Runs rough till it warms up - any ideas? - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 13 (permalink) Old 11-09-2011, 07:18 PM Thread Starter
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Runs rough till it warms up - any ideas?

I have a 1997 (OBS) 7.3 turbo diesel. When I bought it, they previous owner said it had a chip (no idea which one) and a shift kit in the trans. I've added a 3" down pipe and the big intake. But the motor is basically stock.

Lately, it's starting to run rough for about the first 10mins after a cold start (cold for San Diego) It starts up fine, and doesn't smoke...just runs like its missing on one or two cylinders; then, when its warmed up, it runs perfect. From my research on here it could be maybe an injector is bad or they are all going out or it might just be the o-rings that shrink up overnight and expand to seal better when the truck heats up. Any ideas what that sounds like?

This started after I changed to oil using Rotella 15x40 I don't know if the previous owner was using full synth. But I'm going to use the synth. next oil change to see if it makes a difference.

Thanks for your help!

Greetings from the Humungus, Warrior of the Wasteland, the Ayatollah of Rock and Roll-a!
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post #2 of 13 (permalink) Old 11-09-2011, 07:20 PM
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Re: Runs rough till it warms up - any ideas?

check your GPR and glow plugs and valve cover harnesss if it where an injector it would not clear up prob a bad GP

Blue 2012 XLT SCLB 4X4 , 38,550 miles, 3:55's & 18's Camper and Tow packages. Edge insight, Airlift Wireless compressor & Air Bag set-up, Dieslesite filter.
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post #3 of 13 (permalink) Old 11-09-2011, 08:01 PM
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Re: Runs rough till it warms up - any ideas?

I have the same issue. If I leave it plugged it over night she starts and runs fine. What I have found so far is the driver side rear 2 injectors are not working when the truck is cold.
I can unplug there harness at the valve cover and no change. I will be replacing those valve cover harness soon to see if that helps.

My injectors have 300K on them. So I am thinking the electric part of the injector is to weak to trigger when the oil is cold and thick. Just a thought I am probably way off but thats where i am starting.

96 F350 long bed Crew. Rebuilt motor, down pipe and gauges so far.
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post #4 of 13 (permalink) Old 11-11-2011, 01:07 AM
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Re: Runs rough till it warms up - any ideas?

i had that problem with my 96. it was a couple injectors not firing. does it miss then go away like a switch was flipped? pull your valve covers off and start it cold. the injectors that dont have oil squirting out of the little aluminum spout are the ones not firing. someone
told me that it has to do with wear between the solenoid and a valve or something inside the injector that dont contact until they warm up and expand enough to touch. might be time to do all eight....if one or two are to that point them they all might be close.

97 f-350 4x4 sc 5 speed 4.10 afe, 4 inch exhaust, ts 6 pos. chip, 1.0 housing, smf, sd intercooler

84 F-250 RCLB 4x4 6.9 4SP factory turbo
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post #5 of 13 (permalink) Old 11-11-2011, 04:25 PM
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Re: Runs rough till it warms up - any ideas?

just solved a similar problem...Rosewood injectors....truck runs like a champ now!!

'95 F250 SC 7.3 auto 4x4 long box...Rosewood stage 1's tymar intake 3"DP...Dfuser AIC... 263,000 and runnin' strong!!
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post #6 of 13 (permalink) Old 11-11-2011, 10:09 PM Thread Starter
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Re: Runs rough till it warms up - any ideas?

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Originally Posted by mojoman View Post
just solved a similar problem...Rosewood injectors....truck runs like a champ now!!
Which ones did you get?

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post #7 of 13 (permalink) Old 11-11-2011, 10:38 PM
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Re: Runs rough till it warms up - any ideas?

Here's a few thoughts from things that I've learned over the years...

You can check the electrical side in the truck but the oil/fuel side is hard to check until the inj is on the flowbench.

-Verify good electrical to inj and solenoid ; solenoid pulls about 3.2 ohms resistance

-Pull the solenoid top off inj and check the armature plate for looseness and clearance. Must be tight and will have .002" or so clearance. The plate screw must be tight as it moves the poppet (shuttle) valve when the solenoid turns on/off. If the armature is loose, this will disable the inj even though it gets power. Tighten screw or replace the screw with a new torx head replacement. these take only a few in/lbs of torque. take care with removing the solenoid.

-Turn off an injector and watch it while the motor is running. If you see a little oil leak out the spout, the poppet valve leaks. ( This is hard to see.) If you see oil coming out the base of the inj where it enters the head, the oil oring is leaking-- both may show low ICP.

Down below; (these require inj removal and rebuild/replacement)
-Nozzle springs break in old injs and gives poor fuel delivery/spray
-Barrel /plungers score with poor quality fuel and age
-Internal orings wear out

Other stuff
-do a compression test. Old valves leak when cold and seal better when hot

2000 F250 CCSB-- GT4294R, 250/100s, Dahl/Fuelab, PHP, scan gauge, stock 17* pump

1994 F250 4x4 SC (sold)
1997 F250 CCSB 2wd (sold)
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post #8 of 13 (permalink) Old 11-13-2011, 03:45 PM
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Re: Runs rough till it warms up - any ideas?

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Originally Posted by Lord Humungus View Post
Which ones did you get?
I went with the total rebuild stage 1's...about $1330 shipping included...

'95 F250 SC 7.3 auto 4x4 long box...Rosewood stage 1's tymar intake 3"DP...Dfuser AIC... 263,000 and runnin' strong!!
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post #9 of 13 (permalink) Old 11-19-2013, 09:44 PM
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Re: Runs rough till it warms up - any ideas?

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Originally Posted by mojoman View Post
I went with the total rebuild stage 1's...about $1330 shipping included...
did that fix the issue? i am having the same issue
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post #10 of 13 (permalink) Old 11-20-2013, 01:53 AM
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Re: Runs rough till it warms up - any ideas?

Usually it's sticky poppets in the injectors. My 97 would drop an injector when cold, and it would come back when it was warmish, after I went heavy throttle.

If you've verified your valve cover gaskets and wiring is good, start the truck cold with the valve covers off. You'll see what injector isn't working because it won't pump out oil under the deflector. I put in a take out injector I got on Ebay and it runs great now.

Or...a stage 1 rebuild fixes it too.

2005 F350 6.0/5r110
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