Help interpreting BLM cells

[Toady]

I've been chasing high idle BLMs and did the rubber glove trick (boy, that doesn't sound right) on my car. BLMs went down to 116, so I was pretty sure that it was a leak off the vac block. I found a couple, sealed them up, and took the car out for a spin.

The BLMs are even worse! The PCV line was one the problems, so I'll have to test it again, but I'm trying to read the other BLM cells. If I understand this page Block Learn Multiplier and Integrator correctly, then

CELL 0 = unmetered air @ idle causing ECM to dump fuel in
CELL 1 = ECM pulling out the fuel added in CELL 0

but I don't get why CELLS 9 & 10 are showing so lean when the rest are close. What else am I missing? I could post the whole log later if that helps.
Thanks in advance!

 

[norbs]

Disconnect the ECM orange power wire and let it re-learn. It will take a while 10-15 minutes to get the blms learned. If there's any mods done to the car then it will need different fuel curve from factory so the blm numbers maybe off at different rpms and load, a lot of variables can effect blms, tiny exhaust leaks etc.

 

[Toady]

Thanks for the reply, norbs. I did unplug the ECM before starting, and this cap was taken close to 10 minutes into the drive. Stong longblock, T+/LT1 MAF, Lightning 42# injectors, and extender chip. I've read that having every cell at 128 is dreaming, but if I had a mechanical issue, wouldn't that have shown when I had the vac block blocked off?

 

[norbs]

Can you explain the rubber glove trick? Or should i ask?

 

[Toady]

LOL. See, first you make an appointment with the...

I first read about it from Razor. You remove the vac block, place a rubber/latex glove on the throttle body, and bolt the vac block back on. This blocks off all 5 of those lines. If one of them is the culprit, BLMs should come down below 128 because the loss of vac to the FPR causes fuel pressure to rise. I thought I had a pre-turbo exhaust leak, and I still may, but the BLMs going down to 116 during the test indicates that at least the engine isn't "hurt."

I used a Mityvac-type pump to test the lines coming off the vac block.

 

[norbs]

To me it looks like your idle fuel is a bit low causing the blms to be off (153). You may want to invest in a gen II translator, so you can bump up the idle fuel and fuel at light cruise. But you should be sure you have no cracked headers or leaks at the 3 bolt flange. Use the gasket from TA performance or similar.

 

[TurboBob]

whats the chip number?

By the look of the BLM matrix, its ancient.

Bob

 

[TurboBob]

with the engine already warmed up, reset the ECM, and the record the whole drive.

The cells aren't all used very often, and you need to be in a cell for a moment or 2 for it to get changed.

Cell 1 may be from deceleration. Cell 0 is generally idle.

The rest of the cells that are 128 may not have learned.

the 137 cruise cells tells me that the car's baseline tune is a bit lean. Do you trust your fuel pressure gauge?

Bob

 

[TurboDave]

Bob is spot on concerning cells 0 and 1.
You have a lot of unlearned cells so you need more drive time. Specifically cells 7 and 11 (the highway cells) and cell 15, the acceleration cell.

BTW that's my article you refered to.

 

[Toady]

whats the chip number?

By the look of the BLM matrix, its ancient.

Well, this is embarrassing. Bob, the chip in there now came with the injectors (used). I emailed you a while back asking for ID, and you said it appeared to be a fake, so I bought a real one last summer. I put the "suspect" chip back in because I was having some mechanical problems which weren't disarming the anti-theft in the real chip. Between fixing those and going all crazy with the vac pump, like a dumb@$$ I forgot to put the good chip back in.

with the engine already warmed up, reset the ECM, and the record the whole drive.

The cells aren't all used very often, and you need to be in a cell for a moment or 2 for it to get changed.

Cell 1 may be from deceleration. Cell 0 is generally idle.

The rest of the cells that are 128 may not have learned.

the 137 cruise cells tells me that the car's baseline tune is a bit lean. Do you trust your fuel pressure gauge?

Bob

Will do this with the good chip and report back.

I *did* trust my gauge, but now I'm not so sure.

 

[Toady]

BTW that's my article you refered to.

Cool. I don't know how you chip guys keep all this info straight, much less program around the shortcomings. Just trying to get a grasp on what my car is doing is making me lose sleep.

 

[Toady]

To me it looks like your idle fuel is a bit low causing the blms to be off (153). You may want to invest in a gen II translator, so you can bump up the idle fuel and fuel at light cruise. But you should be sure you have no cracked headers or leaks at the 3 bolt flange. Use the gasket from TA performance or similar.

That's two votes for low idle fuel. I hope a GEN II won't be required...this car already has some expensive parts that should make it way faster than it is, if only I could get everything working at the same time.

On my short list is adapting a boost leak tester to test the exhaust from the cat forward.

 

[Toady]

I was able to get some drive time last night, but not a lot because it started raining (in Oregon?). This was with the good extender chip, but I blocked off the PCV hose as the idle BLMs were still climbing. When the rain stops - in June - I'll take the car out again and do as Bob suggested, resetting the ECM when the car is warm. Also need to figure out what's with the PCV line.

 

[TurboDave]

That raises the question, are you sure you have the correct PCV? These cars are VERY fussy about that.

 

[Toady]

It is a Delco PCV, but it's several years old and may need cleaning.

 

[TurboDave]

But what's the part number???

 

["More Boost"]

interested in outcome, having similar issues as Toady

 

[Toady]

But what's the part number???

Had to dig out the boxes...CV893C. The one in there now is shiny, while the two spares are kind of a tarnished green. Is one style better than the other?

 

[Toady]

interested in outcome, having similar issues as Toady

I ended up testing all the lines coming off the vac block again, and the main culprit was my catch can no longer holding vacuum. Also found a bad check valve before the EGR solenoid and several sections of suspect vacuum hose.

Replaced all check valves (tested them before installing!), bad hoses, cleaned the pass. VC breather, and added the AutoZone PCV1162 suggested by Eric Marshall in another thread. No catch can or PCV check valve for now.

And since the weather's getting better, I should be able to take it out for some real driving this week.