Howdy--new member!

While I have been tuning cars for some time, they have either had mechanical fuel injection (1973 BMW 2002tii) or dual sidedraft carbs (1969 BMW 1602ti). Both are track-only. My 1995 Chevy K2500 350 TBI truck needed a new engine, and I had been planning to build a stroker, so I ended up getting the GM Performance HT383E crate engine (6.3L) and an upgraded Monster 4L60E transmission. I initially got an "internet tune" chip and the truck runs well, but mileage was terrible so I decided I should learn how to tune the TBI system myself.

I've been reading a lot and have much to learn. I have succeeded in pulling the .bin off the custom chip, doing a compare with the difference tool, and just got datalogging to work. Emulating and programming is still a ways off. I have the 16197427 PCM, BCC Code BJYL, Mask $0D, and am using the 0D_TPV5_v250.xdf definition file. I believe the correct data stream for my truck is A217. Got my Innovate MTX-L wide band installed and am running TunerPro RT5 on Windows XP SP3 with the Moates APU1 hardware.

While I understand some of the theory, the practice of tuning a computer-controlled engine is very new to me. Learning on the truck will help me with another project--I am upgrading on of my track cars to fully sequential EFI. I am using a Haltech PS1000 ECU, a new slide throttle system I commissioned with the injectors placed at the top of the air horns, dry sump oil system, etc. The Haltech system is deep, so this should be great for getting my feet wet.

EDIT: I see as a new user I am rated "Carb and Points!" Somehow that just seems appropriate :cool:

Thanks, Fred

:welcome:

Feel free to post a data log and ask questions.

dave w

:welcome2:

OK, my first real post and data log. Advice was to do a lot of reading and research so I did and now I have a number of questions! http://www.gearhead-efi.com/Fuel-Inj...cons/icon7.png Apologies if this is too long....

UPDATE (9/16/14)
After more research, data logging and tuning, and talking with Dave W, I have answered many of my questions. Summary of answers below in red, perhaps they will be useful for someone who is just starting out with all this.

QUESTION SUMMARY

• How do my data logs look?

Chip was rich overall

• What values should I use in re-enabling the knock sensor?

I used about 2/3 of factory values, may up to full factory value

• What might be causing observed knock counts?

Determined not false knock, but too much SA in some cells. Reducing SA a touch is fixing this.

• What values should I use to re-enable EGR?

After talking with Dave decided not to enable EGR. May revisit this at some point

• Does the stock 350 TBI flow enough air to support 340 HP?

No, it does not. My engine is air restricted, which may be why the chip was very rich from the get-go. Recently purchased a 350 TBI bored to 46mm with ultimate TBI mods (radiused air horns, etc). According to the supplier, this should flow enough to support up to 360 HP.

• Can the 350 injectors support 340 HP if fuel pressure increased?

No, would need about 30 psi which is getting to the limit of stock injectors. I was going static in a few cells at 18psi, and when I have enough CFM to feed the HP the injectors will certainly be too small. I purchased a set of "cop car" injectors with the new TBI, with the suggestion of running at 22 psi.

• Will the 16197427 PCM work with a vacuum reference pressure regulator?

Yes, but have not explored. Would likely need if ran 454 injectors as would be rich at idle

• Is my injector flow rate correct?

Adjusting this moves the VE map up/down. Dave W. suggested keeping the VE in the 40-95 range for best tuning ability

• Why doesn’t engine lean out if injectors actually going static?

The reason I was at 12.5 AFR @ WOT with static injectors is likely that the stock throttle body cannot flow enough air. Would likely go lean with the new 46mm throttle body.

• Do I have sufficient spark advance for the Vortec heads?

After looking at Vortec spark maps and other examples I saw my spark table needed quite a bit of adjustment and smoothing. First job was to kill the knock and I did that and cleaned up the SA table a bit. Now focusing on fuel maps, then will go back to spark tuning once new throttle body dialed in.

• What values should I use to re-enable spark retard for torque management?

Decided to leave torque management off for now, but when starting from a stop in the rain the other day the tires spun very easy. May try putting back in 20-30% of stock TM values.

• Is my RPM/VSS Ratio correct for my tire size?

I don't think it is, but need to research this more before changing as I still do not know what is affected by this parameter.

In new news, I recently downloaded the $0D transmission parameter adx files and am doing some transmission data logging. I like being able to see the transmission temperature and wonder if I can tap into the wiring harness to feed data to a temp gauge. But that will be the subject of a different post....

BACKGROUND
To recap, I have a 1995 Chevy K2500 with a new GM Performance HT383E crate engine with the Vortec heads, 4L60E transmission, 1650 RPM stall converter and 3.73 gears. About 3000 miles on it so far. 16197427 PCM, $0D, modified BJYL bin, 0D_TPV5_v250.xdf, $0D-16197427-V5.6.adx. The truck runs well and tows fine, but shows knock counts, is rich in some load cells, and does not engage EGR. I started with a Harris chip and it ran pig rich. One iteration helped this—he increased the injector flow rate from 61.0 (stock) to 65.1 lb/hr and bumped up the VE map.

Based on my research I have decided to do the rest of the bin setup and tuning myself. I have gone through and identified all parameters that are different from my stock BJYL bin. Most of the changes make sense and seem to be in the right direction. A few give cause for concern. From here I want to better understand the parameter settings and which ones should be adjusted before I start to tune the VE and then the SA tables.

SPECS AND MEASUREMENTS

• Base timing confirmed at 0 deg.
• Stock 350 injectors and Delco EP381 fuel pump (155 LPH free flow)
• Stock 350 TBI w/AFPR, using 18 psi spring and measured fuel pressure is 18 psi
• TPS at is 0.55V at idle and 4.49V at WOT
• IAC current position at warm idle averages 18 in Drive and 20 in Park
• Mid length headers, 1.625” primary, 3” collector, Y-pipe into 3" free flow single exhaust
• NBO2 installed in factory position, just before cat
• Innovate MTX-L WBO2 installed, not yet added to data stream
• EGR retained, added external EGR tube to header collector
• GM HT383E spec is 340 HP @ 4750 RPM and 435 lb-ft @ 3600 RPM
• Passed MD tailpipe test with no problem

DATA LOG ATTACHED
My bin, mask, definition and two data logs are attached. The first log has a few short WOT runs and a fair number of knock counts. The second log has more steady state TPS and a lot of knock counts, which has me concerned.

I realize these logs are not as clean as you would like as there is some PE, AE, DE, DFCO, open loop at WOT, and engine was not fully warm to start from run #1. Next step is to modify the bin with these parameters disabled, knock retard enabled, and the WBO2 data stream included and do some controlled data logging. Just wanting to get some first impressions and identify any issues of major concern before I go further.

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Data Log 1 Notes

• AE, PE, DE, DFCO all active
• 1095 counts of WOT (3 minutes)
• BLM Min = 105
• BLM Max = 129
• INT Min = 104
• INT Max = 137
• SA Max = 36.2 deg.
• IDC Max = 116% (calculated)
• 12,250 knock counts in a 13-minute run

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Data Log 2 Notes

• AE, PE, DE, DFCO all active
• 5 counts of WOT
• BLM Min = 105
• BLM Max = 129
• INT Min = 118
• INT Max = 139
• SA Max = 35.5 deg.
• IDC Max = 61% (calculated)
• Over 42,000 knock counts in a 10-minute run

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KNOCK QUESTIONS
I am getting knock counts under a variety of conditions. I don’t hear audible knock (I did when I had a bad plug wire) and have read about the issue of false knock. The old 350 knock sensor is installed, I don't know if mechanic torqued it correctly. Also I don’t know what knock chip is on the Harris MEMCAL. I’ll be using my original BJYL MEMCAL with the G1 Adapter once I start emulating so I’ll know it is the right one (not a V6 chip). The Code 43 Knock Sensor Circuit Failure was not set but I will set for the next tune.

The “Maximum PE Knock Retard vs. RPM” and the “Maximum Knock Retard vs. Vacuum” tables have been zeroed as would be done if running without a knock sensor. The other knock settings are still enabled; meaning the traditional knock hiding method was not used. Would using the stock BJYL spark knock retard values be good for a start?
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Data log 1 Notes

Knock at High MAP, Low RPM

Sample # 1437 - 1480
Sample # 3202 - 3227

Knock at High MAP, Mid RPM

Sample # 1642 - 1665
Sample # 2197 - 2211
Sample # 2719 - 2737

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Data log 2 Notes

Knock at High MAP, Low RPM

Sample # 2040 - 2140 (85 MAP, 45 TPS)
Sample # 2269 - 2351 (92 Map, 57 TPS)
Sample # 2607 - 2651 (88 MAP, 40 TPS)

Knock at High MAP, Low-Mid RPM

Sample # 866-871 (96 Map, 100 TPS)
Sample # 1440 - 1450 (92 MAP, 60-70 TPS, Max IDC 61.3%)
Sample # 1604 - 1618 (75 MAP, 45 TPS)
Sample # 1746 - 1776 (85 MAP, 55 TPS)

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EGR QUESTIONS
I understand some EGR can improve MPG. Minimum Speed for EGR is set to 7 mph (vs 0 mph stock), so EGR would not function during tailpipe test. In addition, RPM for EGR On is 6150, so EGR is fully disabled. Should I return to the stock 0 MPH and 800 RPM? Any downside to enabling?

FUEL AND AIR QUESTIONS

Air Flow
Does the stock 350 TBI flow enough air to support 340 HP? I noticed the truck pulls a lot smoother to the 5000 RPM redline when I removed the filter and housing. For now I have removed the snorkel and trimmed the air box muffler, eventually will fab a deeper filter housing so I can run a 4” intake tube to the inner fender well. Internet carb CFM calculators suggest that somewhere in the range of 470 – 660 CFM, depending on VE, is needed to support the HP. I understand that 350 TBIs flow about 490 CFM and 2” bore 454 TBIs flow about 645 CFM.

Fuel Flow
Everything I have read here and calculators online suggest that the 350 injectors, rated 61.2 lb/hr @ 13 psi, are insufficient to support my HP even at 18 psi. E.g., if BSFC = 0.5 then two 350 injectors @ 18 psi (roughly 72 lb/hr each) only supports 245 HP @ 0.85 DC. Since my WBO2 reads 12.5 AFR @ 5000 RPM that has me wondering if I don’t have enough air flow. If the injectors were going static it would lean out at high RPM, which I don’t see now. I could increase the fuel pressure if need be, but have read here that much above 18 psi using a Vacuum Reference Pressure Regulator may be needed. Can the 16197427 PCM be set up to handle a varying injector flow rate?

Bin Settings
My stock BJYL bin had an Injector Flow Rate (TBI lb/hr) of 61.0 @ 13.0 psi (measured). The current Harris chip has injector flow set at 65.1 at 18 psi (measured). Why would it not be set at 72 lb/hr, which is what the stock injector should flow @18 psi? I do understand that changing this parameter can have a big effect and require adjusting the VE table and perhaps other things.

Duty Cycle
The IDC reported by the ADX is half of the calculated as has been reported in other posts. Using the formula IDC = (BPW*RPM/300) I find a max IDC of 116%. But the knock occurs well below 85% DC, so that is not the issue there. Why does it not lean out if it is truly going static? Need to get that WBO2 hooked up!
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Data log 1
Calculated Max IDC of 116%
Sample # 2161 - 2192
WOT, PE, MAP 90-93, Spark 30.6 deg., RPM 3,875 - 4,925
-----------------------------------------------------------
Data log 2
Calculated Max IDC of 61%
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SPARK QUESTIONS
Spark Advance

• Maximum spark advance in the SA table is 33 deg. Max observed in data logs so far is 36.2 deg. I have read Vortec heads will want more spark than my old L05 engine. Comparing to the BRDW spark tables as read by $0D mask (1996 TBI/Vortec G30 Van, L31, $63), the Harris chip has more SA. Comparing to the AMUR-0055 ($42) spark tables the Harris chip is similar, but with less SA at low MAP and more at high MAP. The Performance AMUR AT-Vortec 350.bin ($42) from Dave W. is very aggressive and I certainly would not try it until I get my knock issues sorted out.

• I know VE must be tuned before changing SA. Do my current values look reasonable for the Vortec heads?

Spark Retard

• Maximum Spark Retard for Torque Management has been zeroed. I understand that TM is used to reduce load on the transmission during upshifts. Some folks say zero it out, others say reduce it by 70-80%. Should I put it back to the stock -7.7 deg, or perhaps some lower but non-zero value?

VSS QUESTIONS
The RPM/VSS Ratio in my stock BJYL was 40.718, now is set at 37.116. Neither of these agrees with the calculation for my tire size, 265/75/R16, which comes to 39.569 for the 3.73 gears. The stock options were 225/75/R16 (43.0) and 245/75/R16 (41.1). The setting currently appears to be 6.2% lower than it should be. What will happen if I increase it? Does it affect the speedometer and perhaps the mileage calculation?

Thanks for taking the time to read through all this. I could have done separate posts for each question, but since the engine, PCM and other components all work as an integrated system, I thought it best to have all my thoughts in one place. I do realize that I should make one change at a time so I can see the individual effects—that takes patience! I look forward to your insight and suggestions. --Fred

I'm very limited on time lately.

The attached screen shots show the BLM averages Near Idle / Off Idle. Numbers above 128 are lean. Numbers below 128 are rich. Overall, the chip is rich. The following are removed from the BLM averages, AE / PE / Open Loop. Near Idle is data from Idle Flag on.


dave w

Dave--Thanks for the quick analysis. No rush on a response, I know I asked a ton of questions. --Fred

Quote:

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Originally Posted by FB73tii

Dave--Thanks for the quick analysis. No rush on a response, I know I asked a ton of questions. --Fred

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I was looking for an excuse to use my newly developed Excel spreadsheet to analyze a log file. The above screen shots are both .xdl files combined. Send me a PM If you would you like to be a "Beta" tester for my Excel spreadsheet.

dave w

You bet! PM Sent.

About a month ago I posted 12 questions stemming from my first attempt to get into tuning my truck. I have since been able to answer most of my questions through more research, input from Dave W., and now actual tuning experience. I have added answers to my own questions to my original post (in red font above) in the hopes that perhaps they can be helpful to other beginning tuners like myself.

I have been using Dave W.'s beta Excel tuning spreadsheet and it has been very helpful to me. If you have not used it yet, give it a try!

Fred