DME: Trimming, oxygen sensor before cat., Bank 2

[andrewwynn]

PS: if you don't have a tool with you to do adaptation reset, My original trick of unplug all O2, start the car a couple times, the plug them all back in seems to do the same function; even with my car running fairly lean (+7% long term), the error didn't come back for about 100 miles.

[Fifty150hs]

Originally Posted by andrewwynn

I had same problem/ish and did the same and it worked for like six months and came back. I'm suspecting i now actually have a vacuum leak or bum MAF. I'll probably finally make/rent/buy a smoke tester and if no smoke, i'll swap MAF back from wife's car to see if there is a change.

I did notice in my case that six mo. ago when i originally did like above and swap MAF with wife, the fuel trims were more like +6, ±1% (short/long) and now there are both showing like +5 +7, so the computer is definitely seeing too much air or too little fuel.

what are your fuel trims now showing? if the long term is close to zero i think you're golden. I think i just acquired a new vacuum leak not the same problem returning.

Wouldn't a vacuum leak throw a code?

[Fifty150hs]

Originally Posted by andrewwynn

I had same problem/ish and did the same and it worked for like six months and came back. I'm suspecting i now actually have a vacuum leak or bum MAF. I'll probably finally make/rent/buy a smoke tester and if no smoke, i'll swap MAF back from wife's car to see if there is a change.

I did notice in my case that six mo. ago when i originally did like above and swap MAF with wife, the fuel trims were more like +6, ±1% (short/long) and now there are both showing like +5 +7, so the computer is definitely seeing too much air or too little fuel.

what are your fuel trims now showing? if the long term is close to zero i think you're golden. I think i just acquired a new vacuum leak not the same problem returning.

Short terms are variable. -3 +/- to -4 +/- Long term steady at +7

[andrewwynn]

Originally Posted by Fifty150hs

Wouldn't a vacuum leak throw a code?

Yep sure does. Im getting a code within 10-50 miles after reset. I think it's actually MAF or an intake leak.


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[andrewwynn]

I think my lean codes mystery was solved last night when my fuel pump died. Hard failure just stopped while driving.

After it stalled I poked the fuel rail valve with a screwdriver and didn't even get a splurt.

The weird part is I thought I could hear the fuel pump hum but perhaps just too slow to generate any pressure.

Going with OEM brand this time. Knock off didn't last a year. I realized after I already had the knock off, so been mentally prepared for a while.

Funny thing is I actually thought to myself "if I don't have a vacuum leak, low fuel pressure will also cause a constant state of lean".