Running on 7 Cylinders When Warm - Ford Powerstroke Diesel Forum
Powerstroke.org is the premier Diesel Truck Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 02-28-2014, 07:42 PM
Member
 

Join Date: Feb 2014
Posts: 61
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
Running on 7 Cylinders When Warm

97 Powerstroke, starts and runs fine when cold but develops a miss/lope when up to temperature. It is definitely not running on all cylinders when you stand on it, it is down on power and runs rough. It doesn't seem to build any boost either. It doesn't have any blow-by, the turbo bearings are nice and tight, and the fins looked fine when I checked for turbo issues.

Oil is new 15-40W Rotella with a Motorcraft filter. New fuel filter. Where do I start looking for this problem? I'm about to pull the valve covers and inspect the wiring, is there anything I should do first though?

I unplugged the two connectors on the drivers side and checked the injector pins, all checked fine with the multimeter. I'll do the same with the drivers side tomorrow when its not dark out. I'm suspecting/hoping it is just injector o-rings. It does have a slow oil leak that seems to be coming from the plug in the rear drivers side oil rail in the head, though its slow enough I don't see it causing the problem.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 02-28-2014, 08:00 PM
Member
 

Join Date: Feb 2014
Posts: 61
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
Forgot to mention I have no CEL, and my cheap scanner doesn't pick up anything. I know the CEL bulb works, because it was flashing at me a while back when I was having trouble with my idle validation switch.

It sounds exactly like this guy's excursion when warmed up:
Reply With Quote Quick reply to this message
  #3  
Old 03-01-2014, 05:30 AM
Compression Ignition Addict
 

Join Date: Feb 2008
Posts: 748
Thanks: 2
Thanked 4 Times in 4 Posts
Feedback Score: 0 reviews
You need a good scanner and do a Cylinder Contribution test. Although you can remove the valve covers and unplug one injector at a time and see which one has no effect on engine performance. It would also help to see what your ICP levels are at. A good scanner would also be able to check this however you can rig up a gauge.

Use the search to find the ICP gauge setup

Where are you located? Many guys on here are willing to help if you're close.
Reply With Quote Quick reply to this message
  #4  
Old 03-01-2014, 05:40 AM
Member
 

Join Date: Feb 2014
Posts: 61
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
I'm outside Little Rock, Arkansas.

What scanner setup do you recommend? I might as well buy one, since I plan on having the truck (or a different 7.3) for a long time.

I am leaning towards a scangauge since they seem to monitor a ton of useful stuff, I would like the MPG readout as well. I have read they will do a buzz test and pull codes on our trucks, is this true?
Reply With Quote Quick reply to this message
  #5  
Old 03-01-2014, 07:53 AM
Compression Ignition Addict
 

Join Date: Feb 2008
Posts: 748
Thanks: 2
Thanked 4 Times in 4 Posts
Feedback Score: 0 reviews
I'm not sure on the Scangauge. I know guys used to like the Snap On "red brick" scanner as they're now cheap and do the tests on these trucks. I have a Matco Proscan and it works great.

Before going to far I would inspect all UVCH's for burnt connections. On a few I've done I've always pulled the oil cap and taken a smell, you can usually smell the burnt connection before pulling the valve covers. If they are OK check the engine wiring harness to the plug on the driverside inner fender. I've seen pins pull out of the connector there. If that's OK, get the scanner and buzz test the injectors. If they're coming back OK you get to dig a little farther.

Once you determine what cylinder(s) is giving you an issue you can take proper action with a compression test, swap injector between cylinders to see if the issue follows the injector etc etc.

These engines aren't that hard to work on and usually require just a little patience to work under the hood. There is many how to's on here that cover the basics.
Reply With Quote Quick reply to this message
  #6  
Old 03-01-2014, 08:03 AM
Member
 

Join Date: Feb 2014
Posts: 61
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
Ok I got around to pulling the intake and testing all the injector circuits. All tested right at 3.5 ohms on the drivers side, and the front three tested 3.5 on the passenger side.

The rear cylinder on the passenger side is showing 4.5-5 ohms every time I test it, so I hope I found the problem. Off to pull the valve cover, looks fairily easy.
Reply With Quote Quick reply to this message
  #7  
Old 03-01-2014, 08:05 AM
Compression Ignition Addict
 

Join Date: Feb 2008
Posts: 748
Thanks: 2
Thanked 4 Times in 4 Posts
Feedback Score: 0 reviews
Good, glad you found it easily.
Reply With Quote Quick reply to this message
  #8  
Old 03-01-2014, 09:30 AM
Member
 

Join Date: Feb 2014
Posts: 61
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
Got the valve cover off, there isn't really any obvious damage to the harness.

It has a LITTLE bit of melting on the plug to the rear glow plug, I guess I'll replace it anyway. It runs fine with the cover off, unplug that injector and it runs like it does warm.
Reply With Quote Quick reply to this message
  #9  
Old 03-01-2014, 11:16 AM
Member
 

Join Date: Feb 2014
Posts: 61
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
Ok, replaced the gasket and wiring harness on that side. Took it for a test drive, did the same thing. It ran great until it got warm, then back to running on 7 cylinders.

The injector resistance was right when I tested it with the new harness, 3.5 ohms at every injector.

Its the number 7 cylinder that is giving fits, 90% sure. Can I just swap it with any injector?
Reply With Quote Quick reply to this message
  #10  
Old 03-01-2014, 11:31 AM
Compression Ignition Addict
 

Join Date: Feb 2008
Posts: 748
Thanks: 2
Thanked 4 Times in 4 Posts
Feedback Score: 0 reviews
Did you replace the pigtail on the valley side? You can switch the injector with any other one, however I would get a couple of new O ring sets for the switch. If you don't want to switch them, do a compression test after its warm and see what you get. I was in ORielly auto parts the other day and they rent the diesel compression tester.
Reply With Quote Quick reply to this message
The Following User Says Thank You to rolsmojave3 For This Useful Post:
jlee9541 (03-05-2014)
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Ford Powerstroke Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may 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 On
Pingbacks are On
Refbacks are On



All times are GMT -8. The time now is 06:49 PM.


Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.1
Garage Plus, Vendor Tools vBulletin Plugins by Drive Thru Online, Inc.

vB.Sponsors