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P0170 1997 Montero - frustrated

Model: 1997 Montero Fault Code: P0170 Posted: 2014-06-14 13:17

My 1997 Mitsubishi Montero has been throwing a P0170 code for the past 2 years and after several trips my local mechanic and the dealership it's still not fixed. Some 2 years ago after several repairs I was able to get the Montero through emmission althought the P0170 code was present the Check Engine light had not come on yet and passed. What I can tell you based on all my code readings with my generic scanner tool is it alwas has Misfire, Fuel and Comp as "Ready"; none of the others show ready at any point from what I can tell which include Cat, EVAP, O2 and EGR. Note: at no point was my car running bad, maybe bad gas milage but not sure, it gets about 230 miles to a tank of gas and I do allot of city driving. 1st time at my mechanic he replaced some vaccuum lines, fuel filter, air filter and suggested it most likely was the Mass Air Flow Sensor but want to try these first, light came back in with in 100 miles after reset, took it back to him and not exactly sure what he did as he didn't charge me and said in about 50 miles the drive cycle should be ready and go to emmissions - it failed the first time as the sensors were not all ready 2nd figured I would get a second option so I took my Montero to a reputable garage and had them check it out, they suggested a Mass Air Flow sensor and or the PCM/ECM (computer) was probably at fault but not guarenteed; estimated repairs was well over $1000 bucks so I decided to replace the MAF sensor myself, reset P0170 code, after about 100 miles the Check Engine light came back on and yup P0170 is the code. Frustrated at this point, decided I'd replace the ECM/PCM but bought a used one from a salavge yard with the exact same serial numbers, pluged it in and of course the code was reset as I unhooked the battery. I drove my Montero around for about a week and maybe put 150 miles on it, I check it and the P0170 was present again but no check engine light. I took it up and had the emmission retested and it passed. about 40 miles later the Check engine light came back on. Since the car was running fine and I passed I just removed the bulb and left it alone. 2 years later I need emmissions done again but want to mention that I had allot of service work done on my Montero over the last two years to include full tune up, all fluids replaced, timing belt, water pump, valve seals, valve cover gaskets, etc. as I really like my SUV and wanted to keep it going for a long time. 3rd place, I replaced the bulb so that I could go through emmission again hoping to get though like I did before but decided I should take this to the dealer, both previous mechanics suggested this as well but I did since I got though emmissions. The Mitsubishi dealer replaced a emmisions valve solenoid, vacuum lines and advised that this could be the cause of my P0170 but believed the O2 sensors were bad. Well about 150 miles later my Check Engine light is back on and again P0170 code is back - argh so frustrated at this point. I decided to replace the O2 sensors both up and downstream, I used Denso replacement O2 senors as these were what were on my Montero and based on my research what the factory used. Well in about 30 miles bam, my Check Engine light is back on again with P0170. I have no idea what to do at this point and really concerned since my Check Engine light came back on so quickly, I've spent allot of money, time, and just plain frustrated at this point. I love my Montero and other than the stupid light it's perfect in every way. I have since bought a nicer OBD tester and can provide the full scan results if someone is kind enough to help me. Seems like in general these P0170 are a real pain in the butt - I couldn't agree more but if the pros can't even figure this out what am I suppose to do??? I would greatly appreciate anyones advise, feedback, suggestions. Today, I cleaned to the orginal MAF sensor and reinstalled it, cleaned air intake system, air filter, PCV value and replaced a tube t hat went to the valve cover to the air cleaner hose as it was pretty dry rotted. My system is resent, crossing fingers but thinking this is a long shot. I still can't figure out why all my sensors don't show ready except the general 3 misfire, fuel and comp but yet I did get it to pass two years ago. Sorry for the long story - HELP

Related fault codes
P0170
Comments (13)
Anonymous 2014-06-14 14:11

do you have a scanner capable of live data?

Anonymous 2014-06-15 08:45

Hi Kev2, Yes I have a CEN-TECH OBDII scan tool and my live data is below, this was shortly after the reset yesterday. I can also provide the live data prior to my reset with the P0170 showing. Just let me know. Oh quick question, it seems as if the data reads are the same but why does the scan tool come back with multiple data for the same thing? I only posted a couple from the about 8 data sets returned. Live Data Numbers of DTCs 1 Fuel system 1 statusOL Fuel System 2 status-- Calculated Load Value(%)28.2 Engine Coolant Temperature(¡£F)192 Short Term Fuel Trim -Bank 1(%)4.7 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 882 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)15.0 Intake Air Temperature(¡£F)114 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.02 Absolute Throttle Position(%)0.4 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)4.7 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.040 Short Term Fuel Trim Bank 1-Sensor 2(%)4.7 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL Fuel System 2 status-- Calculated Load Value(%)28.2 Engine Coolant Temperature(¡£F)192 Short Term Fuel Trim -Bank 1(%)4.7 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 910 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)15.0 Intake Air Temperature(¡£F)114 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.02 Absolute Throttle Position(%)0.4 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)4.7 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.040 Short Term Fuel Trim Bank 1-Sensor 2(%)4.7 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL Fuel System 2 status-- Calculated Load Value(%)28.2 Engine Coolant Temperature(¡£F)192 Short Term Fuel Trim -Bank 1(%)4.7 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 898 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)15.0 Intake Air Temperature(¡£F)114 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.02 Absolute Throttle Position(%)0.4 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)4.7 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.040 Short Term Fuel Trim Bank 1-Sensor 2(%)4.7 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL Fuel System 2 status-- Calculated Load Value(%)28.2 Engine Coolant Temperature(¡£F)192 Short Term Fuel Trim -Bank 1(%)4.7 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 914 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)15.0 Intake Air Temperature(¡£F)114 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.02 Absolute Throttle Position(%)0.4 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)4.7 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.040 Short Term Fuel Trim Bank 1-Sensor 2(%)4.7 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL Fuel System 2 status-- Calculated Load Value(%)22.0 Engine Coolant Temperature(¡£F)192 Short Term Fuel Trim -Bank 1(%)4.7 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 773 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)15.0 Intake Air Temperature(¡£F)114 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.01 Absolute Throttle Position(%)0.4 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)4.7 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.040 Short Term Fuel Trim Bank 1-Sensor 2(%)4.7 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL Fuel System 2 status-- Calculated Load Value(%)27.5 Engine Coolant Temperature(¡£F)192 Short Term Fuel Trim -Bank 1(%)4.7 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 742 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)10.0 Intake Air Temperature(¡£F)114 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.01 Absolute Throttle Position(%)0.4 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)4.7 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.040 Short Term Fuel Trim Bank 1-Sensor 2(%)4.7 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL Fuel System 2 status-- Calculated Load Value(%)26.3 Engine Coolant Temperature(¡£F)188 Short Term Fuel Trim -Bank 1(%)4.7 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 738 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)10.0 Intake Air Temperature(¡£F)114 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.01 Absolute Throttle Position(%)0.4 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)4.7 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.040 Short Term Fuel Trim Bank 1-Sensor 2(%)4.7 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL Fuel System 2 status-- Calculated Load Value(%)28.2 Engine Coolant Temperature(¡£F)188 Short Term Fuel Trim -Bank 1(%)4.7 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 878 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)12.0 Intake Air Temperature(¡£F)114 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.02 Absolute Throttle Position(%)0.4 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)4.7 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.040 Short Term Fuel Trim Bank 1-Sensor 2(%)4.7 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL Fuel System 2 status-- Calculated Load Value(%)28.6 Engine Coolant Temperature(¡£F)188 Short Term Fuel Trim -Bank 1(%)4.7 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 886 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)15.0 Intake Air Temperature(¡£F)114 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.02 Absolute Throttle Position(%)0.4 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)4.7 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.040 Short Term Fuel Trim Bank 1-Sensor 2(%)4.7 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL Fuel System 2 status-- Calculated Load Value(%)28.2 Engine Coolant Temperature(¡£F)188 Short Term Fuel Trim -Bank 1(%)4.7 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 898 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)15.0 Intake Air Temperature(¡£F)114 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.02 Absolute Throttle Position(%)0.4 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)4.7 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.040 Short Term Fuel Trim Bank 1-Sensor 2(%)4.7 OBD requirements to which vehicle is designedOBDII ---------------------- Thanks in advance for any advise. I appreciate it.

Anonymous 2014-06-15 09:00

check for a vacuum leak after the MAF- try the old school spray trick. FT are compensating and the idle RPM looks high.

Anonymous 2014-06-15 10:42

Thanks Kev2, could you explain exactly what the "old school spray trick" is, I googled it but lots of different opinions on it. Again thank you very much

Anonymous 2014-06-15 10:44

Also, here were the live scan results with the P0170 Read Codes P0170 $00 Generic Fuel Trim Bank 1 Live Data Numbers of DTCs 1 Fuel system 1 statusOL-Drive Fuel System 2 status-- Calculated Load Value(%)67.5 Engine Coolant Temperature(¡£F)192 Short Term Fuel Trim -Bank 1(%)0.0 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 0 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)61.0 Intake Air Temperature(¡£F)143 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.00 Absolute Throttle Position(%)0.0 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)0.0 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.020 Short Term Fuel Trim Bank 1-Sensor 2(%)0.0 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL-Drive Fuel System 2 status-- Calculated Load Value(%)67.5 Engine Coolant Temperature(¡£F)192 Short Term Fuel Trim -Bank 1(%)0.0 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 0 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)61.0 Intake Air Temperature(¡£F)143 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.00 Absolute Throttle Position(%)0.0 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)0.0 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.020 Short Term Fuel Trim Bank 1-Sensor 2(%)0.0 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL-Drive Fuel System 2 status-- Calculated Load Value(%)67.5 Engine Coolant Temperature(¡£F)192 Short Term Fuel Trim -Bank 1(%)0.0 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 0 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)61.0 Intake Air Temperature(¡£F)143 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.00 Absolute Throttle Position(%)0.0 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)0.0 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.020 Short Term Fuel Trim Bank 1-Sensor 2(%)0.0 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL-Drive Fuel System 2 status-- Calculated Load Value(%)67.5 Engine Coolant Temperature(¡£F)192 Short Term Fuel Trim -Bank 1(%)0.0 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 0 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)61.0 Intake Air Temperature(¡£F)143 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.00 Absolute Throttle Position(%)0.0 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)0.0 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.020 Short Term Fuel Trim Bank 1-Sensor 2(%)0.0 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL-Drive Fuel System 2 status-- Calculated Load Value(%)67.5 Engine Coolant Temperature(¡£F)192 Short Term Fuel Trim -Bank 1(%)0.0 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 0 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)61.0 Intake Air Temperature(¡£F)143 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.00 Absolute Throttle Position(%)0.0 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)0.0 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.020 Short Term Fuel Trim Bank 1-Sensor 2(%)0.0 OBD requirements to which vehicle is designedOBDII ---------------------- Numbers of DTCs 1 Fuel system 1 statusOL-Drive Fuel System 2 status-- Calculated Load Value(%)67.5 Engine Coolant Temperature(¡£F)192 Short Term Fuel Trim -Bank 1(%)0.0 Long Term Fuel Trim - Bank 1(%)12.5 Engine RPM(rpm) 0 Vehicle Speed Sensor(mph)0 Ignition Timing Advanece for #1 Cylinder(¡£)61.0 Intake Air Temperature(¡£F)143 Air Flow Rate from Mass Air Flow Sensor(lb/s)0.00 Absolute Throttle Position(%)0.0 Location of Oxygen SensorsB1S12--B2S---- Oxygen Sensor Output Voltage Bank 1-Sensor 1(V)0.040 Short Term Fuel Trim Bank 1-Sensor 1(%)0.0 Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.020 Short Term Fuel Trim Bank 1-Sensor 2(%)0.0 OBD requirements to which vehicle is designedOBDII ----------------------

Anonymous 2014-06-15 11:56

no need to post all that data... looking for a vacuum leak- using a can of carb cleaner- have engine at idle- spray possible vacuum leak areas*- if a leak is sprayed the engine RPM and sound will react to the carb cleaner - a quick subtle audible change in the engine will indicate a likely leak area. * all ducting after the MAF, all vac hoses lines fittings- PCV system. all gasket areas throttle body, manifolds, EGR< sensore in intake IAT MAP any possiable leak area.

Anonymous 2014-06-15 22:01

Thanks Kev for the additional information; I'll try this tomorrow and sorry for all the data I appreciate your help

Anonymous 2014-06-19 09:59

Hi Kev, sorry for the delay. So I did exactly as you recommended with the carb. spray (actually twice using almost two cans), I referred to my Mitsubishi dealer shop manual to locate all the emission vacuum lines to hone in on those areas. Not a bit of fluctuation in the RPM's/idle. Additionally, I used MAF cleaner and cleaned my OEM Mass Air Flow sensor, cleaned out all the intake lines, throttle, replace air cleaner, PCV valve and tightened all the hose/air duct connections. Cleared the P0170 code, about 65 miles after this work was performed the Check Engine light returned my infamous P0170 code. Any suggestions? Thanks again, I appreciate it.

Anonymous 2014-06-19 20:27

Were you ever able to go into closed loop as read on your scanner?

Anonymous 2014-06-20 10:17

I'm not 100% sure but what I can say based on what I read online regarding closed and open loop it most have. I didn't have my detailed scanner with me, just my pocket scanner and when the P0170 code appeared without the check engine light on, I immediately took it to get the emissions tested and it passed. Yay but still the darn code is present and about 5 miles from the testing facility my Check Engine light came back on. Grrrrrr I haven't cleared the code so I can get an updated reading for you if that will help. Thanks in advance. Adam

Anonymous 2014-06-20 12:33

Reason i asked is because your scan data always shows Fuel system 1 statusOL. The ECT/MAF are normal but B1S1 sensor is pegged lean(.04v). Since you haven't found air leaks,i would try to see if sensor will respond at all. Is this a one or two bank engine. I only see bank one data so guess its a one bank. Watch the O2 sensor voltage should be switching from 0-.8 about once a sec. If not PCM may stay in open loop and you can't finish monitor test you mentioned. While in Park and at idle quickly accelerate a couple of times to see if scan voltage responds at all. If not measure for v at sensor. You said you changed sensor at some point. Maybe it isn't sitting far enough into the exhaust stream. Also check sensor heater voltage and wiring from sensor to PCM if needed.

Anonymous 2015-07-23 10:42

I thank all for this discussion. I realize now that it's not just me and I've done all the things I should have to try and clear this but here I am again. My PO170 on 2001 Montero Limited has had this on going code come up for about 6 years. Check engine light is still on and I've done everything mentioned previously as you all have and every time I have to play the dance to get it to pass the emissions test. Well it's time again and I'm praying she passes.

Anonymous 2015-07-23 12:34

I feel your frustrations ladyingram and still have not resolved my check engine light issue, 1.5 years and I'll be going through the same thing but hope someone will help us out. I'm at a loss of what it could be but my Montero runs like a champ, uses no oil, starts every time and I just can't think of parting with it.