Welcome to the Australian Ford Forums forum.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and inserts advertising. By joining our free community you will have access to post topics, communicate privately with other members, respond to polls, upload content and access many other special features without post based advertising banners. Registration is simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact us.

Please Note: All new registrations go through a manual approval queue to keep spammers out. This is checked twice each day so there will be a delay before your registration is activated.

Go Back   Australian Ford Forums > Club and Speciality Forums > Forum Community Car Clubs > AU Falcon.com.au

Reply
 
Thread Tools Display Modes
Old 01-02-2021, 06:03 PM   #1
zanewindle59
Starter Motor
 
Join Date: Feb 2021
Posts: 3
Default Rough idle

Gday, I was wondering would anyone know what would be causing rough idle to the point where my 1999 au falcon sounds like a rotary. All leads are getting spark but one cylinder isn’t firing even after I replaced that spark plug for that cylinder. Any help appreciated. Cheers


Sent from my iPhone using Tapatalk
zanewindle59 is offline   Reply With Quote Multi-Quote with this Post
Old 01-02-2021, 08:14 PM   #2
PG2
#neuteredlyfe
Donating Member2
 
PG2's Avatar
 
Join Date: Apr 2012
Posts: 10,303
Default Re: Rough idle

You need to change the coil pack.

Also, welcome to Ford Forums.
PG2 is offline   Reply With Quote Multi-Quote with this Post
This user likes this post:
Old 01-02-2021, 08:21 PM   #3
zanewindle59
Starter Motor
 
Join Date: Feb 2021
Posts: 3
Default Re: Rough idle

Hey man cheers for that


Sent from my iPhone using Tapatalk
zanewindle59 is offline   Reply With Quote Multi-Quote with this Post
Old 01-02-2021, 09:18 PM   #4
Uncle_Ken
Next upgraded Mk1 Leopard
Donating Member1
 
Uncle_Ken's Avatar
 
Join Date: Jan 2005
Location: Sydney, in the burbs
Posts: 4,899
Valued Contributor: For members whose non technical contributions are worthy of recognition. - Issue reason: Always putting some imput into the forums to help or make it a bit easier for others Tech Writer: Recognition for the technical writers of AFF - Issue reason: Writing tech articles 
Default Re: Rough idle

There are a few posts about AU coil packs, use the search bar to find more info on the preferred types.
UK
__________________
Plastic Surgery 1 AUII Monsoon Blue
Plastic Surgery 2 AUIII XR8 220 Rebel
Plastic Surgery 3 Watch this space ??? Living in AU Heaven
How 2's: Change rear view mirror, Install backfire valve, Change foam front seats, Install auto transmission cooler, Replace Trans Shift Globe, Remove front door Trim, Paint AU headlights, install door spears, Premium Rear Parcel Shelf, go here...
Uncle_Ken is offline   Reply With Quote Multi-Quote with this Post
Old 10-02-2021, 05:18 PM   #5
zanewindle59
Starter Motor
 
Join Date: Feb 2021
Posts: 3
Default Re: Rough idle

So I went down to the local mechanic and he’s said if the lead is getting spark which it is then it’s not the coil pack. Any other suggestions


Sent from my iPhone using Tapatalk
zanewindle59 is offline   Reply With Quote Multi-Quote with this Post
Old 10-02-2021, 06:15 PM   #6
aussiblue
FG XR6 Ute & Sedan
Donating Member3
 
Join Date: Oct 2006
Location: Bibra Lake WA
Posts: 22,298
Technical Contributor: For members who share their technical expertise. - Issue reason: Has been floating around the oze tech section for a long time and is always there to give advice when people have an issue. 
Default Re: Rough idle

More likely a leaking intake manifold gasket.

But on the issue of spark; how much spark do you have? When you check for spark, bear in mind Ford specify a minimum 6mm spark plug jump test; i.e. the spark at number 1 (or any other lead) must jump at least 6mm (in a healthy system it should actually easily jump about 15mm or more) ? Easiest to test with a tool similar to this https://www.supercheapauto.com.au/p/...ter&lang=en_AU or https://www.supercheapauto.com.au/p/...ter&lang=en_AU If the spark can't jump more than 6mm the car often won't start at all let alone run correctly. It should also be blue rather than yellow (yellow is often an indication that the spark is weak). These efi engines need a very strong spark for a very short time that is timed for the short time injector spray. You will often find car that won't start or run as the spark falls just short of the 6mm jump test.

However, in sound to me more like a major vacuum leak at the intake manifold gasket. Check for vacuum leaks particularly at the inlet manifold at the bottom of number 1 and 6 intakes near the head both when the engine is hot and cold (as the expansion and contraction of the head and manifold with heating and cooling will change the extend of the gap and leak).

Use a length of windscreen washer sized hose with one end in or close to the ear to listen for the no mistaking tell-tale sucking noise of a vacuum leak while poking around under the manifold at idle. Note that the old pre-computerised fuel injection trick of using/spraying engine start sprays, benzene , water, oil etc around the manifold will most often not work to find these leaks as the ECU rapidly adjust for the change in air in the mixture and it's hard to pick up any change in the engine noise or rpms using this old method. The manifolds typically leak at number 1 and or 6 as the nuts on the manifold retaining studs there loosen over time and the bottom parts of the gasket then burns out. Because a small part of the gasket has burnt out, simply re-tightening the nuts won't fix it and you will need to replace the gasket remembering to torque to specification in a circular patter from the center of the manifold outward.

You can reuse the thin metal gasket on the upper variable length plenum intake (after giving it the thinnest even coating of Hylomar gasket goo you can) that you have to remove first when replacing the main intake manifold gasket.

Also check the PVC valve for vacuum leaks but a leaking intake manifold gasket is the most common cause.
__________________
regards Blue
aussiblue is online now   Reply With Quote Multi-Quote with this Post
2 users like this post:
Reply

Thread Tools
Display Modes

Forum Jump


All times are GMT +11. The time now is 12:14 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Other than what is legally copyrighted by the respective owners, this site is copyright www.fordforums.com.au
Positive SSL