I'm trying to understand a little more about this. What makes it go up and down. I do know that you want to see it as close to 128 as possible.

The reason I ask is because in my last datalog session I noticed that in certain areas my BLM's would go up as high as 140. (at least I think this is high). And I can't find any consistancies relating to position of IAC, MAP, A/F. I did notice that I would go Closed loop and Open loop quite a bit on the 8 min datalog.

What should I be looking for in my datalog for the reasoning behind the cause of the BLM issue?

My BPC is set to 99, I'm running 14psi, with 90 lb injectors

Thanks

 

The BLM follows the INTegrator. As the INT goes above 128 (+ a couple of counts) the BLM will also increase. Above 128 and the fuel trims are adding additional fuel.

When the INT falls below 128 (- a couple of counts) the BLM will then decrease.

If there is no consistency to the RPM and MAP vs the BLM, then there is something skewed. It may be an exhaust leak, varying fuel pressure, lid gasket leak, or not enough heat in the XRam.

RBob.

 

I had a header flange leak a while ago. someone forgot to add lock washers. That caused a very high never ending BLM that continuously added fuel so I was at 100 in some places for VE.

Quote:I did notice that I would go Closed loop and Open loop quite a bit on the 8 min datalog.

B4 I used a heated NB That would occur on a very cool day once I got to cruise speed of 65mph. I would go CL then OL then eventually back to CL. That OL disallowed overdrive and I would drop out of 4th to 3rd at 70 mph!

 

I did go back into my datalog and the only consistancy I found the times the BLM's shot up was when the RPM was at 1800... BUT.... not everytime nor MPH weren't the same. The INT would be around 131 132 when the BLM shot up as well.
I went back into the EBL calibration pages to look up INT..it gave me INT tables but I'm not getting exactly what it is? Can you explain?

I guess I'm gonna have to search out for a leak. I'm gonna tend to believe its more in the Xram rather than exhaust I think. I'm starting to see that the Xram is nice but not "tuner" friendly per say.
EGR is blocked off, My air pump is still in operation...but I am running a Test pipe right now. Would any of that play a part. The line that goes to the cat is not connected nor is it blocked off.

Thanks guys I appreciate your responses.

 

I think this article may help explain the INT, BLMs, along with the proportional gains some. Go to the DIY_PROM board (here on TGO) in the ticky's is the Tuning Guide Book. Chapter 5, '8746/'8063/'7747 section, there is a fueling logic link. See if that helps out.

Note that the EBL doesn't support an AIR pump, so the solenoid to it should be unplugged. Note that in this mode the valve should divert to atmosphere at all times.

RBob.

 

I'm gonna try and find that thread.
Since I should disconnect the wires on the divert solenoid, should I also disconnect and plug my A.I.R fittings on my headers as well? Wonder if that may be why I get some of my lean readings on the WB?

 

You shouldn't need to plug the tubes on the headers. As long as the valve is in divert then no air should go to them. But if the valve leaks then it can cause issues.

For the thread check the very top of the DIY_PROM board for the Tuning Guide Book.

RBob.

 

Found the guide thanks

I unplugged the divert solenoid. Must be when its plugged in it diverts to outside air, because when I unplugged it the car ran steady 16-17 according to the WB. Plugged back in came down to 15.6

 

So far I haven't found any exhaust leaks.
What I did do this morning is rather than doing VE learns off of WB, I switched back to BLM VE learns in hopes that may that will help compensate for the problem.

 

Here's just a short area of my log that I'm referring to.

 

This is getting frusterating! I had to walk away and take a deep breath.
Seems like I just can't find an answer as well regarding my BLMs. I just ran the car and my blm's are hitting 160. Ran a couple different bins and all have the same result. My fuel pressure is constant unfortunetly 12psi. I can't seem to get it adjusted to where I want it.
I read and read and I just don't seem to get. Int is going to 132. Heck even after reading I'm still not understanding that either.
I've checked for exhaust leaks, Vac leaks, even lid leaks and can't find anything.
sorry just needed to vent a bit... and I've gotten discouraged with diy tuning.

 

Maybe I mentioned this before but I had the same situation develop. It turned out to be a leak at the header flange to ext pipe. Running BLM tuning the NB02 saw the leak and pushed BLM to max(160) which caused my VE to max as well(100). By coinsidence the WB side was not leaking as much so that bank registered stoich.

I see the log of 02 sensor appears to be switching nicely. So 02 looks OK.

The XRam tends to leak primarily at the plenum to manifold area or lesser at top plate. I dont believe that will cause a max BLM as ECU should compensate. High idle rpm would result for sure.

 

The first thing I have to do is figure out why my fp won't adjust. The only other thing i have noticed is my vac runs 10hg at idle. I've been told it should be 14-20hg. If thats true then I have a vac leak as well. I'll get a can of carb cleaner and start spraying hoses and the xram.
The last time i had a leak on that it was the gasket between the manifold and plenum. When that went bad it sounded l like I had a supercharger on there.
And of course all this shows up now.... since this winter I'm putting my HSR on.

 

What FPR are you using? And what spring?

I agree Vac Leak. I recall I am at 14 hg (224/230@.05 114 LSA) and 37 MAP at 775 rpms at idle(manual trans).

 

I have the stock FPR and have tried the stock spring as well as the spring from top down solutions. Suppose to be able to get between 12 and 20. Vac is monitored just before the brake booster and I have no egr.

 

As RBob said fuel delivery problem. With TDS spring you should be able to over 15 and hold it as RPMs come up rev in neutral. Be careful not to coil bind. I did and blew the REG diaphragm.

I have an Aero unit with weaker spring(5-20) as they provide two springs, set at 20 with VAFPR disconnected. when connected it pulls down to 11 lbs FP idle. Stiffer spring set 20 pulled down to 14.

 

Wanted to update you two as to where I'm at. i always like a thread finished.

here it goes
1) Used a test vac gauge, test back of tb's, intake manifold, and the location where my in car gauge connects. All read 20hg... seems as though my gauge is not reading correctly.

2) Went through entire fuel system. Got to the point where i went and picked up a LT1 fuel pump. After removing my fuel pump (85), I saw the rubber that connects the pump to the plumbing had a big crack. That was the problem. i went ahead and just used the LT1 pump since I had it opened and the HSR is gonna go on soon. Now I'm getting 15psi to the tb's as I should.
Thanks for your help. Weather permitting I'll get the laptop hooked back up and take it for a ride in the morning.

 

BLM is your long term fuel adjustment, and INT is your short term adjustment, and both are meant to compensate for ever changing loads and conditions to maintain an ideal value of 128, or close to it. The ECM will cycle the INT in an attempt to maintain stoich, and it does this by averaging the time spent being rich, and the time spent being lean....

 

I deally one would tune car under same environmental temps and same baro pressure and same load on engine. Lets say you tuned car for fueling so that all your BLM data read 128 accross the board. the following day the air temps dropped from 80dF to 60dF. One would expect a higher BLM accross the board as air is more dense and result is ECU will add fuel. This is where the smoothing feature helps. you may get nice BLM data
in 40% of your cells but never see a hit in certain cells in between. smoothing should help in blending those "un hit" cells.