First off, I have been reading thirdgen messages boards for 2 weeks now and finally signed up. This is a tremendous resource and I hope it stays alive for a long time then becomes a reference for years to come.

I am currently working on a new engine for my 88 1/2 ton pickup with the 7747 ECU. I have a crate 350 (1996-2000) block with stock vortec heads and the roller cam. Right out of the crate its getting the entire GMPP LT4 hot roller cam kit with springs for .525/.525 lift. Sitting on that will be an Edelbrock 7116 intake, Holley 17-45 TBI adapter and a bored throttle body from CFM-TECH. I'll be running the 90# injectors with 255lph fuel pump and around 18psi of fuel pressure (roughly). This setup with a carb is tested to yield around 410HP at the block. I really hope to get close to that with the TBI, but Im really really new to the tuning stuff.

I guess my question here is to the experienced guys out there. Im want to see how feasible the PROM tuning will be

1. Can a custom chip configuration be created for my setup and goals?
2. (dont laugh, but) any chance it will still pass emissions testing after PROM tuning the engine to extract the optimal power
3. Is diving straight into this PROM tuning as a newbie a bad idea for such a radical setup? (or maybe its not so radical to you fellow rodders out there).
4. Do you have any other suggestions besdies reading historic posts as to where I'd start with my tuning?
5. If I do the engine swap from my stock 350 to the one described above, will it even run with the stock .bin config?

Any help input would be much appreciated.

-Aaron

 

1. Absolutely
2. Dont know as I have no emmishions
3. That is what I did. It was a bit frustrating tuning as well as the hardware/software/chips/etc. But it eventually got done. I would invest the $$$ and get EBL for sure. Worth every penny.
4. Yes
5. This is the tough question. You will need to use a Vortec spark table. They are on this site. Once it starts running and comes up on temp it will flip closed loop and should be at stoich and OK for cruise. you will have to tweek cold start and especially AE and of course the VE tables. You will see a trend soon and make global changes in VE. I would suggest tipping the table to BLMs <128 and then your logs will see a need to remove fuel. EBL will make this so much easier it is not funny. If you wish to maintain 7747 control look at Craig Moates site for hardware required and a cable that works.

 

What is the opinion on getting started with a custom chip from TBICHIPS.com since I have zero experience programming. Then work the bin he gives me if necessary? Is this a waste of money or have others tried this? Its not cheap, the chip + fuel pump kit sells on ebay in his store for around $345. I just dont want to spend tons of time trying to dial in my new engine as I will want to test its behavior for mechanical integrity so I am confident in the machine work to the new block.

I'm just a bit hesitant to start from prom tuning 101 to an accurate tune for a 400 hp engine in any reasonable amount of time.

thoughts?

 

'88GMC

1. Forget about Chips - it is so 20th century. Ronny is right on the money with EBL (I run EBL flash). 7747 is a C3 ECM and it is less than optimum in its original form for dialing your setup. EBL conversion removes PITA aspect out of DIY tuning. There is a learning curve with DIY tuning. Mail order tune will get close, but it will never be perfect.

2. Emissions passing depends on many factors - including visual, functional and tail pipe levels. This engine will never pass CA visual, since Vortec is a post 96 engine (no EGR passage in intake manifold). The only way in CA to get Vortec to pass into an earlier truck is to perform a complete drivetrain swap. Basically you can not mix drivetrains and emission equipment. In your case laws and rules might be different - check very carefully.

3. The LT4 cam is not that bad with duration at .050 in. 218/228, Lift .492/.492". The LSA is 112 deg which is a bit short side, but should be OK. Expect some idle tuning, both DIY and mail order.

4. Hmmm, yes I would start with DIY EFI 101

5. Your stock 350 calibration may be good enough to fire up that engine - and that's about it.

//RF

 

Thank you both for your recommendation. The whole purpose of me probing here is to avoid reinventing the wheel. Thanks to your input, I have decided to invest in the EBL setup. (still reading up on any decisions or options I need to consider there).

RF, as for the emissions, Im in CT, and I believe all they do is throw my truck on dyno and stick a sniffer in the pipe. They simulate a series of laod scenarios and take some sort of average, but thats all I know. Im not even sure they are allowed to look under the hood unless I authorize it. (as if that will stop them ;-) That said, I'd be mainly concerned with whats coming out the tailpipe.

Also, it sounds like you know are familiar with the GMPP LT4 hotcam but one thing I'd add is that I went with the 1.6:1 roller rockers, not the 1.5:1 so the effective lift is .525/.525 instead of .492/.492. Im not sure if that will affect things, but I'd guess it would affect idle vacuum levels?

I gotta do my homework on the EBL ASAP. Do you guys know offhand if I can easily revert to the 7747 when/if necessary or does the EBL require rewiring? I actually have 2 7747's sitting here so I could keep one untouched/unmodified as a spare.

 

Should be able to pass emission with that setup properly tuned. My setup is similar and has passed. See the following link.
https://www.thirdgen.org/forums/tbi/...mmissions.html

 

1. CT probably uses a 15 and 25 MPH test sequence profile which is identical to what we have here in CA. The problem with CA smog check is visual check requires tech to verify that nothing has been modified! If anything is out of place you better have EO number that has been approved for use on that particular vehicle, drivetrain combination. Otherwise enter the twilight zone. It is always very frustrating and problematic to say the least.

2. General comment (just my opinion) - save your money and do not put 1.6:1 rockers. Stock Vortec heads flow 'stalls' at higher valve lift. In other words flow does not increase substantially at valve lifts above 0.500. Right now I have pair of stock Vortec heads that I am about to rework for 350 or 383 build up. Based on several magazine articles stock Vortec heads work best with valve lift below 0.500. Additional valve lift should also be matched with porting. Now, you'll have to do ROI - better aftermarket heads or extensive porting. Something to consider...

3. EBL is an internal conversion PCB that replaces existing daughter PCB within you 7747 ECM. There is no wiring harness changes involved what so ever. With that in mind I would strongly recommend to get another 7747 ECM - these are very common and readily available. I get my ECM's from local JY for about $30, and make sure that ECM came of V8 truck. Verify that candidate ECM works as is with your current engine (at least that engine can start and idle) and then perform EBL upgrade. This way you always have a safe back up. Think of EBL as dropping a 454 into Chevy Vega in terms of flexibility and adaptability. If you do chose EBL go with a flash version - the best in flexibility - no chips involved. You'll need laptop with RS232 com port and TunerPro-RT software - free (our for donation 10 second nag is removed). Do some reading on EBL tuning - there is a long thread. Check out FAQ on EBL page.

//RF

 

Perfect, thanks for all this info. I did research the EBL and read through all his literature, the WUD looks like a really helpful tool.

Random thought: Any idea if its possible to use the EBL ECM to create a BIN that I could take over to my non-EBL 7747 which I run on a bone stock truck? The reason Im thinking of this is because I want to make a few tweaks there eventually when I slightly increase the fuel pressure and put a slightly "larger" cam in. Any idea if that would work? After reading about the EBL, it almost sounds like the BIN would not work since it has more data, but I may not have fully understood.

 

Yes, you can transfer VE and spark tables from EBL ECM to stock ECM configuration. It is not a direct transfer since EBL uses extend range tables, but it can be done with a help of spreadsheet. ITHK there was a thread discussing this and other ideas.

//RF

 

I've got the EBL up and running for about 2 weeks now. I have been self-educating and experimenting with making changes to the BIN. Right now I'm still running my stock engine setup but figured I'd give the VE learn a shot.

I disabled EGR, Disabled CCP, and disabled Lean cruise. I then ran about 12 ve learns and when I log, I still see variations between 114 to 139 BLM. is this ok (normal?) I feel like the VE learns are correcting one way, and then back, and so on (a circular effort). I have my smoothign factor set to 8. I've also tried it at 4 or even as high as 12, but Im still seeing the ve learn "correcting the corrections" if that makes sense.

Could my single wire non-heaed NBO2 be causing this? Should I invest in a heated 3-wire or is that a waste of money? Im not quite prepared to start tuning with a WBO2 at this point, but figured I'd ask to see what the experience has been out there with EBL and the NBO2.

 

Couple of Questions:
1) Did you update bin between each VE learn test drives??
2) Did you drive over exactly the same course while maintaining the same driving style?
3) Same weather conditions over 12 VE learns?
4) Where is your NBO mounted? Do you have headers or stock manifolds?
5) Engine performance???

7747 does not have IAC - expect wider variation in VE tables over ambient temperature.

//RF

 

Couple of Questions:
1) Did you update bin between each VE learn test drives??
A: Yes, the bin was updated and flashed to the same bank overwriting the previous each time. I verifed with both PROM ID and new value deltas
2) Did you drive over exactly the same course while maintaining the same driving style?
A: I did try to keep it as close as possible, but I would not be comfortable in saying "exactly the same"
3) Same weather conditions over 12 VE learns?
A: Yes, weather conditions were nearly identical.
4) Where is your NBO mounted? Do you have headers or stock manifolds?
A: NBO is mounted on the stock exhaust manifold, drivers side (no headers)
5) Engine performance???
A: No change in performance. The corrections are typically betwen 5 and -5 in range from the VE learn.

7747 does not have IAC - expect wider variation in VE tables over ambient temperature.
Unless IAC refers to something else, I do have an Idle Air Control valve and I'm using the stock stepping from the 7747 bin provided with EBL.

 

OK

IAC = inlet air sensor - my typo, brain fart on my part. +/- 12 is a bit on a wide range, but I'll have to go over my notes to see what my VE learn experience was about a year ago when I was going through the same VE experience. My BLM's end up being in the 118 to 131 range. I've developed a VE learn test route of about 15 miles consisting of city streets and a bit of highway and drove it over a period of three month. Over time my BLM's got to be +/-5 i.e 123 to 132 (after about 15 drives). I have a fully heated aluminum intake which keeps things a bit more stable over ambient temperature range once engine warms up ( you have non-air gap as well) and IAS (6965 ECM from B-body).

//RF

 

Datalog attached. Also notice the knock, is this excessive?

(remove the .txt and open as .csv)

 

It appears when TPS above 35% you get higher knock count. It looks like under higher load, higher MAP values, you get more knocks. Once you get into throttle a bit more knock count goes up - looks like you need to back off on timing at at higher TPS values. Also, you can see higher KS count at higher MAP values which indicate greater load. Take couple of degrees in the effected VE cells.


//RF

 

Quote: I feel like the VE learns are correcting one way, and then back, and so on (a circular effort). I have my smoothign factor set to 8. I've also tried it at 4 or even as high as 12, but Im still seeing the ve learn "correcting the corrections" if that makes sense.

Are you identifying by looking at newlearned.bin that corrections in fact appear in new bin? Use "compare" feature in TP. You should see the changes that Learn created. As far as smoothing I use .90 not 9.0

Also lately I have been playing back my datalog(fast speed) while LEARN VE is in effect. then I look in WU for the % amount of corrections that occurred. If I was seeing 10% corrections each succeeding learn.bin should be less %. Closer to perfect. If you can print that screen or print the VE tables off TP you can see the change in VE table. I started from scratch this spring as I tweeked my BPC/VAC table so I am at a point after 15 burns it is about where I want it. Make sure no EXT leaks at header flange to ext pipe.

 

QUOTE: As far as smoothing I use .90 not 9.0
Are you talking about the smoothing factor in WUD software? It only allows me to use integer values. I tried using 0.9 and it changes it to 0 after I hit save.???

 

Also Ronny, what do you mean by tweaked the "BPC - BPC vs VAC" table, isnt it just a matter of plugging in the fuel pressure and Injector lb/hr rating to rbob's spreadsheet and then filling in the BPC constants? He has built in formulas for static FPR as well as VRFPR.

 

My error. I was refering to Tunerpro. Inspect the B4 and after the smoothing takes place in WU VE table. If I recall it displays whole numbers not decimal to the .01. In WU I also witness the % change. For instance for smoothing if I have a value of say 60.40 and that cell is smoothened it likely will change to say 60.55 I do not see large changes as a result of smoothening. Maybe .90 is not the best one but it does make the efffect.

I would expect the AERO VAFPR to be consistent in manufacturing tolerences. That being said I copied another members values. He determined that table by use of a Mighty VAC devise. By inducing VAC he was able to calibrate that table. The process is described in a thread. Start out with 0 VAC or WOT for your BPC and work your way down table. He and I have similar fueling needs(80 lbs inj at 24 lbs FP). Yes there is a couple of spredsheets out there. I just found one. I plugged in my values as stated and it suggests 60 VAC(40 MAP) which is my idle VAC should be 15.3 PSI. I am 14+ so off a bit. I would say close enough. My VE table is now calibrated to my values in BPC vs VAC.

 

After a long summer of a few hours here and a few hours there, I turned the key on this build today. I only ran it for about 5 mins when I noticed the bed was steaming from the heat off the mufflers right after the cats, when I looked under the hood, the headers were getting red. Coolant temp was only 138 deg F. I was running the stock timing table from the TBI non-vortec headed tune which I know is way wrong. I did change the BPC to 78 according to the EBL flash spreadsheet calculations. My fuel Pressure is 18 psi with 90 lb injectors.

Would the SA table being WAY off cause this red header effect? I have alot of work to do on the tune, but before I can even get started on a VE learn, I need to get it "somewhat close" so that I dont do any damage to my brand new engine on the first drive.

 

All I know is the vortec uses less timing in the tables. Fast 355 posted some vortec tables here. I would shoot him an email as he is maybe the best contact person here on Vortec-truck. If your headers are red hot I would believe the combustion is occurring too late in the cycle? Is your physical position of the distributor with the est disconnected the same as in your .bin(initial timing). IOW 6 deg for example at dizzy should be 6d adv in the .bin(initial timing).

 

BPC is confusing/concerning me. If I use the equation, its simple, 18 PSI and 90 LB injectors = BPC of 78. Since it was way fat, I dropped the pressure to 15 PSI. I have also lowered my BPC to 72 but still Im geting %DC at a max of around 60%. From what I understand the goal is around 85% max for best driveability and idle characteristics.

Anyway, I am still doing VE learns and while the VE window is closing more and more, BLMs are still way out of range on both ends. Attached is my most recent datalog. As you can see the %DC is all around low, BLMs still way off despite 30 or so VE learns, and power is just not there. I am starting to wonder if PE needs to be locked out becuase I get hesitation and poping out of the throttle body when I accelerate hard. Any thoughts?
http://dunphy.homeip.net/downloads/10_23_2009_0333.zip

 

I am running a similar setup to yours but with a comp cam. You said the power is just not there. On my setup that was generally an indication of not enough timing. I could not find what your timing tables look like but I attached a copy of what I am currently using. You should be careful here, mine is fairly aggressive and may not be right for your heavier truck. As for the popping on accel, that is generally a lean condition. Try adding some AE.

 

Attached is the timing table I'm using. Someone recommended it since the Vortec heads are so much like the B-Car LT1 heads.

 

The timing in that table is all wrong for a car with a cam. Lots of SA at low load, but not enough at low RPMs and moderate MAP. Cams like more timing at lower RPMs to prevent the engine from surging or bogging. Id also try to keep the timing at no more than 40 degrees. Keep in mind that a V8 dist. can only develop 40 degrees of advance before it starts cross-firing to the next terminal.

 

Take a look at Alans table. Thats about what my SA table looks like, but with less advance as my setup didn't require as much as he has. The thing to pay close attention to is the SA at lower RPMs around idle. You'll notice that the minimum there is about 17 deg at high MAP, and not 0. Ive found that its important to get these areas set up right or the engine will surge or bog down as it crosses into those areas and wants to stall out from not having the correct ammount of timing.

Its impossible for me to summarize how to set up the timing in one thread, but remember that with timing, theres no one ammount that works. Generally I shoot for the minimum ammount of timing that allows the motor to run well. This ensures that there is sufficient timing for it to make good power, but not so much that the engine is overtimed.

 

Thanks Dimented, I thought it looked like way too much timing too. I guess I'll go something closer to what Alvanwie posted as a new starting point. The stock Vortec table looks like this below. Any major mods needed for the hot cam?

 

I've got my spark table closer to Alvan and dimented now. Took it out for a 2 hr drive this morning. Not much difference. I dropped my BPC way down to 60 and still the %DE is only averaging around 40%. I' tripled checked the fuel pressure and confirmed 15PSI consistent. (did the gauge under the wiper for the entire ride). A smaller pulse width should result in a higher duty cycle? Yes/No?

Its still sluggish when you step on the go pedal. It acts like it wants to go then bogs down even with light acceleration. I bumped up the "AE - Map Filter" table by 7% then another 10%, but no change in behavior. I'm starting to wonder about these new injectors. I just cant make sense of why the DC is so low with such a low fuel pressure and BPC. I guess I'll pull the injector pod off today and inspect it. I verified with the injector guy that they are 90lb injectors. I wonder if I should put my stock 61.2 back in just to see how it behaves.

This setup has proved to make 412HP, so I know there is potential, but as of now, there is hardly any difference in power from my stock engine at 210HP with 350,000 miles on it :-(

 

Lowering the BPC will decrease the injector PW. Making the engine run leaner. For a 350 with 80.5#/hr injectors at 15 psi the BPC should be about 96. As for the injector size, I'll bet that they are really 80.5#/hr, not 90#/hr.

A larger PW will give a higher injector duty cycle.

Is the engine combo still what was outlined in the original post? Such as the Performer RPM intake? Were the Vortec heads set up for the added lift of the cam? Just not the springs? The guides are tall and can be hit by the retainer if not machined down.

There is one are in the log where the knock counts are steadily increasing. At 0:03:54 you are getting into the throttle. There is a fair amount of knock counts.

It also looks just like you mention, the vehicle isn't accelerating, no power. Unless this was a steep up hill, which would account for the lack of acceleration.

If the power is really down that much then I would look for a mechanical issue. Firing order, cam timing, restricted exhaust, and so on.

Have you tried the Vortec timing tables that are provided with the EBL?

RBob.

 

Anything is possible but from the behavior I'd guess larger than 90, not lower, dont know

Yes, the engine is as described at the head of the post. A crate 350 from GM for a 96-2000 van. I machined the heads myself for the larger LT4 springs and .525 lift. I have the 1.6:1 rockers, LT4 hot cam, headers, full true dual 2.5 exhaust with an X pipe before the cats. Edelbrock 7116 intake, Holley 17-45 TBI adapter and a bored throttle body from CFM-TECH.

I want to clarify that the vehicle is accelerating, its just not a steady and strong pull. Whether on a flat or up a hill, it goes, just not as I'd expect. I will recheck the firing order. I am certain the cam timing is 0 from the pictures I took while assembling. Exhaust is 100% brand new from headers back fabricated by yours truly, so thats not an issue either.
Yes, I have tried this table from the EBL_F_1000.BIN shipped with my EBL, but the behavior is the same.

 

OK, found another area in the log where the engine was taken to a higher RPM. It is leaning out. Check out the graph in the picture. Even though it is a NB O2, it is still useful.

There is still a lot of injector duty cycle available. The VE in that area is in the 86 - 89% range. But the VE is also at 94% at 1900 RPM, 90 KPa. Which means that the VE table isn't set up correctly and the BPC is too low.

The VE% will be the highest right above the RPM of peak torque. The VE will rise from low RPM to the peak torque, hold, then drop off as the RPM climbs above and past peak torque.

I would increase the BPC, and reduce the VE at lower RPMs. Take a look at the 331 ci calibration. Don't copy it, but check the VE tables. That shows the affect more cam has. You may also want to go with the stock Vortec SA tables. Actually I recommend that until the fueling is squared away.

Then once the fuel is OK to the upper RPM levels you can then go back to working on getting the SA sorted out. It will then be a bit of back and forth with the fuel and the SA.

RBob.

 

Something I forgot to mention in the previous post. You will want to disable async injection mode. This will prevent the un-even fueling at the smaller PW's as the ECM switches in and out of async mode.

Zero these two calibration entries:

INJ - ASync Transition Hi
INJ - ASync Transition Lo


That will disable the async mode for small PW's.

RBob.

 

RBob, Thank you!

After reviewing the parts of the log you pulled out as well as my VE tables, I realized that I was in need of a fresh start. The VE tables had absolutely no characteristics like any of the stock or even the modified 331 BIN. It did not reflect the Torque curve as you described to me. I started with a fresh copy of the VE tables from the 0011 for the 88 1/2 ton since thats what I have. I also disassembled the injector pod, inspected it and while off, I bumped the pressure up to 20 PSI.

I started with the fresh VE, 20PSI of fuel, BPC vs Vac set to 80, async disabled and fired it up. It was rich as ever so I decreased both VE tables by 10% all around. I then did a VE learn and found all "-10" values so again, bumped both tables down another 10% all around. From there, I did the VE learns and actually used the BIN they created instead of throwing it out as I had on the previous 2. I took a nice long ride and did a series of NB VE learns.

I am also wondering if folks using the EBL use the VE learn alone, or do you also then go in by hand and smooth out the table so it stays consistent? The reason I ask is that because parts of the table are never reached in the learn, but do perhaps get read from during TPS over 40%. Perhaps this is where the WB comes in?

Anyway, I've posted a zip file with my current VE and log. I have to paw through the logs a bit more, but I think I'm doing a bit better although that darned %DC is still low. Either I'm still not understanding the principal or these are some huge injectors. (I'm sure its something I'm not comprehending and not the later.)

 

You need to bump up the VE in the 3400 - 4000 RPM, 90 - 100 KPa area.

Note the time from 0:10:21 through 0:10:23 in the data log. The NB O2 is dropping off as the engine is leaning out.

I would continue the VE bump up to 6400 RPM. Add to the curve the whole way. Much safer being rich then lean.

I noted that the barometric pressure at key-on, engine-off is 97 KPa. So there is some elevation involved. Not a lot, but it will make some difference in power.

RBob.

 

Now that I'm getting the hang of it a bit more, I'm confused as to why my ve learns are decreasing my VE tables by as much as 10% at a time when if you look at the O2 at that time, its way lean. Seems like what I have is a much better tune in OL but as soon as CL kicks in, it goes way lean and the VE learn is pulling more and more fuel off. How can that be right?

Notice the O2 below as well as BLM, yet the VE for this snapshot ranges from 59-61 yet the VE learn is bringing that down to 53-55.

RUNTIME RPM MPH MAP BRO VAC VE% TPS CTS IAT I/C O2 G/S SA KnkCt sPW aPW DC% Ay Ae De Id Pe Dc Cl Ln Fn Ac Tc Cp Eg Cel INT BLM BPC IAC AFR WB dTPS tpsAE dMAP mapAE aePW
0:07:11 1125 22 59 99 40 59 8 171 104 172 102 32 23 3721 1.526 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0 0 0
0:07:11 1125 22 58 99 41 59 8 171 104 172 204 31 23 3721 1.495 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0 0 0
0:07:12 1125 22 59 99 41 59 8 171 104 172 354 32 23 3721 1.343 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0 0 0
0:07:12 1100 22 59 99 40 58 8 171 104 172 606 32 24 3721 1.373 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0 0 0
0:07:12 1100 23 59 99 40 59 8 171 104 172 664 31 23 3721 1.404 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0 0 0
0:07:12 1075 23 59 99 40 60 8 171 104 172 690 33 23 3721 1.434 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0 0 0
0:07:12 1100 23 59 99 40 59 8 171 104 172 686 32 23 3721 1.404 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0 0 0
0:07:12 1075 23 60 99 40 61 8 171 104 172 686 33 23 3721 1.434 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0 0 0
0:07:12 1075 23 59 99 40 59 8 171 104 172 659 32 23 3721 1.404 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0.9 0 0
0:07:12 1100 23 60 99 39 59 8 171 104 172 642 32 23 3721 1.434 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0.3 0 0
0:07:12 1075 23 60 99 39 61 8 171 104 172 354 32 23 3721 1.495 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0.6 0 0
0:07:12 1075 23 60 99 39 60 8 171 104 172 235 32 23 3721 1.465 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0.9 0 0
0:07:12 1100 23 60 99 39 61 8 171 104 172 150 33 23 3721 1.465 0 5 N N N N N N Y Y N N N N N 1 121 108 80 57 14.7 0 0.4 0 0 0 0

 

The BLM is 108 which is bottomed out (in removing fuel).

Note that the O2 value is oscillating, which it should be in closed loop. Since it oscillates in closed loop you need to use the BLM to see how far off and in what direction the VE needs to go.

Once in open loop (and PE mode), the O2 won't be forced to oscillate.

And, in PE mode if the BLM is less then 128 it is ignored. When above 128 it is used to add additional fuel.

RBob.

 

I assume you meant to say Once in Closed loop (and PE mode)... ???

 

In open loop the proportional gains are disabled. Which are what the ECM uses to force the AFR to oscillate (and the O2 to follow). PE/WOT mode is also open loop. Although if the ECM was in closed loop prior to entering PE/WOT mode, the closed loop status flag stays set while in PE/WOT mode.

This is so the ECM can immediately re-enter closed loop upon exiting PE/WOT mode.

In the Tuning Guide Book sticky, Chapter 5, '8746/'7747/'8063 ECM, there is a Fueling Logic link. That explains how the closed loop fueling works.

RBob.

 

Subscribed!

It would be really cool to put the carb back on and do a datalog to see where your 02 sensor is when the truck is happy. This would rule out any problems with the NB. From what I read, a 3 wire is the way to go, but I have not got one yet either.

You could just use the timing controls of the ebl and run the carb. Just a thought. And if you got a WB, then the log would be that much more helpful in determining the best WOT settings for PE and AE. At least then you are comparing apples to apples.

I need to get mine on the dyno. I ran a 14.6 at 99mph, so there is some out of the hole tunning I need to get my 60' down. Recently I have been hitting only 94 MAP. Thought I burnt out the cat, but I removed it and am still low. I'll start my own post for this issue once I get the data together.

 

88GMC quotes:

I dropped my BPC way down to 60 and still the %DE is only averaging around 40%.

I have to paw through the logs a bit more, but I think I'm doing a bit better although that darned %DC is still low.

Im geting %DC at a max of around 60%.

Ron says:

Your DC% may be correct. I would not sweat the DC%. Heck when I first started tuning I did not have DC% in my logs. You mention "average"? I only see a snapshot of DC when I log. 60% for me with a similar setup is about right when I accerate on Xway ramp. Unless I am into the pedal really heavy, which I have diffifcuty doing where I tend to drive, I might see 80-83%. I really need to get car on a dragstrip.

I would run the conservative SA tables, get the VE table stabilized so not seeing the large corrections, and then move the SA and revisit the VE(I doubt it changes much).

ps. Do you have a WB as of yet?

 

I agree with Ronny. The only time the DC is an issue is if you are above 85%. If the car can idle and run well throughout the RPM band, then no worries.

What are you using for induction. My car is extremely sluggish when it is even above 70 since I am using a regular 14" air cleaner. I had the hood off during a cold spell here and could not believe the difference when snapping the throttle. I think my IAT was at 50F! My ride in today the outside air was 45 and the car was screaming.

Like others have noticed, cold air induction is worth a lot on a TBI with a heat soaked intake manifold.

 

I am running an open air 14" filter. I dont have an IAT, but if there is that much bennefit, I'd be willing to fit one in provided it doesnt take too much modification to the ECM. Not sure if ADC channels can be used to remap the output or not.

I'm still doing my ve learns and drive-ability is getting worse. The idle is 10x better but as the VE gets more and more in range I am experiencing surging when I am on the pedal lightly. Nothing at idle, nothing at over half throttle, but in between if I hold the pedal in one spot, it surges.

My biggest issue is that Im starting to get back to where I was originally. That is basically when I hit the pedal it will want to go but then sorta bogs until I let off and then the same thing if I hit the pedal again. I dont want to get to crazy yet as my VE tables are still way off, its just taking a long long time to get them closer with the ve learns. Maybe once the entire portion of the table I can reach is closer I'll see some of these symptoms go away.

One interesting observation was that when I was convinced my injectors were dumping too much fuel depsite the log numbers, I put my 61# pair back in and the off the line was smooth and pulled really hard. The problem is that I didnt want to spend time tuning with those baby injectors since the engine is capable of 400 HP and I dont want to starve it up high.

 

Concentrate on the VE tables for now and live with the acceration enrichment issue. I would hope the VE tables stabilize at 124-132 after a few VE learns. Engine can BOG from too rich as well as too lean. I would start lean on AE, witness the lean pop on AE, and then add AE. I had way too much AE in values last year. I reduced them significantly this year and all is better. Also since my tables go to 50% TPS I pulled out the 30-50% AE area and made them flat with no increase in value in that area. As a side note I also added IAC throttle follower fuel and that helped. That somewhat follows AE as well and or will occur when TPS changes a little but does not invoke AE..

Yes you are coorect BB injectors can flow a lot of fuel.

When I added VAFPR I found the drivability was better after I retuned. throttle response was better.

 

Got my LC-1 today, will have to wire it up and see what WB learns look like.

 

Cool. Be sure to wire the grounds separately. Don't use the EBL internal grounding terminal strip like I did. Ground the sensor wire were the ecm is grounded, typically for us it is on the rear of the passenger side cylinder head. Accessory grounds are on the driver side. Get power from the IGN on the fuse box; that way you can see what your AFR is on start up.

Why don't you have an IAT? Did you just leave it unconnected? I think there are some offsets that use the IAT. I know there are several that use the CTS for sure, maybe a few based on IAT.

Maybe not. I just looked at TunerPro and only saw things for CTS/IAT blending which at this stage of the game you don't want to even try to get into. Just keep everything based on CTS.

My point about induction was not about the IAT, it was that using that 14" is bad for your application. My IAT usually reads around 180. It was 50 with the hood off. You will really benefit from some type of cold air induction. Check out Spectre for some DIY kits. I actually picked up a cowl hood, but then sold it when I found out I'm gonna be a Daddy. I'm gonna part out my bird and just build my z-28 instead.

 

Something tells me his truck came with a 7747 that he EBL'd. Regardless check on dynamicefi.com site to see which "unused pin" RBob uses for IAT. Sensor is about $20 and to install all you need is a tywrap and wire and appropriate male connector to harness. I would use EBL table for the coolant vs sensor split. If you use a cold air kit, which Graeb recommended, it is a must. spectre offers several variations. Being a truck you may benefit from the Sprectre adapter that rivets to a appropriate spot where a cone filter resides. Add a carb bonnet and you are looking good.

 

Ronny, you are correct, I run a 7747 (EBL'd). There is no IAT with that by default as you indicated. So basically Graebz28, I have a static value of 104 that never changes.

For now I need to focus on getting the VE's in line. Each day I do about a half dozen learns. There are still parts of the table that are seeing "-10" which means 108 BLM and thus out of range. The parts of the table at idle and in gear with foot on brake are all 0, and its...ok at best. Other parts of my "normal driving" are "-1" and "-2" so nothing major yet it still seems to have no power in those areas. Im really wondering about the spark tables at this point, but many senior members on here keep recommending I not touch that yet. I am just running the stock Vortec table from EBL_F_1000.BIN. I also have aSync mode disabled.

 

Ronny,

Are you blending CTS and IAT. I was going to do that until I saw that there is a table for 17 %CTS values based on temperature. I am not dialed in enough to begin complicating SA more than I need to. I wish there was a way to keep temps constant for tuning. I started tuning in the winter. By summer it is off again. I know that you could compare logs to use some of the CTS compensations, but again a bit over my head with that stuff.

88 - Make sure that your exhaust is as good as can be. Any leaks in the system will skew your O2 reading and drive ya crazy.

 

It looks like you are at the point where other changes and checks can be made. You mention areas that the VE corrections are now low, but lack power. Try adding some SA to those areas and see how the engine responds.

Note that there are two signs that there is too much SA:

The engine pings/detonates
The engine gets rough

An engine that runs smooth is fast, it doesn't feel fast, but it is.


The other check that needs to be done is WOT fueling. This was touched on previously.

Crowd WOT RPM and then check the O2 and the injector DC%. Need to be rich enough to not damage the engine (and provide power) and the DC% needs to be less then 86%.

Make sure that there is enough fuel at 3600 RPM before continuing to 4200 RPM. And so on.

Make VE adjustments along the way to higher RPMs. If the VE goes over 100%, then need to increase the BPC. If the DC% goes over 85% then need to increase the injector flow rate (and lower the BPC in response).

It is better to figure out how much WOT fuel is required now, then later after the whole 'driving' area of the VE table has been learned in. Saves a bunch of time.

RBob.

 

rBOB, out of curiosity would you be willing to share the algorithm for NBO2 VE learn? As a fellow programmer, I'm a bit curious as to what the math looks like behind the scenes. It may also help me fill in parts of the table that are out of reach during a drive.