Random High Idle / Sticking Idle - <master thread>

[Jerry Dobson]

Random High Idle / Sticking Idle
I wanted to start a new master thread to help resolve the high idle and random sticking idle that many of our Vipers experience.

What I am looking for are Vipers that idle normal and at times the idle will hang for a period of time.

I have read the prior posts about high idle issues (I started some of the threads).

I am not looking for the following:
-Mechanical adjustment that fixed the problem
-Any type of device to limit idle air control flow
-Battery replacement (this just resets PCM)
-PCM resetting

Please answer these questions if you have the problem
1) At what outside temperature does the problem occur?
2) What year is your car?
3) Is your car BONE stock with this problem?
4) Do you have K&amp;N filters and smooth tubes?
5) Do you have Headers installed and if so what brand?
6) What other modifications do you have that might have triggered this problem?
7) What steps have you taken to attempt to cure the problem?

 

[Jerry Dobson]

1) Usually if the temperature is below 60 degrees
2) 1998
3) When my car WAS stock...I did not have the problem
4) Yes
5) Yes, Belanger
6) None
7) Replaced the 02 Sensors/battery

My PCM was not holding SRI memory data. So under warranty I had it replaced. Odd thing is that I went from a factory 704AD PCM to a 702AC. This alone might have caused the problem.

I am starting to lean towards Headers and the location of the 02 sensors in the collector. A friend just installed headers and he now has random idle hang (never had it before).

 

[JimDavis MT 97GTS 650R]

Jerry, I admire your resolve concerning this issue. Most respondents will tell you that there is no one lasting solution for this problem. Most all of us have experienced it from time to time, modified or not. One time is TOO many. I find it disappointing that DC can engineer a replacement part for a minor problem on a Viper, but not address obvious safety issue. IMO this is a dangerous problem that should be resolved. I also think a "class action" by Viper Owners should be considered. (God forgive me)...If enough owners contacted the U.S. Dept. Of Transportation and complained, perhaps in ten years we might have a fix. I am not a lawyer, much less an engineer, but this much I know....every time I get in my Viper it's my A$$ that is ultimately on the line for the safe operation of my car. If DC has a "defective product" here, they need to be made to step up to the plate and make it right ASAP. DC's "mind set" seems to be exemplafied by the latest issues with early Durango/Dakota ball joint problems. Any thoughts?

 

[Gerald]

*********************I guess this is a good time to FINALLY, AFTER 4 years of suffering from IDLE HANG, IT'S FINALLY GONE*********** no ifs and or buts. It's F***** GONE.!!!!

I've had it for 4 years. On BOTH MY VIPERS. It made driving my viper horrible to the point of not wanting to drive it too much. I hated it in traffic. So I can relate to you guys that have it.

I tried all the little fixes posted . Some of it helped. But they were just band aids and never completley fixed the problem. A small dowel in the IAC tube,New Battery, Resetting computer,setting and adjusting the throttle body linkage to a nats ass, cleaing IAC filter and motor, new IAC motor. Some of it helped, but after about 100 miles and many false alarms, it came back.

But for the last 2 weeks and after about 600 miles, It's gone.. It drives FINALLY like it did when it was brand new..... What a pleasure to drive... No band-aide, no little trick. It's fixed. No false alarm. It's gone, 100%. I can rag all over the car.. I can boost all day long. I can drive it like stock. And I can finally drop the car in nuetral at ANY speed and ******, magically like it was new... back down to about 750 RPM's.... I can haul ass up to 100mph, then slam on the brakes.... come to an idle and not even touch the throttle.. and ******** magically , LOL!!!!, back down to about 750 rpms.... It's a thing of beauty.....!!!!

REJOICE REJOICE REJOICE

That is all

Gerald

 

[ViperRichRT10]

*********************I guess this is a good time to FINALLY, AFTER 4 years of suffering from IDLE HANG, IT'S FINALLY GONE*********** no ifs and or buts. It's F***** GONE.!!!!

I've had it for 4 years. On BOTH MY VIPERS. It made driving my viper horrible to the point of not wanting to drive it too much. I hated it in traffic. So I can relate to you guys that have it.

I tried all the little fixes posted . Some of it helped. But they were just band aids and never completley fixed the problem. A small dowel in the IAC tube,New Battery, Resetting computer,setting and adjusting the throttle body linkage to a nats ass, cleaing IAC filter and motor, new IAC motor. Some of it helped, but after about 100 miles and many false alarms, it came back.

But for the last 2 weeks and after about 600 miles, It's gone.. It drives FINALLY like it did when it was brand new..... What a pleasure to drive... No band-aide, no little trick. It's fixed. No false alarm. It's gone, 100%. I can rag all over the car.. I can boost all day long. I can drive it like stock. And I can finally drop the car in nuetral at ANY speed and ******, magically like it was new... back down to about 750 RPM's.... I can haul ass up to 100mph, then slam on the brakes.... come to an idle and not even touch the throttle.. and ******** magically , LOL!!!!, back down to about 750 rpms.... It's a thing of beauty.....!!!!

REJOICE REJOICE REJOICE

That is all
:thumbs
Gerald

GERALD, And how do you explain this fix?

Rich

 

[BadVenm]

Please answer these questions if you have the problem
1) At what outside temperature does the problem occur?
2) What year is your car?
3) Is your car BONE stock with this problem?
4) Do you have K&amp;N filters and smooth tubes?
5) Do you have Headers installed and if so what brand?
6) What other modifications do you have that might have triggered this problem?
7) What steps have you taken to attempt to cure the problem?

1) At any temp
2) Has happened on my 94, not on my 97, and yes on my 99.
3) 94 when stock NEVER had any hang, post modification idle hang. My 97 was bone stock except K&amp;N's, smooth and rear **** delete, NEVER had idle hag. My 99 when stock NEVER had idle hang, but once modified it had idle hang.
4) Answered above.
5) Currently on my 99, heads, cam, t-bodies, headers, Vec-2, all kinds of other goodies.
6) To many to list. But Never did one single mod trigger an idle hang.
7) I did the IAC plug with the 3/16's hole in it. It does help but once in a rare while I still get idle hang. But post plug it is down to once every 3 or 4 times I drive it, not every time I put in the clutch like it was before the plug was installed.

How's that fake avatar change coming?

 

[JimDavis MT 97GTS 650R]

Gerald, what joy. Congratulations. I don't want to sound doubful but.... enjoy it while it lasts. When you have achieved a full season of driving your Viper and several thousand miles w/o a problem, then I will believe you have fixed it. My experiance has been a simple battery bump etc will fix it for awile. Anything that will cause the PCM to "re-learn" it's peramaters will work, but in the end the problem will come back. FYI my hang tends to be most evedent after high RPM hard running in hot weather. The problem developed prior to my moding the motor. The closest I have come to stoping this problem was when I had the Dodge Store reflash my PCM with the latest down load program from their computer for my model year.(ie:'97) I suspect this rearranged some PCM perameters that took longer to learn than before. Thought I had it fixed, but it eventually came back after a couple of thousand miles. Pritty cool huh. More freaking finiky than a Ferrari if you ask me. The diffrence is that the Ferrari could be fixed. Oh well, the plugs are cheep and what's a little hang'en throttle. I think it is the PCM, but with no factory re-designed replacment I guess we just gota live with it.. LOL

 

[Jerry Dobson]

I think the problem is the PCM. It has something to do with a bad program code.

The factory programmed in a slight delay when the throttle is released. They had to. With the big V10, you get lots of "engine brake". If the RPMs would drop to idle after a red line burst, you might lock up the rear wheels and smack the windshield. This delay code might be related to our idle hang.

Some people had high idle but not "idle hang". Some were just mechanical adjustments. They had high idle at all times, that is a different issue.

I agree that idle hang is DANGEROUS! When you are driving around and you let off the gas and nothing happens...like cruise control is stuck..that is not cool.

 

[FlyBryViper]

Jerry
Do we know for a fact the ...the factory programmed in a slight delay when the throttle is release...
I agree that this make sense, and almost all manufacturers do this to some degree. But, it is unwanted by road/track racers, and if there is ever a "hang", even for only a few seconds, it can become dangerous.
I have not noticed any hang on the track, but occasionally get one when on the cool-down lap or exiting the track. It can be damn embarrasing!

 

[Gerald]

Gerald, what joy. Congratulations. I don't want to sound doubful but.... enjoy it while it lasts. When you have achieved a full season of driving your Viper and several thousand miles w/o a problem, then I will believe you have fixed it. My experiance has been a simple battery bump etc will fix it for awile. Anything that will cause the PCM to "re-learn" it's peramaters will work, but in the end the problem will come back. FYI my hang tends to be most evedent after high RPM hard running in hot weather. The problem developed prior to my moding the motor. The closest I have come to stoping this problem was when I had the Dodge Store reflash my PCM with the latest down load program from their computer for my model year.(ie:'97) I suspect this rearranged some PCM perameters that took longer to learn than before. Thought I had it fixed, but it eventually came back after a couple of thousand miles. Pritty cool huh. More freaking finiky than a Ferrari if you ask me. The diffrence is that the Ferrari could be fixed. Oh well, the plugs are cheep and what's a little hang'en throttle. I think it is the PCM, but with no factory re-designed replacment I guess we just gota live with it.. LOL

Doubt all you want !! I had it for 4 m*****f*****years. It was so bad it was stick at times no matter what I did. I'd sit in traffic and sound like a little kid revving my engine for years, trying to blip it downl I had permanent cruise control.

I don't blame you for having doubts. I had doubts for years. My last try was the dowel suggested by Sean Roe. It worked great, but I could tell my car still wanted to idle hang and it had a horrible erratic idle (but not as high)....




Gerald

 

[Gerald]

It's really very simple, nothing to do with your PCM or anything like that. And I can guarantee I had the worse idle hang around if not the worst.


I would imagine they (all the cars) are doing it for the same reason and all the symptoms are the same.

Gerald

 

[Jerry Dobson]

Gerald,
What did you do to fix the problem?


Others,
Does anyone have the problem on a bone stock car?

 

[PDCjonny]

It's really very simple, nothing to do with your PCM or anything like that. And I can guarantee I had the worse idle hang around if not the worst.


I would imagine they (all the cars) are doing it for the same reason and all the symptoms are the same.

Gerald

So why the F*** don't you mention what fixed it despite being asked repeatedly??????????????????

 

[ViperRichRT10]

Gerald,

Are you ever going to tell us what you did to fix it??? This is starting to sound like a Sean Roe "I got more coming in 2005" tease! Do tell...

Rich

 

[PhoenixGTS]

The breakthrough for me was syncronizing the throttle-bodies. Idle hang has been gone for 1k miles. I also have a restrictor in the IAC air hose with 25/64" hole.

 

[Gerald]

Solution

ViperJon,

I do hope you were just kidding and not being an a$$****. If you were being an a$$, don't read below.

Pheonix hit the nail on the head, sometimes it just takes synch'ing the t.b's as it will synch them (duh!!) and cause the t.b.'s to use the correct return spring force. Read on..

On another note, Rich, Jerry and others who asked for the solution I'll give it as best as I can although I'm not a mechanic. About 1 month ago I sent my Viper back to DLM for an upgrade on my blower setup (went from a Lvl II to a LvlIII/IV) and told Doug how upset I was with my car because of the idle hang (not his fault of course). He said he knows how to fix it and it is pretty easy as he'd done it over the years many, many times. I was VERY skeptical as a few of you are. Of course, seeing (or in this case) driving is believing.

When my car came back I immediatley drove it to see about the idle hang and ********** it was gone. It hasnt' come back and I've been driving it everyday for a couple or three weeks. Before when I thought it would be fixed it would come back (time and time and time and time again) after the car had maybe 30 or 40 miles on it. or the computer would relearn the correct parameters) The car has now about 500 to 600 miles and it's flawless now. Just like it was new and I can't begin to tell you what a pleasure it it so drive.. Sooooooo....

What Doug replaced was the ENTIRE throttle cable assembly. When the car gets a little older the original throttle cable assembly tends to get a lot of drag in them. If you pull on them you can actually feel the drag. This is why blipping the throttle worked sometimes as it would pull the cable back with a quick stab of the throttle.

The right side (pass side) screw MUST be touching the back plate so that the return of the throttle cable uses BOTH THE driver side AND pass side stock return springs. Some ppl adjust their t.b's so that there isn't enough force or that their car only uses ONE return spring (driver side)... And this isn't enough force to completley close the t.b.'s..... And they must be synched, correctly. Also the right side (pass side) linkage adj. screw MUST be touching against the stop. This is why sometimes when your idle hangs if you quickly take your foot off the accel. and put it UNDER the gas pedal and lift UP, then release, the idle hang will go away at times. (it uses more return force than otherwise because lifting up returns the tb's with more foce than the stock springs) !!

There is too much drag in many older throttle cable assy's to let the spring "pull" the cable back, letting the car drop back down to a perfect idle. They stay OPEN JUST ENOUGH so the car doesn't know where to idle at causing the crazzzy idle and STUCK idle hang at Highway speeds, etc.

Below is the setup Doug at DLM did ALONG with what is written above to safegaurd so there is more enough force to return the cable.. Note the spring pulling BACK on the throttle cable.. With some cars, this might be enough, but I doubt it. It's a combination of them all.

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Note the return spring. The one put on my car isn't a very strong one, but isn't a weak one either.


Sorry, but it HAS NOTHING to do with the PCM or the computer, battery, IAC motor, etc, etc, etc. Although restricting the airflow WILL work for some cars. (It ONLY acts as a bad-aide to a car that is getting more air due to the throttle not closing all the way because of old cable and not enough force in return springs) But over time it will get worse as the throttle cable will get worse and springs lose tension.

I also had my throttle bodies totally cleaned up and asked Doug if that had ANYTHING to do with it and he laughed and said it has nothing to do with it.

I'm sure he will chime in later and I hope this helped some members out. It's a factor of a few things, but they are all related and it boils down to force on the return springs by correctly adjusting factory spring tension by adjust tb's correctly, adding an additional return spring and getting a new throttle cable ass'y as the old one , over the years, will create or get drag in it working AGAINST the springs.

After YEARS of idle hang, from 2,500 RPM to about 1750 RPM sitting in traffic, 60mph in the fast lane. There's nothing worse then lifting off the gas and your car is still going forward and relying on blipping the throttle. Mine was so bad even when I slowed down it would stay at the previous RPM at times and MPH. Every stop light, every stop. Putting the dowel in helped the RPM, but not the hang. But I still had an erratic idle but instead of 1,700 to 2,500 rpm it was from about 800 rpm to about 1,200 rpm. It made it better, but STILL MADE MY BLOOD BOIL...

 

[ViperRichRT10]

Re: Solution

Gerald,

Great response ! Thanks for your help...

Rich

 

[PhoenixGTS]

The breakthrough for me was syncronizing the throttle-bodies. Idle hang has been gone for 1k miles. I also have a restrictor in the IAC air hose with 25/64" hole.

Just to clarify, I did NOT add any return spring to my throttle cables, and they are the original cables. Also, when I had the hang, it was VERY uniform in its rpm level and that it would immediately stop once I slowed down to about 5 mph - which leads me to believe that it is indeed the result of an electronic command rather than a purely mechanical problem. I think it is a mechanical issue that in turn affects the electronics, or maybe it is better to say something mechanical triggers the electronics to make a "bad" decision and command the hang behavior.

 

[Todd Richmond]

Yep - mechanical fixes are a critical part of debugging this problem. When I discovered the weak return spring issue quite a while back, a couple people replied that it was exactly their problem. Thankfully I had 3.73 gears at the time so I had only gone partially crazy . The fix was obvious once I found it, but it took me days of trying everything else before I noticed that the return was off by no more than a hair and then only if you let it close slowly(friction from the pedal/cable). Blipping the throttle from under the hood lets everything close up solid. I went low tech and just moved the spring end to stop up a bit higher/tighter

Once the return spring is fixed, what is the exact method for syncing the TBs? I have read conflicting responses to that question

 

[PhoenixGTS]

Once the return spring is fixed, what is the exact method for syncing the TBs? I have read conflicting responses to that question

Get them to close exactly the same, then slowly adjust so that the driver's side opens ever so slightly before the passenger side. Best way to determine this is by sticking your thumbs in the throttle bodies up against the butterflies and have someone barely touch the throttle. That said, now that it is a colder outside, I am getting some low-speed bucking and need to give it another shot on my car to smooth it out.

 

[Gerald]

When you guys get a new throttle cable assembly, return spring, correctly adjusted and synched TB's etc as I listed I'd love to see if it helped the many "plagued" idle hang victims..
Let me know if you get it worked out. I drove it for another 50-60 miles and puuurfect. It hasn't even hung ONCE...


Gerald

 

[Gerald]

Just checking in with an update on the idle hang issue..


Car has been daily driven with about another 200 miles on it. Back and forth to Tampa a couple times, "spirited" driving and bumper to bumper.

Still no idle hang..... awesome!!!!


Gerald

 

[ChicagoGTS]

I also have suffered from idle hang, mine started when I put my Roe blower on last November. Yes, I put on the 70mm TB's. Since Phoenix's original post I've synch'd my TB's and it has made nice improvements especially during low speed (parking garage style) driving. BUT, when my car get's warm anywhere from 150+ degrees during hard driving idle hang rears it's ugly head. Blipping the throttle used to work before I synch'd but now it only ceases when I come to a complete stop, exactly like Phoenix's problem. It's very uniform every time it happens. Blipping while driving does nothing for me, and it goes back to idle like clock work every time I get under 2mph. However the harder I drive the more severe the hang is, almost like it's still burning fuel in the cylinders (loud popping and hunting idle). This does lead me to believe that it is a mechanical issue that triggers an electronic one, since I never had the issue before the mods. Perhaps it's the TPS not reading the enlarged TB's correctly, I don't know. I'll continue to play with the TB synch, but I've tried everything including tightening the springs. If I put anymore pressure on the gas pedal it will be to stiff. Gerald I'm glad to hear your problem is gone and look forward to the day that mine is as well, it's especially embarassing when I have someone in the car. I'm very tempted to put my stock TB's back on, but I really do like the look of the Accufab's. However, it's a no-brainer when comparing the minimal gains to the idle hang headache .

P.S. - I'll post when I get my stock TB's on. Hey Phoenix, do you have 70mm or stock TB's?

~Matt~

 

[Gerald]

Have you tried what i posted? We have/had the exact same issues and symptoms. It's NOT your TB's or, Throttle Position Sensor, it's the spring tension/Throttle cable assy.

Matt, why don't you try what I suggested. I really hope what I posted would help ppl out. Don't be skeptical. LOL!

I will continue to post an update to see if the idle hang issue has come back for those that are skeptical. I will post and resurrect this thread about once a week for a few weeks.


Gerald

 

[Qualitywires.com]

This is the most intelligent response gerbil boy has come up with! LOL! Good job!

 

[PhoenixGTS]

Convincing evidence that idle hang is a software problem, not a hardware problem. After over a 1,000 miles of absolutely no idle hang with my Mopar Performance PCM, I installed a WCV tuned unit from the same 1998 year. Good news is that the car is faster (specifically a dead spot in the power-band from 2k to 3.5k rpm is gone). Bad news is that idle hang is back worse than I ever had it before. It hangs at around 1,500 rpm and will not come down until after about a second after you come to a complete stop. When I had it before it would come down once you went slower than 5 mph or so. This takes noticeably longer. I am going to try and re-synch the throttle-bodies this weekend and see if it helps, but understanding that it only takes five minutes to swap computers, and absolutely nothing mechanical was changed on the car, it looks like the hang is completely software related. I had forgotten just how bad idle hang sux. I'm not happy.

 

[Gerald]

It's not software. You contradict yourself. You DO or did have it.

Your new PCM is reading diff parameters in the slightest of changes. Your cable pulls your TPI sensor back which reads a certain voltage which is transalted by your pcm and you changed your pcm..

Also in your sig I see you have 70MM TB's so your tb's have been messed with as has your tb throttle assy, etc

oh by the way, my idle hang is still gone.. LOL!

You can lead a horse to water...........

Good Luck,

Gerald

 

[PhoenixGTS]

It's not software. You contradict yourself. You DO or did have it.

Gerald: today I am going to be fiddling with and fine tuning the throttle-body synchronization. Hopefully, I will be able to back you up by showing that getting the t-bodies dialed in will not send whatever magic signal that is causing the PCM to hang the idle. Cross your fingers. It might be possible that the WCV PCM is simply more sensitive to whatever the problem is that a slightly un-synch'd t-body situation caused my old PCM to hang, but if I cannot get it, that I changed no hardware and the PCM change itself brought back a hang indicates a software issue. The PCM isn't hardware after all.

 

[AJT]

Doug had my computer reprogramed &amp; mine is gone!

 

[supratime]

Re: Random High Idle / Sticking Idle - &lt;master thread&gt;

I have the same problem with my 99 rt/10. The rpms idle and sticks at 2000 rpms when I come to a stop.

1) At what outside temperature does the problem occur? Any temp. Usually when it is cold.
2) What year is your car? 1999
3) Is your car BONE stock with this problem? Not sure. I bought it modified.
4) Do you have K&amp;N filters and smooth tubes? Yes I do.
5) Do you have Headers installed and if so what brand? Yes, I have headers but not sure of the brand. It was on there when I bought the car.
6) What other modifications do you have that might have triggered this problem? The ECU is modified, exhaust, headers, K&amp;N smooth tubes, high flow cats. I wish I new which one of these mods caused this problem.
7) What steps have you taken to attempt to cure the problem? I brought it to the dodge dealership and they changed the IAC motor and clean the throttle bodies. The problem stopped for a few months but came back.. please help!

Eric