not sure what causing your problem, but your afr is a bit on the lean side unless youre running stock maps. after my reflash, my afr is ~13-14

 

Thanks for sharing that, it goes towards confirming my thinking that I'm running lean.

 

Thank you DaveB,

I haven't checked PCV Valve, haven't measured engine vacuum, haven't cleaned the MAF. O2 sensors have never been mistreated.

I will check these items and report back.

 

take a look at your spark plugs as well, that should give you an idea whats going on inside your engine.

 

OK, driving this morning, the problem decided to pretty much fix itself!

One minute a loud droning exhaust, then over a period of a couple seconds, the deep drone faded and my normal exhaust sound returned!

Power is now much better, though still seems not quite spot on.

I ran a data logging session and found little change, although there are a few things maybe worth noting: Excluding the lean out periods with AFR readings of 30, the average AFR was and is 14.76.

The average difference between B2 and B1 AFR was +.05 before and is now +.25 (leaner on Bank 2)

The avg AF Corr was: 101.7 B1 and 101.11 B2
The avg AF Corr IS now: 100.0768 B1, 100.6365 B2

I don't know if this means anything. I'm very happy my car is now running much better, but frustrated to not know why, what was wrong, whether it is actually fine now or just less bad, or what to do next time it happens.

Does anyone know if loud droning as an intermittent condition can be caused by anything other than the exhaust? Maybe I should be looking for a bad baffle in the center pipe resonator or something like that.

 

Spark Plugs look great.

 

PCV Valve ok
Checked for vacuum leaks, intake connections secure.
Throttle body/butterfly looks ok.

Didn't check or clean MAF yet, but now that the car suddenly improved dramatically on its own, I wonder, could a MAF fault or dirt MAF cause such a problem intermittently? I kind of doubt it.

It remains to check idle vacuum.

 

ive never heard of a situation like yours with the exhaust. in regards to your a/f, are you sure you have the correct map selected? i'd have to go back and see if i have any older logs from before my exhaust/test pipes but i dont think it was that high. its not dangerously lean but it doesnt seem like a performance tune. on a side note, i was looking to get a circuit sports strut bar and wanted to know if that thing hits your plenum at all? i was planning on getting the engine brace to go along with it as well

 

I do have the right map selected.

Uprev gave me my tune based on stated mods, it's never been dyno'd with AFRs logged and had the tune corrected. I guess I should get AFRs logged on a dyno and send them to Uprev to retune. It is worth considering that the AFRs being logged are using the stock early 04 narrowband o2 sensor system.

Not that this will have anything to do with whatever was causing the droning and loss of power. I'll have to solve that next time it happens, which I expect will happen.

Circuit Sports bar fits fine over plenum with spacer, without engine cover, or over engine cover without plenum spacer, but not over both. I like the way the Circuit Sport strut bar fits a lot.

 

sending your logs back to uprev is a good idea. jared is usually quick to respond to any issues people have and hopefully get to the bottom of this. he may have sent the wrong map or something. as soon as i recover from spending almost a grand on a double din stereo and oem trim to install it, im definitely going for the circuit sport/stillen engine dampener. its like the only one piece bar i can find for the g

 

94K miles on the car? When I hit the gas black smoke comes out and I smell it in the car now some time.

 

Hi, I just wanted to say. I have learn alot from the information that has been giving out for every one to read. Now for a couple months now my car has been making a ticking noise from the top of the engine burning at least quart of oil a week. Today I change the PCV valve and clean the MAF. I crank the car up and drove to a friend house I notice the had stop for 2 minutes then it went back to the tickin noise again what going on do I need to change valve train to stop the noise?