SD 5.0 not running just right after startup. - MustangForums.com


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Old 07-21-2008, 08:22 AM   #1  
DJ19895.0
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Default SD 5.0 not running just right after startup. O2's Fixed it!

For as long as I can remember, my car just does not run 100% about 5 mins or less after startup, but lately it has become a little worse. The problem is that it kind of stumbles and runs rough for about 2-5 mins after startup. It does not matter what the coolant temp is either. If you bring it above about 3k rpms, it seems to be fine. After 5 mins of running though, it runs perfect. Here is a list of new related parts in the last about 10k miles: fuel pump, fuel filter, used ford fuel injectors with about 30k on them (4 port kind if I remember correctly), autolite spark plugs gapped, distrubuter cap and rotor, cleaned air filter (k&n), pypes o/r x pipe, and one o2 (broke one on the x-pipe install). It has red ford motorsport spark plug wires, msd distrubuter, msd 6al box, and msd blaster coil. My only guess is running one new o2 and one old o2, or maybe there is something wrong with the open-loop.
Thanks again!!

Edit: The wires are red ford motorsport wires, not msd wires, they checked out fine on the ohm-meter. I also forgot I cleaned and re-greased the injector wiring harness also. I asked a mechanic and he said that maybe it is getting too much fuel when it runs bad and I should check the ecu for any chips the previous owner may have put in.

Last edited by DJ19895.0; 08-26-2008 at 09:36 AM. Reason: Problem Solved, thanks.
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Old 07-28-2008, 07:55 PM   #2  
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Default RE: SD 5.0 not running just right after startup.

Anyone?
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Old 08-03-2008, 12:31 PM   #3  
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Default RE: SD 5.0 not running just right after startup.

Do you still run your air pump? It tricks the engineto run rich when it pumps thru the exhaust at start up. The O2 sensors sense more oxygen and will run rich.
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Old 08-03-2008, 08:46 PM   #4  
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Default RE: SD 5.0 not running just right after startup.

I did remove the air line that went to the exhaust when I put in the x pipe. Everything else is still there.
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Old 08-03-2008, 08:50 PM   #5  
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Default RE: SD 5.0 not running just right after startup.

Probably running too lean then till it warms up. If you can live with it leave it alone otherwise you have got to get the air divertedto the O2 sensorsduring the warm up time.

Hey did you notice a difference with the x-pipes? Would you recommend the Pypes brand? Is it a lot louder? How was installation?...difficult?
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Old 08-03-2008, 09:18 PM   #6  
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Default RE: SD 5.0 not running just right after startup.

Thanks for the advice, but the air goes into the system well after the o2's, so I find that hard to believe that that would make any difference. As far as the pypes x-pipe goes, It sounds better but not much louder than my stock h with punched cats. The install was fine, but you will need to fab up your own brackets to hang it. No power difference noticed.
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Old 08-03-2008, 09:42 PM   #7  
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Default RE: SD 5.0 not running just right after startup.

Good point, I haven't crawled under there in a while...sorry, I should have looked before my quick reply. If the air pump is still hooked up (upstream of thesensors)you have got me baffled then.

Thanks for the info about the Pypes. Nice paint job!
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Old 08-05-2008, 06:33 AM   #8  
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Default RE: SD 5.0 not running just right after startup.

Ok, so I am trying to pay close attention to the problem and have figured out that the problem does not occour every drive and it will go away if you floor it while it is running bad. This tells me that maybe it is running rich when it happens, and giving it more air cancels out the problem? Still don't know what it could be...
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Old 08-05-2008, 08:44 PM   #9  
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Default RE: SD 5.0 not running just right after startup.

That tells me it is an oxygen sensor problem. I had an identical problem that went away when I would floor it and would keep coming back quicker and quicker each time. It will probably get worse again. I replaced an O2 sensor and the problem went away. Try replacing that old one you were originally talking about being the culprit.
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Old 08-06-2008, 07:06 AM   #10  
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Default RE: SD 5.0 not running just right after startup.

Yea, origionally when I went to buy the o2 that I broke, I thought I would buy them both with the $60 I had in my wallet at the time. I was a bit surprised when I found out they were $45 each. Anyway, i'll replace the other one in a few days and tell you what happens. Thanks again!
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