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Old 06-05-2012, 09:55 PM
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94 f150 5.0 runs rough at low throttle

guys I'm new and have a question. I've looked through the forum but can't seem to find an answer so here goes. I just put a reman engine in my 94 f150. Engine runs good while acclerating but a little rough at cruise. I've pinpointed down to the EGR system but can't figure out what is happening. It seems that the EGR valve is staying open too long. I can unplug the valve and it runs fine. I've replaced the valve and the EGr solenoid but it still does it. You can slowly throttle up and the engine shakes like it's skipping but with the valve unplugged it revs up fine. Any ideas?
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Old 06-07-2012, 11:27 PM
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Excellent question! I wish I had an excellent answer for you. But......and I'm no expert by any means.....

This is what I have heard and understand about the EGR valve. The valve directs a small portion of exhaust gasses back into the inlet air charge and lowers the maximum temperature of the burning fuel. The valve then makes sure that the EGR system is off at idle, where it would lead to erratic and loping idle, as well as at full throttle, since adding exhaust gasses robs power from the engine. Therefore, maybe the valve is staying open??? Possibly the ECM is telling it to stay open? Have you checked your O2 sensors? Could there be a vacuum leak? Keep the EGR valve unplugged? I think I might be I'm shooting in the dark, but no one else has replied and didn't want you think we didn't care. If this doesn't help you, I hope you find the answer soon. These things can be a pain the butt. I wish you the best of luck!

If you figure it out...please let me know what the culprit was.
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Old 06-08-2012, 05:20 PM
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Thanks for the reply. It's an odd situation for sure. What happens is when you crack the throttle just above idle it seems that the engine is skipping. There is no check engine light. Once you start to rev it smooths out and runs fine. The problem is when you are cruising down the road that is about where the throttle ends up and causes that same skip feeling. It's almost like when you put a small amount of vacuum on the EGR at idle how it lugs the engine down. I will definitely let you know if I figure it out.
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  #4  
Old 06-10-2012, 12:00 AM
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Location: Houston,Tx
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try a search for egr to see if you can more info on site. Also check the dpfe valve on your egr system

Last edited by K.R.newbie; 06-10-2012 at 12:07 AM. Reason: more info
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  #5  
Old 08-18-2012, 08:39 PM
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I'm still muckin with this issue. With the EGR disconnected there is a slight vibration around 1500 RPM but when I connect the EGR it gets alot worse. I have looked for a vacuum leak but can't seem to find one. Any ideas? This is driving me crazy. It wasn't doing this before the engine change which makes me wonder if something was hooked up wrong.
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Old 08-18-2012, 08:39 PM


 
 
 
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