Concerning fuel trims

Gen pu > gen juan

 

I'm tempted to say o2 since afr's jump around as soon as the car gets up to temp. When cold, afrs were steady.
Cold:

Warm:


Going to get a sensor from the junkyard, also have been looking for an intercooler aswell

 

Did you ever unplug the secondary?

 

Sorry haven't gotten around to it. Had a few things I wanted to look at the junkyard, but tomorrow will give it a shot. Ebay currently has a 15% off deal so I'm thinking just buying a brand new one since the car is most parts but the motor is at 230k miles now.

After driving around today, even with the car hot from driving about 40 mins with many stop and goes twice and 3 on/off cycles; the car's ltft has remained +12%. A large improvement from the sudden +17% before. I'll unplug secondary tomorrow to see what changes as this time.

Side note, picked up a used intercooler with 0 bent fins and the only issue being it's filled with oil. Will clean out to replace my current one someday, not anytime soon. Since my current one looks like it's ate flat heads screwdrivers.

 

Did you spray any brake clean/carb cleaner around the leak with the bubbles you found? while the motor was running and watching your trims?

I'll take a screen shot of the ForScan pids to log later on..

Keep your Rear O2 plugged in and use it validate the front O2 sensor and what your trims are doing.. You want to log it and get the data..

 

If the rear o2 is the problem (and I've personally had this issue before, which is why I don't run one anymore), leaving it plugged in will continue to cause issues until he's replaced that rear o2. Leaving it unplugged does NOT harm anything and it's a simple test that doesn't cost anything.

There's clearly a reason I'm having him do that.

 

Get a proper data log first with it plugged in.. There's a diagnostic process I am suggesting since this problem can be 90% diagnosed with 1 test drive and proper data log... I don't disagree that the rear O2 can cause a problem... But when you don't follow a data based process you just get lost and throw parts at a problem and drive yourself nuts.. which is whats happening at this point..

 

How can you tell if the secondary is out of whack when it's logged as lean? Wonky trims for no reason is pretty much the same issue I had.
Also, in case you missed it, there's a log at the bottom of page 1.

 

Sorry for taking so long. Been a really busy week but had time this weekend to work on the car.

So, unplugged secondary o2, and results seem to be the same. Only as the car starts to get warmer does fuel trims get worse, though ever since the whole smoke fiasco I had, it has never went passed 14% ltft.

Warm
Hot


And that's basically it. I should've mentioned aswell, unless I forgot I did; throughout this whole fuel trim troubleshooting I do notice crackles in exhaust when giving it a small rev (under 3k) and idle nothing really pops. Crackles aren't loud, nor is it alot, very minimal. As much I like it, I'm pretty sure unburnt fuel ain't correct here.

Also cel for o2. I assume from it saying sensor 2, I did unplug the right one?


Going to reconnect the plug since nothing changed.

Edit: Suddenly as I was typing this out (5 minutes) long term decided to go to 13.28%.

 

Just odd. The car has reamined at 7% ltft after a drive today.

The only thing that changed between then and now is today is 65 degrees, yesterday was 80. Also ecu was reset during the whole o2 thing since I had to remove the battery to do it.

 

Why'd you post a photo of your driver's license?
Edit: Maybe it was a bad connection on the secondary O2.

 

Odd, accidentally hit the wrong pic on the gallery, had hit cancel before it finished uploading but might've gone through, thanks for letting me know.

I'll wait for a hotter day and maybe dog on the car a little bit to see if it will produce the same results for +12 ish and see if maybe it has to do with ambient temp, or I wonder if whatever deposits might've been on said sensors could've shaken loose after dogging the car more often than usual.

Will update either later today if I go out again, or later in the week when it's +80 outside.

 

Back to the usual it seems. Was a little hotter today than the previous. Until it gets back to being 80 degrees again, I'm gonna go out on a limb and say it maybe ambient temp related. Today was 65 but unlike yesterday when it was raining, today was full sunshine and definitely hotter.

When ltft was 14%, temp outside was 80+.

 

Did you spray the area you found bubbles with brake clean(non chlorinated), carb cleaner or propane while watching your trim data live??

You watch the O2 from cold start as it comes on line during warm up.. You watch how it's responding to changes in driving condition.. Generally bad rear O2's will cut out/ or not come on line properly... Occationally you'll see them bias either lean or rich, in which case you'll see that during a WOT pull and then decel event.. Other patterns indicate that the cat is starting to go bad.. Usually as a cat goes bad the ECU will try and run things richer to get the cat up to temp... Some of this stuff you can see with switch rates during steady state driving and response rates when going between a decel even to steady state load or going from steady state load to a decel event..

 

Fair enough, completely forgot that some people are actually legal.

*cough*

 

Yep did do that and nothing changed in fuel trims strangely when I sprayed into said hole. I'll give it a shot again but have been repairing my A/C this weekend.

 

An update, nothing concrete. It's been a long time and I haven't seen any crazy fuel trims. Right now in average it's remained below +10% on the long term. I've repaired my a/c so I haven't let the car get too hot as it increases the radiator fan speed. But occasionally attempted to let the car warm up further on a 80 degree day, and it did not increase. This image is the result of that.

Have been getting o2 bank 1 sensor 1 voltage too high, but went away on its own after a drive. Had that happen twice in the past weeks but besides that, nothing crazy.

To conclude, my assumption is o2 sensor, and a mix of possibly having a boost leak which I probably corrected by tightening clamps while I was troubleshooting. +10% isnt ideal, and I think I'll try replacing the upstream sensor since thats what the cel's been occasionally for.

 

IIRC +-8% is factory spec but 10% (below cruise) isn't too terrible, actually. Codes get thrown at either long or short 20%.