Have a 2001 Lightning. Having popping sound or similar to exhaust leak noise from engine compartment. It almost sounds like a popcorn machine when in upper gears on throttle at low speed or just excelerated. Any ideas of whats wrong? Also have back fire through exhaust when off throttle going down hill.

Curious for feedback.

Thanks

 

i wanna say vavle spring but with this motors plug issues i'd say give your truck a quick check of the all the spark plugs and see how snug they are.

 

Possibly pinging/detonation. Be careful.

What mods? Tuning?

 

slvrprple

Do not continue to drive your truck or run your engine until you check all your sparkplugs for tightness!!!!!!!!

Here is something I copy and pasted long ago. check the archives for other info and pictures. This forum has tons of info.

How do you like that truck and living on the island. To bad gas isn't a little cheaper for you. Last summer I was there paying $2.40 for the cheapo regular.

Good luck. Plan on a few hours the first time.


Spark Plug changing tips from Chuck - aka ltnbolt on www.nloc.org

The first thing you need to know is where the release for the wire connector to the coil pack is. It is on the bottom in the middle back next to the wires. You push up on it.
Tools needed are: 3/8" ratchet with (2) 6" extensions, (2) 3" extensions and 5/8" sparkplug socket. 1/4" ratchet with (2) 2" extensions, (1) 4" extension and 7mm socket.
1/4" small breaker bar (I call it that) this tool will make life easy on the third 7mm bolt back on drivers side because a regulator sticks out off of the fuel rail making it a tight fit.
You do not have to take fuel rails or power steering tank brackets off to do this job.
Disconnect the wire to the coil pack then remove the 7mm bolt and twist coil back and forth. The coil should come right out with a long rubber boot on the end. After you get it out wipe any dirt off with a rag so it won't fall back in the hole going back in. If you have air blow any grit out of the hole before removing plug.
The 3/8" ratchet,(2) 6" extensions and socket do most of the plugs. The passenger side 4th plug takes a 3" extension in the plug socket to make it in the hole because of a metal hose.
On the drivers side the first plug takes all of your 1/4" drive extensions to be able to get to the 7mm bolt because of a bracket. This bracket is also over the plug hole. Now just use your 3" extension on the plug socket and slip it in the hole from the front of the truck. Then put put another 3" on it and take it out no problem. It helps to unplug the hard plastic hose from the rubber intake boot for more room.
The only other problem is the 7mm bolt on the 3rd plug back on the drivers side. It's too tight to even use a swivel above the socket. This was after going to three stores to find one. I had to finally crank it over at a 90 degree angle and use it like a breaker bar.
This is why I suggest you get one of those little breaker bars on the front end and you'll have no trouble. By knowing the tools you need on the front end and knowing when to use them this should be a 2 hour or less job.
It was a 5 hr. job for me between borrowing extensions twice, going on my shopping spree for a swivel and wrestling with that 7mm bolt.
Tips: Put antiseize on your plugs, start your 7mm bolt by hand and your plugs before putting a ratchet on then. You don't want to cross thread that aluminum.

 

Check your plugs as others have said.

Engine Backfires:

1. EGR system not functioning properly
2. Ignition timing incorrect
3. Vacuum leak at the intake manifold or vacuum hoses

Dan

 

Only Mods - glass pack exhaust, jet chip, volant intake

 

You may have poped off a roller rocker if one is off of a exhaust valve it will pop when the intake opens on that cyl. I have seen 5.4's do this. do you have a miss?

 

Pull the chip and let us know if it still makes the noise.

If that gets rid of the problem, it shows it is a poorlly tuned chip.

I bet thats the problem

There have been a lot of engine failures due to a Jet chip.

call one of the supporting venders here and get a real chip.

 

Ditch the Chip. My friend put one in his 99 and it was worse than stock

 

I GUARAN-DAMN-TEE you that you have a sparkplug that has come loose, and is preparing to exit stage left!!!

As was stated above....STOP DRIVING YOUR TRUCK NOW!!! and CHECK YOUR PLUGS IMMEDIATELY!!!

The couple hours time and few scraped knuckles you may get will be worth your while, especially if it prevents you from having to replace or repair a cylinder head (which can be very costly in terms of convenience or expense)...especially if the truck is not still covered under warranty!

Goodluck,
Rob