LT5 ECM Tuning thread

[ShawnZR-1]

Originally Posted by rkreigh

Hi todd,

I have a question, I had the secondaries removed and unfortunately VA has cut the HC standard down to 48. it's made it impossible to pass.

car does have cats (random ss, probably not nearly as good as stock) and I haven't yet had a wideband to see how rich the car is running but it seems WAY rich at light throttle.

I need some help to tune the car to pass emissions. marc is a bit too far away in chicago. I do have EASE, and I could install a wideband or take the car to a shop with a dyno.

the car is an LPE 390 and has the big 234 cams. do you think there is ANY way I can get this car to pass??? I tried doctoring the gas with alchy a few years back when I had the LPE chip in the car (open loop). it was even more rich and I could get the HC down to about 97 running 2/3 alchy, but I don't think that will work anymore, when I last tried the "cocktail" it still was up to 150 HC and I couldn't get the car to run with as much alchy in the gas. I love the ZR-1, but this is a problem

any ideas (besides moving)

Well, to go along with the "Check Mechanical" before tune, I would pull the plugs and get a read on them. You'll be able to see if they are running rich.

High HC is usually a symptom of incomplete combustion. It's possible the spark is advanced too far or your plugs are fouled.

What kind of test does VA perform? Is it a two-speed, dual load or just an idle test?

[tpepmeie]

Originally Posted by rkreigh

any ideas (besides moving)

Ron, it'll never, ever pass. You'll have to get rid of it... just sell it to me, and that will solve your problem.

Seriously, though, I'm not sure I have many good ideas in this case Especially from afar. you might have to bring somebody in to tune it in person. Is the VA test dynamic ie., on the rollers or just idle?

There are various tricks always mentioned, but I've never tried any of them (fortunately my state doesn't require testing). Dom is right, if it's been done, you'll find it on ThirdGen.Org DIY-PROM board. I just don't have any answers off the top of my head.

Good luck.

Todd

[XfireZ51]

Originally Posted by ShawnZR-1

No, there's no popping with DFCO disabled. Well, there's kind of a burble on decel but with DFCO set to stock, there was a nasty surge and POP as it decelerated down the RPM band. VERY annoying to say the least! The car is almost undrivable with the stock chip.

Sort of sounds like what RBob was describing. Can you do a bin compare between stock and modified and see what if any difference there is?
Do you have a scan of the motor when its doing this?



RK,

As for your issue, my "suspicion" is the cam overlap. Particularly at low rpm. I am going to stress the word SUSPICION. I don't want to do a Bill Frist on your Z from hundreds of miles away.
Again, is your problem primarily at lower rpm and idle? I'm guessing it probably is if its on one of those IM240 EPA Test dyno cycles.

[rkreigh]

yes it's the IM240, they test at 15 and 25 mph

with the cam overlap it's going to be pretty tough at these standards

I need someone who can tune on the emissions machine which has proved hard to do.

I know the car is currently running rich, and hopefully leaning it out will help but I doubt I can get it down that low.

thanks for the advice

[XfireZ51]

rk,

Any idea what the O2 is reading at idle? Does it show lean? What about the BLMs?

[ShawnZR-1]

Originally Posted by rkreigh

yes it's the IM240, they test at 15 and 25 mph

with the cam overlap it's going to be pretty tough at these standards

I need someone who can tune on the emissions machine which has proved hard to do.

I know the car is currently running rich, and hopefully leaning it out will help but I doubt I can get it down that low.

thanks for the advice

What are the numbers? Reading/limit ?

[tpepmeie]

Originally Posted by XfireZ51

Shawn,

Maybe Todd can tell us where the Prop Gain tables are for the $AFA, $AF Mask ID. Whadya think Todd, would that help?

Dom, Proportional Gains tables are below...Some of the formatting got messed when I pasted, but it should get you going.

 
 ORG $86D8
************************************************************
** F6EEC TABLE      
** BASE PROPORTIONAL STEP SIZE VS. CLFLOW  
**        
** TABLE VALUE = COUNTS     
************************************************************
F6EECC FCB 9 9 'CTS' 0 AIRFLOW
 FCB 24 24  16 
 FCB 24 24  32 
 FCB 24 24  48 
 FCB 24 24  64 
;      
************************************************************
** F9EEC TABLE      
** PROPORTIONAL STEP GAIN VS. O2 ERROR COUNTS  
**       
** TABLE VALUE = MULTIPLIER * 256   
************************************************************
F9EECC FCB 64 0.251 'MULT' 0 O2 ERROR
 FCB 64 0.251  8 
 FCB 64 0.251  16 
 FCB 64 0.251  24 
 FCB 70 0.2745  32 
 FCB 72 0.2824  40 
 FCB 88 0.3451  48 
 FCB 96 0.3765  56 
 FCB 104 0.4078  64 
 FCB 112 0.4392  72 
 FCB 120 0.4706  80 
 FCB 120 0.4706  88

Todd

[XfireZ51]

Originally Posted by tpepmeie

Dom, Proportional Gains tables are below...Some of the formatting got messed when I pasted, but it should get you going.

 
 ORG $86D8
************************************************************
** F6EEC TABLE      
** BASE PROPORTIONAL STEP SIZE VS. CLFLOW  
**        
** TABLE VALUE = COUNTS     
************************************************************
F6EECC FCB 9 9 'CTS' 0 AIRFLOW
 FCB 24 24  16 
 FCB 24 24  32 
 FCB 24 24  48 
 FCB 24 24  64 
;      
************************************************************
** F9EEC TABLE      
** PROPORTIONAL STEP GAIN VS. O2 ERROR COUNTS  
**       
** TABLE VALUE = MULTIPLIER * 256   
************************************************************
F9EECC FCB 64 0.251 'MULT' 0 O2 ERROR
 FCB 64 0.251  8 
 FCB 64 0.251  16 
 FCB 64 0.251  24 
 FCB 70 0.2745  32 
 FCB 72 0.2824  40 
 FCB 88 0.3451  48 
 FCB 96 0.3765  56 
 FCB 104 0.4078  64 
 FCB 112 0.4392  72 
 FCB 120 0.4706  80 
 FCB 120 0.4706  88

Todd

Thanks Todd. I was able to create items in the AFA and AF .xdf
For RK's issue, I'm wondering if we couldn't modify the O2 swing points because of his bigger cams, particularly at low airflow. Would you confirm for me that the addresses for these items in $D0A mask are the same or not?

[Pete]

Originally Posted by rkreigh

yes it's the IM240, they test at 15 and 25 mph

with the cam overlap it's going to be pretty tough at these standards

I need someone who can tune on the emissions machine which has proved hard to do.

I know the car is currently running rich, and hopefully leaning it out will help but I doubt I can get it down that low.

thanks for the advice

Ron, we had the same test here in Illinois what we would do on big cams install an air pump and pump fresh air in the exhaust lots of it and alchy.
Heck connect 2 leaf blowers if you have to

What i use to do with my Z i had Show Car insurance 2500 miles a year or less which was legal in IL got waiver from Emmisions.

Now Illinois is done testing OBD1 cars.

Pete

[Tyler Townsley]

Originally Posted by tpepmeie

Dom, Proportional Gains tables are below...Some of the formatting got messed when I pasted, but it should get you going.
Todd

Damn that looks familiar. He he.

Before tearing the calibration apart get a WB, log the O2s vs other perameters and post the log. That is the way we do it on the Megasquirt forum and it has proven to be the best way to get informative help. If I read the earlier part of this post its present in both stock and moded cal. That tells me its something else. From what i read I can't tell if its a too rich or lean.

Yes the calibration can be changed to allow O2 info to be reported in the ALDL stream and its simular to what was reported on the other forum.

Ron I am pretty sure you could get an emissions only calibration tha would pass. PM me later in the week for some thoughts, I am at the NCRS meet this weekend and am rather busy trying to make it happen

Tyler