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2004 Mustang GT Knocks when starts up sometimes?

2340 Views 13 Replies 6 Participants Last post by  justin73, 
Johns90GT
04 Mustang GT Knocks when starts up sometimes?

Every now and then (about half the time) when I start my car I get a loud knocking sound that goes away quickly but is loud enough for people to ask me "what was that?" I don't know what to say so I always reply with.. I don't know, but everything works :)

I'd just like that know what it is and if it's common and how to get rid of it, if that's possible.

Thanks.
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1
check your timeing
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Johns90GT
How do I check on a mod motor? And aren't they pretty dead on with their timing?
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1
have u done any mods or messed with the cpu at all even if yea it is newer mustang i have an obd1 i dont know much about the obd2's if the cpu was mess with like u got the vehicle chiped u could have done something wrong
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Johns90GT
I've only done cold air intake and flowmaster and offroad xpipe. It did it when I bought it from the dealership though when it was 100% stock.
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1
id just take it to a auto parts store with maintenance bay and have them run a diagnostic on it sry i couldent help
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Johns90GT
About 50% of the time I get a loud knock that sounds like it's coming from the engine when starting up, cold or warm. Just trying to figure out what it is and if it's bad or not and how I can fix it if that's possible. I posted this question in the other Tech. section before I found this one specific to 4.6l motors.
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Johns90GT
Anyone else know what this could be?
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joker1999
sound like the wrist pins start running 50w kendall racing oil u can get from auto store and put a bottle of lucas oil in it 4 qts and 1 lucas this is VG STUFF IT WORKS! GOOD LUCK.
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Johns90GT
wrist pins? why would they be making a knocking noise? the car only has 48k miles on it.
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P
i was thinking along the lines of fuel grade maybe?

I know if i run 87 in mine, it'll knock at start up for a few seconds but goes away shortly after..

what fuel grade are you running?
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Johns90GT
I run 93 octane all the time. I've heard of this before on other vehicles and goes away once the knock sensor corrects it but that's on every start.
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A
I had a very odd problem with my 02 doing the same thing. It was not very often and I was told it was wrist pins. It was too inconsistent to be wrist pins. I started using Lucas Oil Aditive for Synthetic and always had 7qts (6qt of 5w20 and 1qt Lucas) of oil in the pan.
The noise just stopped (not immediately but after a couple of months after I started using Lucas) and never did it again with no explaination. The only other thing I could think that could be the issue is a sticking valve on startup possible from excessive carbon. I would recommend a Sea Foam intake fogging and addative for your fuel. A combination of all 3 of these will at least help lubricate the top end well.
As I always state, I am no expert just giving an opinion.

AJ
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J
My o4 gt does the same thing the problem is the oil filter needs changed i use motorcraft oil filter after i change that that solves my knocking problem until the filter gets dirty again
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