Holty

iTrader: (6)

Has anyone ever had problems with misfires and/or backfires and actually found that they have a broken or weak valve spring?

I've been doing some searching, i can't find anyone that actually had a problem, that was acutally resolved by replacing a bad/broken valve spring that didn't cause catastrophic engine damage.

LS motors only , please.

mhotrodscooter

iTrader: (13)

I'm sure anything is possible. I'd try & compression test & leak down test. Could be a burnt valve.
Is it throwing any codes?

slow67

iTrader: (2)

When I had a broken valvespring, it would barely idle it was misfiring so bad. It seemed to clear up a little above idle.

grey matter 04

iTrader: (9)

do a compression test to locate what cylinder has the issue look at valve spring see if its broke, If not broke swap springs to another cylinder retest to see if problem moved cylinder or still exist
If it still exists on original cylinder you have a valve issue or if it has moved the spring maybe weak not closing the valve completely

dirt track racer 81

iTrader: (45)

Pull valve covers do a visual. Pull the plugs and compare all of them to each other, if one looks different than the others start your compression test there.

Holty

iTrader: (6)

sorry guys, i don't mean to be a jerk but you are not answering my questions. I'm not asking for help troubleshooting just if anyone has actually found that they had a misfire or backfire issue that was actually caused by a bad or weak valve spring.

i've already done all that stuff.

https://www.performancetrucks.net/fo...opping-481263/

grey matter 04

iTrader: (9)

yes i have had a random missfire code cause by a broken valve spring

Jokeman

iTrader: (4)

Same here.

I did get a random pop like a backfire, it always occured after a cold start and if I hopped on the gas before the truck warmed up. Now that I read this thread, I dont remember the truck doing it now that I changed the broken valve spring. I always attributed it to being a little rich at idle and the wideband heating up.

budhayes3

iTrader: (19)

You said LS only, but I've had a weak valvespring on a small block Chevy that caused the engine to miss, especially under load. (different engine design, but same mechanical concept). It was a frickin' nightmare to diagnose too...I did pretty much what you did, eliminated absolutely everything else until the valvesprings were all that was left...

DrX

iTrader: (7)

Here's another: Bad Misfire and Dieseling Upon Shutdown after Driving in the Rain