Need opinion, lean condition
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TECH Senior Member
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From: Watertown, NY
Need opinion, lean condition I went out and did some logging tonight since I havent driven the car in 3 months. My LTFT Bank 1 was showing a percieved lean condition and adding %13 more fuel, way high. Bank 2 LTFT was around 2, which is good enough. Now i do have a wideband hooked up in the bank 1 stream. I had it dialed in before so that WOT AFR was at 13.0 actual. Now at WOT it is like 11.0-11.5 due to this percieved lean condition which is making the PCM add more fuel at WOT. If there was a real lean condition then i wouldnt be so rich at WOT so I am assuming the lean condition is percieved and there are no intake leaks.The oxygen sensor seems to be working ok abd switching enough. What are my possible problems? I was thinking there may be an exhaust leak before or right near the bank 1 oxygen sensor. A few months ago I did mess around with the block offs for the AIR and EGR, so maybe thats whats going on, although I cant hear a leak audibly. What do you guys think??
Even an o2 thats still switching fairly quickly could be showing signs of age and its switchpoint could start to stray away from stoich. I had this happen when one bank was much leaner than the other. Id replace them both just for piece of mind.
Thread Starter
TECH Senior Member
iTrader: (23)
Joined: Aug 2005
Posts: 8,797
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From: Watertown, NY
Originally Posted by GuitsBoy
Even an o2 thats still switching fairly quickly could be showing signs of age and its switchpoint could start to stray away from stoich. I had this happen when one bank was much leaner than the other. Id replace them both just for piece of mind.
Anyone else have an idea?
An injector problem could make a single cylinder lean out
and bump up the whole gang. One that is slow to open
for example, would affect the low end out of proportion
to WOT.
Similarly a small air leak on the intake or exhaust side,
would not be flow proportional but jack the low-flow
cells (0, 1, 4, 5) more than the rest.
As they age they also need more heat to stay working.
Headers can aggravate this big time, a brand new one
can get weak pretty quick if the pipes are shedding a
lot of heat.
and bump up the whole gang. One that is slow to open
for example, would affect the low end out of proportion
to WOT.
Similarly a small air leak on the intake or exhaust side,
would not be flow proportional but jack the low-flow
cells (0, 1, 4, 5) more than the rest.
As they age they also need more heat to stay working.
Headers can aggravate this big time, a brand new one
can get weak pretty quick if the pipes are shedding a
lot of heat.
