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Discussion Starter · #1 ·
I'm usually pretty well "in tune" with how my vehicles are running. Over the last few weeks, my truck feels as if it's losing power. For the last couple of days, it has developed a bit of an erratic idle (a small stumble every few seconds). No real loss of boost, and no discernable change in smoke, but the truck just seems to be less responsive - especially at lower RPMs and lower throttle input. It's taking longer to build boost also. Today I noticed that it is running quieter than normal as well (not a bad thing, but I'd like to know why). I've been running the gray CPS from Ford for about 2 years. I did have a small leak in the up-pipes (waiting for my new shop to get finished, so I have a place to fix that), but today I can't hear that leak anymore.

Any ideas?
 

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Discussion Starter · #2 ·
OK - I took the truck for a long drive tonight to my daughters track meet (about 150 miles). I noticed some other things. In my highest chip setting (TW "street/race") it has noticeably less smoke. My mileage is also down by about 3mpg on the highway. The rough idle is happening in all chip settings. On the stock setting, it feels laggy on the bottom end and slow to build boost, but seems to make somewhat normal power once it spools up. On the heavy tow setting the pedal is much snappier and seems to run much as it always has - with a little less power. In the daily driver program the pedal is very laggy and slow to build boost. Once it spools up it has less power than it used to. In the street/race setting, it spools up fairly quick, but smokes less and had less power than before. The oil is rotella and was changed along with the fuel filter about 1000 miles ago. Sorry about these long posts from a "newb", I'm just hoping for a little help. I've been reading this site and the "other one" since I bought this truck 8 years ago.

Thanks fir any ideas you guys can offer
 

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Discussion Starter · #4 ·
Kind of like a miss, or a stumble. Hard to describe but the idle just doesn't sound smooth like it used to. Every couple of seconds it does this, and you can feel the cab shake when it does it.
 

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Sounds like it might be a boost leak. Are you getting a CEL.
 

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Discussion Starter · #6 ·
No CEL. The only CEL I ever get is in my heavy tow program when I'm really getting on it. Tony says my HPOP can't keep up with what he programmed in there, and I need to have him adjust it.

I checked all of the connections to the intercooler and turbo last night, and couldn't find any leaks. Can't hear leaks, and it still builds to the same boost numbers as it used to, just takes a while for the turbo to light off.
 

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How is fuel pressure? And it could be an up pipe leak. Look for soot on the firewall, behind and below the turbo.
 

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Discussion Starter · #8 ·
I don't have a gauge to check the fuel pressure. I'll check the firewall for soot tonight. I looked at both of the up pipe connections to the turbo last night with a flashlight, and couldn't see any soot.
 

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How long has it been since you changed the fuel filter?
 

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Discussion Starter · #10 ·
1000 miles - just about 3 weeks ago.
 

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How dirty was it then. Might want to pop the cover and have a look at it. Also might see if there is someone close by that can check fuel pressure. Where are you located.
 

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Discussion Starter · #12 ·
Wasn't too bad - no worse than any other time I've changed it. What should I be looking for if I pull it back out to inspect?

I'm near Portland, Oregon
 

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Crud in the filter.

Reason I am mentioning fuel pressure. The PCM does not monitor fuel at all. It just calls for it and assumes the truck is delivering it. A quick, down and dirty test. Get a hose that will attach to the bowl drain line. Stick it in a gallon jug. Open the fuel drain valve. Turn on the key. It should pump a quart in fifteen seconds.
 
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