Wednesday, May 1, 2013

TBI Tuning: Spark

I've pretty well dialed in the VE (fuel) tables with average BLM numbers between 126 and 130 for most cells.

BLM is Block Learn Mode and basically indicates how much fuel the computer is adding or subtracting versus what's called for in the VE table. Low numbers suggest rich condition, high numbers suggest lean condition.

Earlier this week I worked on adjusting timing, starting with Bill USN-1's timing table on Binder Planet. After driving and minor tweaking, the part throttle timing appears to be pretty good, now.

Two issues remain. Sudden WOT from idle/stopped results in popping and stumble. I'm looking at a possible lean condition and/or timing issue.

Second, the vehicle has little power at 30mph (low rpm). Part of the problem is my transmission shift kit refusing to do part throttle downshift at this speed. Transmission linkage seems properly adjusted.

Using a '7747 ECM, $42 ASDU bin, there's the Main SA (Spark Advance) table, but it's modified by several things. There's a table for power enrichment spark advance which shouldn't be needed in my case and may be causing the first problem. There's also an accelerator enrichment (same function as a carburetor accelerator pump) which I've increased slightly to prevent lean out in hopes of preventing the first condition occurring anywhere else.

Finally, I've restored the Warm Bias setting. The Main SA table can be biased, that is, the zero point can be set to a positive number to allow negative SA numbers. The stock ASDU bin has this set to 9.84, in other words, that value is subtracted from any cell in the SA table to get the 'real' value. A value of 9.84 in the table is zero. A value of 19.84 is 10.00.

I had removed this bias and adjusted my timing table down by 9.84. Just in case this is causing problems elsewhere, I reversed this change, adding 9.84 to my SA table, and restoring the 9.84 warm bias value.

I haven't had a chance to test drive yet.

Due to personal reasons I need to take time off from the Jeep and the blog for several days.

Thursday, April 25, 2013

Grizzly Lake


One weekend in August, 2007 held several firsts for me and what is adventure if not experiencing new things? Adventure can also be found in places you've been, so long as you're steering your life outside of the daily grind into different territory. Both metaphorically and literally in this case.

Monday, April 22, 2013

TBI Test Drive and Super Chief

TC successfully completed the first cross-town test drive since rebuilding the throttle body. I wanted to go see Scott's newly painted Super Chief.

Scott's 86 GW, "Super Chief"
His truck is way prettier than my ugly, faded, dented, rustbucket.

I just did new injectors, new gaskets on the throttle body, and new gas tank. Before that, I had issues I couldn't seem to tune away. Lean spots where I couldn't bump the VE table up any further. I had to increase base pulse width (BPW) to an insane degree and still didn't quite get it solved.

Running the stock ADSU bin, it starts up easily--unlike before--and it drove pretty good but had some serious lean spots at high load, low rpm. I was able to tune those out and the drive back was improved.

More lean spots remain and it's running rich in the low load, low rpm areas. Hopefully I can tune those out, then get on with the highway tuning, and get it ready for emissions later this week.

Friday, April 19, 2013

TC is running again!

I finally started TC today! First, the TBI module went on. Then, I took a quick trip to the gas station to fill my 'new' vintage U.S. military jerry can, transfered 5 gallons into TC's tank, then discovered problems with the fuel pump.

A little persuasion (with a hammer) got it delivering fuel again. The pump was clogged, most likely, with the same fine rust in the old tank.

The truck fired up and ran surprisingly well on a stock bin. I could never get to run right before so perhaps the new injectors saved the day. I'm sure soaking the TBI in cleaner and replacing all the gaskets didn't hurt, either.

Now, back to tuning after such a long hiatus, then time for emissions and tags.

Thursday, April 18, 2013

San Juan Mountains

Way back in 1999 I discovered a jewel among the Rockies, a getaway offering some of the most beautiful alpine views in all of Colorado.

The mountains are flecked with the history of adventurous miners. Old buildings in the towns of Ouray and Silverton silently stand watching the decades pass, sparking the imagination, painting a ghostly panorama of life around the turn of the last century. Out on the old trails, feelings of awe can be found around most every turn.

How do you explain to someone who voluntarily incarcerates themselves among streets and concrete what it is they're missing? Pictures are pretty but a 4 inch by 6 inch flat piece of paper doesn't convey the size and space standing among eons old mountains, or the brilliant splashes of color in crumbling rock and delicate flowers clinging to them.


I've been to the San Juan Mountains a half dozen times in ten years and the adventure never gets old.


I wrote that in 2008 preparing for a trip that never happened because of a loss we experienced that year. The last time we were in Ouray was 2005. I haven't been to Ouray since, but our wonderful little girl, born in 2009, has taken a shine to the "Big Jeep" over the last few years.

At long last, I'm making serious preparations to take her on some four wheeling and camping trips, something I've tried to do for the last three years. Maybe, just maybe this is the year, 2013, I'll get to share the wonder of the San Juans with her.
 Time passes quickly. Don't watch as it passes you by.

Find what's most important and grab onto it as if you won't live forever...