Unstable AFR during crusing
Hi ! New with tuning. I have a LQ9 in my Firebird -68. When I cruise at low speed and low load (TP 5-15%) the AFR (WBO2 LC-1) bounce between 12-18. This occurs even if I don´t move the throttle. Both narrowband O2-sensors are new. The LTFT for both banks shows -14,8% during long periods. Could some one give me a hint. The engine is stock except Long tube headers and deleted cats.
Last edited by Ram Air IV; August 15th, 2010 at 07:45 AM.
I would give a little more details on your tune. Preferably attach a copy for readers to look over. Are you running SD or MAF? I know you are attempting to run Closed-Loop, but you might want to take a look at your DTC's. You are so rich it is throwing DTC codes.
Post up a tune and we can take a look..
Some more information.
First of all, I use the original tune from the Cadillac Escalade, so I am running MAF-mode.
My DTC is 0172 and 0175 (system to rich I think). I will post my tune when I am back home later to day.
Your MAF needs to be calibrated. B5001 I assume that since this is a transplant into a different vehicle that you rerouted the air intake thereby modified the air flow thru the MAF.
This will cause your trims to be off and you will have several issues as a result even if your VE is perfect.
Sometimes reasons for 'scattered' AFR are rather prosaic: clean your airbox/airfilter first, and then log again, see if it got any better. I know it sounds very silly, but you'd be surprised how much that helps.
So if I need to calibrate my MAF, how do I do that ?
What is B5001?
Here is my tune if it could help,
Thanks all / Magnus
I scanned over your tune briefly. Something seems amiss with your Injector Flow Rate B4001.
On the MAF, there are hundreds of threads on it. Check these two links first:http://forum.efilive.com/search.php?searchid=37904 & http:///download.efilive.com/Tutorials/PDF/Calc.VE Tuning Tutorial.pdf.
After you do some reading and more logging, or if you really get stuck..feel free to post up.
Good luck..
Hi Magnus, welcome to the forum
Do you have a manifold referenced fuel pressure regulator...?
Which injectors do you have...?
Since your MAF/intake plumbing is different than the vehicle the .tun file is for, you should correct the MAF table as suggested above...
to do this, follow the Auto VE tutorial, but with MAF enabled and B0120 set to zero, and of course create a B5001 look-alike map (copy/paste the map labels from B5001).
Thanks all, I will study the Auto VE tuning tuturial.
Joecar, I running the Corvette 2001 filter/pressure regulator.
My injectors are from a LS1 2001.
So, your FPR is with the fuel pump in the fuel tank (i.e. not at the fuel rail)...?
If so you need to use the B4001 IFR table from a stock LS1 file, see below (from www.holdencrazy.com see stock 2001/2002 Camaro/Firebird files).
The stock 2001/2002 IFR table requires fuel rail pressure to be at 58 psi; if yours is not 58 psi then you need to recalculate the IFR using your actual pressure (see the spreadsheet at the following link).
Calculating-Injector-Flow-rate
2001/2002 LS1 IFR B4001 (copy, then paste-with-labels):
Code:LABELS Injector Flow Rate (Grams/Second) Manifold Vacuum kPa {link: GM.MANVAC} Value 0 3.617188 5 3.640625 10 3.664063 15 3.687500 20 3.710938 25 3.726563 30 3.750000 35 3.773438 40 3.796875 45 3.812500 50 3.835938 55 3.859375 60 3.882813 65 3.898438 70 3.921875 75 3.945313 80 3.960938
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