Need help w idle

[FasNuf]

Well I'm no expert and you and Dreksnot sound like you have more experience than I do tuning. Looking at the log, the o2's oscillate fine to me in closed loop but that thing is just hunting like crazy. I assume you checked every possibly hose that something didn't get pulled off. Crazy idea, but how's the gas cap? ( just throwing it out there ) Definately lean on the LTFT's.

[joshnmn]

They are lean, but it's because I reset them.

The hunting is what wears me out too. Isn't that crazy? I haven't found anything out of the ordinary. Also, the backfiring led me away from a vacuum leak.

I really appreciate you guys spending time thinking about it. That's what makes this forum great

[FasNuf]

Originally Posted by joshnmn

They are lean, but it's because I reset them.

The hunting is what wears me out too. Isn't that crazy? I haven't found anything out of the ordinary. Also, the backfiring led me away from a vacuum leak.

I really appreciate you guys spending time thinking about it. That's what makes this forum great

Well that's what gets me because LTFT's shouldn't be out that much if the tune is good and everything is running correctly. For instance, my LTFT's are +/- 3% and that's a street tune I did 4 months ago in 100 degree weather. If I'm in 4th gear only, they're closer to zero.

I suppose there could be an issue with the ECM itself, but that will be hard to prove without replacement.

Just throwing this out there, but did you weld on the car by chance without disconnecting the battery?

I think you did already, but you could try disconnecting the negative and cycling the ignition to drain any capacitance and let it stay disconnected overnight then reconnect in the morning. This will again reset the trims, but may help something else. Strange things happen. Oh, keep a well charged fresh battery of course.

Good luck - Mark

[joshnmn]

Yes, I did leave it disconnected overnight. That was step #1 because it seemed like a throttle issue and I wanted the TB to relearn.

[FasNuf]

Something to try for grins. I know that you failed the o2's by maxing readiness, but try forcing open loop through the diagnostic while the engine is running and see if it clears up.

(closed Loop OFF)

[joshnmn]

Can we do that? Pretty sure mine only has Command closed loop.

[FasNuf]

Originally Posted by joshnmn

Can we do that? Pretty sure mine only has Command closed loop.

I don't have it in front of me, but that sounds right so you can toggle that OFF and it will go open loop. I'm just curious if it'll change how it runs because the command is most likely processed in the ECM differently than the O2 Rediness 450* and it won't require flashing.

[morepowerjoe]

Forgive me if I'm wrong on this, I am learning. The open loop consists of the ecu running off of the commanded fuel in open loop / base tab. And if that is really a stock tune it should run in open loop. The closed loop consists of running off of the o2 sensors, correct? And if it won't run in closed loop, I was thinking that maybe it could be the absence of the mufflers causing the change in the A/F ratio. If you want, you could try using my closed loop settings for my long tubes and see if that does it for you. In hp tuners go to engine, fuel, oxygen sensors, and to proportional airflow mode. It says prop base and the setting are like this. So, you have columns that are
0 16 24 32 40 58 64
0.0035 0.0140 0.0140 0.0168 0.0168 0.0168 0.0105

It's just a thought
What do you have to lose?

[joshnmn]

Originally Posted by FasNuf

I don't have it in front of me, but that sounds right so you can toggle that OFF and it will go open loop. I'm just curious if it'll change how it runs because the command is most likely processed in the ECM differently than the O2 Rediness 450* and it won't require flashing.

That would be easier. I'm pretty familiar with the software and never thought to use it like that.

I'll try tomorrow

Joe, thx, but I have plenty of tunes. I've tried them all

[FasNuf]

Originally Posted by joshnmn

That would be easier. I'm pretty familiar with the software and never thought to use it like that.

I'll try tomorrow

Joe, thx, but I have plenty of tunes. I've tried them all

There's quite a few things in HPT that lends itself to diagnostics. Another one I remember off hand is the injector ON/OFF, great to figure out which injector is causing a lean condition and rough idle. Not saying that's your issue, just that it's there to use.

Hope you find it soon.

[joshnmn]

I have used that one before and it might be in the near future.

What I think* has happened is one of the 4 DOD intake valves is sticky. Works as it should sometimes, and sticks in the collapsed state other times. The timing has to be completely coincidence (it's always 10 or 20 seconds after startup). So it acts like a huge vacuum leak.

Thoughts?

[FasNuf]

I would think you would hear a lot of noise if your DOD lifter was collapsed. I would expect there to be misfire codes and possibly others.

[joshnmn]

There misfire codes and backfires, but I think it's the general code. Not specific. Also, Service Stabilitrack pops up every now and then (which I have seen is affected by DOD).

But I was just thinking- if an intake VLv lifter was collapsed, it fails the valve closed, not open. Hmm

[FasNuf]

Service Stabilitrak seems to come on for just about any reason. Sometimes when mine comes on, I can just shut down the car and restart and it'll go away. The other day it didn't though. Turns out I forgot to reconnect my MAF. Strange indeed.