Hanging Idle, Can NOT correct! Help?

[02 WS6 TA]

I've searched threads for the last 2 hours, tried almost every concievable suggestion, and I absolutely CANNOT get my idle to stop hanging once I'm off the throttle. H/C M6, as I depress the clutch to come to a stop, idle hangs 1600-2200 RPM, and requires as much as 15 seconds at times to return to normal(950-1000) I'm ready to throw a match at the thing and toss the laptop on top for kindling- Any ideas?

[MMGT1]

Throttle cracker/follower tables?? Have you corrected those? You didn't say what you have tried yet. Can you post a tune??

[02 WS6 TA]

Yep, even zeroed the cracker. I'll post the tune in a bit, I've moved on to another car at the moment.

[Bill@HPTuners]

has the throttle blade been drilled any? Have you messed with the idle set screw at all?

[02 WS6 TA]

it has a BBK 80 on it, undrilled.

[Bill@HPTuners]

Make sure its not sticking...I had a customer with a BBK intake & TB setup that the TB would stick at 0 tps and make it hard just to get the car to move because of it, and then would only go 90% tps at wot meaning the blade wasnt opening all the way. Also if its undrilled you might be working that iac too much so.

[S2H]

post a file please...
tune And logs...
we really cant help unless we know more details...
preferrably some logs with IAC counts and TPS position

if its a vehicle that is electronic throttle then its possible you need to drill the TB blade to get your IAC counts down so that it isnt too far open...
past a certain percentage and it likes to hang but it wont throw a code....untill it goes too far..

if its throttle by cable...then look and see fo anything is catching...
even just having the slack in the cable too tight will cause it to hang like that...

its also possible that you have a small leak somewhere...possibly at the seal of the bbk to your intake...or possibly on the intake itself...
I tuned a vette about a year ago...couldnt get idle to settle down like normal coming down from a stop...couldnt figure what was up....found out his fast 90 was cracked through further investigation..then after it sealed up with some epoxy and put back on.....it was ok...till a few weeks later when it cracked again from the stress of racing and the epoxy not being done correctly...so the same issue popped back up again....

[02 WS6 TA]

Thanks for the suggestions soundengineer...It's a cable actuated unit, and this may be some of the problem- The BBK was on the car before we did the H/C swap, and nary a problem, but it's been hanging at high idle for soem time afterward- To be honest, 2 years. It's my personal car, and I've neglected it's driveability for some time as It rarely sees street use. I loaded a few goofy tunes in it from the repository just to see, and no luck. Kinda peeves me, as Everyone elses car I tune works great, and mine is a giant PITA! LOL

[pknowles]

Did you mess with the "Torque loss % vs spark retard" or the "Spark retard vs Torque reduction" tables? If you did set them back to stock and see if it goes away. Don't make any other changes other then those.

[BlackSS]

I had a similar problem that I've almost solved by lowering the RAF (Running Air Flow) table about 40%. I drilled my throttle body before I started having problems though.

[Russ K]

I've searched threads for the last 2 hours, tried almost every concievable suggestion, and I absolutely CANNOT get my idle to stop hanging once I'm off the throttle. H/C M6, as I depress the clutch to come to a stop, idle hangs 1600-2200 RPM, and requires as much as 15 seconds at times to return to normal(950-1000) I'm ready to throw a match at the thing and toss the laptop on top for kindling- Any ideas?

Do a cold start scan with this idle config file. Don't touch the gas pedal till operating temp. Then do a scan while driving around when the idle is hanging. What size camshaft, and don't drill the TB larger than stock.

Russ Kemp

[S2H]

actually drilling a TB is just like opening an Idle bleeder on an carburated vehicle...except for the fact that you can change an idle bleeder back smaller if you ned to..drilling is just a "fixed opening" for idle


its pefectly OK to drill...
you just need to be sure you get the right size hole and not go too large...
for most people it means starting small and working it up until your fully warm AC off and Fans off IAC counts are around 60 ish...
I also recommend leaving your hood open to keep under hood IAT temps down as they will skew readings a well..

a lot of people like to use the TB set screw...which is not the intended design purpose of that screw...its there to keep TB from sticking when it slams closed...If GM intended that to be yoru Idle set screw they would have left out the hole in the stock TB to begin with and relied soley on that...and your PCM woul dnot care about how far you move it...the pcm cares greatly about that set screw as shown in TPS and if you get past a certain point it throws codes and messes with other stuff too..

others try to change their IAC steps vs Effective area table(which doesnt work to fix teh idle issue)...which is the wrong place to do it at as it can mess up other stuff relating to idle as well...

you really need to investigate for possible leaks before doing any of this as it really sounds liek you have a small leak somewhere...anytime I have had a vehcile hang for like 15 seconds or more even..its always been a leak....
you can always take a medicine dropper and drip water around the intake and watch for it to dissappear...if its not on teh sides then you might remove teh intake and do an inspection for cracks

[02 WS6 TA]

Thanks for the continued suggestions- I'm out of town for a funeral, but will be back first of the week, and I'll post data as requested. Once again, thank you all!

[FRC_Tom]

Increase the Throttle follower tables also I have found decreasing the accessary torque table (0-1200 rpms) in the Torque Management/Engine Torque area sometimes helps.

I also solved the problem I would have when a Fast 90/90 was installed.
As soon as the ac was turned on the car would go into a like cruise control, by decreasing the AC torque vs. AC pressure and vs. IAT it goes away.
I'm not sure if there are any side effects scaling these tables but the cars idle perfectly.

Just fixed a S/C C5 today using the above tables.......
Infact I was getting the opposite when turning the ac on, it was hunting between 400-900 rpms. I increased the AC tables and no more hunting idle....

[Arcolog]

Hey there,

Wondering if you ever came up with a solution?

I also have this same issue. But to shed a little more light on the problem that I am having is this....

If I drive around, and clutch in, my TPS reads 2% until I come to a complete stop. During the 2% TPS time, I get the lovely cruise control type idle between 1700 and 2000 rpm's. Also I can force the RPM's down by letting the clutch out in 5th gear and then it will idle and have 0% TPS.

I thought it would have something to do with the follower tables, but can't seem to put my finger on it.


And to add to the mods in sig. I know a previous "tuner" drilled a slightly larger hole in my NW90 and I checked to make sure that my TB screw wasn't the cause.

OH one other thing I noticed. Sometimes when I jump in the car after it was sitting for a period of time and press on the gas pedal, you can hear some sort of adjustment going on, from the area of the Cruise Control box thingy(lol) I will try to narrow that down in the morning

[colamotas]

me also