Hello everyone. I just finished up a build and the combo is as follows:

2002 Chevy Camaro A4 stock bottom end
PRC 227 heads 62cc's
TSP MS4 cam 239/242
Fast 102 with Nick Williams 102 TB
4l60e w/ shift kit and a Yank ss4000 converter

I believe that sums up the relevant info on the car.

I finished up the build and got tuning. I began with the VE tables then moved on to the MAF tables everything went fine. I finally began to attempt tackling the idle tuning. I ran into some issues.

To accomplish the idle tuning I adjusted the spark tables main advance as well as idle advance. From there I loaded the tune and proceeded to attempt to tune the RAF tables using the RussK Idle-Air config. I input the numbers I got from the config and the car began to idle worse and worse. I could not start the car with out giving a little throttle and it would not hold idle on its own. I ensured the TB blade was opened up enough to achieve decent counts (20-40ish) at hot idle.

I could not make any progress on getting the car to idle using the values from the russK configs. So I began to add to the RAF tables until i was able to get the car to start and idle on its own. From there I got a cruise control effect when driving and the idle hangs when off the gas and rolling at speed. It does not return to my desired idle speed until a complete stop has been made. A quick blip of the throttle will result in a hunting idle and at times the engine will stall while at others it will hold idle again. I adjusted throttle cracker and follower slightly to try and correct the issue but no luck.

I'm not sure if I need to make any changes to the IAC steps vs. effective area table for the enlarged TB and if that may be what is messing up my RAF numbers? But that's just a speficic thing I was unsure about.

I am still learning and have read through many stickies, tutorials, guides etc,. I also have the GM EFI tuning book by Dan Maslic. I would appreciate any help, advice and instruction that you can offer me. I have the tune that is currently in the car, two logs one driving and the other parked idling with a blip of the throttle and the car dying. I also have the config I used while logging the car. I logged a lot of things in hopes to provide any necessary info to get me pointed in the right direction. If any other parameters need to be logged or any specific scenarios need to be logged I can provide those.

So please help me figure out where I am going wrong on this tune as well as how I can correct it! Let me know if you need anything else to help me. Like I said I am also learning so, Thank you in advance!

** I can't upload the scanner config here so here is a link to my post on hptuners where you can find the config I was using.**http://www.hptuners.com/forum/showth...Auto-Idle-help

 

It seems some of the professional literature is taking you in left field and then in circles. We do offer remote tuning services to help get you either back on track or fully tuned. Let us know if we can be of any help!

 

I'd like to try and get this figured out so I could learn from it. But if I am not able to, I may have to go with something along the lines of your tuning services. What are your prices?

 

We basically teach you as we go, so it is a win win. And if you get stuck, we can sure help there too. We offer better guidance than use this config and copy and paste.

You can find the pricing here, but we do have some special offers going on also.

 

try this, in the idle>airflow>base running airflow>idle airflow table raise each value in both gear and p/n by 0.50 especially where you;re at operating temp. my pcm is a 01 but im running an OL tune. at 176*F mines at gear:14.55 and p/n:13.20

 

I tried out the raf tables higher and lower both. I will mess with them some more. How do you guys come up with the values for your RAF tables? The Idle-air config in the scanner?

 

Many many tunes lol. Although every combo is different. There is an easier way to get airflow at idle and not max out your tables.

 

I would data log with the transmission in gear at 0MPH from cold to operating temperature. Then using the "Idle Desired Airflow" numbers in the data log, fill in each cell in the row idle airflow>gear at the appropriate ECT's. Id also just put the same values in the idle airflow>park row for now because it will be somewhat close.

Also make sure the units are the same when doing this between the scanner and tune. lb/min, g/sec etc.

 

There may be a better way than that. It appears to have been overlooked though.

 

That's the way I do it. Except I copy & paste the desired airflow histogram (last values) into the RAF table of the editor. Do the in P/N first, then the in gear.

For the lower temp cells that weren't hit, just make them the same difference as the next warmer cell the you did get data on.

With the MS4 cam, the idle should be 1000 RPM. And add the same RPM to the stock table cells at the colder temps. I also change the adaptive idle airflow max & min to 3.00 g/sec & -3.00 g/sec respectively.

And you will need to increase the throttle follower airflow table by 2 g/sec at a time to help with the idle undershoot when lifting the throttle.

That cam has a lot of overlap and will be a challenge to tune.

Russ Kemp

 

Russ, that's the way I tried to do it. I think where I am going astray is by using the average values rather than the last values from the histogram. I'll bump the idle a bit to get to 1,000 rpm. I maxed out the Adaptive idle airflow tables but I will change them to 3.00 and -3.00 and give it a shot.

**Just seen your reply on hptuners.** Thanks

 

I spent the extra credits and enabled the real time tuning and dialed in the idle airflow by watching the idle trims. You can change the base running airflow while its idling and watch the stit and the ltit and get them to zero out or at least close. HPtuners help file has an example of doing it this way. I am new to using HPtuners also but that's how I fixed that table.

 

Step back some, and think about whether this is a setpoint problem
or a stability problem. You can have either or both. But if it's not able
to hold a stable idle you can get real confusing data and learn nothing
useful.

With that much cam your idle-range VE is going to be way bent from
where it was, stock. You don't get to sit there and log what happens
at 400RPM, to know. That error makes it run rich, soggy and unstable
as a result. All you can do is shave back the 400RPM, and a little off
the 800RPM, and see if it gets better.

But bidirectional controls is a good way to probe what's going on and
break the closed-loop weirdness, too. You can bump the IAC up, find
that indicated air mass flow the motor is pulling when it's at the RPM
you want, mess with timing and fueling to see what error or preference
there is, etc.