I need Tuning Help. Somebody has to know...

[badazz81z28]

Hey,


Seems the LStech guys are clueless on this issue from the lack of responses.

My issue is before I got the car dyno tuned the car would die when coming to a stop. Now after the tune, ONLY when the car is up to temp, the RPMs hang coming to a stop coasting in neutral and stay there while stopped for about 8 second until it will finally drop to the correct RPM. I can't seem to find the exact conditions which it does it, except when the car is up to temp. But even then 1 out of 10 it doesn't do it. I have a 5 speed manual.


Is it tuning or the IAC?

http://www.youtube.com/watch?v=6tKzxq7ee4M&feature=youtu.be

[jlcustomz]

Sounds to me like an issue with the speed sensor circuit, this can cause idle fluctuation or dying when coming to a stop. Late model engines can be wired to work without one, But they exist for a reason. my former tpi issue was random, didn't have correct enough speed sensor.
More details of what you have for harness, speed sending unit? Also keep in mind all these sensor circuits are low voltage , which makes them more susceptible to bad connections and GROUND issues.

PS, nice choice in gauges , had my ultra lites for over 10 years now & just ordered 5 matching air pressure gauges for my airride .

[badazz81z28]

Thanks for posting. I tired to do the easiest thing first and bought a new IAC from autozone ($120!!). Good news is...I drove it around for for an hour or so and didn't have the idle hang issue, but the car idles lower (wants to stall) and periodically does stall. So I don't know if I got a bad IAC out of the box or my old IAC was "bad" in a good way (sorta). I put the old IAC back in and idles like a champ. I don't think the new IAC was working, with the old IAC you can see the idle move up and down to keep it running etc like it's functioning.

I ended up buying an HP Tuner...when I get it I will see what I can do. Arg!!

[howehot]

With the Fast EZ EFI for a LS you need to adjust the throttle blades to balance out the idle. The IAC will only control so much. With the Locar cable I used, it has adjustability built into it. This is was the hardest thing to adjust. Use vey small adjustments and let the car idle to relearn the new setting. Don't know if this will help you or what computer you are using. Hope it helps

[71RS/SS396]

You need to take it back to your tuner and have him work on the idle air flow tables. I had the same issue with mine because I have a fairly large cam and a light weight clutch/flywheel combo and my dyno guy was able to straighten it out for the most part, but the idle still hangs a little if the clutch is pushed in while moving but settles down as soon as I come to a stop.

[badazz81z28]

You need to take it back to your tuner and have him work on the idle air flow tables. I had the same issue with mine because I have a fairly large cam and a light weight clutch/flywheel combo and my dyno guy was able to straighten it out for the most part, but the idle still hangs a little if the clutch is pushed in while moving but settles down as soon as I come to a stop.

My tuner is a 200 mile trip. I guess a tank of gas....I did end up buying an HP tuner. Hopefully some online knowledge will help me out. I'm cool with the idle hang while driving. But when I stop, I would like it to settle rather quickly.

[AintQik]

Its probably in the tune. I've seen this a bunch, it is one of the hardest things to get straight. My Vette did it, then the with new the new tune it went mostly away. My LS3 with 600 horse has ZERO issues. So, what I am trying to say is there is hope. Unfortunately in my experience its a combination of things. You touch one, and 3 more need to be tweeked. I wish I could tell you, "to go to the idle air flow table and change this", but its not that easy.

[badazz81z28]

The bad thing is I can't figure out the exact conditions which it hangs. Its most definitely when warmed up, but sometimes it doesn't do it. I'm convinced it is the tune, but also the inconsistency make me wonder differently. The bad IAC out of the box got me nowhere.

[Gandalf]

You need to take it back to your tuner and have him work on the idle air flow tables. I had the same issue with mine because I have a fairly large cam and a light weight clutch/flywheel combo and my dyno guy was able to straighten it out for the most part, but the idle still hangs a little if the clutch is pushed in while moving but settles down as soon as I come to a stop.

^^^ What Tim said. Had the same thing happen. You mention having HPT - if you have the Pro version you can log some miles and get that to your Tuner (email). They can email an updated tune file for you to try. At the very least that may get you in the ballpark. If not, the 200mile round trip will seem like nothing once you resolve that issue - I know how annoying that can be on the street.

Keep us posted.
G.

[badazz81z28]

Does anyone here have tuning experience? I don't understand why its random. If it was any of the ECM settings, wouldn't it always hang?? I do somewhat suspect the VSS issue because its random, but the data long does show the TPS at 0% when the idle hangs. So I'm confused.

[badazz81z28]

Sounds to me like an issue with the speed sensor circuit, this can cause idle fluctuation or dying when coming to a stop. Late model engines can be wired to work without one, But they exist for a reason. my former tpi issue was random, didn't have correct enough speed sensor.
More details of what you have for harness, speed sending unit? Also keep in mind all these sensor circuits are low voltage , which makes them more susceptible to bad connections and GROUND issues.

PS, nice choice in gauges , had my ultra lites for over 10 years now & just ordered 5 matching air pressure gauges for my airride .


I have a TKO 600, the VSS it came with. and I'm using a PSI harness.

[LSXperformance]

Keep in mind iac use a stepper motor and are prone to sticking/ dead spots. Your tunner probly tuned your set up to your original iac. So when you changed it thinking it was bad it was doing as programmed. Put the supposeable faulty one back in and tune from there. I would recommend getting one from gm tho. you need it to hang for a bit anyhow it keeps it from stalling. When you tune cars and you go WOT you can make it go 100% then as it drops to idle it pulls back. and the thing is all of these stepper motors have slightly different resistance values so a change of them can some time cause it to stall. So my guess is that your original sensor was bad or had a dead spot in it. And you need to try a new gm sensor and tune from there. make sure your maf is good and clean as well!
any?s feel free to pm me and I can call you

[badazz81z28]

Keep in mind iac use a stepper motor and are prone to sticking/ dead spots. Your tunner probly tuned your set up to your original iac. So when you changed it thinking it was bad it was doing as programmed. Put the supposeable faulty one back in and tune from there. I would recommend getting one from gm tho. you need it to hang for a bit anyhow it keeps it from stalling. When you tune cars and you go WOT you can make it go 100% then as it drops to idle it pulls back. and the thing is all of these stepper motors have slightly different resistance values so a change of them can some time cause it to stall. So my guess is that your original sensor was bad or had a dead spot in it. And you need to try a new gm sensor and tune from there. make sure your maf is good and clean as well!
any?s feel free to pm me and I can call you

I will swap it out and try again. How do I tune the new IAC? Mess with follower and cracker?

[redpine]

Is your vss circuit wired to your ECM or gauges? I had the same exact problems you have when I swapped my trans from auto to manual,

[Rhino]

What PCM are you using? A GM 411 I'm assuming?
Cracker and Follower won't have much to do with your idle characteristics. It's been a while since I touched a cable driven throttle body setup but, if I recall correctly, there's a separate idle air table which dictates airflow through the IAC.

[LSXperformance]

idk what hp tuner calls it I use efi live...

[badazz81z28]

Yes, I have the VSS connected to the transmission like a 2000 F-body through the ECM and harness. The output wire from the ECM hooked to the gauge.

I am using a 411 PCM. There are quite a few idle settings. I do recall an Idle steps chart.

Because the problem comes and goes, hard to say its a specific setting in the tune...May it is a bad IAC and the ECM is trying to over correct it.

[Rhino]

idk what hp tuner calls it I use efi live...

The tables themselves are dictated by GM, not your software vendor. They may be ordered different in the interface but under the covers the exact same changes are being made.

[badazz81z28]

The tables themselves are dictated by GM, not your software vendor. They may be ordered different in the interface but under the covers the exact same changes are being made.

Well, I ordered a new IAC. Where to start as far as tables to mess with?

[redpine]

Do you have any check engine light,codes?

[LSXperformance]

It seems they rarely have codes unless they have ckt failures my experience anyhow. Idk they name stuff stange in efi live I am no expert with it by any means but have it say they dont name pcm 411 etc they call it ls1A and Ls1B then the rest are normall. I could hook up to my car and see what its named and let you know values in mine for IAC mine is a 98 pcm I don't know if this helps let me know... its mild cammed cathedral headed 6.0L with ls6 intake.

[badazz81z28]

Yeah, NO codes. Other than the idle hang, the cars runs great

[ctd]

I've seen your bitching in other forums that might be reason no one has helped you. There is no Silver bullet to this type of tuning, basics need to be solid & you go from there. The Pro's that earn there lively hood from this are not going to spoon feed you to solve your tuning issue should that be the problem. Many times mechanical issue's plague the tune.

This is my very first post on this forum & I would like to try & help you. Basic's include correct injector data.

Post up the HPT files & I will have a look. I'm not a pro tuner & do not make my living by tuning, enthusiast only trying to help.

I like your PT deal :-) that is why I'm here! You guy's amaze me what you fabricate & how it's done. Talents I only wish I had.

:cheers:

[badazz81z28]

I've seen your bitching in other forums that might be reason no one has helped you. There is no Silver bullet to this type of tuning, basics need to be solid & you go from there. The Pro's that earn there lively hood from this are not going to spoon feed you to solve your tuning issue should that be the problem. Many times mechanical issue's plague the tune.

This is my very first post on this forum & I would like to try & help you. Basic's include correct injector data.

Post up the HPT files & I will have a look. I'm not a pro tuner & do not make my living by tuning, enthusiast only trying to help.

I like your PT deal :-) that is why I'm here! You guy's amaze me what you fabricate & how it's done. Talents I only wish I had.

:cheers:

The reason why I got frustrated is because when you ask for help...people tell you post the tune, you spend $500 to buy a tuner, post the tune and you get crickets....The guys that really do this for a living want the $$$....As you probably read in another post, I have no intention to full out "learn to tune", I just want to fix my issue and move on. I live in the middle of nowhere, hours away from anyone who tunes. I truly thought the whole purpose of the HP tuner forum was to work through tune issues...not the case. I got a mail order tune from a guy who refuses to help, and when you post the tune on the net, he freaks out!! Its comical...

[Poopy]

That's gotta be frustrating, have you checked for any vacuum leaks? Something that is wiggling loose? Cracked vacuum line? That will cause a high idle. I'm fortunate to have one of the best tuners/wiring guys around live 20 minutes away, a good tuner is invaluable.

[ctd]

I understand your frustration, been there. Still doing it BTW it's a never ending learning process & learning curve. HPT forum is well..........again I understand.

I've spent some time reviewing your log & tune, I sent you a email. You have a very good understanding of HPT , the only missing PID regarding your problem that I would like to see in a log is commanded idle & that is not a big deal.

[badazz81z28]

That's gotta be frustrating, have you checked for any vacuum leaks? Something that is wiggling loose? Cracked vacuum line? That will cause a high idle. I'm fortunate to have one of the best tuners/wiring guys around live 20 minutes away, a good tuner is invaluable.

I did suspect a leak, but the car is so dependable on this hang. Like when I'm coasting it will hang at 1500 rpms and remain there until I stop. I have coasted down a hill for a good mile, the idle hangs the entire time until I stop which 5 secs after it will idle. If I coast for 10 feet, same reaction. So something is telling the IAC to remain open, but don't know what or why. Folks had told me the cracker, which I zero'd out and no difference. I also suspected the throttle follower, but than again why is it random. Its a tough one. I bought a new GM IAC, so thing will be another trial and error.

[ctd]

I don't think there is vacuum leak although now that I've been thru Rob's build thread the airflow thru the MAF seems low. 228/228 with ported heads & a Fast Intake I would expect 10-12g/sec airflow. Rob is correct in that the adaptive idle routine is not starting so the IAC counts stay high so it won't idle down.

The desired idle airflow, STIT's are not making any sense which equals wrong BRAF. Hopefully once that is figured out the other issue will go away. If we cannot get that one squared away the unmetered air, like a vaccum leak may have to be revisited.

Hey Poopy I'm located in Sicamous so we are almost neighbours, who is the tuner you mentioned? It's been frustrating for me finding tuners.

[badazz81z28]

I posted my actual tune in post #18 here: http://www.hptuners.com/forum/showthread.php?42711-Where-to-start-Neutral-Coasting-Hanging-Idle

I made a mistake posted one of the "trial" tunes after doing the Russ Idle Config. It told me to set the BRAF # way low..of course the engine didn't like it.

What would prevent the adaptive idle routine from kicking in?

Today while driving around....no hang

[ctd]

Did you get the IAC counts up to the 60-80 range? Also did you add the TPS voltage PID? This is the one I'm suspicious of.

There is an enable Temp for the adaptive idle, I think I looked @ that already. Never hurts to re check though.

[badazz81z28]

I'm trying to figure out how to get the TPS voltage on the PID....Than I will run the scanner again. How do you change the IAC counts? By opening the blade?

I also looked at the min ECT for adaptive idle and it's 176...I do have a 160 thermostat.

[ctd]

When you have the scanner open you need to close the log. Then bring up the table & click one of the boxes & you should get insert. Click on the that.

To get the IAC counts up you want to close the blade, that reduces air flow around the blade so more is going thru the IAC. Is there a hole in Blade?

Watch your ECT in the log & see if it's lower than 176*

[Hotwire]

I'll take a stab at it. I've had a bunch of s10s with 5 speeds, they program the IAC to stay open during shifts so people that don't know how to drive get a smooth gear change. If you don't hold it in gear while slowing down below 30 mph the IAC stays open for a 5 second duration after you reach 0 mph. It doesn't bother most people but once you put an aftermarket exhaust on them that issue became quite evident. There's a blurb about it in the owner's manual but I just sold my truck, so I don't have the correct terminology in front of me.

Basically hold it in gear so the slow down helps pull the engine rpm down and see if that helps.

[badazz81z28]

I'll take a stab at it. I've had a bunch of s10s with 5 speeds, they program the IAC to stay open during shifts so people that don't know how to drive get a smooth gear change. If you don't hold it in gear while slowing down below 30 mph the IAC stays open for a 5 second duration after you reach 0 mph. It doesn't bother most people but once you put an aftermarket exhaust on them that issue became quite evident. There's a blurb about it in the owner's manual but I just sold my truck, so I don't have the correct terminology in front of me.

Basically hold it in gear so the slow down helps pull the engine rpm down and see if that helps.




That would make sense if it did it ALL the time, but it doesnt. Its very random...I swapped the IAC today for a new one and no change.

The scanner does show the IAC open when it hangs, so it's a tuning problem which something is changing the way it reacts. I'm thinking AIT...but I don't know.

[Hotwire]

It was random in s10s too, try it and see if anything changes.

[Hotwire]

Brain fart, the term you're wanting to search for is idle flare.

[badazz81z28]

Brain fart, the term you're wanting to search for is idle flare.



Really....How do you rid of it?

[Hotwire]

Really....How do you rid of it?

If you don't hold it in gear while slowing down below 30 mph the IAC stays open for a 5 second duration..

Basically hold it in gear so the slow down helps pull the engine rpm down and see if that helps.

:look:

[badazz81z28]

:look:



Nope, that doesn't work. You could slow it down till it about dies. Push the clutch in and it shoots to 1500 RPMs.

[ccmc]

Disconnect your cable at the throttle body and make sure it moves freely. You could have a broken strand that is hanging up the cable occasionally.

[badazz81z28]

Disconnect your cable at the throttle body and make sure it moves freely. You could have a broken strand that is hanging up the cable occasionally.


Thanks, but the scanner shows the IAC is open letting air in.

[badazz81z28]

Thanks, but the scanner shows the IAC is open letting air in.


I'm leaning towards a bad ECM