I was driving home from work today and doing a bit of data logging. I noticed that the BLM's stayed right at 128 for the longest time whether I was accelerating or idling right after start up... Well at idle after I drove the car they would fall to 140ish. Anyway, they pretty much stayed right there at 128. The INT was ALL over the place though. It went from low 100's to 140's. Does this mean that my part throttle tune is very close to being correct just using my injector constant to tune it? Also I should mention that the reported engine temp was 140*. Could it have been false or erroneous data from the O2 sensor causeing this? Maybe it wasn't up to operating temp.

Question #2. Why does my idle go so lean? I know its not that bad but if part throttle behaves so well, shouldn't idle work itself out too? If not, where should I begin to get the idle right near 128? FP is set to 45psi and timing is right at 6*. All the little stuff is worked out.

'89 MAF car 165 ECM.

Thanks guys.

 

INT is short term adjustments and wiil change. The only way to lock is run open loop. At 140 are you sure you were in closed loop?.

Just remember that reporting false info to the ecm gets errors in the output, ie the commanded AFRs won't be what are expected.

Nothing works itself out, if the engine is the add fuel where it tells you it's lean.

One of the advantages of EFI is being able to accurately tune it.

 

Red IrocZ,

There is nothing bogus with your tuning method, and using the injector constant is fine if you can get the desired results with it. 124-128 is pretty decent and a few more small tweaks might be able to make it better.

As for the Idle I have found that my 350 and even this engine idled smoother and steadier at the 135-140 BLM range. So that is really a situation where you can alter it and see if it make a difference you like, but something that isn't a show stopper.

You have done a good job thus far.

There is a post from KVU a while back on how to nail the idle blms in one quick adjustment of the first MAF table. I did it about 1 yr ago and it worked fine....I will see if I can find the link to it for you.

L8r

 

Grumpy, the ECM's commanded timer to enable closed loop had expired, what is it 300 seconds, and thats when it registers that its in closed loop. I do however seem to remember that in my .bin the closed loop enable temp is ~100*? Maybe I am wrong. Should I raise it to 160*?I'll check in a bit. I have to go apply for a loan. Transmission is on its way out and axle seals have blown apart... damn rear end is only 10,000 miles old.

ski, I seem to remember that post you are referring to. Wasn't it somthing to the effect that you changed the values at .55V and .73V in the #1 MAF table? I am not sure if thats the one that you are talking about. It just never mentioned what you had to change it to..... thats my problem. People always tell you what you have to change, but they never mention that based on "x" parameters you have to move it "y" amount. I am going to assume that you are supposed to raise the values in those 2 locations... I don't know for sure though.

This would be a lot easier if I could figure out how to use Moates adapter and the 29C256 chips I have. flash proms are way cooler than erasing the chips. Any advice on this? Start to finish step by step or a link to it? I have seen somthing somewhere but I still have questions.

Thanks!

 

Here is what worked for me, and I know others have used it with great success as well. ....

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Its from KVU:

With all my time tuning mafs using the pw vs batt volts is not the best way(on maf)to cure a lean idle.Thats more for like old or aftermarket injectors.I hear that works great for sd though.I have a friend that tunes grand nationals in missouri.All the custom bins he hacked the maf tables was changed. Check my maf tables topic post on this board.You'll need to change one of the 4 points (counts 0,64,128,192)on your 1st maf table.Check your gr/sec at idle,mine is 7grams.This value should be used in one of these counts.Then smooth counts 0,64,128,192 to the rest of the scale.
The way I do it is get my engine warm.Use the scan tool and read your gr/sec @ idle with trans in park.Then put it in drive but at a stop and check the gr/sec.Put the park gr/sec in count 0 then the drive gr/sec in count 64.In a perfect world this would be it for a lean idle.If your injector contant is far off from your actual inj flow then your counts in the maf tables will be off. Not to mention your iac need set and be in perfect tune.Oh yeah you need to do this on a warmer day with low humidity.Email me if you want direct help.
Before the seniors citizens hassles me,just listen.This has worked for me so I am sharing it.I tried pw corrections a very long time ago.Yes my blms would go to 128 but the int was crazy.I want it perfect so my way gets a rock solid 128.Besides I could'nt find one person on this board that can tell me(in any detail) what the maf tables are,what they do,and how they relate to ve(not ve tables)etc..
Tunercat told me and countless others that the maf tables should not be touched.Unless the maf is modified.This is wrong,I had to change my 1st table to fix my lean idle.Not because I have a modded maf but because my gr/sec is different than stock in many areas.Not to mention the tables needed tweaked here and there after the 30 pounders.Tunercat does have one **** of a job though.


Last edited by kvu on 05-09-2002 at 11:35 AM

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In regards to your chips hassels with UV light. Check out the Xtronics.com Romulator. I picked one up about 1 month ago. It allows you to make all your changes right off your laptop, with near instant results, and no chip burning until your happy with your tune. Totally eliminates that hassel of chips. I will also say that my first Romulator I just purchased ~3 weeks ago is dead I called Xtronics and they had me go through a whole slew of tests, but none helped. There is suppose to be a new unit in the mail as we speak. Hopefully that will remedy the problem, and there will be no other hassels. But they did take tare of me with no problems. I suggest that you get one if your planning on a bunch of tuning.

Keep us posted on how the idle works out.

 

The way your BLM'S are acting does sound wierd.
Is you enable temp @ 100 degrees celcius? if so lower it.
I know tunercat is in celcius.
Are you using headers? have a heated 02?
Watch your closed loop enabled/disabled on your scan tool when this occurs.
As for the lean idle,long as most part throttle driving is in good range (which you don't seem to know yet because of the blm problem)
But if it is then watch on your scan tool, what grms/sec this is occuring at ,and change that area in you maf table 1 by the % blms are from 128 - actually just go half the amount first.
If the bad grams sec area is between two values on the table,
change them both by 1/2.

 

Yeah guys, thanks for the help! Finally I got a question answered to my satisfaction! I guess that since I have been at this a while, I know how to ask a question a little better now


I'll try the MAF table. The engine was at 170* today and the idle smoothed out to about 134 BLM or a little lower sometimes. Down to 128 but never under 128. I also noticed that sometimes the BLM's at cruise would go down to 120. Looks like a little more injector constant tuning and I'll be pretty good. Then after that its on to the WOT stuff. I can say though, that this tune makes the car fly after 5000 rpm... I guess thats where the Stealth Ram likes to make power. On the other hand, I think that my transmission is holding me back. Its almost like when I smash the pedal it revs to 4000 rpm and then the power starts. But at the same time it doesn't feel like its slipping. Just makes a lot of power up there. Feels like an LS1 taking off at high RPM. Sets you in your seat quiote nicely.

Overall I think that I have gained a fair amount of power just from injector constant and fuel pressure settings.

Thanks guys, I'm gonna eat and try this stuff out.


Grunpy, whats the textbook definition difference between INT and fine fuel correction? Do these numbers have a bearing on tuning much like the gravity of the BLM's?

 

Not Grumpy, but this is a good question and should be explored further.

I done a lot of observations on the INT and BLM, both with locking and unlocking the BLMs. Part of the solution lies in the actual source code for controlling the Block Learn Memory.

There are factors for controlling your Block Learn that affect the BLM and INT updating and displaying. For example, when I tune my VE Tables initially by locking the BLM and adjusting solely on INT, I can get a very accurate INT value within +/- 2 on INT alone from 128.

When I unlock the BLMs and begin to let them change freely, I will initially notice some "interesting" numbers show for both the BLM and INT. Not clearing the ECM can cause this. But, even then you may still see some errant numbers. I have found clearing the ECM again, and just driving around for a little while can make everything back to 128/128 (or very close).

There are other situations where you have a transitional change where the ECM is going rapidly through a lot of different cell in the Block Learn table (such a road race with a manual). As the ECM goes rapidly from cell to cell, it sometimes can give these "interesting" INT values momentarily.

I do have to read up more on the Block Learn in the code. I think there can be a few "stickies" on Block Learn tables for both MAF and SD.

 

How does the .55 and .73 voltage correspond with the four points? There are 9 voltage measurements on MAF table 1.

I have hot idle BLM's of 140 and am trying to figure this out. My scanner says low 6's for MAF g/s and my MAF table 1 says 6.2 at .55 volts which would make what I'm scanning agree with what's in the bin.

 

I'm using GMECMEdit and a copy of my MAF table is below.

Ski - I'm thinking this is different than what you are seeing using TunerCat.

If running BLMs of 140 at idle while flowing 10g/sec what do I need to adjust so that the ECM will add fuel to the mixture and bring my BLMS closer to 128s??

 

wrong post for thread. sorry.
Although my earlier question in this thread is still valid

 

Ragtop>
I'm not Ski, but I can tell you that you need to increase the g/sec value for the .91v row.
I'd go up to abt 12 g/sec, and increase the neighboring values so the graph looks right and re-check the BLMs.

Here's my table #1 values:
22.27
17.69
14.64
12.21
10.24
8.26
6.74
5.12
8.35

These values may not work for your set-up, but if you graph them, you'll see how the graph looks some what normal again.

BTW, I also flow abt 10 g/sec at idle.