That makes sense, thank you! Now to throw a wrench in the works, this application has a low-range transfer case which will skew the N/V ratios. Does it matter? Would it be better to leave the N/V option bit unchecked and not use the N/V table?

Excellent, thank you!

 

{edit: here are the names of the idle speed tables:

IAC - Idle Speed: Drive
IAC - Idle Speed: Prk/Neut

I've got these two. 700 for park. 600 for drive. Problem is there really isn't a choke idle for very long, decays out rather quickly.

 

Yes, the idle is set to what is in the tables. It sounds like you want the idle to be like the '7747 ECM idle. If you are not having any issues with the idle speed, and/or stalling, then it is all OK.

If there are stalling issues then raise the idle speed's in the idle tables. An item to understand is that the '7747 idle routines are lacking. This is why there is such a difference between those and the EBL actions.

RBob.

 

With regard to this choke AFR, I've noticed there is a table for delaying the choke decay via CT. You have this set at 80*. Is this a 'set in stone' figure or could it be lowered? The 'choke' still seems to hang on a long time and really 'chugs' at idle under choke despite having lowered the values in 'choke-AFR' as you suggest. Or maybe I just need to keep reducing thses figures?
Thanks, Mark.

 

The choke delay threshold can be changed. This is for the initial delay of choke decay. The inital delays should be in the 2 to 5 second range.

In the case that the choke values are getting small, increase the AFR in the Open Loop AFR vs CTS & VAC table. Do it along the entire row for the CTS in question.

RBob.

 

As I rarely get the drift right without some correction, let's see if my rendition of this is any where near correct. At start up, mixture is determined by crank AFR ,which after initial delay times out,becomes openloop AFR VS CTS with choke AFR added in.Choke AFR is then decayed out at intervals set by decay delay,AFR reduced by amount in decay multiplier,until value in AFR VS CTS is reached. If CTS is above initial decay CTS threshold,no choke AFR is used? Thanks, Val

 

If CTS is above initial decay CTS threshold,no choke AFR is used?

The initial decay CTS thres (IDCT) defines which delay value is used before the choke starts to decay out. There are two delay values, one for above the IDCT and one for below the IDCT. From table Choke - Initial Delay.

RBob.

 

RBob,

When I am traveling at a level throttle under load, the car feels as if it is bucking although the motor doesn’t sound or feel that way. It seems to happen at about the 2300-2700rpm range the most and smoothes out with throttle or under acceleration. BLMs appear ok. Any ideas or suggestions I could try?

 

Proportional Gains, too much timing @ cruise, possibly knock retard. What is the 02 doing while this is happening?

 

Tho it ain't worth much, my 2cents worth would be to add injector correction offset. I have done so to try and eliminate low end surge (buck).... (buck-buck like a chicken) and the engine seemed to smooth out all the way up, am still chasing the buck and maybe for life. Am running a Holley 670 and delight in blaming it for most all unpleasantries,Val

 

Are proportional gains still an issue when running open loop?

 

No

Proportional gains are only there to make the A/F ratio cycle back and forth above and below 14.7:1. Basically to keep a Catalytic converter happy.

Properly set they really make or break the driveability of a modified engine.

 

Fast,

The timing is in the mid to higher 20s at that point so not sure that's it. I suspect the Prop Gains more since the O2 is swinging from rich to lean and not really transitioning. IOW, more like an On/Off switch. I'll bump them 5% and see what happens. I have the KR disabled so I can check for Knock at WOT. Not getting any. Motor seems to like AFR in the low 12's. Accelerates quite a bit faster there and the acceleration rate stays much more constant. Motor doesn't lie down after 4500rpm. Actually seems like torque peak may be at higher rpm than what I initially thought.

 

Does the surge persist if you switch to open loop as a test? The most timing that I can run wo knock @2800is from 17.23 to 27.07,, 2400 is from 16.7 to 26.02. This was fine in summer, but have started to pick up knock since air temp is lower. Maybe it fits, good luck, Val

 

Val,

Haven't tried O/L yet. Whenever I have run into symptoms like this with a steady throttle surge and an exhaust pop on decel I start to suspect the TPS. It runs ok but starts to sound ragged not smooth. And I have had some issues with this TPS switch not showing Closed Throttle. I thought I had addressed it but I guess not.

 

Fast,

I have attched a sample of a log I just took yesterday. You can see where the O2 sensor is just swinging between very lean and very rich. Wonder if the O2 has gone bad or that I am not getting power to it. Its does drop out of LEARN during Decel but it seems to stay out of Learn a bit after opening the TPS again. Notice the PW and DC swinging. Either because of or causing the O2 swings.

 

It looks as though the prop gain is a tad high. Also, at the beginning the VE% is jumping a bit. This is in the 00:05:37 block. There may be too much of a jump in VE% at that point in the table.

As for the prop gain I would change this table:

PRP - Gain Multiplier vs Airflow

At the airflow shown in the data log: 38-40 gms/sec. Reduce the values at that area by 10-15%. See if that helps steady things down. The WB shows the actual O2 swing which is quite high.

RBob.

 

Bob,

Thanks. I'll give that a shot when a dry day shows up here. Now I think I understand what you meant when you described too much gain as a feeling like a worn u-joint. Would you reduce the PG Duration offset also?
Happy New Year!

 

RBob,

Would you elaborate more on the the Prop Gain Offset and the PG Duration.
I realize one ins the amount of gain and the other is how long that gain is in effect, but how would you go about using the two to tune the motor. Or do you primarily use the offset and leave duration alone?

 

In one of the threads I was reading it was mentioned that RBob had written a paper on this subject. Where might we be able to find it? I did a search on here but didn't come up with anything. I think a reprint might be appropriate for this subject as it seems to come into play with the EBL. At any rate I would like to read it for educational purposes as I don't think I'm in a position to mess with it yet.

 

Considering the timing is stable, the BPC is stable, the MAP is stable, and the VE% is more or less even, seems like the proportional gains are to blame. Also notice that your wideband is indicating that you are well into the 16:1s, then it dips down way rich, then lean again. Try shortening the Proportional Gain Duration. That should cause less of a swing.

 

Check the tuning Book up in the stickies. Under the 8063/8746/7747 ECM, fueling I believe.

RBob.

 

I don't mess with the prop duration too often. Mostly change the proportional gain. Then once the gain is low enough for a little rich/lean, if the INT starts to swing I'll slow that down.

RBob.

 

Fast/RBob,

Dropping the Gain v Airflow certainly has helped quite a bit. It also seems to have helped my warm-up. Its not going into convulsions when it goes C/L. This little episode taught me something about Prop Gains.

 

This prop gain is a bit over my head. At any steady rpm (no load) my nbO2 is swinging from 4 to 900+ (not so dramatic on idle), INt's are swinging 128 to 126 typically, wideband hardly seems to notice it, which equates to rpm's fluctuating by a couple of hundred at worst.
So should I lower the values in gain vs O2 Err or Gain multi vs Airflow?
And should anything else be altered to complement this change?
Thanks, Mark.

 

I usually start with reducing the Gain multi vs Airflow. If the values become small (large injector flow rates), I'll then reduce the values in the gain vs O2 Error table. With this table I'll do an across the board percent reduction in values. This is to maintain the same shape to the table.

Then to fine tune use the gms/sec flow rate from the data log to define which are to change. This is with the Gain multi vs Airflow table.

Sometimes the INT starts to fight with the prop gains. Slowing down the INT update time helps in this regard. It can be helpful to slow the INT update down when doing prop gain cals. Just to keep it out of the way.

RBob.

 

The main problem area with the PG seemed to be in the 25-60gms/sec range.
I have been dropping the PG v Airflow by increments of 2-3%. This has made for a much happier motor. I now suspect that the surging I was experiencing at idle during warmup was due to the PG being too high. It would idle fine in O/L but once C/L kicked in, it started to seesaw until it warmed up enough. Now the motor note at 2500rpm in fourth is much cleaner and there's no "bucking" sensation. Interestingly, the DGD shows that I get better mpg at 2500rpm in 4th than if I shift it to 5th at 1600rpm. Cam works better in the higher rpm range.
Anyway, this has been a very good learning experience for an area of tuning that has been a bit murky and tough to understand. I'm sure I am not alone on this. But the effort is well worth it because it makes the motor sound soooo much happier.
Are Prop Gains unique to SD based EFI or would you find it in MAF based systems as well? I am sure its not an area very many tuners even bother with.

 

RBob,
I hope this is the right forum for asking this question. I have a fairly modified 91 Pontiac Firebird Formula 305 tbi (supercharger, cam, intake, exhaust, etc.). I want to upgrade my ECM. I am considering EBL. I have been monitoring EBL posts for a few weeks. It seems to me that many of the questions people (with EBL) ask indicate that they do not understand values in tables nor how to change them to make improvements to their cars. I am wondering just how difficult tuning with EBL really is. I am sure that it is somewhat dependent on an individuals talent. Is EBL for anyone/everyone? Can you tell me what kind of info is provided with EBL to assist in tuning?
Thank you RBob,
305tbi

 

From a personal point of view, I'd say that THIS is the owners handbook for EBL. There are some very knowledgeable people on here that can help with all problems and RBobs efforts go beyond the call!,....I sometimes wonder when (if) he sleeps!
Just about anything you need to know would have been covered here, or soon will be.
After having messed about with a stock '7747 set up, this EBL is MUCH easier to use even with my limited knowledge.

 

If you haven't experienced the rapture of tuning a 7747 then its difficult to describe how much better EBL is. And part of what you read here is people trying to take advantage of the "rich" code that RBob has put together. He really has covered the bases in terms of flexibility and enhancing driveability.
From personal experience I can tell you that EBL is worth at least 25-30hp on my setup and I think even more now that I have honed the WOT tune.

 

Another personal point of view. I started on a 7747 ecm. When you start on a particular ecm you get used to the terminology and the ways different routines are handled. Alot of what is asked is from people like myself that get used to a certain layout and get confused trying to corrolate from one ecm to another. EBL is very user friendly and Rbob has a very complete guide book of explanations/definitions of what every single item is for and does. Just switching from a stock ecm to EBL was a performance enhancer with the starter bin that you get with the package. Also sometimes there are events that rely on two or three other events happening before that particular event can take place. It is nice to come here to "work thru it" with others that are dealing or have dealt with the same issue. Good luck and welcome!!!

 

I don't know much about what is out there for tuning aids with after market systems, but I really doubt if you will come close to the features that are available using EBL.The ability to log sessions,play them back while observing sensor feed, and do ve learn from the logs is really huge, but the ultimate tool (in my opinion) is the dump log analysis feature. Check out DynamicEFI and view some of features. There might be groups like this for the after market products but I think you will learn a lot more about ECM function /engine interaction than is possible with other approaches. I've certainly been happier with this route than with the years spent with the "use your money not your brain route".Gotta admit it does make my head hurt tho. The one thing you gotta have is patience. (and beer) Good luck, Val

 

My plan for tomorrow is to re-introduce EGR and then Hiway lean.
If this is the correct order to do it in, should EGR be allowed to alter the AFR much? How much? I presume I have to manually raise or lower the values in the relevent areas on the VE tables.
Is enabling the HiWay lean a 'do and forget' thing or do I need to monitor the AFR here to? If so, what is a safe AFR for lean cruise?
Any advice appreciated as always!

 

By all means continue to watch the AFR in HWY mode, max lean should be 16.5/1, my understanding is that is too lean with EGR in use, I think 15 or 15.5/1 is it for EGR. But I have read that the fuel tables will have to be changed, others will know more about EGR complications, If I had to pass an emissions test, I would look into exploring chip stacking. Good luck, VAl

 

I just wanted to let you know that I am not ignoring your post. I think that the responses from the other posters covers your questions better then I could have answered.

One reason for the number of questions is that this thread is a central point. When there is a question this is where it gets asked. There are also users that have yet to ask a question. These a more experienced tuners that just install it, tune it, and use it.

RBob.

 

Yes, do the EGR before the lean cruise. When in closed loop with the EGR active the NB O2 should still swing about stoich. The EGR BPC Multiplier is used to reduce the PW when the EGR is active. This compensates for the displaced O2 from the EGR in the intake.

You don't want to use the VE tables for EGR compenssation. Once the VE tables are learned in (without EGR) then stay put. Activate the EGR, data log, and adjust the EGR - BPC Multiplier vs VAC table for the proper BLM value (128).

RBob.

 

Thanks for the info, unfortunatly being several hours ahead of you (geographically!) I set off before I saw your reply.

I need your help gentleman, RBob your help would be greatly appreciated. I'm going on a 2000 mile road/wheeling trip in 10 days time and want to get this working safely. My observations from today are as follows and need some advice to help me get sorted as soon as possible. I know it's a bit of a cheek asking this, and I'd like to find out as much for myself as possible but time is against me.
Driving today with EGR and Hiway lean re-activated , at around 60 mph (I'm running in my motor), approx 1800-2000rpm my AFR was in the high 16s to mid 17s, INTs locked at 128, BLM around mid 130s(144 for the first few miles of hiway lean but didn't see this much again)(would I decrease pulse width to bring the BLMs down?). Engine temp stayed stable all day at 89-91c and no knocks.
Any comments? I know now from RBob's reply that I need to adjust BLMs prior to Hiway lean use anyway but any other comments?

My acceleration at WOT or near to WOT is really poor. I noticed an AFR of around 10:1. Too rich? What tables do I alter and how to rectify this?

Lastly...I hope, I couldn't get DFCO to happen. I re-set the Enable temp after VElearn but haven't altered anything else. Anything below look wrong? Should it happen in the rpm range I've been driving in today (up to 2500rpm)
Drop to exit 3187.50rpm
Map increase to exit 99.69Kpa
Fuel pulse upon exit 3.51 mSec
Enable delay 2secs
Delay between DFCOs 400mSecs
Map Enable delay 3 sec
Enable threshold 1.57 tps%
Decay multiplier 37.65 mult%
Enable temp 59.75*c
Exit SA mult 37.65%

Thanks for any advice guys, I appreciate your patience.

 

southernspeedThanks for the info, unfortunatly being several hours ahead of you (geographically!) I set off before I saw your reply.

I need your help gentleman, RBob your help would be greatly appreciated. I'm going on a 2000 mile road/wheeling trip in 10 days time and want to get this working safely. My observations from today are as follows and need some advice to help me get sorted as soon as possible. I know it's a bit of a cheek asking this, and I'd like to find out as much for myself as possible but time is against me.

Driving today with EGR and Hiway lean re-activated, at around 60 mph (I'm running in my motor), approx 1800-2000rpm my AFR was in the high 16s to mid 17s, INTs locked at 128, BLM around mid 130s(144 for the first few miles of hiway lean but didn't see this much again)(would I decrease pulse width to bring the BLMs down?). Engine temp stayed stable all day at 89-91c and no knocks.
Any comments? I know now from RBob's reply that I need to adjust BLMs prior to Hiway lean use anyway but any other comments?

The AFRs you are seeing are in the general range. If the vehicle drove OK in the mid-17 AFR then I'd leave it. If the vehicle seemed to cut in and out then it is too lean. In this case bump the HiWy - AFR down. At low to mid engine loads the engine is not as likely to be damaged from lean AFR conditions as WOT operation.

My acceleration at WOT or near to WOT is really poor. I noticed an AFR of around 10:1. Too rich? What tables do I alter and how to rectify this?

Yes, too rich. First check the BLM during this time. If it is 138 or higher the VE table is off. Usually the last area before WOT.

If the BLM is OK check the PE - AFR commanded table. These should range from 12.8:1 to 11.5:1 if there is a cat-con.

Where it is too rich adjust the VE table in that RPM & MAP area. Bring the VE down 5 percent at a time while checking the WB O2 value. In the end it should match the AFR in the PE table.

Lastly...I hope, I couldn't get DFCO to happen. I re-set the Enable temp after VElearn but haven't altered anything else. Anything below look wrong? Should it happen in the rpm range I've been driving in today (up to 2500rpm)
Drop to exit 3187.50rpm
Map increase to exit 99.69Kpa
Fuel pulse upon exit 3.51 mSec
Enable delay 2secs
Delay between DFCOs 400mSecs
Map Enable delay 3 sec
Enable threshold 1.57 tps%
Decay multiplier 37.65 mult%
Enable temp 59.75*c
Exit SA mult 37.65%

Thanks for any advice guys, I appreciate your patience.

It may be the low TPS% threshold. Some TBI units after some miles tend to stick open a little. This can put the TPS% at 2 to 2.5 %. The WUD display will show this.

Then check the MPH & RPM tables. These have the upper & lower limits.

RBob.

 

Thanks RBob and all who replied. Much appreciated. I am probably the oldest car guy on this site; almost 70. The first car I modified was a 1952 Buick Riviera; been modifing ever since. It gets in your blood. I will probably be ordering EBL soon and asking questions too.
Thanks again and see you down the road.
305tbi

 

Thanks RBob, yes the truck drove fine at 17 afr but as I said, it was only as around 2000-2500rpm, so I check it at higher rpm when i get a few more miles on the motor.
I don't have a cat.con. so should I look for different afr under PE? If I'm reading your reply right, the PE is only a different commanded afr and the fueling is actually only based on the VE table but at the very low vacuum end of it?

Just a side thought, if I don't have a cat. con. do I need the nbO2 swinging? Can it be locked down?
Many thanks, Mark.

 

With the lean cruise, once the load gets higher (by the MAP threshold) the ECM will drop out of lean cruise. And if enough load is requested (via TPS%) the ECM will enter PE mode. So at higher loads/RPMs most likely the ECM will not be in lean cruise mode.

Without a cat-con I would put the WOT vs AFR table at 12.5 across the board. Then adjust the VE table via WB O2 value to match. I'm recommending 12.5 as it is a safe value to shoot for when starting out on the tune. Then later when finalizing the tune can lean it to 12.8 or so.

The VE table is always being used. Crank, warmup, WOT/PE, lean cruise, the VE table is in use. The other modes, such as WOT, and lean cruise, open loop, cranking, just command a different AFR. And are still using the VE table.

This is why the actual WOT AFR is adjusted to match the commanded AFR by changing the VE table. Once that matches the actual WOT AFR will track changes to the commanded WOT AFR (via the table).

As for running open loop all of the time, yes, you can do that with no cats. With the road trip coming up I wouldn't try too many different things. If the closed loop running is decent I might stay with it until after the trip. And, if you have problems with an item such as EGR, just disable it until later.

RBob.

 

OK thanks, that's all good info as usual. I wasn't planning on O/L operation, I didn't know the nb swing was also necassary for C/L operation.
I've just done another 100 miles and got the EGR BLMs dialed in pretty good with Hiway lean disabled, then re-enable the lean cruise and it all seems happy. I started playing with the VE tables to lean up my WOT acceleration and got it into the high 11s instead of 10s (AFR) so I'll work on that (already much more responsive) but with a fresh built motor I'll go easy on that for a while. I think I'm pretty well set up for my trip now, thanks to you! When I get back I'll start a bit more in depth tuning and probebly get some high flow injectors and more fuel pressure as it seemed to fall on it's face at higher rpm's before I rebuilt it.
I still need to work on the DFCO as it's not working and my TPS in dropping to 1 or 0% on a closed throttle.
One thing that does baffle me a bit from todays drive. At a constant 60-65mph at about 1800rpm on a gently rising and falling motorway, my IAC is reading anywhere from 75 to 150 counts, is this correct? Surely this is similar to having a bad air leak?
Mark.

 

And now for something completely different! I've just tried to open TPrt to edit the .bin I was running with today, and everytime I try to select the .bin I get a message box saying "File is larger than max file size" and it won't open!

HELP!!!

EDIT- just noticed my previous .bin was 16.00kb and my new one that I can't open is 6.05mb ! What's happened and how do I get my .bin back????

 

If you can zip the file up and email it to me. I'll see if the first 16kb of the file is the BIN. If so I'll email back the BIN.

If what I think may have been done was done, then the first 16kb of the file is your bin. The rest is your data log.

RBob.

 

RBob, I've emailed you...something! Does a 6mb file become 2mb when it's zipped?
If you can salvage my .bin i'll be eternally grateful !
Many thanks, very stressed of England.

ps:....if you can salvage, please let me know how managed to screw it up! Thanks.

 

Brilliant! Thanks RBob, got your email with my .bin. Goodness knows how I managed to data log in a .bin instead of .dat file. I'll have to be more careful!

On a different matter, now that I've got a good basic tune with my BLMs and WB AFR all pretty much where I want them, how 'adaptable' is the EBL system?
All my tuning has been done within a few hundred feet of see level. Although most of my road trip will be at a reasonable altitude, the wheeling I'll be doing in the Alps will be at 2500 to 3000 metres and well below zero degrees C. I have IAT in the aircleaner and the factory pre-heat for the cleaner. Will the system compensate OK for the altitude and temperature?
Thanks again for recovering my .bin, the wife will be happy too as I won't be so stressed tonight!!
Mark.

 

These tables seem to have very narrow windows but then I've no idea how they should look. At present they are as supplied at:

DFCO upper lower
map 40 25
mph 20 15
rpm 1100 800

Any suggestions? Thanks, mark.

 

You asked about IAC of 75-150 during cruise. This is normal. As the TPS% increases there are throttle follower steps added to the IAC. During a warm idle the IAC steps should be around 5 to 10. GM normally has them in the 40-45 step range. You can increase the idle stop screw a bit at a time until the warm idle steps drop to the 5-10 range.

Even with the elevation change and cold temperatures the TBI setup will run well. Only recommendation from an EFI stand point would be to bring the original ECM with you as a spare. Tends to keep Murphy at bay.

DFCO:

map 40 25: to enter DFCO the MAP needs to be below 25 KPa, once above 40 KPa will exit DFCO

mph 20 15: to enter DFCO the MPH needs to be above 20 MPH, once below 15 MPH will exit DFCO

rpm 1100 800: to enter DFCO the RPM needs to be above 1100 RPM, once below 800 RPM will exit DFCO.

These RPM & MPH setttings are OK for an auto equiped vehicle. For a stick vehicle they should be higher to prevent stalling. The MAP of 25 KPa may be preventing DFCO. As its main purpose is cat-con protection on long decels, it isn't that important.

RBob.

 

Southernspeed,

Just as an example, my settings for DFCO are:

MAP 45/35.9
RPM 1300/1000
MPH 20/15

Any lower and the motor would stall out coming to a stop with the clutch in.
I still would like to have DFCO so I don't get any popping out of the exhaust.

 

OK thanks for those replies. Did another 100 miles last night (at around $8.00 a gallon in a truck that sees the wrong side of 18mpg this is expensive tuning! lol). All seems pretty good. Still mailing down the WOT rich afr problem but it's getting much better.
I've been adjusting the prop gains a bit but it's making no difference to the extreme swing (4 to 900+) so I guess I'll have to be brave and make bigger changes.
Thanks for all your help so far, really appreciate it.
Mark.