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Ask Dodgerench Your Own Question
Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3404
Experience:  30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
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Ram 1500: 03 dodge 1500 5.7 hemie bad miss no codes what could

Customer Question

03 dodge 1500 5.7 hemie bad miss no codes what could be the problem?
Submitted: 2 years ago.
Category: Dodge
Expert:  Dodgerench replied 2 years ago.
Hi, my name is Ed. Welcome to JustAnswer!. Does it feel like a single cylinder miss? A rhythmic vibration that happens at all engine speeds?Or is it a general (ever all) rattiness that makes the engine feel weak and sick at all times? Does performance improve somewhat as you go deeper into the throttle?Did this happen all at once? Good then.... but not so much the next second? Give these questions a thought and let me know what you think. Talk in a bit,Ed
Customer: replied 2 years ago.
Yes a single cylinder miss,yes it does improve deeper into the throttle you go,yes all at once it happened fine then this began if I keep the engine over 2000 rims it runs ok under that it wants to stall
Expert:  Dodgerench replied 2 years ago.
Thanks. The degree of misfire I'm thinking of can vary, depending on the actual severity of the failure.... but I'm thinking you have a broken valve spring.While a broken valve spring can happen to any engine at any time, the 2003 Hemi seems to have more than its share of that sort of thing. When it happens, the affected valve can't return to a seated/ sealed position with the engine running and it allows engine exhaust to be pulled back through the affected cylinder and into the intake manifold, where it pollutes the intake charge of other cylinders as well. The act of going deeper into the throttle decreases intake vacuum, which reduces the pressure disparity between intake and exhaust, reducing the transfer of oxygen-poor gases back to the intake side of the engine. Your performance... although still reduced... will seem less awful with more throttle with a broken spring.
Expert:  Dodgerench replied 2 years ago.
Finding the spring is a bit of an egg hunt, unfortunately. The OBD-2 Misfire Monitor is ill-equipped to find something that affects multiple cylinders, so you're faced with a choice of pulling a valve cover for inspection... and there isn't a good way to predict which side will be the troublemaker.
Expert:  Dodgerench replied 2 years ago.
I'm expecting that you will get off easy with this one, since your performance isn't horribly affected. A broken spring usually has enough rebound to it that it keeps the valve from being hit by the piston and even enough closing force to evade a compression check. The valve may close completely to show good compression at cranking speeds of 300 RPM, but fall apart quickly at 700 RPM with the engine running. If this is the case... GOOD! A valve certainly hasn't been bent and you can change the spring, no cylinder head removal is needed.
Expert:  Dodgerench replied 2 years ago.
With the work you've already done, I'm pretty confident that you'll find just this... a broken spring. There aren't many things beside the list of repairs you've already done that could cause these symptoms and (like I said) the 2003 Hemi does have more than its share of valve spring issues.