LTFT at 25 :(
Thread Starter
TECH Apprentice
Joined: Jul 2002
Posts: 393
Likes: 0
From: Tucson, AZ
LTFT at 25 :( Well, I got my EFIlive yesterday and aside from those bi-directional controls (which I'll go back to later), everything works Ok. Now the problems:
Codes (current):
1) P0121 (throttle/pedal position sensor/switch a circuit range/performance problem)
2) P0137 (O2 sensor circuit low voltage, Bank 1 Sensor 2)
3) P0157 (O2 sensor circuit low voltage, Bank 2 Sensor 2)
At WOT both LTFT are at *** 24-25% ***
and typical values at cruise/idle are 5-12%, B1 is typically slightly higher (~2%)
Both B1S1 and B2S1 at WOT are VERY low (<100mV) and knock at WOT is common - up to 4 degr....
Advance at WOT is 25-29.5 (less when KR kicks in).
AFR at WOT goes to 11.7 (doesn't say much, I guess)
The car is a 99 model with 73k miles and does have hand-ported MAF ends, however that was done 1.5 years ago and I started to notice problems (KR) this summer.
So what could possibly cause that? The plugs (TR55) have ~10kmiles on them and will also be replaced shortly, but I don't think that's an issue..
I'm thinking about replacing the fuel filter ASAP, please tell what could be an issue, 'cause I don't feel good at all.
Codes (current):
1) P0121 (throttle/pedal position sensor/switch a circuit range/performance problem)
2) P0137 (O2 sensor circuit low voltage, Bank 1 Sensor 2)
3) P0157 (O2 sensor circuit low voltage, Bank 2 Sensor 2)
At WOT both LTFT are at *** 24-25% ***
and typical values at cruise/idle are 5-12%, B1 is typically slightly higher (~2%) Both B1S1 and B2S1 at WOT are VERY low (<100mV) and knock at WOT is common - up to 4 degr....
Advance at WOT is 25-29.5 (less when KR kicks in).
AFR at WOT goes to 11.7 (doesn't say much, I guess)
The car is a 99 model with 73k miles and does have hand-ported MAF ends, however that was done 1.5 years ago and I started to notice problems (KR) this summer.
So what could possibly cause that? The plugs (TR55) have ~10kmiles on them and will also be replaced shortly, but I don't think that's an issue..
I'm thinking about replacing the fuel filter ASAP, please tell what could be an issue, 'cause I don't feel good at all.
Thread Starter
TECH Apprentice
Joined: Jul 2002
Posts: 393
Likes: 0
From: Tucson, AZ
Originally Posted by BLKTA
Put the stock MAF back on and that should take care of the lean condition. I'm suprised you haven't set codes for that.
Anybody else have a theory? I'm thinking, and this is supported by EFIlive.com people, that the fuel system is clogged or something like that. I did run a bottle of GM fuel injector cleaner before my last oil change. I'll change the fuel filter tomorrow and see what happens but would very much like to hear opinions.
Thread Starter
TECH Apprentice
Joined: Jul 2002
Posts: 393
Likes: 0
From: Tucson, AZ
Originally Posted by horist
no exhaust leaks correct? if there's an exhaust leak (corrosion near cats maybe?) it can mess w/the computer...
Is there a way to tell for sure? ...if that's the case, then it's time for the headers :p
TECH Senior Member
Joined: Nov 2001
Posts: 9,246
Likes: 3
From: Troy, AL
An exhaust leak should mess up your Ltrims at cruise and idle but you said you're within' 5-12% so I don't think you have one (you should hear it anyway.) Likewise, a vacume leak should screw with it at idle and cruise too.
Your S2 sensors aren't effecting your performance so don't worry about that unless the SES light in your face is bothering you.
You're getting no S1 codes, right?
Your O2 readings of .100 at WOT is certainly a problem. A fuel system shortage is my guess. Hook a fuel pressure gage to the fuel rail and monitor at WOT. The pressure shouldn't drop below 50 psi.
Your S2 sensors aren't effecting your performance so don't worry about that unless the SES light in your face is bothering you.
You're getting no S1 codes, right?
Your O2 readings of .100 at WOT is certainly a problem. A fuel system shortage is my guess. Hook a fuel pressure gage to the fuel rail and monitor at WOT. The pressure shouldn't drop below 50 psi.
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Thread Starter
TECH Apprentice
Joined: Jul 2002
Posts: 393
Likes: 0
From: Tucson, AZ
Originally Posted by Colonel
An exhaust leak should mess up your Ltrims at cruise and idle but you said you're within' 5-12% so I don't think you have one (you should hear it anyway.) Likewise, a vacume leak should screw with it at idle and cruise too.
Your S2 sensors aren't effecting your performance so don't worry about that unless the SES light in your face is bothering you.
You're getting no S1 codes, right?
Your O2 readings of .100 at WOT is certainly a problem. A fuel system shortage is my guess. Hook a fuel pressure gage to the fuel rail and monitor at WOT. The pressure shouldn't drop below 50 psi.
Your S2 sensors aren't effecting your performance so don't worry about that unless the SES light in your face is bothering you.
You're getting no S1 codes, right?
Your O2 readings of .100 at WOT is certainly a problem. A fuel system shortage is my guess. Hook a fuel pressure gage to the fuel rail and monitor at WOT. The pressure shouldn't drop below 50 psi.
That's what I'm thinking. I just replaced the fuel filter, it has not been replaced in a while, and reset the PCM, so all LTFT's are at 0, STFT's don't look maxed out, but I'll check again next weekend and check the fuel pressure at that time.
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