one bank normal, other bank rich
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Joined: Jan 2001
Posts: 50
From: So. Cal.
one bank normal, other bank rich
In trying to diagnose low dyno numbers, we noticed that autotap was showing each bank running very different fuel numbers. From what I recall, the numbers were about around -12.7 on one bank, and around 4.5 on the other. The car is a '97 LT1, here's some of the recent changes:
-plugs and wires are fairly new <15k miles
-o2 sensors are fairly new <15k miles
-injectors are new (previous injectors had the same issue)
-the MAF was originally throwing a code, but we cleaned it and it's no longer throwing codes, but the problem didn't go away
-no misfire codes
-fuel filter is new
Alas the problem is still there. What else can we check?
-plugs and wires are fairly new <15k miles
-o2 sensors are fairly new <15k miles
-injectors are new (previous injectors had the same issue)
-the MAF was originally throwing a code, but we cleaned it and it's no longer throwing codes, but the problem didn't go away
-no misfire codes
-fuel filter is new
Alas the problem is still there. What else can we check?
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Joined: Jun 2003
Posts: 709
From: Oklahoma
my first guess would be an o2, then i would say a dirty/bad injector, but u seem to have that covered. Must be pcm related unless you have used any kind fuel system cleaner that maybe have damaged one of them?
Thread Starter
Registered User
Joined: Jan 2001
Posts: 50
From: So. Cal.
This problem goes back about 5-6 months, and at the time one of the first things we tried was changing the O2's since they were the stockers. Although they have about 10-15k miles on them now, at the time they were swapped out new so I figure it can't be those.
Same for the injectors (our second guess). I had stock injectors that had about 50k miles on them so we changed them out with Accel's figuring that they may have been clogged. But that didn't help either
I haven't used any fuel system cleaner. I do always use 92 octane gas though and 99% of the time from the same place, the Chevron right near my house. I'm picky on gas and it always seemed like the car ran as good if not better (compared to other places) when filling up at that Chevron so I've stuck with it. The fuel filter was very recently changed though.
The motor has about 61k miles on it now so I figure theres just some other part that's beggining to fail or reach the end of its usefull life. Not sure which one just yet
But I assume it's responsible for the low dyno numbers since the best we can tune it now is to run one half of the motor correctly and the other half rich
Same for the injectors (our second guess). I had stock injectors that had about 50k miles on them so we changed them out with Accel's figuring that they may have been clogged. But that didn't help either
I haven't used any fuel system cleaner. I do always use 92 octane gas though and 99% of the time from the same place, the Chevron right near my house. I'm picky on gas and it always seemed like the car ran as good if not better (compared to other places) when filling up at that Chevron so I've stuck with it. The fuel filter was very recently changed though.
The motor has about 61k miles on it now so I figure theres just some other part that's beggining to fail or reach the end of its usefull life. Not sure which one just yet
But I assume it's responsible for the low dyno numbers since the best we can tune it now is to run one half of the motor correctly and the other half rich
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Joined: Sep 2002
Posts: 2,481
From: Arlington, VA
Originally posted by joker454
This problem goes back about 5-6 months, and at the time one of the first things we tried was changing the O2's since they were the stockers. Although they have about 10-15k miles on them now, at the time they were swapped out new so I figure it can't be those.
Same for the injectors (our second guess). I had stock injectors that had about 50k miles on them so we changed them out with Accel's figuring that they may have been clogged. But that didn't help either
I haven't used any fuel system cleaner. I do always use 92 octane gas though and 99% of the time from the same place, the Chevron right near my house. I'm picky on gas and it always seemed like the car ran as good if not better (compared to other places) when filling up at that Chevron so I've stuck with it. The fuel filter was very recently changed though.
The motor has about 61k miles on it now so I figure theres just some other part that's beggining to fail or reach the end of its usefull life. Not sure which one just yet But I assume it's responsible for the low dyno numbers since the best we can tune it now is to run one half of the motor correctly and the other half rich
This problem goes back about 5-6 months, and at the time one of the first things we tried was changing the O2's since they were the stockers. Although they have about 10-15k miles on them now, at the time they were swapped out new so I figure it can't be those.
Same for the injectors (our second guess). I had stock injectors that had about 50k miles on them so we changed them out with Accel's figuring that they may have been clogged. But that didn't help either
I haven't used any fuel system cleaner. I do always use 92 octane gas though and 99% of the time from the same place, the Chevron right near my house. I'm picky on gas and it always seemed like the car ran as good if not better (compared to other places) when filling up at that Chevron so I've stuck with it. The fuel filter was very recently changed though.
The motor has about 61k miles on it now so I figure theres just some other part that's beggining to fail or reach the end of its usefull life. Not sure which one just yet
But I assume it's responsible for the low dyno numbers since the best we can tune it now is to run one half of the motor correctly and the other half rich
Thread Starter
Registered User
Joined: Jan 2001
Posts: 50
From: So. Cal.
Thanks for the ideas guys! We'll check those out, but at this point we're thinking there is something more fundamentally wrong with the motor. Everything feels like its running just great (smooth, no knock, good dyno chart, no codes, etc...) but it just isn't making the power it should. With these mods:
K&N
Hotcam kit (cam/rockers/springs)
SLP shorty headers
LT4 KM
3.73's
Yank 3000
A4
Flowmaster catback
LT1Edit tuning
...the car made 274rwhp with my buddy Elis using LT1Edit doing the tuning. All the data looks ok, but we're missing 30-40rwhp somewhere. So far we've been changing parts here and there but nothing has made a difference yet so looks like its time to crack open the motor and figure out whats going on. Just gotta save up the $$$ for it
K&N
Hotcam kit (cam/rockers/springs)
SLP shorty headers
LT4 KM
3.73's
Yank 3000
A4
Flowmaster catback
LT1Edit tuning
...the car made 274rwhp with my buddy Elis using LT1Edit doing the tuning. All the data looks ok, but we're missing 30-40rwhp somewhere. So far we've been changing parts here and there but nothing has made a difference yet so looks like its time to crack open the motor and figure out whats going on. Just gotta save up the $$$ for it
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