S197 Idle Surge. Need help! - Page 6 - Ford Mustang Forum
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Quote:
Originally Posted by marylandGT View Post
Quote:
Originally Posted by MasterX View Post
They work well as long as you pay them proper respect, they are dangerous if your power system is dodgy. Measure twice, cut once, and make sure the battery is charged, and keep your mits away from the keys and everything else until you hear the jingle that says its done.
What???
I think what he means is that when using the SCT tuner to upload a tune to your ECU, you need to make sure that you follow the instructions to the letter, that the battery is properly charged, that there are no other accessories in use, that the tuner is firmly plugged into the OBD 2 port, and that there's nobody else around (especially kids) to distract you. Any interruption to the process could cause the upload to fail, leaving you with the nightmare scenario of the ECU being "bricked". In such a situation, the car is basically dead in the water and would need a tow to the stealership to have the stock tune reloaded.



2006 GT Deluxe - 5MT - 12.52 @ 109.33
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post #77 of 84 (permalink) Old 07-04-2019 Thread Starter
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The rpm surge with just the stock tune is about 400-1200rpm so it's pretty bad. I just hope I dont tow it 3 hours to find out somethings messed up in it. And I need to send my X4 in to SCT before I go so they can unmarry it, this is a nightmare lol

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post #78 of 84 (permalink) Old 07-04-2019 Thread Starter
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I just checked my codes from the short drive I went on yesterday. There's P0340 and P0345, could it just be a failing alternator thats causing this horrible idle problem since I have an '06? It is the original alternator with 88k miles on it. Just a thought.
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Brain's got some good suggestions on items to check regarding these codes.




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Yup. You may indeed have a bad alternator diode that's allowing an AC ripple current to leak back to the battery.
Check YouTube for videos on how to do an AC ripple test to confirm if that's the problem.


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post #81 of 84 (permalink) Old 07-04-2019 Thread Starter
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Well I only have a cheap multimeter and I used it at the battery since the positive on the alternator is almost impossible to get at, so the reading might be totally inaccurate but I did notice that the AC was 3.5 higher when the car is on. But again I did it at the battery with a cheap meter so it might be nothing.
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post #82 of 84 (permalink) Old 07-09-2019 Thread Starter
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Since I can't really do the diode test, can anyone tell me if a bad diode in the alternator would really make the idle surge almost 1000rpms before I spend the money on a new one.
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When mine went out it only caused the CEL to come on with a cam phaser code for bank 1. Car ran fine otherwise. I went ahead and replaced the sensor but it came back. Then I came across multiple forum threads regarding the alternator diode bridge having a history of failing and allowing ripple in to the system and causing the CEL to come on and give a false phaser code. Replaced the alternator and no more CEL.



Even though mine ran fine, I would think that enough ripple were allowed into the electrical system it could cause some severe symptoms to manifest. I would go to Autozone, get an alternator and see if it cures the problem. If not, then just take it back. They have a very liberal return policy.

2006 GT- Airaid Race CAI, 62mm BBK TB, SR Performance UD Pullies, FRPP Hot Rod Cams, CMDP's, Excedy Stage One Clutch and lightweight flywheel, Pacesetter Long Tube Headers with matching O/R H-Pipe & MBRP Street Axlebacks, Lito 91 Octane Tune
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post #84 of 84 (permalink) Old 07-19-2019 Thread Starter
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I just got back from the dyno tuner and everything went good. My idle issue stemmed from worn out phasers so they would turn the cams too far and the pcm tried to compensate for it which is what gave me the surge. The guy locked the phasers out in the tune and the problem went away, it's only a band aid but itll work just fine until I can get new phasers or physical lockouts at some point. My idle stays right where it should now but when I'm in a low rpm and stomp on it the car gets a little jerky sometimes until it gets to 3000rpms, but that could just be the nature of the cams and not having longtubes.
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