Was -20 to -25 (idle) LTFT 0 to -2. Lexus is currently somewhere between 4 and 7. The 3 codes I got in May were the p0170 (MAF) P0130 P0133 (02 sensors). Autozone has a GP/Sorenson FPR PN 800-302 listed for the 2000 PAU and 2005 PAU. 7:1 A/F. I did an initial scan and. the fuel trim goes down as soon as I step on the gas, and it goes back up. I checked the fuel pressure. The engine computer (PCM) uses the signal from the MAF sensor for operating the fuel. Now let’s say the fuel gauge is reading 1/4 of a tank, and the tank has a 20-gallon volume. Short-term fuel trim is based on readings from the current engine operating conditions. Bank 2(P0430) had a bad sensor. Long Term Fuel Trim. 42. I checked & all the readings checked correct except for vref voltage (5 volts) on PCM pin 90 key on. So here is the current puzzle. Short Term Fuel Trim -Bank 2 0. 3 for bank 1. The Air metering one can be a vacuum leak or a bad maf. STFT is an immediate response to the air/fuel mix. 00 a pop to scan. Check the fuel pressure. It basically uses low RPM (below around 2k rpm's) and high (above 2k), referenced against 6 different MAP voltage set points. Maintenance Shop - Fuel trim readings got me chasin my tail - Hey everyone, This is my first time on here so I hope im in the right spot. of fuel. greater than 50 mph in order to ensure proper warm-up of the engine. Long term fuel trims seems high at idle (+13%) - but when throttle is applied, long term fuel trim comes to about +5%. So a short term fuel trim reading of +20 percent indicates 20 percent more fuel had to be added to achieve the proper air-fuel mixture. If you know the correct answer to this and you know about the SRT intake you would get a better understanding as to what the SRT r-ecu really has to do. STEP 4: CHECK FUEL PRESSURE. It does the same thing as the first one. But I noticed that it drops to zero or negative as the RPMs increase to 1500 RPM !Amount of fuel plus enrichment = (6. Alright, so my inspection is due soon, so this is frustrating me a bit more than it should. Since the first worked fine on the suzuki car, I don't think it's the scanner. P0102: Mass Air Flow (MAF) Sensor Circuit Low Input. Have a 97 Escort 2. I was hoping the one reading N/A was the issue with them not cycling back to ready, but will try to run through the drive cycle a few more times today and tomorrow to see if they reset. g. Fuel trim is what the ECM implements to. The STFT was at +22% and the LTFT at +20%, and these trims were occurring at idle on a warmed-up engine. When all of the gauges or warning lights in your car stop working at once, the problem is something that all of the gauges and lights share in common. August 31, 2010. A week ago bought one of those obd2 code readers for the cell phone and here is the info from when the code appeared, that is P0300and P0420, Calculated engine load 13. The fuel pressure was checked with the engine running. Short or long term fuel trim readings beyond -10% are a clear indication. Long Term Fuel Trim (LTFT) is a longer term average of what the engine computer has been doing to balance the fuel mixture over a. Vacuum leaks – PCV hoses, vacuum hoses, intake manifold gasket. Fuel trim can also be expressed as either a positive (+) or negative (-) percentage. It has a '98 program in it also. A negative fuel trim means fuel is being taken away. Poor engine performance. This graph shows a fuel trim voltage drop-out caused by a faulty mass air flow sensor. Faulty evaporative emissions system - bleeding fuel vapors into engine (not commanded by computer) 5. possible causes: MAF dirty. Fuel injection jetting was adjusted until an optimum spark plug reading was achieved. bluetooth stereo. Either the engine is taking away fuel or adding fuel so the exhaust byproducts, measured by the oxygen sensor, add up to an efficient operation. Worsening fuel economy. It will typically flow better than a clean filter. The appeal of the Escort, particularly the ZX2 Sport, is its affordability. 0, similar to your -6. High fuel trim readings. At the same time, the short-term fuel trim will lock even tighter to a number, and stay that way until it all clears. So on your scan tool, you’ll see the short-term fuel trim readings switching back and forth between. 34 % Long Term Fuel Trim - Bank 2 0. The short term fuel trim. 5 and 0. Fuel trim is the adjustment the engine computer makes to the fuel mixture to maintain a balanced air/fuel ratio. Too low fuel pressure can cause the engine to run lean, causing the O2 sensor to read low voltage as described in step 3. The DTCs directly related to fuel trim problems are: P0170: fuel trim bank 1; P0171: system too lean (bank 1) P0172: system too rich (bank 1) P0173: fuel trim bank 2should cause negative fuel trim read-ings at idle and low airflow. Technician B says that . Short Term Fuel Trim. When at around 25% throttle and 50kpa MAP LT fuel trim is just -1%. To bring the. They have a 10% window that will only affect the Long Term Fuel Trim (LTFT) if the fueling correction is beyond the 10% window for 10 seconds. REAR FUEL TRIM: Since rear fuel trim (RFT) operating strategies vary widely among manufacturers, you’ll have to learn as you go. However, if the amount of compensation is too much, a P0173 code may set. tech b says percentage is used. I would expect the readings to be a bit negative winding the motor at 3600 rpm and seeing the intake air temp at 104 degrees. Now add 2 gallons of volume for the hoses and carbon canister; 15 gallons + 2 gallons = 17 gallons of vapor space volume. 0% and 10. Either the engine is taking away fuel or adding fuel so the exhaust byproducts, measured by the oxygen sensor, add up to an efficient operation. At idle (in gear) STFT reads around -6 to -10 pretty consistently when i come to a stop sometimes dipping to -12 at times. if this is a MAF engine and your trims look good at idle, I would move away from vacuum leaks. With the replacement MAF sensor, its now 0. Be scared of anything above 10% or below -10%. Use the information to target the next di-agnostic steps. Checking MAF sensor data using generic OBD data. Snap throttle and idling held at 64 psi even though I have a bad check valve when the engine is off the pressure bleeds off. For example, a car with a 0-60 mph time of 4. Fuel trim is usually displayed as a PERCENTAGE reading on a scan tool. this procedure is ½ fuel tank level. Not entirely sure how you can say it's non sense. Even some in-line four cylinders have two sets, one per cylinder pairing (cylinders 1-4 and cylinders 2-3 t ypically). Codes P0170 through P0175 indicate issues with the fuel trim – six codes covering banks 1 and 2. On the other hand, when the engine is running lean, the PCM will increase fuel delivery, resulting in a positive fuel trim value. Here is the vehicle description, problem description, data, and parts that have been replaced. Short term fuel trim (STFT)is quick changes to the injector. is this enough information to determine if my fuel pump needs to be replaced? 2. 0% and 10. Sent the first scanner back & received a another scanner today. With iso-octane ("ideal" gasoline), Lambda of 1. P0171 Causes. 0 OHV. I have just installed 2 new O2 sensors and the Fuel Trim % for the B1S2 sensor is still pegged at 99. In the event your Ford cranks easily, but doesn’t start within the first five or six revolutions of the starter motor,. by 3FOX » Wed Jul 12, 2017 3:27 am. The percentage reading represents the difference either above or below the anticipated amount. OBD-II Trouble Code Chart. And the fuel trim readings are still around -25% with the O2 sensor readings stuck at ~0. The sending unit is where the whole process begins. Engine Fuel Trim Diagnosis And O2 Sensor Performance. A restricted exhaust on one side of a dual exhaust system can cause an imbalance of fuel trim between banks. So a short term fuel trim reading of +20 percent indicates 20 percent more fuel had to be added to achieve the proper air-fuel mixture. Loren Champlain Sr Veteran / Moderator Apr 22, 2009, 2:16 PM. The higher the reading, the more it’s trying to cut fuel. On all models, to exit Self test, turn ignition Off. Black smoke from the exhaust. We need fuel pressure readings at idle then at 2,000 rpm's. 7 parts of air to one part fuel). Low fuel pressure- Normal to lean at idle trending leaner. Scott Brown. The fault codes say you have either an air leak or a bad MAF. But, in general, you want fuel trim values under 10%. The purpose of this immediate reaction is to bring the combustion chemistry back into stoichiometry as soon as possible. 48 gallons/second. , etc. However, in some cases, the displayed value for long term fuel trims can be as high as 6 to 8. 14% is a bit high. If greater than 10, it indicates a fuel mixture problem. Again. P1138 and P1158, both I believe are 02 sensor rich codes. Preparation. Code P0173 is triggered by the engine control module (ECM) when it detects that the air-fuel ratio is too lean or too rich. Adding STFT +LTFT = +42% of total fuel trim when the code was set; it was obvious the ECU was adding fuel to. V6 and V8 engines have two sets of both fuel trim PIDs, one for each side (bank) of the engine. Technician B says that a fuel pump’s maximum volume can be affected by the condition of the fuel injectors. #1. This increase in LTFT appears to be linked with the intake air temperature; on days when the air is hotter than usual, LTFT can get. LEAN DTCS: In general, a + 25% or greater fuel trim correction will store P0171/P0174 DTCs. Are you faced with a customer’s vehicle performance concern? Or a. Avoid suddenFuel trim can also be expressed as either a positive (+) or negative (-) percentage. my situation is the opposite. OBDII Fuel Trims. ) both bank 1 & 2 have LTFT of -5. So it goes with using fuel trim data. The percentage reading represents the difference either above or below the anticipated amount. Press the test button and the test window will show. View Image Gallery . The ECM will detect this and try to correct that. There's also a deceleration and idle fuel trim cells for above and below 2k rpm's. 4LT, 84K. Fuel trim is an essential indicating metric that can shed tons of light on how hard the engine controller is working to achieve its desired air-to-fuel ratio otherwise. If an o2 sensor reads a lean condition, the short term fuel trim will be positive, meaning the PCM is raising the injection pulse times on the injectors. If there is a consistent amount of fuel trim needed in a particular area, the fuel learning will adapt to that amount, so that the Fuel Trim can work near zero adjustment. I have just installed 2 new O2 sensors and the Fuel Trim % for the B1S2 sensor is still pegged at 99. In this case, the fuel trim numbers are a recently cleared PCM’s response to a good O2 sensor. net!. Short Term Fuel Trim -Bank 1 -1. Under normal conditions, actual atmospheric pressure or air pressure is usually around 14. As your vehicle runs, the sending unit is constantly monitoring the level of fuel in the tank. Service pass code is 4011. causing a positive fuel trim. A -20 percent short term fuel. Engine misses at idle and under acceleration, if kick gas pedal down til engine reaches between 3200 to 4000 RPM miss will clear up and run good for awhile. Codes 171 and 174 indicate a lean condition for banks 1 or 2. Point of clarification on the fuel trim values: In my OBD-II reader app, the values are shown as follows: Fuel trim bank 1 sensor 1 = FT 1x1. Most common is 32. 03%, Short term fuel trim B2 + 2. Replied by Andy. A -20 percent short term fuel. It doesn't show o2 readings & the fuel trims are still -100 in live data. In a properly functioning system, the ECU will react and immediately make changes as the exhaust gases change. . Reading the codes helps but there is much more info to be seen and understood in the quest of maintaining or repairing an ailing car. 2 posts • Page 1 of 1. or contaminated mass airfl ow (MAF) 30 mph), moderate load (40 to 50. 3. system assigns a number between 0 and 255 to define fuel trim, with 128 being the middle point. 7 units of air to 1. Fuel trim is the adjustment the engine computer makes to the fuel mixture to maintain a balanced air/fuel ratio. The opposite happens when the o2 sensor sends a rich mixture signal to the PCM. The Fuel Learn is saved in the computer’s memory, and can only be cleared by setting the “Reset Fuel Learn” to 1, and then turning. For values >+ 7% adaption, fuel is added to compensate for lean running. That is where the long term fuel trim kicks in. The short term fuel trim (STFT) refers to immediate changes in fuel occurring several times per second. Starting at just $13,145, the Escort ZX2 offers a compelling entry-level value, but the price rises quickly as power goodies are piled on. So a short term fuel trim reading of +20 percent indicates 20 percent more fuel had to be added to achieve the proper air-fuel mixture. Faulty evaporative emissions system - bleeding fuel vapors into engine (not commanded by computer) 5. The long-term fuel trim (LTFT) is the accumulated data from the short-term trims. If I swap for a new sensor, the short term trim values go up to 30% even as high as 40% and the long term values typically drop to 0% and hold so steady that it seems it isn't trusting the readings. 2. A fuel pump current test reveals higher than normal current flow. 97 4.