Please help: lterms are lean : O2's are rich how is this possible?
Thread Starter
Staging Lane
Joined: Nov 2001
Posts: 57
Likes: 0
From: Warren,MI
Please help: lterms are lean : O2's are rich how is this possible? I have a 01 T/A A4. I have air lid, maf ends, baker hose, and timing tricker resesistor mod. The Lterms at Cruise are a little lean +3 to +13.3
But, at wot the O2 are rich .9 - .94. I don't understand how i can be lean at cruise and rich at wot. If i installed the stock maf, wouldn't i be even more rich at wot? Could the risistor in my air temp throw off the readings. Does any one else have the same problem or have seen anything like it? Finally, would it be worth it to buy a maf translator? Please help
Marco
But, at wot the O2 are rich .9 - .94. I don't understand how i can be lean at cruise and rich at wot. If i installed the stock maf, wouldn't i be even more rich at wot? Could the risistor in my air temp throw off the readings. Does any one else have the same problem or have seen anything like it? Finally, would it be worth it to buy a maf translator? Please help
Marco
TECH Apprentice
Joined: Dec 2001
Posts: 357
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From: Whitby Ont Canada
Re: Please help: lterms are lean : O2's are rich how is this possible? In my case after porting my MAF I was lean in cruise and WOT. Not saying you should buy a MAFT but with it you do have the option of adjusting the base and WOT A/F independently. You could set your base rich and your WOT slightly lean. <img src="graemlins/gr_chug.gif" border="0" alt="[chug]" />
Re: Please help: lterms are lean : O2's are rich how is this possible? I have been having the same issue. Never thought of the resistor as the culprit though. Mybe I will remove it. I can't seem to lean out the O2s no matter what?
TECH Senior Member
Joined: Nov 2001
Posts: 9,246
Likes: 3
From: Troy, AL
Re: Please help: lterms are lean : O2's are rich how is this possible? Sounds to me like a vacume leak (effects both banks) or an exhaust leak (would only effect the bank with the exhaust leak.) The unmetered air makes the O2s lean at idle and part throttle and the LTrims go positive trying to fix what the ECM *thinks* is a lean problem. Since the WOT is based on these enrichening closed loop settings, the result is a rich running engine. (Actually, it's running rich at all times in these scenarios but the ECM thinks it's running lean at anything other than WOT.)
Just a FYI, having a dead O2 sensor will do the same thing on the bad bank but you would see that in your O2 readings. The sensor would read .450mv or thereabouts at all times.
Just a FYI, having a dead O2 sensor will do the same thing on the bad bank but you would see that in your O2 readings. The sensor would read .450mv or thereabouts at all times.
