Rough Idle -- Bad Battery? - Focus Fanatics
Focus Fanatics Ford Focus Forums
HomeContact UsAbout UsGalleryDiscussion ForumsMarketplace

Go Back   Focus Fanatics > Ford Focus Tech Discussions > General Technical Chat

General Technical Chat This section is for technical discussions relating to general maintenance, electrical issues, engine trouble, and recalls.

Search This Forum | Image Search | Advanced Search    
FocusFest Ford Focus Tire & Wheels FocusFanatics Merchandise

Thread Tools Display Modes
Old 12-17-2006, 11:15 AM   #1
Focus Jr. Enthusiast
Join Date: Oct 2006
Fan#: 39705
Location: NY
What I Drive: 2005 ST

Posts: 44
FF Reputation: 1 GearDriven Good Standing Member
Buy-Sell-Trade Rating: (0)
Rough Idle -- Bad Battery?

So my 2005 Focus was in an accident. It sat on a lot and the battery discharged. They got it charged and it started right up after 10 days sitting. It's been having a rough idle ever since. The cause appears to be a slow idle. The battery may be on its way out, as I am also getting a low voltage DTC. Any ideas? The dealers are all backed up around here.

GearDriven is offline  
    Reply With Quote
Sponsored Links
Old 12-17-2006, 12:22 PM   #2
Focus Enthusiast
FocusDog's Avatar
Join Date: Mar 2006
Fan#: 33087
Location: Colorado Springs, CO
What I Drive: 2000 Green SE Wagon

Posts: 157
FF Reputation: 1 FocusDog Good Standing Member
Buy-Sell-Trade Rating: (0)
I'd take it to Autozone or PartsAmerica or whatever you have in NY, and get a free code read done. They can also put a meter on the battery and see if you're putting out the right voltages at idle and at higher RPM.

If the battery fully discharged sitting on the lot, the computer needs to learn all the idle parameters again. This is accomplished on first startup after the battery is reconnected, and is described in your owner's manual. The repair folks may not have done this properly, and the car's idle will suck until the car slowly figures everything out. You can disconnect the battery, wait awhile, and reconnect it, then follow the relearning procedure properly and see if that helps the idle.
"Yes, that's right, its a Wagon..."
FocusDog is offline  
    Reply With Quote
Old 12-17-2006, 01:23 PM   #3
Focus Enthusiast
Zetecrazy's Avatar
Join Date: Nov 2006
Fan#: 41292
Location: Albemarle, NC
What I Drive: 2002 Yellow ZX3 MTX

Posts: 305
FF Reputation: 5 Zetecrazy Good Standing Member
Buy-Sell-Trade Rating: (3)
A battery would not make your car have a rough idle. If you have a worn battery your car would have 3 effects. They include not starting obviously, lights dimmed while driving, or a hesitation when starting the car (the car woul take a few cranks to turn over). If you have a rough idle I would check the following items first; Spark plugs to see if they are fouled, ignition wires, and even check the air filter).
SRI, 2 1/2" custom catback-FC race header, Xcal2, NOS 75 shot, heater and fuel pressure switch, Zex purge, AZFS22C plugs, Bomz Racing seats, CF hood, Roush kit, pillar gauges, whiteface gauges, CF mirrors, halo headlights, Bomz coilovers.
Zetecrazy is offline  
    Reply With Quote
Old 12-18-2006, 11:56 AM   #4
Focus Jr. Enthusiast
Join Date: Oct 2006
Fan#: 39705
Location: NY
What I Drive: 2005 ST

Posts: 44
FF Reputation: 1 GearDriven Good Standing Member
Buy-Sell-Trade Rating: (0)
My thought is that maybe one of my plugs is fouled/not gapped right and it's not related. OR: the prior owner removed the resonator or did some other internal mod to the stock intake and the ECU was "reset" by the battery death and hasn't "relearned" what was wrong before.
GearDriven is offline  
    Reply With Quote
Old 12-18-2006, 12:11 PM   #5
Captain TMI
whynotthinkwhynot's Avatar
Join Date: Jan 2005
Fan#: 18416
Location: the armpit of TN, Memphis, TN
What I Drive: 05 ZXW; 02 Windstar; 13 C-Max SEL

Posts: 19,800
FF Reputation: 267 whynotthinkwhynot Outstanding Standing Memberwhynotthinkwhynot Outstanding Standing Memberwhynotthinkwhynot Outstanding Standing Member
Buy-Sell-Trade Rating: (1)
Dead battery= reset ECU, your computer has to re-learn it's map, especially the idle map. If you don't do it how the manual describes it will take about 2 weeks, and then suddenly one day- poof, clean idle. That's how long it took mine before I knew to allow it to sit for 5 mins idling.
Be eclectic.
---The Complete How-To Archive--

Moderating everything now, let me know if I can help.

Originally Posted by the user formerly known as ZX3_Chick View Post
You're special aren't you.
whynotthinkwhynot is online now  
    Reply With Quote

Bookmarks & Social Networks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Does a bad DPFE sensor cause the engine to stall at idle? odengiz General Technical Chat 3 03-06-2006 04:08 PM
ATX Shifts Hard After Fluid and filter change 2k2zx3 General Technical Chat 5 02-16-2006 08:03 PM
Battery light on at idle... SVTbrit General Technical Chat 4 12-08-2005 11:22 AM
Battery Light Question buickregal General Technical Chat 1 06-13-2005 09:47 PM
rough idle CowsGoMoo ZETEC Performance (2000-2004) 9 10-16-2003 03:11 PM

All times are GMT -5. The time now is 07:45 PM.

Copyright 2002-2014 All Rights Reserved : Terms of Use : Privacy Policy : Advertise Information : Site Map

Focus Fanatics Ford Focus Forum offers many fun ways for you to engage with other Ford Focus Owners from across the world. Whether it be about the aftermarket performance modifications, technical how-to's, European tuned suspension or awesome fuel economy similar to the Acura TLX. You can find all Ford Focus related information here. Join our Ford Focus discussion forums and chat with local Focus enthusiasts in your area.