Mitsubishi Eclipse 3G Club banner

1 - 15 of 15 Posts

·
Registered
Joined
·
496 Posts
Discussion Starter · #1 ·
ok, so i ve got a problem w/ my car. Sensors say its running crazy lean, but i can smell fuel in the exhaust. This is causing my car to misfire. Ive been trouble shooting it for about 3 weeks now... ive replaced all the o2 sensors, recheched my injector and emanage wiring, checked for exhaust leaks, and reset the ecu multiple times. Still cant get it fixed.

I was working on it tonight and;

took out the emanage again. and filled up on gas. turned the FP down as low as i could get it (it was 20 psi while idling), car was going lean again.

I turned up the FP (went to 35psi at idle). now the wb shows the AF coming down to 14.7, but something weird happens.

watching my fuel trims it starts at

LTFT bank 1 = -25%
LTFT bank 2 = 24.2%
STFT bank 1 = -18%
STFT bank 2 = -18%
STFT bank 1 sensor 1= -18%
STFT bank 1 sensor 2= 99.2%
STFT bank 2 sensor 1= -18%
STFT bank 2 sensor 2= 99.2%

but the AF is at a high 16, low 17. then the AF starts to come down and the bank 2 fuel trims start climbing. Gets to about 14.7 and the fuel trims are

LTFT bank 1 = -25%
LTFT bank 2 = 24.2%
STFT bank 1 = -18%
STFT bank 2 = 18%
STFT bank 1 sensor 1= -18%
STFT bank 1 sensor 2= 99.2%
STFT bank 2 sensor 1= 18%
STFT bank 2 sensor 2= 99.2%

then all of a sudden, the fuel trims jump back to the negative numbers again, and the AF spikes back to 16-17. Then climbs back to 14.7 as the fuel trim climbs back up, then when it hits stoich again, resets back to negative and higher AF. i dont quite understand whats going on here.

Also, is it kinda wierd that i have 450cc injectors w/o any kinds of fuel correction at 35psi and the car is idling ok , and in fact, having to add fuel?

maybe i got a few bad injectors up front?
 

·
New daddy
Joined
·
3,352 Posts
The front bank is definately running lean. Both banks should be running about the same fuel trim. You should make sure all of your injectors are firing. Recheck all of your wiring. I have also heard of several people frying the an injector driver in the ECU when going with bigger injectors.
 

·
Registered
Joined
·
496 Posts
Discussion Starter · #4 ·
all wiring was checked, ecu reset, injectors mixed around.. same result..

starting to lean towards fried ECU :scream:
 

·
First Sergeant
Joined
·
671 Posts
Not sure if this will help, but I will say I had my share of issues... I remember when soldering the new injector clips, the two wires for each injector had a common wire. I made sure the common was in the same place for each clip and it cleared the issue of the banks running leaner than one another.
 

·
OMFG
Joined
·
6,632 Posts
6g72 said:
ok, so i ve got a problem w/ my car. Sensors say its running crazy lean, but i can smell fuel in the exhaust. This is causing my car to misfire. Ive been trouble shooting it for about 3 weeks now... ive replaced all the o2 sensors, recheched my injector and emanage wiring, checked for exhaust leaks, and reset the ecu multiple times. Still cant get it fixed.

I was working on it tonight and;

took out the emanage again. and filled up on gas. turned the FP down as low as i could get it (it was 20 psi while idling), car was going lean again.

I turned up the FP (went to 35psi at idle). now the wb shows the AF coming down to 14.7, but something weird happens.

watching my fuel trims it starts at

LTFT bank 1 = -25%
LTFT bank 2 = 24.2%
STFT bank 1 = -18%
STFT bank 2 = -18%
STFT bank 1 sensor 1= -18%
STFT bank 1 sensor 2= 99.2%
STFT bank 2 sensor 1= -18%
STFT bank 2 sensor 2= 99.2%

but the AF is at a high 16, low 17. then the AF starts to come down and the bank 2 fuel trims start climbing. Gets to about 14.7 and the fuel trims are

LTFT bank 1 = -25%
LTFT bank 2 = 24.2%
STFT bank 1 = -18%
STFT bank 2 = 18%
STFT bank 1 sensor 1= -18%
STFT bank 1 sensor 2= 99.2%
STFT bank 2 sensor 1= 18%
STFT bank 2 sensor 2= 99.2%

then all of a sudden, the fuel trims jump back to the negative numbers again, and the AF spikes back to 16-17. Then climbs back to 14.7 as the fuel trim climbs back up, then when it hits stoich again, resets back to negative and higher AF. i dont quite understand whats going on here.

Also, is it kinda wierd that i have 450cc injectors w/o any kinds of fuel correction at 35psi and the car is idling ok , and in fact, having to add fuel?

maybe i got a few bad injectors up front?
Looks to me like your O2 sensors are doing a freaky dance.
 

·
Registered
Joined
·
496 Posts
Discussion Starter · #11 ·
rear o2 is at 920-940mv w/ injectors leaned out as far as the ecu can handle (-25% ft), front is at 305-315mv w, injectors at max (24.2%ft), o2s in the dp range from 650-750mv (stoich to rich). i thought it might be a bad o2 but i switched it out twice, and when i switch it w/ the widband, the wb reads lean in the front mani, and the stock narrowband reads stoich in the dp so its reading ok.
 

·
Registered
Joined
·
507 Posts
This may be a stupid newbie type question, but could one of the the 2 pre-cat 02 sensors be replaced with one of the 2 post cat 02 sensors?
I ask b/c I have a similar problem.
 

·
Registered
Joined
·
507 Posts
Let me tell you my story.
First I'll tell you my set up.
03 V6 Manual 35K with CAI, AMSS Headers, No CAT, and A Greddy Cat-back, Magnacore Wires and Denso Iridium plugs. I also have an Apexi S-AFC I (not really tuned).
Been running like this for at least a yr (except for the cat-back) that's only been like a month.
So here's what happened. I am driving home and as usual I'm running slitly rich according to my AF Gauge (like usual). Suddenly it starts lighting up all the way from lean to my normal rich level. Does this for like 3-4 minutes and then just stays at extremly lean. With no surprise on comes the SES light.
So after going to autozone, my ECU tells me Bank 1 too lean. A code that popes up from time to time for me. So I adjust my S-AFC a little and reset my ECU. When I turn the car on no SES light, but still reading lean and with in a few minutes SES back on.
I too smell gas when I'm just idling at a light or when I park so I know there's plenty of gas flowing, but still it's reading lean. I figure I just need to replace the 02 sensor. I just thought since I have a sim for the rear 2 maybe I can just swap them out.
Oh I forgot to mention I also have a ZEX 75 dry shot of NOS, that I use extremly sparingly. Though I did use it a few days before this all happened.
God that was a lot to type.
So any advice?
 

·
Registered
Joined
·
496 Posts
Discussion Starter · #14 ·
<80> said:
Let me tell you my story.
First I'll tell you my set up.
03 V6 Manual 35K with CAI, AMSS Headers, No CAT, and A Greddy Cat-back, Magnacore Wires and Denso Iridium plugs. I also have an Apexi S-AFC I (not really tuned).
Been running like this for at least a yr (except for the cat-back) that's only been like a month.
So here's what happened. I am driving home and as usual I'm running slitly rich according to my AF Gauge (like usual). Suddenly it starts lighting up all the way from lean to my normal rich level. Does this for like 3-4 minutes and then just stays at extremly lean. With no surprise on comes the SES light.
So after going to autozone, my ECU tells me Bank 1 too lean. A code that popes up from time to time for me. So I adjust my S-AFC a little and reset my ECU. When I turn the car on no SES light, but still reading lean and with in a few minutes SES back on.
I too smell gas when I'm just idling at a light or when I park so I know there's plenty of gas flowing, but still it's reading lean. I figure I just need to replace the 02 sensor. I just thought since I have a sim for the rear 2 maybe I can just swap them out.
Oh I forgot to mention I also have a ZEX 75 dry shot of NOS, that I use extremly sparingly. Though I did use it a few days before this all happened.
God that was a lot to type.
So any advice?
please make your own thread, dont thread jack mine.. Im trying to get advice...
 

·
Registered
Joined
·
507 Posts
Sorry, I thought they were similar enough that we could both benifit.
 
1 - 15 of 15 Posts
Top