what is code of system too lean bank 1
11-23-08, 09:15 PM
#1
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I need the serious input of knowledgeable mechanic
I have a 1998 GS 400 with 225,000 miles no problems until now. A couple of months (warm weather) I drove the car about 15 miles then all of a sudden it would not response to the throttle, it would only take fuel and pull out when I would push the foot accelerator to the floor. I cleaned the MAS (mass air sensor) and it ran ok for 2 months until I thought I would change the fuel filter. After changing the fuel filter the car ran excellent all that day, but the next morning it would not start and when it would try to start it was rough idle and would not take fuel. I took the fuel assembly back out, I had failed to put the plastic line reducer that comes from the filter to the top of the assembly to go to the fuel line going from the fuel pump to the fuel line to the engine. This time it ran excellent for 1 or 2 days then got code po171 I think (it was system too lean bank 1). I then changed the MAS and it helped a little but now ( warm weather mornings) the car cranks longer to start and when it starts it runs ok for 10 seconds then idles down to die, I can pump the accelerator and when I push it down the engine dies down and when I let off the engine idles up, so I have to pump the accelerator to keep the car running. After 5 minutes or so the car runs fine and at 2500 rpm it really takes off. I called the Lexus dealer he said I needed to bring car in, well I did and guess what they said I needed both oxygen sensors and that would fix it. When I picked up the car the check engine light was off for about 5 miles then back on, I called them and they said I needed a new fuel pump for $550 I purchased one myself for $240 and installed it,the car ran excellent for about 4 days and close to 1000 miles. Then it started to be hard to start, but now it's cold weather and the car start better but still won't take gas upon starting and after 5 minutes it runs better. Now it runs ok after let idle for 10 minutes but upon heavy accelerating I often get a back fire through the intake and the car doesn't take fuel too good when pulling up hills, you can fill the surge. This car has a mind of its own, sometimes runs good and sometime its dangerous to pull out in traffic. I had a local mechanic look at it and he said he heard a clicking sound near the throttle body and when metering one side showed 0 and the other side had 15, I really do not know what he was talking about, so I took the car to a local Toyota dealer and they put a meter on the car and said that the throttle body showed 19 % at low throttle and only 49% at full throttle. The mechanic there thought I needed a new throttle body, but when I mention it to Lexus they said they had never heard of replacing a throttle body. So I am confused the car now shows a check engine light and when I check it the code was system too lean bank 1. I really love the car and hope to be able to keep it for another 100,000 miles, but I really can't continue to drive with the engine running so poorly. I am new to this forum, but seems most people here are great car guys and very knowledgeable with honest information. Seems the Lexus dealer didn't try to find the root problem, I had talked to the service manager many times about the problems, but when I took the car in he didn't get involved. I think any time you have a fuel problem (rich or lean) the sensors would signal a check engine light and not necessarily need changing. I plan to purchase the 1998 GS 400 manuals if I can find a set reasonable.
Hope this is not too much, but seems this problem may be common and fixable.
Hope this is not too much, but seems this problem may be common and fixable.
Last edited by kyGS400; 11-24-08 at 08:34 PM. Reason: title
but the code is P0171
09-02-10, 01:37 PM
#3
I have a 1998 GS 400 with 225,000 miles no problems until now. A couple of months (warm weather) I drove the car about 15 miles then all of a sudden it would not response to the throttle, it would only take fuel and pull out when I would push the foot accelerator to the floor. I cleaned the MAS (mass air sensor) and it ran ok for 2 months until I thought I would change the fuel filter. After changing the fuel filter the car ran excellent all that day, but the next morning it would not start and when it would try to start it was rough idle and would not take fuel. I took the fuel assembly back out, I had failed to put the plastic line reducer that comes from the filter to the top of the assembly to go to the fuel line going from the fuel pump to the fuel line to the engine. This time it ran excellent for 1 or 2 days then got code po171 I think (it was system too lean bank 1). I then changed the MAS and it helped a little but now ( warm weather mornings) the car cranks longer to start and when it starts it runs ok for 10 seconds then idles down to die, I can pump the accelerator and when I push it down the engine dies down and when I let off the engine idles up, so I have to pump the accelerator to keep the car running. After 5 minutes or so the car runs fine and at 2500 rpm it really takes off. I called the Lexus dealer he said I needed to bring car in, well I did and guess what they said I needed both oxygen sensors and that would fix it. When I picked up the car the check engine light was off for about 5 miles then back on, I called them and they said I needed a new fuel pump for $550 I purchased one myself for $240 and installed it,the car ran excellent for about 4 days and close to 1000 miles. Then it started to be hard to start, but now it's cold weather and the car start better but still won't take gas upon starting and after 5 minutes it runs better. Now it runs ok after let idle for 10 minutes but upon heavy accelerating I often get a back fire through the intake and the car doesn't take fuel too good when pulling up hills, you can fill the surge. This car has a mind of its own, sometimes runs good and sometime its dangerous to pull out in traffic. I had a local mechanic look at it and he said he heard a clicking sound near the throttle body and when metering one side showed 0 and the other side had 15, I really do not know what he was talking about, so I took the car to a local Toyota dealer and they put a meter on the car and said that the throttle body showed 19 % at low throttle and only 49% at full throttle. The mechanic there thought I needed a new throttle body, but when I mention it to Lexus they said they had never heard of replacing a throttle body. So I am confused the car now shows a check engine light and when I check it the code was system too lean bank 1. I really love the car and hope to be able to keep it for another 100,000 miles, but I really can't continue to drive with the engine running so poorly. I am new to this forum, but seems most people here are great car guys and very knowledgeable with honest information. Seems the Lexus dealer didn't try to find the root problem, I had talked to the service manager many times about the problems, but when I took the car in he didn't get involved. I think any time you have a fuel problem (rich or lean) the sensors would signal a check engine light and not necessarily need changing. I plan to purchase the 1998 GS 400 manuals if I can find a set reasonable.
Hope this is not too much, but seems this problem may be common and fixable.
Hope this is not too much, but seems this problem may be common and fixable.
03-15-13, 10:14 PM
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Did you fix this problem?? I hav the same problem although mine has gotten worse to where the car is almost undrivable..I either have the gas pedal mashed or ill go no where...I've replaced throttle body all sensors on throttle body. .maf sensor..coil packs..plugs..fuel pump and just replacd one o2 sensor..car still reads codes P0172 and P0175 I think those are t he codes....but its bank 1 &2 too rickw
01-15-16, 05:44 AM
#7
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03-12-16, 04:01 PM
#8
I have a 1998 GS 400 with 225,000 miles no problems until now. A couple of months (warm weather) I drove the car about 15 miles then all of a sudden it would not response to the throttle, it would only take fuel and pull out when I would push the foot accelerator to the floor. I cleaned the MAS (mass air sensor) and it ran ok for 2 months until I thought I would change the fuel filter. After changing the fuel filter the car ran excellent all that day, but the next morning it would not start and when it would try to start it was rough idle and would not take fuel. I took the fuel assembly back out, I had failed to put the plastic line reducer that comes from the filter to the top of the assembly to go to the fuel line going from the fuel pump to the fuel line to the engine. This time it ran excellent for 1 or 2 days then got code po171 I think (it was system too lean bank 1). I then changed the MAS and it helped a little but now ( warm weather mornings) the car cranks longer to start and when it starts it runs ok for 10 seconds then idles down to die, I can pump the accelerator and when I push it down the engine dies down and when I let off the engine idles up, so I have to pump the accelerator to keep the car running. After 5 minutes or so the car runs fine and at 2500 rpm it really takes off. I called the Lexus dealer he said I needed to bring car in, well I did and guess what they said I needed both oxygen sensors and that would fix it. When I picked up the car the check engine light was off for about 5 miles then back on, I called them and they said I needed a new fuel pump for $550 I purchased one myself for $240 and installed it,the car ran excellent for about 4 days and close to 1000 miles. Then it started to be hard to start, but now it's cold weather and the car start better but still won't take gas upon starting and after 5 minutes it runs better. Now it runs ok after let idle for 10 minutes but upon heavy accelerating I often get a back fire through the intake and the car doesn't take fuel too good when pulling up hills, you can fill the surge. This car has a mind of its own, sometimes runs good and sometime its dangerous to pull out in traffic. I had a local mechanic look at it and he said he heard a clicking sound near the throttle body and when metering one side showed 0 and the other side had 15, I really do not know what he was talking about, so I took the car to a local Toyota dealer and they put a meter on the car and said that the throttle body showed 19 % at low throttle and only 49% at full throttle. The mechanic there thought I needed a new throttle body, but when I mention it to Lexus they said they had never heard of replacing a throttle body. So I am confused the car now shows a check engine light and when I check it the code was system too lean bank 1. I really love the car and hope to be able to keep it for another 100,000 miles, but I really can't continue to drive with the engine running so poorly. I am new to this forum, but seems most people here are great car guys and very knowledgeable with honest information. Seems the Lexus dealer didn't try to find the root problem, I had talked to the service manager many times about the problems, but when I took the car in he didn't get involved. I think any time you have a fuel problem (rich or lean) the sensors would signal a check engine light and not necessarily need changing. I plan to purchase the 1998 GS 400 manuals if I can find a set reasonable.
Hope this is not too much, but seems this problem may be common and fixable.
Hope this is not too much, but seems this problem may be common and fixable.
03-12-16, 04:09 PM
#10
back firing could be caused by valve timing your timing belt could have jumped a tooth. a/f sensor could be stuck lean and not making the adjustments. you need to check your freeze frame data it would tell you alot.
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