Rattling/Backfire from Exhaust?
 

Wassup Ya'll,

Ever since I bought my FX4 Scab, I have noticed that when I rev the engine after starting, at around 3500 -4 4000 rpm's or so the truck makes this horrible rattling noise I am not sure but I think it is in the muffler/exhaust, I took it to get looked at the dealership and the service advisor told me there where no problems, low and behold when I get home I do my own test and it happened again.

I will probably take it back and get the same answer. Any suggestions or reccomendations on what the diagnosis is? That way I have something to argue, for all I know they probably didn't even look at it. The sound is more annoying than anything, it only happens after I start the engine, I never hear it during driving. Any help is greatly appreciated.

Thanks,

DJ ANIMALE

First of all, why do you rev the engine to 3-4K after starting? And if anyone on this board goes out to their truck cold and cranks it up and revs it to 3-4K, it will backfire and pop in the exhaust like a son of a b!tch. I don't know if you are talking about the same thing, but this "popping" or "backfiring", also kind of like a gurgling from the exhaust if you rev it after a cold start is due to the fact that the mixture is very rich and some of the unburnt fuel is igniting in the exhaust system, probably in the hot catalyst and exhaust manifold. If it isn't a backfire but only a rattle you hear, then I don't know what that is.

I hope your not revving your engine that high after just starting it especially cold. The fluids aren't even warm and the engine hasn't had enough time to properly distribute the oil.

Attention!! J-150 Come in J-150
 

Ok J-150, I have to admit that after what I said to you in RedRum05's post, I feel I might have been in error. Ok, I'm wrong. I'M WRONG J-150. I now understand. I'm sorry. Please forgive me. Will you forgive me? :angel:

Had a dynomax muffler that one of the inside baffle plates had broken loose, it would rattle at idle and when I revved her up. Check your muffler! :cool:

everytime i start my truck i let it warm up to a cool 196F, and then i drive off, but wait new cars dont really like to idle to warm up, so what he is doing is fine, theres is no load against the tranny, no harm no foul. but if he was reving that high in gear i wouldnt advise

I meant if he is revving his engine out of gear cold. Even in gear without it being warmed up enough to have the oil fully distributed is foolish. I saw a person I know test drive a new Mustang GT and floored it right out of the parking lot. It hadn't been running more then a minute. When he brought it back he tossed the keys to the salesman and got in his own vehicle and left. I wouldn't buy that mustang for half price now.

Always makes me wonder if that's why some of these new trucks have problems so early sometimes. I honestly went and test drove a used 05 Mustang just for that reason. I don't think it's right to tear up a new vehicle. Also, are there ignorant shaggers working at some lots that test the rpm limiter as soon as they turn the key? This is one of my paranoid reasons that I do all my own work on the truck.

Why are you revving the engine at all during startup; no need to the PCM sets the correct rpm for whatever climate your in.

Pretty much any new vehicle Ive been in where you rev the engine on a cold startup will pop, for a good example of the sound Im referring to go to magnaflows webpage and listen to the 05 GT they have on there, see if it sounds similar to your problem.

Thanks
 

Thanks for all your posts, I will see what happens after leaving it on for a few minutes. I have some automotive knowledge but am by no means a mechanic. As far as some of the more smart comments, I appreciate your insight but there is no need to try to make someone sound like a complete idiot.

I have read the way some people on here roast other members when they have an off the wall idea or a question that may sound silly or amatuer, I know this is a public forum where we are entitled to our own opinions, but we can be mature and mindful of others.

Thanks,

DJ ANIMALE

DJ ANIMALE

First are you revving your engine cold? Second if so why? You can start your truck and drive away cold but to rev it without the engine being under load puts undue stresses on it.
Third if anyone here or anywhere told you that its ok to rev up a cold engine then get away from them because they are complete and total idiots. Nobody in their right mind would dare rev up a completely cold engine and expect it to last more then a few hundred miles :fyi:

2005F150SC,

Thanks for your help, its appreciated.

:confused: What’s this about? Everyone who posted gave their opinion on the question you put forth. If you don’t want opinions don’t ask

I appreciate everyone's opinions and suggestions about what the problem is, that 's why I asked for them. But the thing that I was a little upset with was some of the smart comments that were posted. I guess I shouldn't have said anything about it, it's not that serious of an issue. I do appreciate everyone's help though.

Thanks,

DJ ANIMALE