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Hello all, I have been a long time lurker and finally decided to create an account and make a post to ask for help. I have searched everywhere, every thread related to P0171 & P0174 codes but I could not find anything that was close to how my FJ has been acting lately. Here is what happened:

I have a 07 FJ cruiser with 216,000 miles. Last Friday afternoon after work I drove to Costco to put gas (I always use 87), a couple hours after (maybe less) my CEL turns on along with other 3 warning lights right below it. At first I thought maybe it was a loose gas cap but I tried tightening it and it was fine. I drove to AutoZone and that is when I get the P0171 & P0174 codes. My FJ was acting fine right until that point. As soon as I drove out of AutoZone the FJ starts jerking under acceleration, kinda like it was drowning. I took it to my mechanic the next day and he believes I need to replace the oxygen sensors, which according to this forum seems to be the solution. (already ordered along with URD fuel pump and will replace next Saturday), I also cleaned my MAF but that does not seem to help.

The past couple of days the FJ has become almost undrivable. I can't accelerate, anything past 2k RPM the engine starts jerking way too much, sometimes in the highway I hit the gas and there is no acceleration at all, other times as I try to pass a car or merge into the highway and when I accelerate the engine basically dies, RPMs go to zero immediately and it does not come back to its "normal" RPM level until I step off the gas. Every time I accelerate I have to make sure to keep it under 2k RPMs, and I can drive up to 60 MPH as long as I am very easy on the pedal.

As I mentioned before I will replace all 4 o2 sensors and fuel pump this weekend, but seeing how the FJ has been acting lately I am not sure if that will fix the problem or if there is anything else wrong with it. I also read somewhere that it might be due to "bad gas" so I put 4 gallons of 93 and I believe it made it a little bit better but the issues are still there.

Some information that I believe might be useful: Before this started, my FJ was experiencing an annoying surge between 2k and 3k RPMs, It was never noticeable under high acceleration but maybe at 30-50% gas, when passing on the highway. Here is a thread by another member that explains what happens.

I bought my FJ two months ago, and it has been perfect, despite of the miles it had no issues besides the surge I just described and now this.

Also, the only mods on my FJ are a 3-inch lift kit and 34 inch tires.
 

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Hello all, I have been a long time lurker and finally decided to create an account and make a post to ask for help. I have searched everywhere, every thread related to P0171 & P0174 codes but I could not find anything that was close to how my FJ has been acting lately. Here is what happened:

I have a 07 FJ cruiser with 216,000 miles. Last Friday afternoon after work I drove to Costco to put gas (I always use 87), a couple hours after (maybe less) my CEL turns on along with other 3 warning lights right below it. At first I thought maybe it was a loose gas cap but I tried tightening it and it was fine. I drove to AutoZone and that is when I get the P0171 & P0174 codes. My FJ was acting fine right until that point. As soon as I drove out of AutoZone the FJ starts jerking under acceleration, kinda like it was drowning. I took it to my mechanic the next day and he believes I need to replace the oxygen sensors, which according to this forum seems to be the solution. (already ordered along with URD fuel pump and will replace next Saturday), I also cleaned my MAF but that does not seem to help.

The past couple of days the FJ has become almost undrivable. I can't accelerate, anything past 2k RPM the engine starts jerking way too much, sometimes in the highway I hit the gas and there is no acceleration at all, other times as I try to pass a car or merge into the highway and when I accelerate the engine basically dies, RPMs go to zero immediately and it does not come back to its "normal" RPM level until I step off the gas. Every time I accelerate I have to make sure to keep it under 2k RPMs, and I can drive up to 60 MPH as long as I am very easy on the pedal.

As I mentioned before I will replace all 4 o2 sensors and fuel pump this weekend, but seeing how the FJ has been acting lately I am not sure if that will fix the problem or if there is anything else wrong with it. I also read somewhere that it might be due to "bad gas" so I put 4 gallons of 93 and I believe it made it a little bit better but the issues are still there.

Some information that I believe might be useful: Before this started, my FJ was experiencing an annoying surge between 2k and 3k RPMs, It was never noticeable under high acceleration but maybe at 30-50% gas, when passing on the highway. Here is a thread by another member that explains what happens.

I bought my FJ two months ago, and it has been perfect, despite of the miles it had no issues besides the surge I just described and now this.

Also, the only mods on my FJ are a 3-inch lift kit and 34 inch tires.
Have you checked if the fuel filter was ever changed?
 

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Sounds like it could be starved of fuel, I'm interested to see what the urd kit does for it. My engine used to kinda surge when accelerating with light throttle, but nothing like yours is acting now. I installed the urd pump and it's been great since. I think the screen/filter in the pump was the problem, it was very dirty when removed.
 

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There is no replaceable fuel filter on North American FJs.

However, your symptoms are consistent with a mixture-control or fuel starvation problem. Suggested actions are:
1. Inspect the air induction ducting to make sure there are no holes, cracks, or loose clamps that would allow air to be drawn in bypassing the MAF sensor. This would result in a lean condition.

2. The next task is to measure the fuel pressure by using an adapter that connects to the special quick-disconnect fittings on the fuel supply line. This is not a common tool, and probably can only be found in a Toyota dealership's service department.

With over 200K miles, it may be time to replace the fuel pump even if you are not able to measure fuel pressure. When the pump is removed, you will also be able to see if there is any debris clogging the fuel pump pick-up screen.

The fuel tank must be dropped to access the pump, so not something that wants to be done with a full tank of gas.
 

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2. The next task is to measure the fuel pressure by using an adapter that connects to the special quick-disconnect fittings on the fuel supply line. This is not a common tool, and probably can only be found in a Toyota dealership's service department.
I used this one on my 4Runner, same quick disconnect fittings, and it worked well:

 

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Hello all, I have been a long time lurker and finally decided to create an account and make a post to ask for help. I have searched everywhere, every thread related to P0171 & P0174 codes but I could not find anything that was close to how my FJ has been acting lately. Here is what happened:

I have a 07 FJ cruiser with 216,000 miles. Last Friday afternoon after work I drove to Costco to put gas (I always use 87), a couple hours after (maybe less) my CEL turns on along with other 3 warning lights right below it. At first I thought maybe it was a loose gas cap but I tried tightening it and it was fine. I drove to AutoZone and that is when I get the P0171 & P0174 codes. My FJ was acting fine right until that point. As soon as I drove out of AutoZone the FJ starts jerking under acceleration, kinda like it was drowning. I took it to my mechanic the next day and he believes I need to replace the oxygen sensors, which according to this forum seems to be the solution. (already ordered along with URD fuel pump and will replace next Saturday), I also cleaned my MAF but that does not seem to help.

The past couple of days the FJ has become almost undrivable. I can't accelerate, anything past 2k RPM the engine starts jerking way too much, sometimes in the highway I hit the gas and there is no acceleration at all, other times as I try to pass a car or merge into the highway and when I accelerate the engine basically dies, RPMs go to zero immediately and it does not come back to its "normal" RPM level until I step off the gas. Every time I accelerate I have to make sure to keep it under 2k RPMs, and I can drive up to 60 MPH as long as I am very easy on the pedal.

As I mentioned before I will replace all 4 o2 sensors and fuel pump this weekend, but seeing how the FJ has been acting lately I am not sure if that will fix the problem or if there is anything else wrong with it. I also read somewhere that it might be due to "bad gas" so I put 4 gallons of 93 and I believe it made it a little bit better but the issues are still there.

Some information that I believe might be useful: Before this started, my FJ was experiencing an annoying surge between 2k and 3k RPMs, It was never noticeable under high acceleration but maybe at 30-50% gas, when passing on the highway. Here is a thread by another member that explains what happens.

I bought my FJ two months ago, and it has been perfect, despite of the miles it had no issues besides the surge I just described and now this.

Also, the only mods on my FJ are a 3-inch lift kit and 34 inch tires.
Hi there, @Toyobobo2000...

I have a 2008 FJ with roughly 235k miles on it / I am the only owner / Regular maintenance. For the past 3 years, I have had very similar issues (same codes, as well as codes P2197 & P2195). I have not had as severe acceleration/deceleration issues, but I have had all 4 dash lights come on, some "stuttering" upon acceleration at highway speeds, as well as some above average (1000rpm+) rpms at stop lights or signs.

I have replaced O2 sensors multiple times, cleaned the MAF, replaced the MAF, checked for exhaust leaks, replaced spark plugs, replaced PCV valve, cleaned the throttle body, replaced A/F ratio sensor, etc. Upstream sensors are usually reading lean, downstream sensors are reading rich. I have tried using 87 and premium, replacing the gas cap, and yet still continue to have problems. I have taken it to the dealership, as well as a foreign car mechanic--all are stumped when things are not resolved with replacing these parts. My foreign car mechanic is so stumped that he doesn't always charge me for stuff because he hasn't been able to fix it.

Occasionally all lights will clear during a long drive, remaining off for an hour or sometimes 2 months, only to return again. At this point, I am curious if it is a wiring/electrical issue altogether. My FJ has had it's entire wiring harness replaced, but that was only a few months after I purchased in 2008 (thanks to a puppy). The lights seem to go on/off more often when it is raining, but I honestly have no clue if this is related....just an observation. Until this, I have had no problems with my FJ.

Curious if you figured anything else out regarding this issue! Thanks.
 

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Have you considered doing a fuel pressure test as noted by the others above, or replacing the fuel pump as suggested by FJTest?
@norm356, my foreign car mechanic did do a fuel pressure test, which came back fine. I have also considered replacing the fuel pump, but haven't really had any other typical failing fuel pump symptoms. So, was just putting feelers out to see if the pump replacement worked longer term for people for these issues.

At this point, replacing it will probably be my next step since nothing else has really helped! I am still driving it all of the time and have put 50k+ miles on it since this all started happening.
 

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For P0171 and P0174, the service manual says to check:
  • Air induction system
  • Injector blockage
  • MAF meter
  • ECT sensor
  • Fuel pressure
  • Gas leakage from exhaust system
  • Open or short in A/F sensor (bank 1 sensor 1) circuit
  • A/F sensor (bank 1 sensor 1)
  • A/F sensor heater (bank 1 sensor 1)
  • A/F sensor heater relay
  • A/F sensor heater and A/F sensor heater relay circuits
  • PCV hose connections
  • PCV valve and hose
  • ECM
Your FJ is at the age where the PCV and breather hoses have probably hardened and may be leaking or cracked. I recently replaced them on my 2013 FJ because they were hardening (pictures here). In hotter climates, these hoses fail even faster. On another toyota the PCV hose actually split causing the P0171. Maybe do a careful check of the PCV hose and breather hoses. If the rubber has hardened, then the spring clamps can no longer compress the rubber to make them seal, and leaks can occur. It only takes a few minutes to check these.
 
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