BLM's at 160 across the board-best first change?

[jwscab]

Hey all, looking for some guidance if anyone has seen a situation like this before: background: 91 z28, originally LB9 TPI 305 motor. swapped in: L05 from roughly 92-ish buick or cadillac full size, can't remember which at this point. roughly 60K miles, no apparent issues. complete TPI system from 305 is swapped onto 350, with the exception of injectors, these were roughly 80k mile injectors from my 1987 iroc, should be 22lb/hr. Ohmed out OK, and worked fine, were swapped out with no change for an issue with the iroc a couple years ago: that is, they were NOT the issue with the iroc, but it got 24lb/hr injectors and these got shelved. aujp factory replacement memcal installed in stock ecm. the car failed emissions for high hydrocarbons, limit was something like 250-ish, this thing was around 700 or 800. does not smell bad at idle. Cat was a used unit that we had sitting here, from a low mileage swap on a eclipse, then subsequently removed. universal, catco, or something, 3" in and out. We have replaced this with a brand new catco. I ran some logs of the engine running, and it looks like the BLM's are high 150 to 160 across the range of cells that the car ran in, over 2 runs, approx 15-20 minute rides. Cross counts are climbing, and it appears the o2 sensor is working, however it is a bosch, brand new. I'm going to try just changing the injector constant down, to change the complete map, and see if the blms fall in line. This bothers me, as the injector constant should be fine at 22lb/hr. I'm thinking the VE map is going to be a ton different between the lb9 heads, and the l05 heads, but i wouldn't think the engine would think it's very lean...... any questions or comments about the situation are extremely helpful at this point, thanks in advance!!

[RBob]

Might be a spark timing issue. Although I'd check the fuel pressure while driving first.

The L05 heads are swirl port which require less advance. Grab a TBI L05 BIN from say a Caprice and see what the spark is like. Remember to sub off the bias value.

Actually, I can grab a snap-shot, hang on.

Here is the timing from an '89 Caprice, with an L05 and 700R4. Once above 4800 RPM it stays the same.

RBob.

[jwscab]

Thanks Rbob, I thought about that too, and actually wanted to try that.

as far as subtracting off the bias value, is it already subtracted from that table?

So I will check fuel pressure for sure, and compare the timing maps. I will report back and let you know, to keep this a good tuning thread for reference.

[RBob]

Originally Posted by jwscab

as far as subtracting off the bias value, is it already subtracted from that table?

Yes, the values shown are the actual BTDC spark timing of the main table.

RBob.

[jwscab]

thanks Rbob. can i ask what xdf file you are using? Using one from Moate fileman($62), the spark table only goes up to 3600rpm.

[RBob]

Originally Posted by jwscab

thanks Rbob. can i ask what xdf file you are using? Using one from Moate fileman($62), the spark table only goes up to 3600rpm.

It is from a base calibration provided with the EBL system. Even though the stock '8746 spark table goes to 3600 RPM, there is a slope adder. The '7747 also has this function.

This is how the SA continues to advance from 3600 through 4800 RPM.

RBob.

[jwscab]

OK, here is some follow up: I replaced the timing table with the tbi table above, the car started, stalled a couple times, then ran, seemed to be running richer, stinky. (didn't check fuel pressure, i forgot the gauge).

Now, I wanted to make sure, I need to add in another 6 degrees to the table, to account for the distributor base timing, correct? I neglected to do that last night, ran out of time to try adding it in. also noticed a check engine light came on, but did not get a chance to throw the scanner on it to see what's up. The engine rev'ed fine, btw, sounded pretty good.

goal for tonight is to add 6 degrees across the board, hook up the scanner, and see how the BLM's shake out.

[RBob]

The distributor base timing should match the calibrations Initial timing value. When they do so it is a wash. The ECM subtracts out the base (Initial) and the distributors physical location adds it back it.

Then forget about it. No need to add or subtract anything for the actual timing.

RBob.

[jwscab]

OK, got some good results after fighting with a bad image for awhile. Once that was straightened out, We did the following:

changed the timing table to above, ran some test logs. noticed that the blms now start moving around outside of cell 4, in the 130-140's, so we're headed in the right direction.

trimmed up a few cells in the idle area, added some fuel and smoothed out the table. This helped afterlooking at some log files.

the funny thing is the BLM's at idle run down to about 140-ish once the o2 sensor comes alive, and then slowly drifts back up to 160.

is there any other fueling that takes place beside the main ve table in cell 4 idle area I should look at to richen it up a bit?

the next thing is going to hook up the wideband on the outlet and see how rich/lean the exhaust is after the cat.

has anyone developed a peice of software yet that will take log data and histogram/average the blm cells yet? this is pita to sort through the data and figure out how and where to update the ve table.

Rbob, thanks for all the help so far!

[jwscab]

So no new updates yet, but I will post what i find.

Does anyone know if scannerpro will compile the BLM's in a chart like winaldl does? I think this might be easier to use to rough in VE tables if it does.

anyone able to answer my question about any special BLM cell 4 fueling or spark(like closed throttle stuff)?

[jwscab]

wanted to post a follow up.

summary:
new cat converter
changed spark timing to better match L05
tweaked fuel table in the idle areas (added fuel)
BLMS still at 160, but INT values moving around from 110's to 140's, ran out of time to update, so we took the car.

HC was down to 95, CO% was 0, so the car passed emissions. Still have some work to do to tweak the tables to get a 128 across the board, but at least there is some breathing room.

thanks for all the help, again!