30 second stumble

Logan56860

Member
Apr 16, 2020
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I can time an idle stumble every 30 seconds while at a stop. Auto tranny, in gear, at a full stop waiting to go. RPM drops from 800 to 300 every 30 seconds. Like it is re-setting itself! 2013 GT. bought used a few months ago. 55K miles. In really good shape. Anyone know what this is? Is it possible this car had a tune that is creating this situation?
 
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Do these cars have an IAC? Idle Air Control Valve. If so, they are prone to doing that when they get old. Most especially Ford IACs. I've had to replace the one on my 98 Ranger so many times, I lost count. Finally replaced it with a Hitachi from Auto Zone, their premium part. Been good since 2015. The IAC on my Ford Lightning has been replaced three times in the ten years I've owned it. Put the Hitachi on last year. We'll see.

While my Stang is a mere V-6, I'll look in a bit and see it it has one. If there is one, I may just change it and be done with it. The only thing idle wise that happens on mine, I can tell every time the fan kicks on when idling. The idle drops, not a lot, just a little. But I know it's the fan increasing the load on the alternator.

One of the common symptoms of a bad IAC is a fluctuating idle.
 
I just checked, the 05 - 09 Mustangs don't have an IAC. The idle is controlled by the fly-by-wire throttle control.

 
mine is 2013
gt , premium
auto,, because of my daughter,, I know...………. I had my first 79' 5.0 at 16. I drove hard, my daughter does not.

It is very odd, at a stop, in gear, brake down, you can set your watch by it. 30 seconds, and it stumbles for 1/8 second..
Thought the previous owner may have tuned it and I had nothing to attach to it and dial it in. Yet..
What is your opinion on best tuner for light to no mods? Don't want it lowered or loud. Already draws enough attention. Don't need heard for miles, and found!
And thanks for taking the time to respond to my question. I appreciate it. I'll keep diggin
 
I'm not really sure about tuners for these vehicles. Mine is still basically stock except for the intake. I plan on doing a dual exhaust later, but like you don't want it LOUD! Just a pleasant rumble. My Lightning has a Borla exhaust, very nice. It''s got a nice rumble, but the whine of the blower still overpowers it. That's what I like.

I'm sure, using the search function on this site, you will find more information on tuners than you have the time to read. LOL!

I'm not into lowered either. I just put the Cervinni's front spoiler on mine a few weeks ago. I have to wwatch certain driveways and parking lot entrances enough now as it is. If I lowered it, I would probably whack the front spoiler off in the first day.
 

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CB, What year is your Stang (06-07?) On my 2005, Mods--I put a Ford Performance CAI , Performance wires, Bausch Iridium plugs and a Flowmaster True Dual Force II exhaust system. You can really feel the additional horses! 20+ ?? Probably didn't need it, but I upgraded to a Accel Coil Pack too.
 

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It's an 07. Yes, I have the Accel coils and JBA all metal spiral wound wires. WeaponR intake with cold air tube, and Ford Racing strut tower brace. Also, since I never turn the radio on, a CravenSpeed Stubby Antenna. Same on my Lightning.
 

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Funny, I think our cars are "close cousins". (JBA wires here too.) The car only has 63,000 on it so I decided to put the Iridium plugs for my last plug change in my lifetime.. lol I have a Bama tuner which I think is pretty cool. It can change wheel ratio's, trans shift points (On Auto's), all kinds of stuff. See & remove any code issues.. I'm currently on the Performance 87 oct tune, but will fill up on 93 oct to try out the Race tune. Controls and modifies the computers. I really like it considering I'm an "Old School" guy. This is my Toy, where I see you have many Toys!
 
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Mine has 117,000+ miles. But still runs great. Bama tuner, I'll have to look into that. I already run 93 octane anyway, in all my vehicles. It's not overly expensive here, and better to have it and not need it, than need it and not have it. My V-6 Ranger pings so damn bad on 87, even 89, barely gets by on 91. But yeah, it's got a CA and modified exhaust, chip on the computer. It's my bad weather vehicle, so the bikes, Mustang and Lightning can stay in the garage and stay clean.

One can't have too many toys. My Lightning is my kick ass vehicle, as is my 2008 B-King. The B-King is a 9 second vehicle. F*cking scary fast. Going out and ride it here in a short while. ;-)

I put iridium plugs in my Ranger. and 5000 miles later, the center electrodes were gone on all six of them. Now days, I jsut stick with Motorcraft double platinums. The center electrodes last longer. I use NGK TR-6 in my Lightning, gapped less than stock, but that's typical for any application on a Lightning where you're running more boost than the stock 8 pounds.
 
I have Bama tuners on my favorite list now. Will do some looking when I get back from my ride, later this evening.

Yeah, old school. I'm 58, so you and me both. My first car was a 78 Pontiac Firebird Trans Am. My second was a 70 Pontiac Firebird Formula 400. Had two Z cars, a 78 Datsun 280Z and an 80 Anniversary Edition 280ZX. Had a 92 Mitsubishi 3000GT VR4. 93 Mitsubishi Eclipse. Have had over 25 different motorcycles. That's back in the day. LOL!

Old school is where I'm going with this Mustang. Chasing the 69 Boss 302 look. Put a Cervinni's front spoiler on a few weeks ago. Put some nice window louvers on the back two weeks ago. All parts that were kind of obligatory back in the day for any slantback Stang. Hood bra on the front, which goes along nicely with the black front spoiler. Working on blacking out all the orange and red lights. For the present time, using Black Out tape. Will replace with black out assemblies in the future.
 

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I decided to pick up my 05 S-197 platform due to the sixties retro look. My fav is 69-70 Stang's. This is my 3rd Mustang... my first love was the 1966... when later to a Foxbody 1983... not as cool... and now the 05. I was going to PU a 65 or 66 as my retirement Toy up here since I know them so well. But I spotted a S-197 which captured my heart in the love of Mustangs! I had to sell my 70 Mercury XR7 Cougar convertible years back when I moved to England for four years... wish I had em all back. The 05 has been my Fun Stang, Modding it since last year. Now that the weathers good...Corona is in the air #%))**t%#. Long rides in the country are my new form of Social Distancing. I forgot how much I missed the top down.. You won't regret getting a tuner $399 at American Muscle. The S-197 was designed to run on 87 octane with no issues (or knocking). I love the what the mods did to my performance. Looking to get 93 in the tank for the race tune.. don't set the 93 race tune unless you have 93 in the tank. I heard it will run like :poo: if you do..
 
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I have a March 2003 edition of Hot Rod magazine, which a friend gave me after he saw my Mustang. The concept vehicle for the 05-09 Mustang on the cover, called Ford's retro fastback. So yeah, definite retro look from the very concept.

Been eyeing tuners, lots to choose from, don't know enough about them to make a decision. Also eyeing the Borla True Dual catback exhaust with the four inch tips. I can see that addition very soon. American Muscle is my candy store. Much as CARiD is as well. I have several items coming from Cervinni's, painted. Also eyeing their hood lock set.
 
I have a March 2003 edition of Hot Rod magazine, which a friend gave me after he saw my Mustang. The concept vehicle for the 05-09 Mustang on the cover, called Ford's retro fastback. So yeah, definite retro look from the very concept.

Been eyeing tuners, lots to choose from, don't know enough about them to make a decision. Also eyeing the Borla True Dual catback exhaust with the four inch tips. I can see that addition very soon. American Muscle is my candy store. Much as CARiD is as well. I have several items coming from Cervinni's, painted. Also eyeing their hood lock set.
There is a Cervinni's, hood that looks just like a 69/70 hood. Comes with headlight extenders so it really nails those years. ere is a photo of the hood.... Is this a retro 69 Mach I or what?
 

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Looks more like a Boss 302. but, six-of-one, half-dozen-of-the-other. Beautiful car. Has Cervinni's front spoiler on it, and their rear window scoops and the ones on the lower fender. . Those are what I am currently waiting for. Ordered them painted to match. It also has MGP caliper covers. They are available from CARiD. I will be getting some of those pretty soon. Wonder where they got the old school rear spoiler. Looks like it time traveled from 1969. ;-)

Appears to have rear window louvers as well. They were an obligatory item on any slantback back in the day. Can just barely make them out in the second picture.

I have the same caliper covers on my Lightning.
 

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Looks more like a Boss 302. but, six-of-one, half-dozen-of-the-other. Beautiful car. Has Cervinni's front spoiler on it, and their rear window scoops and the ones on the lower fender. . Those are what I am currently waiting for. Ordered them painted to match. It also has MGP caliper covers. They are available from CARiD. I will be getting some of those pretty soon. Wonder where they got the old school rear spoiler. Looks like it time traveled from 1969. ;-)

Appears to have rear window louvers as well. They were an obligatory item on any slantback back in the day. Can just barely make them out in the second picture.

I have the same caliper covers on my Lightning.
Can't wait to see your mods as you build your Boss or Mach 1. I like the lighting brakes... I am sending a few more pics of Mach1 . Stripes, side emblems, gas cap, spoiler and emblems on hood are 1969 OEM stuff...
 

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It's a bad ass ride for sure. Saved those pics to my Mustang folder for future reference.

Here where I live, I see lots of Stangs. Only see them with either the upper or lower scoops, never seen one with both. Haven't seen another with the Roush hood scoop and rear spoiler. So mine will stand apart from the rest, even though it's a V-6.

I love that front end, but it's not aerodynamic friendly. The covered head lights are aerodynamic, so I'll stay with it. Attached below is a wind tunnel test of a 69 Charger, a 69 Charger Daytona and a 18 Challenger Hellcat. The 69 Charger does very poorly due to it's front end. Actually produces front end lift instead of down force. The Charger Daytona, which is very similar to a Plymouth Superbird, does very well even when compared to the Hellcat.


View: https://www.youtube.com/watch?v=2_I3WK8KA38&list=PLmlk4KWwmdi3cTOuht6ak5hhOA-aVTyu4&index=5&t=0s
 
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Funny you should post the above pics with comparison aero's… I am not a Mopar Fan.. I even bought a Dodge Charger Shelby in the 80's... but was plagued with Mopar issues ( a real disappointment car) but was pretty fast when it was running... never again.
I DO Love the late 60/70s Chargers, Challengers, Cuda's, Roadrunners... GTX's.I watch "GraveYard Cars" and love the frame off rebuilds.) The rest of the Mach I pics for your file
 

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