ETC Idle Tuning

[Bill@HPTuners]

I've never tuned an ETC car/truck but I would like to start a post to see how you guys attack tuning them...I've read all the threads about how they technically work no IAC & all but in the real world what works for you guys?

Obviously raising desired idle speed
Base idle airflow tuning is still a must
Did you touch the scalar parameter?
Did you touch the IAC steps vs effective area table?

If so how did it work out? What cam were you using? Any other tips blah blah blah...

I just want to get a discussion going about it to not only help myself understand what works/doesnt work, but to help others understand a little better rather than struggling.

thanks
Bill

[WS6FirebirdTA00]

I dont mess with scalar unless it has a different TB on it. The effective area table is a fit curve to the vette airflow (from what I see) for a correlation between TPS and area (thats what the scalar is for I believe).

They tend to behave better than an IAC motor IMO. Some have stalling/surging issues but I think that is mainly from too fast of response (as least in what I have dealt with). Changing the derivative idle controls and spark corrections really help get that under control.

The biggest thing with ETC cars I have seen is the airflow adders not decayed by the time it comes to idle. I have had several have too high a TPS after a cam swap, yet they had no issues, so I left it.

On a 90mm TB, I have set the scalar to 0.032 I think. I will have to look. It was either that or 0.018, but I think that 0.018 was a special case on one car. I dont know if effective area actually works, but there is no need to adjust that.

[EC_Tune]

ETC Area scaler should be: 0.0190 for a 90mm
Stock is .0255 (edited --- had it backwards)

You can use the IAC steps vs Effective Area from a 4.8L truck (if the car is 5.7L) if it has a 90mm TB.

[WS6FirebirdTA00]

Ah ok, well the one I did needed a higher value, but that could also depend on the type of TB as well I assume.

[superls1]

ETC Area scaler should be: 0.0263 for a 90mm
Stock is .0255

You can use the IAC steps vs Effective Area from a 4.8L truck (if the car is 5.7L) if it has a 90mm TB.

What if it's not a 5.7L?

[WS6FirebirdTA00]

What if it's not a 5.7L?

As long as the effective area tables and TB are the same, it doesnt matter what motor it goes on, AFAIK.

[EC_Tune]

You can move those around so you get a correct Base Running Airflow table (matches the MAF or dynamic airflow value(s) at idle). If your RAF is 5 g/sec and the idle system is controlling it nicely but the MAF says 8 g/sec, you can move things around so that they match. (I would)

[S2H]

I'm still into drilling the TB when they need it....
and yes ETC cars do need it too

[EC_Tune]

I have a 427 high compression big cammed 03 Vette with a 90mm LS2 TB on it. It was drilled previously and that messed up a lot of things at idle. Replaced the TB blade and things started behaving again. IF ETC gets above 11-12% I might consider it but this 427 idles at about 9-10% -- perfect...

[12secSS]

You can move those around so you get a correct Base Running Airflow table (matches the MAF or dynamic airflow value(s) at idle). If your RAF is 5 g/sec and the idle system is controlling it nicely but the MAF says 8 g/sec, you can move things around so that they match. (I would)

Interesting note, thanks Doug.

[Redline MS]

Regarding the effective area when going from a stock to 90mm on an ETC car;

I was under the assumption that the effective area is directly related to the area of the throttle blade. Based upon this I have done this math;

Pi*radius (squared)

90mm/75mm

(Pi*45*45)/(Pi*37.5*37.5)
(6361.725)/(4417.864)
1.44 or 44% change to the effective area

I don't have my 'black book" of notes but I think I ended up at a value of .0157 for effective area with the 90mm.

I have experimented with several cars with 90's and with just changing that parameter alone took car of 90% of the idle issues with a 90. The classic high idle touchy throttle goes away and most of the other idle parameters need either none or little adjustment. It would make some sense that as long as the PCM knows the new effective area that it would rescale all other tables so they wouldn't need to be stretched dealing with the larger area. I guess kind of like changing the axle ratio on an automatic and its effects to the entire shift schedule..

Any thoughts on this?

Howard

[WS6FirebirdTA00]

effective area is the open area for airflow to flow through the TB at 0% TPS.

[BCM]

Regarding the effective area when going from a stock to 90mm on an ETC car;

I was under the assumption that the effective area is directly related to the area of the throttle blade. Based upon this I have done this math;

Pi*radius (squared)

90mm/75mm

(Pi*45*45)/(Pi*37.5*37.5)
(6361.725)/(4417.864)
1.44 or 44% change to the effective area

I don't have my 'black book" of notes but I think I ended up at a value of .0157 for effective area with the 90mm.

I have experimented with several cars with 90's and with just changing that parameter alone took car of 90% of the idle issues with a 90. The classic high idle touchy throttle goes away and most of the other idle parameters need either none or little adjustment. It would make some sense that as long as the PCM knows the new effective area that it would rescale all other tables so they wouldn't need to be stretched dealing with the larger area. I guess kind of like changing the axle ratio on an automatic and its effects to the entire shift schedule..

Any thoughts on this?

Howard

I am in the middle of this now and found the further from stock (.0255) I got (either direction) the more the idle degraded.
I know this does not make sense, thus I am all ears

http://www.ls1tech.com/forums/showthread.php?t=676695

[WS6FirebirdTA00]

You want to bring idle desired airflow and dynamic airflow on top of each other on the ETC since ALL air is being passed through the TB. After doing this, you will need to adjust the idle airflow tables again as it throws them out of wack.

[SideStep]

ETC Area scaler should be: 0.0263 for a 90mm
Stock is .0255

You can use the IAC steps vs Effective Area from a 4.8L truck (if the car is 5.7L) if it has a 90mm TB.

Resurrecting this thread...

I thought C5s (Corvettes) did not use the IAC Steps vs Effective Area table??? Just the ETC Scalar, right?, wrong?

[WS6FirebirdTA00]

IIRC, they use the effective area table and the scalar converts it to a TPS. I could be wrong.

[Sport Side]

They tend to behave better than an IAC motor IMO. Some have stalling/surging issues but I think that is mainly from too fast of response (as least in what I have dealt with). Changing the derivative idle controls and spark corrections really help get that under control.

More on this please. I've been having trouble tuning my dad's 2003 Z06 for a while now. It seems like when coming to a stop, it'll surge sometimes and other times, just fall on its face down to 300 RPM.

This ETC stuff drives me insane. I know it can't be hard tho once you get an understanding of everything.

[WS6FirebirdTA00]

Make sure the throttle cracker and follower are at zero by the time it comes to idle speeds

[Sport Side]

See any problems w/ this '03 Tune for a H/C/I Z06 w/ an ETC TB?

[WS6FirebirdTA00]

as a test, zero out the throttle cracker at 1600 and under, and the throttle follower under 13.5% throttle, see what it does then.