Th400 decel and idle tuning in gear...

[nice shot]

I have a 99 trans am with a cammed 5.3 and TH400 and yes I have the VSS hooked up... I am having trouble getting it to idle when I put it in gear and also dies on deceleration... I ran an Idle config, but I did it with the trans in park.... it runs fine when its in park and if i throw in in neutral and coast to a stop its fine... should I run the idle config with the trans in drive and use those numbers instead??

I did add some timing in the lower rpm range that didn't help it.... Do the DCFO tables do anything now that I have the TH400???

This is my first attempt tuning so any help here is appreciated...

Here is my tune file...

Also if anyone can tell me what a good IAC postion is at idle and what my TPS voltage should be with the blade closed....

[Tre-Cool]

Yes, run idle config with it in drive. there is more load and thus a different vacuum pressure happening.

A manual is considered to be in gear at all times.

[VodeAn]

Do the DCFO tables do anything now that I have the TH400???

Yes. They still function, check the enable and disable parameters. You may want to adjust them for the setup. Be sure you are in advanced mode so all parameters and tables show up.

I concur with Tre-cool

Post a log of it dying. Idle timing in gear, in park, and both main spark tables should have similar timing around idle (the same between both idle tables with your setup).

[nice shot]

Yes. They still function, check the enable and disable parameters. You may want to adjust them for the setup. Be sure you are in advanced mode so all parameters and tables show up.

I concur with Tre-cool

Post a log of it dying. Idle timing in gear, in park, and both main spark tables should have similar timing around idle (the same between both idle tables with your setup).

Thanks... and I will post a log here later the neighbors will complain if i make noise too early...

I did not adjust the park a gear spark tables I wasn't sure if the computer used them anymore with the TH400 that could be a problem... I only adjusted the main tables...

Before I called it a night yesterday I did try and run the idle config with the car in drive when the engine started to warm up about 180 degrees it died... In gear my IAC was around 250 ish at idle.... when it died the IAC maxed out at 310... This is why I am curios what my TPS votlage should be with the blade closed and what a good IAC count should be at idle...

I did drill the TB blade and messed with the blade stop screw to get the engine to idle but I might need to further adjust it...

I am also running the config with the maf and closed loop enabled... should I run in open loop and disable the MAF?

[93camaro_zzz]

Hey nice-shot,

I was having the same problem as you were for a while. It sucks for us, because we have no way of telling the computer that we are in-gear or P/N to change the airflow numbers. So with that being said, and like was said above, we need to tune our cars for idle while it is in drive. Then inevitably when your shift to P/N, the idle is going to jump up higher. No way around it really. So I just tried to tune the car to idle as low as it could comfortably in drive, to lessen the effect of the high idle in P/N.

[93camaro_zzz]

Also, I just took a look at your tune, your RAF values are huge for a cammed 5.3. In comparison, I have values of around 1.3XX lb/min for my cammed 370ci. Are those the numbers that the idle config file was giving you after running the log? No wonder it is maxing out your IAC counts. Because you are commanding a lot of airflow. Also, you have your target idle speed set pretty high, but I imagine you did that because it was dying like you said.

To start out, trying taking the stock 5.3's RAF values, and add around 4-6g/sec of airflow. Notice the units of 4-6 are g/sec, not lb/min. Let us know how that goes for you.

[nice shot]

Also, I just took a look at your tune, your RAF values are huge for a cammed 5.3. In comparison, I have values of around 1.3XX lb/min for my cammed 370ci. Are those the numbers that the idle config file was giving you after running the log? No wonder it is maxing out your IAC counts. Because you are commanding a lot of airflow. Also, you have your target idle speed set pretty high, but I imagine you did that because it was dying like you said.

To start out, trying taking the stock 5.3's RAF values, and add around 4-6g/sec of airflow. Notice the units of 4-6 are g/sec, not lb/min. Let us know how that goes for you.

Thanks for looking.. yes those are the numbers it gave me when I ran the config in park... when I tried to run the config in drive it gave me even higher numbers in the 3.0 range at opertating temp before it died.... The numbers are high prolly because of the setup, it's a built bottom end 5.3 actualy a 5.4, T rex cam, TEA ported trickflow 220s, ect, etc.... and I set the idle there cause it sounds amazing at 1250rpm and yah it helped keep it running...

I was looking at a ls1 with a trex cam I got from the tune repository and thought the same thing the numbers where high but I tried taking away a small amount around .5lb/min and it idle surges then dies...

I didnt get a chance to run a log and post it but I will in a week or so, I'm tired of hearing people complain about the exhuast and I dont blame them its ridiculously loud... so i ordered a Borola replacement muffler for the LM1 garbage thats in there now... I'll continue messing with it when i shut this thing up a lil...

Do you think my IAC count and RAF table could be high because the TB blade is not open enough or I need to drill the TB blade more?

[nice shot]

Hey nice-shot,

I was having the same problem as you were for a while. It sucks for us, because we have no way of telling the computer that we are in-gear or P/N to change the airflow numbers. So with that being said, and like was said above, we need to tune our cars for idle while it is in drive. Then inevitably when your shift to P/N, the idle is going to jump up higher. No way around it really. So I just tried to tune the car to idle as low as it could comfortably in drive, to lessen the effect of the high idle in P/N.

Is there a way that I can adjust how long it takes for the engine to come down off of that higher idle?... like if I was to shift into neutral from drive and the idle jumps up... Throttle cracker decay rate??...

[93camaro_zzz]

Do you think my IAC count and RAF table could be high because the TB blade is not open enough or I need to drill the TB blade more?

Yeah that would be the reason. I think of it this way: there are only two ways that air can get into an engine, around the throttle blade with a change in throttle position, and the IAC valve. I had some issues with mine initially also, because I had a built 370ci with a cam and AFR 225s that was trying to run off of the stock IAC valve. Me personally, I am very much against drilling holes in the throttle blade, I much rather prefere to open the idle set screw, and then rotate the TPS sensor back to reading 0% throttle. I had to slot my TPS sensor to do this, but it was much better than drilling a hole in my $450 throttle body that I can never get back.

Are you still on the stock 78mm TB?

[93camaro_zzz]

Is there a way that I can adjust how long it takes for the engine to come down off of that higher idle?... like if I was to shift into neutral from drive and the idle jumps up... Throttle cracker decay rate??...

Yeah, that would be your throttle follower tables. Try multiplying your throttle follower decay rate table by "0.50" and see how you like that.

[nice shot]

Yeah that would be the reason. I think of it this way: there are only two ways that air can get into an engine, around the throttle blade with a change in throttle position, and the IAC valve. I had some issues with mine initially also, because I had a built 370ci with a cam and AFR 225s that was trying to run off of the stock IAC valve. Me personally, I am very much against drilling holes in the throttle blade, I much rather prefere to open the idle set screw, and then rotate the TPS sensor back to reading 0% throttle. I had to slot my TPS sensor to do this, but it was much better than drilling a hole in my $450 throttle body that I can never get back.

Are you still on the stock 78mm TB?

Yes stock intake and TB... I have a supervictor with an aarons elbow and 102tb, but it wont fit under the stock sleek beek... when I get a hood I'm gona use the 102 so I'll just slot the TPS... I read on that before I was just a lil worried about the TPS possibly moving over time once i break the little locator tab off and give it room to slide on the bolts, but I guess if I tighten it good should be fine..

[Ranger6202]

just my .02....... I had issues with my 6.0-th400 dying when i was driving in 4-low or coming to a stop. I found that my VSS was not setup right. When i was doing 65, ecm was seeing only 2mph. Which i can only imagine it was seeing near 0 when coming to a stop. After calibrating the VSS with a GPS, it has never died again in those conditions.