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Won't rev past 4k

clubracergt1

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This may have been addressed here before, but a search did not find what I was looking for.

I recently picked up a 2003 Edge with a 3.0 and 5 speed. I don't really beat on the truck, but I have found that it won't pull past 4,000 rpm. Actually, it's like the truck is hitting a brick wall. It is far more violent than a rev limiter; and, anyway, IIRC-the limiter is far higher than that. It also seems like it's slightly down on power. Unfortunately, I don't have much to compare it too since I am driving a big truck (18 wheeler, semi, tractor-trailer, rig) 6 days a week. Everything underhood looks fairly new; but it was detailed prior to purchase, so even old parts can look new. I was thinking about throwing a coil on it to see what happens, but was wondering if anyone else had this problem before and what did you do to cure it.

Thanks in advance.
 


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RonD

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Rev Limiter is usually set at 3,000 RPMs
This is tied to clutch pedal or Park/Neutral switch and speedometer, under 5MPH or if clutch is in or automatic trans is in Park/Neutral, Rev Limiter is active.

Could be partially blocked exhaust.
It effects higher RPMs first, loss of power and limited RPMs is the symptom.
This is like a wall, exhaust gases can't easily exit cylinder so new fuel/air mix can't come in.
Put hand over tail pipe while someone revs the engine.
Vacuum gauge can be used to test for blockage.

By-product of burning gasoline(H) with air(O) is water(H2O), this is why exhaust systems rust from the inside out.
Mufflers and Cats collapse internally from this rusting causing partial blockages, while not strictly foolproof you can bang on these and listen for rattling of loose pieces inside.


Other issue could be fuel filter, fuel use is higher under load and as RPMs increase, generally you would get bucking and missing at higher RPMs as fuel pressure/flow dropped because of clogged filter, so less like a wall but still a marked point at which it started to occur, and that point would get lower in the RPM range as time went by.
For $10 it is just easier to replace this than test if it is the problem.
A fuel pressure test won't ID this problem unless done while driving, because it is a volume issue not strictly a pressure issue.
 
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clubracergt1

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2003
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Manual
Thanks, Ron. I'll definitely give this a shot first. I also noticed (I just went for a quick ride) that this only seems to happen at high throttle input and in the higher gears. Just for grins, I lightly accelerated through 4k in first gear and had no issue. Fuel delivery could be a very likely culprit.

I appreciate your input, especially since I no longer work in dealership service departments (was a writer and manager for 13+ years) and I no longer have access to all of the fancy test equipment.
 

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