Okay, so had car set up for tuning the ve.... open loop speed density.


out of no where the car started to run lean...like maxing out my afx wideband (16afr).

now tried tracking down vacuum leaks, cant find any. rechecked my intake manifold bolts, new pcv line, checked header bolts, tried some old tunes and wasnt the tune.

Seems to do it in mostly in idle, and cruising. seems to be about a 15.8afr until i put it in gear then its maxed out.

running lean in both banks, so its not just once side.

I cant see anything cracked after the maf.

umm im tired, can think of what else ive tried as of now.

Im not really sure what to check, im sure im over looking something.

Could it be the IAC...the car seems to surge when in openloop speed density...as in the idle climbs then drops and repeats. not so much with the o2 sensors and maf turned on.

also with the maf and even just the o2 sensors turned on, according to the wideband it fights to get to stoch so its not the wideband.


Like I said any help or directions to look at would be helpful, and I'm sorry I'm tired and didn't lay the information out the best, but I'll go through it in my head at work tomorrow and add anything I forgot.

Thanks


EDIT: btw its a 99 ls1 in a trans am

 

Maybe try the tune/diagnostic forum???

 

May be able to find help for this in the tuning section, as well.

Am not familiar with the AFX, but, 20:1 is full lean. I actually run 16:1 under normal driving conditions, just to save on fuel.

Really, sounds like there's more than one issue. Scaling on your wide band, an incorrect modification to the MAF table, or a vacuum leak. Have you change the MAF table? Did you change ALL of the settings in the PCM required in order to perform the VE tune? Haven't done it in a long time, but recall that there is a MAF parameter that needs to be changed in the program when MAF is eliminated during the VE logging process & then changed back once finished.

Confusing because other tunes don't fix the issue. For this reason, I'd favor a vacuum leak...unless you are using the same modified MAF table w/ all the tried tunes.

Vacuum leak can also happen around an injector or @ the map sensor.

 

new IAC in...the count is low like 32 at idle, so I need to figure out how to reset that and adjust the TB...well find the screw.

In openloop speed density still going lean.

one thing I found that is odd is in idle is 15.6-15.8., put in gear the idle drops then climbs back up...afr goes to 16(max on sensor).
Noticed though everytime I change gear on the selector the idle drops down a few hundred then climbs back up....doesn't matter R to D, or 1, 2,3,D,3,2,1. does it every time.

So still back in square one still. The counts keep the same in idle and drive...like they don't seem to be adjusting for a vacuum leak.

im totally lost at the moment

 

the afx maxes out at 16afr.

The thing with the tuning is I was tuning it and it was fine, then out of no where started going lean slowly and then made it way up to 16. This was without me messing with it, and it only does it in Openloop speed density. I didn't change anything in the tune other than VE and I think fans on off temp since then.

As soon as I go closed loop it goes back down to about stoch(varies with the computer correcting it).

I was thinking maybe the map sensor, but don't really know how to check it back there while on the car, and if I remove the intake not sure how to see if it has a vacuum leak when its off of the car.

How can I check around the injectors?

Sprayed carb cleaner on about everything and no noticeable change in idle.

 

I prefer to run OL MAF. It's easier for me in general & easier to trim Air/Fuel ratio.

Anyway, it's very important to have accurate idle airflow fueling tables from the auto VE log when running OLSD. So, try running another auto VE @ idle. Be sure to look closely @ hits from say approx. 15-45 MPa & guessing your idle, 700-1000 RPM.

Sounds like fuel trims from O2 sensor feedback are bringing it back to stoich when in CL. So, again probably incorrect fuel commands @ idle.

Another option would be to just manually increase fueling in the OL fueling table in the area where it goes lean.

Since you checked w/ starting fluid, probably no vacuum leak. Understood (16:1 is max on your Air/Fuel ratio gauge), Just know that the engine generally won't go lean enough to stumble 'till 19-20:1 Air/Fuel ratio. So for general information, when she's stumbling she's 19-20:1. This info will help you dial in the idle fueling sooner.

 

What do you mean auto ve table? I tune in the primary and secondary ve table...or are we taking the same thing?


I used carb cleaner instead of starting fluid, that should still work right?

Ill have to bump up the ve table about ten percent and see what happens.

Just clarifying some stuff up to make sure I'm not missing something small that ends up making a big difference.

 

Whats your long term fuel trim at? Should be between 10+/10-
When its an intake leak it will go under acceleration. If not it will not go down

 

If you need more help PM me

 

I had one log, wasn't an ideal one in CL where I could watch the fuel trims.

If I am remembering correctly under cruising it had a negative ltft of 7-11. under acceleration it was almost 0. but like I said it wasn't an ideal log either

 

Today I got ambitious. I took my tune and in the ve tables I changed the 800rpm column from I think 25 or 30 to 45 kpa. I added about 7% to those cells. That got me pretty close to where I wanted and I was all happy. So I went on a 17 minute drive, did some logging. Changed the table via lambda error, drove home. Everything was about dead on. Fixed a few spots and flashed the pcm before I went in the house, but I double checked to make sure the car started and wanted to see it at about stoich again(I was getting happy) what do you know, it was leaning out again, so I put it in gear because that's when it does it the worst (gear at a dead stop) which is 800rpm at 45kpa. Changed the table again, nothing really, took it for a drive and the other cells were pretty close still.

Now this got me thinking, so I was watching again at idle because I think it was up to a VE of 75 @800rpm and 45kpa which was waaaay to much. I had noticed the Idle wanting to go and work its way up when it was in gear, and using the display that came with the ngk afx (most people call worthless and un needed because it reads 14.5 when its really 14.7) it would go from about a 14.1/14.3 to almost 16 when the idle increased. I also was logging in hptuners at the time, and was watching the commanded and actual IAC counts. When the AFR was good it was at about 70-80, but when I dropped it in gear they would go up to 160-170 and then it would start running lean again. If I go out driving around it would stop at 60-70 counts because it wasn't at idle and when I would stop afterwards it would be back down to a 14ish AFR.

So now I am thinking I need to do a IAC and TB position sensor reset, and I am thinking I need to adjust the screw for the tb blade to get the counts back down to normal?????

I think I seen somewhere that at idle its suppose to be around 70 counts correct?

Its weird though, sometimes it does it then goes away for awhile.

 

-Yes, when I said auto VE table was referring to those tables used...same thing.

-Carb cleaner/starting fluid, doesn't matter.

Since the problem doesn't occur in closed loop, it's a tune issue. If it's EFI Live, post tune & log.

 

Since we now understand this as a tuning issue, send a PM to this sections' moderator & ask him to move your thread to the tuning section. Add your logs & tune. In addition to ours, there will be more replies & from some very good tuners.

 

Sounds to me like you need to just add some fuel in the right places to your OLEQ table.

 

Its not efi live, its hptuners.

I can still post them...not sure if I can with the files until I try here though.

I think you can dl the demo of hptuners off of their site, I believe its the full version, just you can save modded files with it.

I logged a drive through the country today. It didn't do the whole "lean" thing much, but you can notice it sometimes when I stop the afr slowly climbs up.

I also notice it more when the car is first started up.



Alright just uploaded everything. I couldn't upload my histogram file or the config file so I took screen shots of how they are set up so you can copy the set up I was using to get the same results.

Not sure if you were familiar with hptuners at all.

Going to screenshot how the ngk pid is set up too in the next post

 

ngk afx set up I use, I compensated for not getting exactly 5v at 16afr.

 

Not sure if the comment "it's hptuners not efi live" was directed at me but:

Engine > Fuel > Open & Closed Loop > Under Open Loop on left hand side click EQ ratio button
Add fuel in the corresponding startup areas you are having trouble.
Log again.
Repeat process until target fueling is reached.

Good luck.

 

I have a 1999 Camaro SS and I just experienced a bad IAC today. I took the IAC off to observe the valve, which ended up being stuck. After I put the IAC back on... just for the time being, the idle surged to 3,000 RPM constant at idle, even while driving. It didn't go up and down it just stayed at around 3,000 RPM.
**Solution: I did a search and found that you can reset the IAC by unplugging it, then turning the ignition on (don't start it) for 30 seconds. Then turn car off and plug back in. You should also do the same process for the TPS below the IAC as well. Then when you start your car the computer should have reset it's normal levels.
***P.S. I also unplugged the sensor from the airlid and MAF as well and did the reset process for all of them.

This worked for getting rid of that stupid surging idle for me! This is just temporary too, my IAC still needs to be replaced.

 

I'm bored at work. Wondering if you got this figured out?

 

No it was towards ls1-450, he said if its efi live to post it up.

I seen that table, but haven't messed with it yet, I am thinking about it though.