or even in city), the car keeps knocking over and over again.

I looked online for those who had the same problem as mine, and they said it could be because of the injectors or the MAF (which Im not really sure).

Now I really dont know where I should start to do with this problem. If anyone knows about this problem, that would be a big help to me.

[adamderry]

I think it's probably the #1 o2 sensor aka a/f sensor

[RevHard]

^^+1
I was thinking first of the o2 sensors on the exhaust line, then the MAF.
With a good OBD2 scanner, you can test the o2 sensors seeing if they work properly, and check the MAF readings. Other than that, a good cleaning (MAF + o2 sensors) also may help as a first step.

[GSBoek]

Start with properly cleaning the MAF sensor with CRC MAF sensor cleaner. More often than not P0100, P0110 and P0171 are related to the MAF being dirty or worst case damaged.

Normally you start with the lower codes first and then work your way up. So try to address the MAF first. After that's done you can go for the P0301. That is a code specifically for cylinder 1 misfires. Hopefully you don't have bent or worn valves but it's a possibility.

[radiod]

Originally Posted by RevHard

With a good OBD2 scanner, you can test the o2 sensors seeing if they work properly, and check the MAF readings

Don't even need a good scanner. I use a free app on my android phone paired along with this:

http://www.amazon.com/Soliport-Bluet...eywords=ELM327

The app I was using is called "Torque Lite"

https://play.google.com/store/apps/d...=search_result

You can clear and read current, pending, and historic codes as well as get real time data from a lot of the ECU. It also has a handy emissions drive status since last DTC clear in case you need to go through an emissions test.

As GSBoek said though the best place to start is by cleaning your MAF. Make sure you use MAF cleaner, not carb cleaner and heaven forbid you use brake cleaner! The MAF cleaner is specially designed not to break down the plastics and not leave a residue. Make sure the sensor is thoroughly air dried before reinstalling.

[silver_Streak]

Bump

[guateracer1]

I had the same code not too long ago, I cleaned the MAF and replaced intake manifold gasket because of TSB thats out there for 1zz motors and nothing fixed and then I replaced it with a brand new oem MAF sensor and the code never came back hope it helps a little..

[whitegts05]

I have that same code, but in my case it turns off when I get gas and when I leave the AC on it turns off. I'm going to get an emissions test tomorrow so I'm going to leave my AC on so I can pass lol!

[herry2405]

According to everyone's opinion, I should start cleaning my MAF and o2 sensor. But the car is still knocking and shaking a lot. I dont know if this problem relate to the injector or anything else. I used a seafoam can to clean out the injector and the engine. But there was not a lot of smoke coming out from the exhaust so I guess the injector and the engine are still clean. Now every time I drive, from 1st gear to 3rd gear, the engine shifts fine, but from 3rd gear to 4 gear, even tho it shifts, the rpm keep going up to 4000rpm & up, and the car was knocking as if it's dieing.

I dont know if anyone familiar with the problem Im having right now. If anyone knows about this, please help me out cuz this problem is really worrying me now. Thanks a lot.

[silver_Streak]

I drive a 02 celica gt AUTOMATIC, the check engine light is on and the codes are: po171(too lean) po300(random misfire) and the occasional po429(cat below threshold)

My problem is: when i decide to hit my gas pedal either too fast or too quick, the car bogs for a split second, in which i have to cut back on the gas, then she will drive normal and even have decent acceleration after her fit.

In the past i had a knn oem replace air filter... i had to take it out because of the oil ruining my mass air flow sensor... Went ahead and replaced the air filter with a Toyota air filter and swapped out the old maf sensor for a new oem maf sensor...

My car still bogs. but i know how to drive it without making it accelerate too often,which is not fun and am getting pissed of being restricted from my Celicas potential...


Oceanside,Californian looking for parts, interiors.

[jasonc624]

Originally Posted by radiod

Don't even need a good scanner. I use a free app on my android phone paired along with this:

http://www.amazon.com/Soliport-Bluet...eywords=ELM327

The app I was using is called "Torque Lite"

https://play.google.com/store/apps/d...=search_result

You can clear and read current, pending, and historic codes as well as get real time data from a lot of the ECU. It also has a handy emissions drive status since last DTC clear in case you need to go through an emissions test.

As GSBoek said though the best place to start is by cleaning your MAF. Make sure you use MAF cleaner, not carb cleaner and heaven forbid you use brake cleaner! The MAF cleaner is specially designed not to break down the plastics and not leave a residue. Make sure the sensor is thoroughly air dried before reinstalling.

Bought &downloaded...thanks!

[herry2405]

So I listened to everyone and cleaned the MAF and it did help my car a lot. Now I can tell that the car is running lots better than before. But even tho I already cleaned the MAF, the check engine light is still there and this is wondering me what I should do next for the car... Should I move on to next code or should I check the intake or the o2 sensor?? Please help..!!!!!

[guateracer1]

Honestly since you clean the MAF reset the monitors by clearing the codes and see if that too lean goes away if not you still got some diag. to do check you intake manifold see if you got any leaks or vacuum you have extra air coming into the engine that is why you running to lean

[RevHard]

Originally Posted by radiod

Don't even need a good scanner. I use a free app on my android phone paired along with this:

http://www.amazon.com/Soliport-Bluet...eywords=ELM327

The app I was using is called "Torque Lite"

https://play.google.com/store/apps/d...=search_result

You can clear and read current, pending, and historic codes as well as get real time data from a lot of the ECU. It also has a handy emissions drive status since last DTC clear in case you need to go through an emissions test.

As GSBoek said though the best place to start is by cleaning your MAF. Make sure you use MAF cleaner, not carb cleaner and heaven forbid you use brake cleaner! The MAF cleaner is specially designed not to break down the plastics and not leave a residue. Make sure the sensor is thoroughly air dried before reinstalling.

So you bought the ELM 327, nice choice ;-) I ended with the Memoscan U-571, I needed something more 'hand-held' like tool, I don't like using my smartphone with greasy hands when working on the car

[radiod]

Originally Posted by RevHard

So you bought the ELM 327, nice choice ;-) I ended with the Memoscan U-571, I needed something more 'hand-held' like tool, I don't like using my smartphone with greasy hands when working on the car

Yeah, understandable. Haven't run in to that yet, but I'm sure I will at some point. Maybe I'll just get myself an Android platform that's not attached to any cell contracts or anything and it be my "designated scantool" rather than using my phone.

[jasonc624]

Originally Posted by radiod

Yeah, understandable. Haven't run in to that yet, but I'm sure I will at some point :icon_razz. Maybe I'll just get myself an Android platform that's not attached to any cell contracts or anything and it be my "designated scantool" rather than using my phone.

I think thats the only use a tablet would have.

[xrsfreak]

Originally Posted by guateracer1

Honestly since you clean the MAF reset the monitors by clearing the codes and see if that too lean goes away if not you still got some diag. to do check you intake manifold see if you got any leaks or vacuum you have extra air coming into the engine that is why you running to lean

^^^ Got the code when my intake manifold cracked. You are getting more air after MAF so either MAF (which you took care of) or there is a leak after MAF and most likely Intake Manifold gasket or crack in there...

[silver_Streak]

Originally Posted by herry2405

check engine light is still there

Mine to. My car bogs when i hit the gas to far down.. i have replaced my maf with one from toyota. the original maf sensor was ruined by a knn stock replace air filter, the oils got caught on the sensor parts.

i drive a 2002 celica gt,and has po171 and po300

bump.

[chrisrodrigui01]

Car problem

P0171
System too lean. (Bank 1)
Fuel sys 1 CL
Fuel sys 2 NA
Calc load(%) 34.9
ECT (•F) 194
STFT B1 (%) 12.5
LTFT B1 (%) 21.0
Engine Rpm 717
IAT (•F) 116

These are my settings.

[evolution21]

Damn 21% on LTFT

Sent from my SPH-D700 using Tapatalk 2

[chrisrodrigui01]

So I go home turned the car off and back on. The engine light went off.. Still want to take care of things to keep my baby running.

[2way]

Closed Loop, at Idle, normal temp, Load seems a lil on the high side, and Fuel Trims definitely show a problem. Cleaned or changed the MAF?

[chrisrodrigui01]

Changed my air filter and cleaned out the MAF sensor. Where is the other sensor located so I can clean it just to be safe.

[silver_Streak]

Originally Posted by chrisrodrigui01

Where

its on the air box tube, two gold screws... Use the search feature.

use crc maf cleaner and hit the inside,soak it.Both the matchstick and the two fragile sensors inside.

[chrisrodrigui01]

I did that sensor. I was talking about where the o2 sensor is.

[2way]

On the exhaust in front of the CAT. But, I doubt that's your trouble.

If you don't meet w/success, I suggest that you arrange a get together w/Boosted2.0. He's in Houston also. His shop is over in Sealy, I believe.

[chrisrodrigui01]

Ah I'm I'm Katy. I just want to get these readings to normal settings.

[chrisrodrigui01]

Check engine light just came back on.. -.-

[evolution21]

I have the exact same problem, only when i hit the pedal at WOT does it bog, but like silver streak as long as I take it easy eveything is fine only code I get is the system to lean, cleaned my maf which i could definitely feel improvement but the problem still exist, the A/F O2 sensor is working properly and so is the O2 sensor after the cat which is reading high something like a constant .705 volts....only thinig i can think of is the fuel pump being weak and not able to keep up with the demand at WOT or vacuum leak....Im getting my intake smoked on monday to check for vacuum leaks and also getting my fuel pump tested, let you know what I find....would a clogged pcv or malfunctioning pcv cause these symptoms?????????

[yodaddyguido]

ive gone through my mother-in-law's 01 gt with this problem for the past few months. replaced the maf, all vac lines, checked for leaky gaskets, upstream o2 sensor, and plugs... today i replaced the fuel filter and pump and its STILL bogging BAD at low rpms and WOT. i suspect the injectors... they're pretty much all i have left!

[silver_Streak]

Originally Posted by chrisrodrigui01

where the o2 sensor is.

Originally Posted by 2way

On the exhaust in front of the CAT.

Per Di-15 in the repair manual, "heated o2 sensor" bank 1 sensor 1...This is the same plug as the one you refer to RIGHT?

[silver_Streak]

Originally Posted by evolution21

would a clogged pcv

-It would, but i doubt your car is that filthy...It's easy to check out

Originally Posted by yodaddyguido

the injectors... they're pretty much all i have left!

But wouldn't a fuel pressure test* determine if your injectors are clogged or if you have a weak fuel pump?

*at idle and under load

[brianv3ntura]

Did you Check the VSV?

[silver_Streak]

Originally Posted by brianv3ntura

VSV

Originally Posted by Soon2beriding

PCV=Positive Crankcase Ventilation
The others?????
CCv VSV,Evap Vsv??

Educate me

[chrisrodrigui01]

I went back to the auto part store. Cleared the problem and my check engine light went off.

[silver_Streak]

Originally Posted by chrisrodrigui01

Cleared

Did they hook it up to a reader?What did you have done?

[evolution21]

I hooked mine up to a modus scanner and was looking the readings my injectors bandwitdh were fine, but that was also without a load, mean the car in neutral and me under the hood pulling the cable til WOT, and i can be there all day doing that and the engine sounds beautiful, its only actually driving when it happens, i havent changed the pcv since i had the car at 55000 miles and it has 112000.....but seeing as this guy has replaced almost everything in the fuel system and to no avail, im thinking maybe it goes back to the old problem of our engines eating oil. My compression across thr board is less then 160psi, maybe under extreme load(WOT) the blow by is much that maybe theres enough oil grtting by causing the cylinder not to fire?????? Any thoughts

Sent from my SPH-D700 using Tapatalk 2

[2way]

Originally Posted by evolution21

maybe theres enough oil grtting by causing the cylinder not to fire?????? Any thoughts

That would probably cause the fuel trims to go in the opposite direction.

Originally Posted by chrisrodrigui01

I went back to the auto part store. Cleared the problem and my check engine light went off.

If nothing was repaired/replaced, it will return.

Originally Posted by silver_Streak

Educate me

CCV = Canister Closed Valve
VSV = Vacuum Switching Valve

[chrisrodrigui01]

Originally Posted by 2way

.If nothing was repaired/replaced, it will return.

It returned..

[chrisrodrigui01]

Originally Posted by 2way

On the exhaust in front of the CAT. But, I doubt that's your trouble.

If you don't meet w/success, I suggest that you arrange a get together w/Boosted2.0. He's in Houston also. His shop is over in Sealy, I believe.

Where is boosted2.0 or where can I get in contact with him??

[2way]

http://www.newcelica.org/forums/member.php?u=13909

WWW.DDPerformanceResearch.com

[chrisrodrigui01]

Swweet!!!!!! I'll get in contact with him soon!!

[chrisrodrigui01]

Alright I took the celica up to toyota. They told me it was my injection system needs to be serviced. But instead I was smart and seafoam the car whole bottle to the gas can!

[silver_Streak]

Going to Toyota Carlsbad...po171 po300 (car bogs when i hit the gas down to fast.)

I say 02 sensor?

[lamboceliGTS]

I would say try to clean the MAF. This is something I need to do every 3K miles or so. Otherwise I bog when I hit the gas as well.

[2way]

Originally Posted by silver_Streak

Going to Toyota Carlsbad

Get thee to Smaay instead.

[evolution21]

Originally Posted by silver_Streak

Going to Toyota Carlsbad...po171 po300 (car bogs when i hit the gas down to fast.)

I say 02 sensor?

Do a resistance test on your ignition coils, had same code and problems until. One of my coils died, purchased a new one and all my problems went away....sounds odd I know but it's worth a shot

[silver_Streak]

/.)_/.)

[silver_Streak]

I have changed the mass air flow (oem new) and spark plugs,problem still exist.

took to toyota carlsbad and they say...pulled codes po171 system too lean.tested long fuel train,at 40-attempting to add lots of fuel.>injectors pulse at 8 miliseconds,should be no greater than 3.5 ms.>most likely have to replace o2 sensor or injector.

Then something about propane test through the injectors? idk...

107.00$ car wash.sons a bitches.the want another 221$ for the propane test?whatever that is?The fu^king car runs strong and hard,just gotta not mash the pedal to down to fast/quick to avoid from bogging.

Originally Posted by 2way

Get thee to Smaay instead.

How?

[2way]

Originally Posted by silver_Streak

Quote:
Originally Posted by 2way
Get thee to Smaay instead.

How?

IM him.