1986 L98 Coupe Cast Iron
PCMforLess custom Tune
BOSCH III22lbs (upgrading this weekend to 24lbs as per FIC suggestion)


Couple of questions

Understanding that a BLM reading of 128 is optimal and there is a (+-)10 tolerance where the ECM will adjust.

When is the best time to look at BLM values when doing a datalog?

>>Open Loop idle--mine are steady 128
>>Closed loop idle--mine are around 120 on average
>>WOT
>>Normal Driving---mine seem all over the place --anywhere from 114 to 140 at different RPM's

Also...when i swap in the 24 lb injectors what will i have to change in the tune exactly?

Just curious

 

You want to look at C/L as that's when your sensors are running the tune. It sounds to me like you need a touchup tune.

I prefer +/- 5 on the BLMs BTW, but everybody has their own tolerance level. How are your knock counts?

 

3 knock counts at start up...a few more at WOT...but i don't go there too often. I figure i need to adjust the tune anyways when i put in the 24 lb injectors.

What exactly needs to be changed in the $32 file to compensate for the larger injectors and more fuel that comes with them.

Jon at FIC suggested i go to the 24's to make up for the longer cranking cold starts with the B3 X 22LB.

 

I've never tuned in $32, but I think it's fairly similar to 6e. You'll need to change your inj constant & MAF tables (which are off now anyway). If this is a PCM tune, I think they'll do reburns off your datalog.

WOT is a whole different matter.

 

Where do you change the injector constant in $6E

I see a couple of places like "Single fire FI Size@40 psig" and "double fire FI Size@40psig"....is that where you are talking about. Do i just change the value to 24 in those 2 locations?

 

Those are the constants, change both to 24. As far as your extended crank issue is concerned, inj sizing is an inapropriate way to address the issue. See if your bin has a table for crank fuel pw vs. ref pulse or similar. Our cars are notorious for longer crank times when we remove the CSI. Adding a touch more fuel in the lower ref pulses (1 thru 8) will help quite a bit........start with a factor of .250 to.500 in pulses 4 thru 8 and see if that helps. You can play with it from there.

 

Your BLMs depend on which cell you're in. Here's the chart I made from my BUA 9340 code ('86 auto w/3.07 rear ratio). The later BUA 1728 code raised the first RPM breakpoint to 775 RPM:

Some of the cells are virtually impossible to get into. I don't see how you could be under 700 RPM with more than 34 gm/sec of air flow (cell 12), for example. Same type of logic applies to cell 3.

Basically, you want to tune for cells 0, 5, 10 and 15. Those are the ones you'll spend the most time in.

 

I will be swapping injectors to the 24lb in a day or 2 and then i will datalog again to check BLM numbers.

Will my existing custom tune from PCMforLess with all the changes to spark advance and maf tables for the 22 lb injectors work with the new injectors or should i put the stock BUA9340 bin back in and re-tune from that one?

 

I'd go with the PCM tune, it should be a better bet. Based on your currrent numbers, it's nowhere close at this point though.

 

WE emailed that tune back and forth to Kelley at PCM 4 times and they signed off on the last one??

When i switch injectors, i'll try with both chips (PCM and my Stock file) and post results of the datalogs and any performance issues...hopefully i can get the injectors done tonight...got some free time happening later.

Thanks

 

Oh..Oh..

BIII 24 lb Injectors swapped in tonight...tightened a few bolts on the intake that were seeping oil---got bored and my friend hollowed out the converter to give it some character.

Started up with no issues with the PCM chip...let in run for 15 mins....took it for a short drive...rough idle in gear...sorta like a mild cam??

Changed chip to stock BUA9340 and altered the injector constant to 24.5lb...same thing...bouncy rough idle. Runs okay while cruising...not nearly as smooth.... as it was with the Bosch III's...might have to change them back...not liking the roughness all of a sudden

Too much fuel??? exhaust flowing freer causing the rumble??? ...almost feels like a miss?

Will do a few data logs tomorrow

 

You indicated you were at 120 idle and between 118 &140 cruise, is that based off your final tune or had you done any subsequent motor work? I don't think many tuners would call that close enough...... they're pretty thorough @ PCM; there must be a misunderstanding somewhere.

 

I appreciate your input and how you are following this thread Caboboy...Thanks

Actually looking at the last file Kelley from PCM sent and the latest datalog...The numbers were not too bad but they were still quite eratic
L-TERM and S-TERM bouncing around from lean to rich 120 - 140 with the Bosch III 22lber's.

Update on the rough running issues after the injector swap.
Turns out we left a vacuum line unhooked under the TB...Hooked that back up and the motor smoothed out a touch...still bouncy and rough though.
Took the car for a good hard 1 hour drive and that did the trick...i guess you have to run some fuel through these injectors to wake them up some.

Did a couple of datalogs with both the stock chip (changed injector constant to 24) and the PCM Final tune for the 22lb injectors. The car performed much nicer with the PCM tune, although with both files the car ran rich...For whatever reason the injector constant was at 24.07lbs in the PCM tune for my BIII 22lber's??

The pcm tune BLM counts were on average as follows
S-TERM Counts were very stable and within range most of the time averaged around 124-130 i guess.

L-Term Counts were very low around 108-114 quite often...too rich

What do i have to change in the tune to lean this out and get into balance?? I have posted the latest datamaster scan for someone to have a look at ... http://www.mediafire.com/download.php?brcubpd5v8x7gcp


Thanks in Advance

 

I'm down in Cabo for a couple weeks, but I've got TTS loaded on my laptop here I'll take a look at your log in the next day or so in between cervezas

 

Another member emailed me and told me that if the car is running well and its just too rich with the new 24lb injectors...i can just increase the injector constant to 25 or 26 (play with the numbers) and that should bring the low BLM Count up close to the normal 128.

Sounds too easy?

Your thoughts

Thanks

 

You can absolutely do that & see what happens. Be aware though things like raising the inj constant or lowering F/P are global changes to lean your tune out and will also move any lean areas you have further up the scale. The converse would be true for a lean running tune.

MAF tables are fairly straightforward to calibrate and specific to given RPM/load areas, so that's why I'd prefer to use those for fueling part throttle.

 

I had a look at the MAF tables with tuner pro...wouldn't even know where to begin editing those...will have to do alot more reading on those tables.

I will probably try the easy "fix" of raising the injector constant a notch at a time...do some datalogs this Thursday if the weather permits.

I am a little leery of this because im sure doing that will lean out the S-TERM BLM counts which are pretty much okay right now.
Will post results when i log these runs.

It is the L-TERM Counts that are way rich at around 112 on average

Ray

 

It's not the short term you need to be concerned about Ray, they're just a function of the long term counts (readers digest version). I'll try calling you again tonite...

 

Just want to give a big thanks to Caboboy for all his help working with me over the past 6 weeks to fine tune my MAF readings in my tune to bring the BLM values back in line with the new BIII 24lb inJectors.

The car is running great right now...no more heavy fuel smell (rich)
Good looking fuel curve on the graph. Idle is a smooth as new too

Cant wait for the spring weather to run it a little more often and check the fuel mileage.
Mileage should be back in line after all this fine tuning

Thanks Again Tim
TTYL


Ray

 

You're more than welcome Ray, it was great to meet you! Tell that little goal scoring machine to keep all his teeth, OK?

Shoot me a new log when the weather clears up this spring, we can do a bit better at mid throttle cruise