2G P0170 Error Code "Fuel Trim Malfunction (Bank1)"?

[jrpmp69]

The CEL keeps coming on in my 98 eclipse GST with error code "P0170""Fuel Trim Malfunction (Bank1)", It happened after installing the stock cat (for smog) and a new downstream O2 sensor, anybody have any idea of what could be causing this?

 

[L2RTSiAWD]

It means the car is too rich or too lean and the ECU can't compensate.

 

[jrpmp69]

It means the car is too rich or too lean and the ECU can't compensate.

Whats causing it to run rich or lean? and why cant the ECu compensate?

 

[L2RTSiAWD]

It's tough to say without a logger to read your fuel trims.

 

[L2RTSiAWD]

It tends to happen with you have bigger injecotrs and an AFC.

Or your #1 o2 sensor is goign bad.

 

[jrpmp69]

It tends to happen with you have bigger injecotrs and an AFC.

Or your #1 o2 sensor is goign bad.

I have stock injectors and no AFC, i did change the downstream sensor though and not the O2 sensor by the turbo. I am going to put the old downstream sensor back to see if that is what is causing this.

Any other suggestions would greatly help.

Thanks.

 

[98RedGs]

It's probably the top (main) o2 sensor unit in the o2 housing.
Pull it and make sure it's ok and double check to make sure it's the right one.

 

[jrpmp69]

I noticed that the downstream sensor that i installed was a bit shorter than the original, could it be a 1g sensor? would it affect the readings if it is a 1g sensor?

 

[98RedGs]

I noticed that the downstream sensor that i installed was a bit shorter than the original, could it be a 1g sensor? would it affect the readings if it is a 1g sensor?

Could make a difference...
Are they OEM sensors?

 

[jrpmp69]

Could make a difference...
Are they OEM sensors?

yes.

 

[L2RTSiAWD]

It could make a difference, Id double check the part number.

 

[jrpmp69]

It could make a difference, Id double check the part number.

I just called a Mitsubishi dealership and they told me that both part numbers are the same for 1g and 2g. Maybe its reading different because i didnt change the o2 sensor on the o2 sensor housing and it might be a liltle dirtier than the newer one. I will try putting back the old sensor to see if that is what is causing the error code. I will change it again once i get the other sensor to replace them at the same time.

 

[L2RTSiAWD]

The only thing the downstream one does is check if the cat is working.

 

[jrpmp69]

The only thing the downstream one does is check if the cat is working.

I was running a straight pipe before and the CEL never came on, it came on after putting the stock cat back on for smog purposes, which i cant get to pass.

 

[L2RTSiAWD]

I was running a straight pipe before and the CEL never came on, it came on after putting the stock cat back on for smog purposes, which i cant get to pass.

I also had a test pipe and got no CEL, i'm just saying that's all the o2 does back there.

 

[2GeNTSi]

i've had my downpipe on for a couple of months now and the cel just started to come up. It always happens while I'm on the highway though, so I guess while the o2 is getting a constant feed of exhaust gases and notices that the shit is dirty as hell. I've had about four cels in less then a month, one was that fuel trim one and the other three were for the cat.

 

[tsiturbomm]

The o2 sensor after that cat fine tunes the main 02, that is why you can get away with out them because it doesnt make that big of a difference!

 

[luvmygst]

Fuel trim malfunction usually means an exhaust leak. This causes the fuel trims to get out of wack and they go beyond their set limits, causing the CEL. Check to see of you have and manifold leaks, or a leak between the turbo and the manifold. I was having the same problem and I guy told me this, turns out I did have small leak. When I fixed it no more CEl's. Good luck hope it helps.

 

[always_broken]

Fuel trim malfunction usually means an exhaust leak. This causes the fuel trims to get out of wack and they go beyond their set limits, causing the CEL. Check to see of you have and manifold leaks, or a leak between the turbo and the manifold. I was having the same problem and I guy told me this, turns out I did have small leak. When I fixed it no more CEl's. Good luck hope it helps.

I might have an exhaust leak, is there a way to find out without turning the car on?

Or a way to see when the car is on? I did put a new turbo on along with new gaskets. Two of the exhaust manifold studs broke, one on the far left and one on the far right. Didn't think it would make a difference becuase the manifold doesn't budge.