Go Back   Ford F150 Forum - Community of Ford Truck Fans > Ford F150 Forums > Maintenance Shop
Sign in using an external account
Register Forgot Password?


Reply
 
 
 
 
Thread Tools Search this Thread Display Modes
Old 01-03-2009, 06:29 PM   #1
Junior Member
 
Join Date: Jan 2009
Posts: 5
Mentioned: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Question Wrong firing order on my 88 F150?

I have bought an 88 F150 4.9L used. It was having trouble running rich. During troubleshooting I noticed that my firing order is 152634 instead of the 153624. Obviously the 2 and 3 plug wires are reversed. I corrected the firing order and the truck runs very rough as expected with two crossed plug wires. I put them back and the Truck runs fine. I'm not making a mistake, I checked it five times.

How can this be? I know if you change the cam shaft then you can change the firing order. But come on, whose going to throw a cam in an inline 6.

Anybody got a clue?

Thanks

Dave
Frogman1195 is offline   Reply With Quote
Old 01-03-2009, 08:08 PM   #2
Senior Member
 
rickyp's Avatar
 
Join Date: Dec 2008
Location: LaPlata, MD
Posts: 595
Mentioned: 0 Post(s)
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
Default

could the engine been rebuilt some time in the past?
rickyp is offline   Reply With Quote
Old 01-03-2009, 08:09 PM   #3
Senior Member
5 Year Member
 
wde3477's Avatar
 
Join Date: Jul 2007
Location: Cape Girardeau MO
Posts: 2,394
Mentioned: 0 Post(s)
Thanks: 0
Thanked 23 Times in 23 Posts
Feedback Score: 0 reviews
Default

Welcome to the site!

In short - haven't come up with any good ideas here.

Looked at the rotation - even if one went counter-clockwise on the distributor - should end up with the firing order of 1-4-2-6-3-5, so this ain't it.

Don't think it would be the cam - the swapped cylinders are not in phase or sync, so I would think that a cam with that order wouldn't work in this engine. If I did my ciphering right - the 1 and 6, the 5 and 2, and the 3 and 4 pistons should move together.

Interesting problem - keep us posted.
__________________
1989 F150 XLT standard-cab shortbed 4x4, 5.0L, AOD, 3.55 gears, manual hubs, 31x10.50 tires, 217K miles. Repainted Oct09.
wde3477 is offline   Reply With Quote
Old 01-03-2009, 08:38 PM   #4
Junior Member
 
Join Date: Jan 2009
Posts: 5
Mentioned: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Default Lost still!

It could have been rebuilt, since I bought it used. I know that I change the firing order on a 5.0 when I installed a new cam once, but come on....

I pulled the number 2 plug to make sure that it was firing and the thing is dry and white. I am going to do more investigating tomorrow.

Dave
Frogman1195 is offline   Reply With Quote
Old 01-03-2009, 09:21 PM   #5
Senior Member
5 Year Member
 
wde3477's Avatar
 
Join Date: Jul 2007
Location: Cape Girardeau MO
Posts: 2,394
Mentioned: 0 Post(s)
Thanks: 0
Thanked 23 Times in 23 Posts
Feedback Score: 0 reviews
Default

With the 5.0 - the original firing order was 1-5-4-2-6-3-7-8. The HO version, or for those who stuffed a 5.8 cam in - the firing order became 1-3-7-2-6-5-4-8. The 3 and 5 cylinders, and the 7 and 4 cylinders were swapped in the firing order. This is possible because those respective pistons are in phase or sync with each other, just on opposite parts of the 4-cycle combustion - so a cam change, and related fuel injection harness and plug wire swap are all that is necessary.

When the 3 cylinder is on the compression stroke, the 5 will be on the exhaust stroke. Changing only the cam can reverse this sequence - but only because those respective pistons move together.

For the 300 I6 - changing only the cam would mean that the 1 and the 6, the 5 and the 2, and/or the 3 and the 4 could be swapped in the firing order. To change the firing order beyond this, such as your case of the 2 and 3 cylinders, would involve a crank with a different sequence. Not that this couldn't be done - just haven't heard of any aftermarket stuff that would do this type of thing.

Between this and what you've recently found - may be a case where standard logic does not apply. Again, very much interested to hear what you find out.
__________________
1989 F150 XLT standard-cab shortbed 4x4, 5.0L, AOD, 3.55 gears, manual hubs, 31x10.50 tires, 217K miles. Repainted Oct09.
wde3477 is offline   Reply With Quote
Old 01-03-2009, 10:20 PM   #6
We'd do it
 
Just call me Sean's Avatar
 
Join Date: May 2008
Location: Orlando,Fl.
Posts: 31,841
Mentioned: 2 Post(s)
Thanked 402 Times in 358 Posts
Feedback Score: 1 reviews
Send a message via Yahoo to Just call me Sean
Default

Check to see if the fuel injector harness has been tampered with. Changing the firing order would require modifications to that harness.
__________________
Quote:
Originally Posted by Early Cuyler
Fights begin, fingerprints are took, days is lost, bail is made, court dates are ignored, cycle is repeated.
Just call me Sean is online now   Reply With Quote
Old 01-04-2009, 07:14 PM   #7
Junior Member
 
Join Date: Jan 2009
Posts: 5
Mentioned: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Default More on Wrong firing order!

Ok,
I'm embarrassed. I checked the firing order counter clockwise. Not clockwise. I'm a dummy.

Thanks for all the info guys. Great forum.

Dave

Last edited by Frogman1195; 01-04-2009 at 07:28 PM.
Frogman1195 is offline   Reply With Quote
Old 01-04-2009, 10:07 PM   #8
Senior Member
5 Year Member
 
wde3477's Avatar
 
Join Date: Jul 2007
Location: Cape Girardeau MO
Posts: 2,394
Mentioned: 0 Post(s)
Thanks: 0
Thanked 23 Times in 23 Posts
Feedback Score: 0 reviews
Default

Hey, no problem. :-)

From your original post - are you sure the 4 and 5 don't have something going on?
__________________
1989 F150 XLT standard-cab shortbed 4x4, 5.0L, AOD, 3.55 gears, manual hubs, 31x10.50 tires, 217K miles. Repainted Oct09.
wde3477 is offline   Reply With Quote
Old 01-04-2009, 10:07 PM
 
 
 
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
5.4 firing order dugdamoose Engine / Drivetrain Talk 5 06-10-2008 09:25 AM
Timing/firing order? Ralphis 1987 - 1996 F150 4 05-29-2008 03:13 PM
Firing order for 2oo1 4.6 Triton Drewtilgh Engine / Drivetrain Talk 4 04-03-2008 02:48 PM
firing order on 89 F150 f150bigtruck 1987 - 1996 F150 1 09-02-2007 12:45 PM
firing order kdrifter440 General F150 Discussion 0 04-29-2007 10:54 PM


Tags
4.9l, f150, firing order

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Join F150 Forum

 

The Mustang Source
All times are GMT -4. The time now is 08:58 PM.


Copyright 2006 - 20011 F150forum.com
This site is in no way affiliated with the Ford Motor Company.