Supercharged H2 idling too high uless i unplug the neutral saftey after it starts

[bstuder11]

Ok hopefully someone can tell me how to bypass something or how to fix this problem. My H2 wants to idle at about 1100 when I come to a stop which leaves me holding the brake hard. After I sit there for about 30 seconds it will eventually idle down to about 7or8oo. After frying a few pcms by trying to pull all the idle values I could think of down I was able to determine that if i start the truck, put it in neutral and crawl under it and unplug the neutral saftey switch It idled down and ran PERFECT. Problem is you cant just leave it unplugged obvioulsy because it wont start, let you take it out of park, unlock the doors when you put it in park, shift to 4 low lock ect... someone PLEASE tell me what to do!!! Thanks, Studer
ps. yes I have replaced the Neutral Saftey Switch

[joecar]

Studer,

What year/model/vehicle is this...?

[bstuder11]

2004 Hummer H2. 6.0L with a 2300 Magnacharger.

[joecar]

Ok, I thought Hummer... this is the wrong section, I'll move it to GenIII.

[joecar]

You will need some of what's in here:



Idle Tuning
showthread.php?4661-Idle-Tuning-Helpful-Info-Inside (http://forum.efilive.com/showthread.php?4661-Idle-Tuning-Helpful-Info-Inside)
showthread.php?14439-Idle-Tips-amp-Tricks (http://forum.efilive.com/showthread.php?14439-Idle-Tips-amp-Tricks)
showthread.php?14153-scan-tool-wont-log-rafig-or-rafpn (http://forum.efilive.com/showthread.php?14153-scan-tool-wont-log-rafig-or-rafpn)
showthread.php?14435-Need-help-Can-Start-Car-but-dies-when-I-give-it-any-throttle-before-going-to-CL (http://forum.efilive.com/showthread.php?14435-Need-help-Can-Start-Car-but-dies-when-I-give-it-any-throttle-before-going-to-CL&p=129519&viewfull=1#post129519)
showthread.php?7011-ETC-cars-and-IAC-parameters (http://forum.efilive.com/showthread.php?7011-ETC-cars-and-IAC-parameters&p=61455&viewfull=1#post61455)
showthread.php?14544-Working-on-my-idle-tune (http://forum.efilive.com/showthread.php?14544-Working-on-my-idle-tune)
showthread.php?14794-Help-with-open-loop-%28cold-start%29-tuning (http://forum.efilive.com/showthread.php?14794-Help-with-open-loop-%28cold-start%29-tuning&p=133446#post133446)
showthread.php?149-Idle-%28Transition%29-Tuning (http://forum.efilive.com/showthread.php?149-Idle-%28Transition%29-Tuning)

More Idle Tuning
showthread.php?t=149 (http://forum.efilive.com/showthread.php?t=149)
showthread.php?t=5866 (http://forum.efilive.com/showthread.php?t=5866&highlight=RAFIG)
showthread.php?p=86553 (http://forum.efilive.com/showthread.php?p=86553) post #17
showthread.php?t=2630 (http://forum.efilive.com/showthread.php?t=2630)
showthread.php?t=473 (http://forum.efilive.com/showthread.php?t=473)

Throttle Cracker/Follower
showthread.php?t=3568 (http://forum.efilive.com/showthread.php?t=3568)
showthread.php?t=4081 (http://forum.efilive.com/showthread.php?t=4081)
showthread.php?t=5406 (http://forum.efilive.com/showthread.php?t=5406)
showthread.php?t=5940 (http://forum.efilive.com/showthread.php?t=5940)

[joecar]

It seems to me your IG (in gear) and PN (park/neutral) idle airflow tables need some work, I'm not sure exactly, the answer is in those threads.

[bstuder11]

Yeah, thats what the guy I had doing my tuning thought as well and he trimmed it all down as far as he could and it seemed to help a little bit but then eventually locked up my PCM as well as 3 more before I bought my own V2 and went back to a more stock tune for the idle so now im back to where I was. Its so frustrating because as soon as I unhook the Neutral safety switch It runs and drives PERFECT so i was hoping someone would have ran into this before and know what i needed to do. Thanks for trying to help me though!!

[joecar]

The P/N switch has an input to the PCM, the PCM uses this input to select PN or IG idle tables.

Post your tune file (if that's ok) and some logs, we'll work on it together, hopefully some can guide us...

the PCM should not lock up unless the electronic throttle tables have been incorrectly touched.

[bstuder11]

Ok, thats really cool of you and I appreciate the help. Idk if I'll get it up here tonight though; it's after 11pm here and about to go to bed. The guy who previously tuned my truck has been doing it for many yrs though and he tried all kinds of things from rolling idle to throttle cracker to follower and so on and never could get it to run right until I unplugged the neutral safety and then it runs perfect but needless to say I'm getting tired of rolling under the truck to unhook that and then plug it back in to start it. I wish I could just figure out how to bypass that and it would b all good.

[MECHAN12]

Well you could splice a switch in the line and mount it in the cab for yep use until you figure it out
Donald

[bstuder11]

Yeah that's what I was thinking about doing I'm just not sure which wire to splice

[MECHAN12]

How many dose the switch have of two don't mater

[bstuder11]

Well it took an hour of testing wires and the help of my wife operating the gear shifter and ignition for me but I was finally able to get all the necessary wires spliced together so that the truck will start,come out of park lock,go into 4 low, idle perfect, and get $50 by returning the switch I had just bought because my truck no longer uses a neutral saftey switch :)! Only downside is the dash indicator always shows neutral but that's well worth it for the drivability I have gained!!!!!!

[bstuder11]

Mechanic 12: What? Lol that did not make sense to me

[MECHAN12]

i was on my phone when i wrote that sorry what i i was saying is if the neutral switch has two wires to it you can splice into ether wire

[MECHAN12]

just remember it will now crank in gear
donald

[bstuder11]

No, my switch has about 8 wires.

[MECHAN12]

ok but you have found it now just do not let it stay that way. find the problem and get it fixed so you can hook it back up ,or you might forget one day and crank it in gear and take our a door or too lol
donald

[bstuder11]

Well it's been having that problem every since I bought it. So many people have looked into the tune and the rest of the truck and no one had ever been able to figure it out. It finally runs perfect so I'm probably gonna leave it Like that and take a break from it for awhile. It's an automatic tranny so it's not like it's gonna do any harm even if it did start up in drive....

[joecar]

I think you're going to need wire diagrams... which year H2 is that...?

[bstuder11]

Lol, I think your right. I dont know if ill b needing wiring diagrams or work on the tune or a match for this thing but I just took it to the store and back and even though I got all that stuff bypassed its back to trying to idle at about 1200 untill you sit it gear for 30 seconds or so and let the idle slowly drop. It acts like you hit the defrost button or something and is idleing up for the a/c compressor idk :( I have attached the tune to this reply.

[joecar]

Start reading thru some of those links, we're going to need some logs of idle pids.

[ScarabEpic22]

OK first off there are 12 out of range tables/params in that file...lets get them fixed.

I guessed on G0903 Fan #1 AC turn on temp.

Why did you turn VATS off, its a stock truck...I turned B6602 back on, I dont think you want it upshifting when TC is active. Dont know what trans failsafe enablers you adjusted, Id probably turn them back on (I cant see the history on that).

We should be able to get this idle situation sorted out. I started with a fresh 03 Silverado 6.0L LQ4 file and copied a few tables over to your tune. Flash it and see if it helps any, plus log the required info Joe has posted!

Just the out of range params fixed is the (fixed) tune, the (fixed_tc&tf) has the updated throttle cracker/follower params.

[bstuder11]

Ok first, those out of range codes and that tune was on the truck when I got it programed by someone called squishy or however he spells it. it snapped two tranny input shafts because he had the tranny line pressure set to high so all I have done to the tune was reduce that some, increase the tourque management a lil bit, and lowered the desired idle back down to a couple hundred above stock. Second, this is not a stock truck at all. It has a magnacharger 2300 with an air to water intercooler, lower compression pistions, a blower cam, and an RPM transmission. As far as the fan temp, that is N/A because it does not have electric fan.

[ScarabEpic22]

Ok first, those out of range codes and that tune was on the truck when I got it programed by someone called squishy or however he spells it. it snapped two tranny input shafts because he had the tranny line pressure set to high so all I have done to the tune was reduce that some, increase the tourque management a lil bit, and lowered the desired idle back down to a couple hundred above stock. Second, this is not a stock truck at all. It has a magnacharger 2300 with an air to water intercooler, lower compression pistions, a blower cam, and an RPM transmission. As far as the fan temp, that is N/A because it does not have electric fan.

Thats interesting your tuner left them out of range, but it can mean you are writing values the PCM sees as incorrect and it tends to do weird things in the overall tune. For example, in my P10 tunes there is an 02 OS that if you change a acceleration limiter parameter from the stock value it makes the truck only shift using the 4HI tables. Nothing remotely related to what you're actually changing, but there must be some code overlap somewhere. Verified this on 2 separate trucks.

I didnt touch line pressures, I see you made some changes (sounds like for the better, 2 input shafts = ugh!).

I should have clarified, you are using the PCM/engine in an OEM application. Aka stock application and not an engine swap, that is the reason I questioned the VATS params.

I know it has a blower, but the Cracker/Follower parameters were setup with a flat value in different load and rpm areas. The best way to get a good tune is start with stock values and modify them until they work for you. Clearly the old values werent working as you are experiencing this high idle, so we go back to the beginning and work our way up.

The fan param was out of bounds so I maxxed it out like the factory calibration did. I was using the Silverado LQ4 cal as a reference because I dont have a stock H2 LQ4 tune and they are the same engine.

Hope this makes sense as to my reasoning. The blower will effect how the TC/TF parameters work, but since the old ones arent working we need to work them out little by little.

[bstuder11]

ok, I have attached a copy of the stock H2 tune, and I have also retuned my Cracker/Follower parameters back to stock as you suggested but still no difference

[joecar]

Check for airleaks.

Then follow these:
showthread.php?4661-Idle-Tuning-Helpful-Info-Inside (http://forum.efilive.com/showthread.php?4661-Idle-Tuning-Helpful-Info-Inside)
showthread.php?14439-Idle-Tips-amp-Tricks (http://forum.efilive.com/showthread.php?14439-Idle-Tips-amp-Tricks)

[bstuder11]

Thanks, air leaks was the first thing I checked when I bought it and notices the problem. Thank you guys so much for all the help!! It was the throttle cracker; I set that to kick in and out at 200 mph (disabled it) and now everything is working great :)

[ScarabEpic22]

Really?! Great news!!

Didnt even have to tune the cracker, disabling it worked? Interesting, whoda thought?

It is so much nicer to have a truck that acts correctly when driving down the road, I still need to get rid of the annoying 2->1->2 downshift issue the TBSSs have at low speeds.