Couple issues

[Criscone]

Ive had this issue for awhile now, i thought it was a minor exhaust leak. After the tune it became a LOT louder. It sounded like a diesel truck under load/lower RPMs (i think into the upper RPMs also but not 100% on that). So i did the following as told per AmericanMuscle(called blaming it on the tune/timing):

Replaced fuel filter
1 step colder plugs - autolite 103
checked all connections
swapped coils around
replaced gas with new gas, thinking maybe i got a bad batch of 93

Still had the issue, so i removed the tune. It went back to the way it was, a faint 'exhaust' leak aka just a more quiet version of it with the tune. I gapped the plugs at factory spec, is this normal for a colder plug? I was going to swap out for factory plugs/gapped to spec this weekend. Just dont want to waste the time if its not a possibility. Thanks!

 

[Race_Red_5Oh]

If you can get a sound clip or something cause exhaust sounds are different from fuel related issues usually. Any additional info would help

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[Criscone]

Its only under load it seems. Won't do it if I rev it in any gear. Can there be exhaust leaks only under load? I've never heard of it, but maybe? It's just weird that with the tune in its 10x louder and much more noticeable.

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[Criscone]

I'll try and get a video leaving work today.

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[MaximumRisk]

from the description sounds like an exhaust leak coming from the headers (that diesel truck sound you mention USUALLY happen when you blow a header gasket or when you warp a header) so check around the exhaust manifold first, look for carbon deposits around them, then re-check the rest of the exhaust.
This is just a guess based on your description, a video would help.
By the way, why did you go to colder plugs? what type of power adder are you running? how much boost or how big of a nitrous shot are you running?

 

[Criscone]

Nitrous is here just not installed. 75-125 shot capable. However like I said never installed yet, American muscle are the ones who said to run a colder plug and new fuel filter. Which did nothing. I know to run colder with my zex kit but like I said its still in the box..... And I never mentioned it to them. So idk, I just did as I was told. He seemed very knowledgable.

How bad are the header gaskets to do? I know headers you have to pull k member an all that, hopefully that's not the case for 2 measly gaskets.

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[FrostByte]

Sound to me like detionation possibly. ?? An exhaust leak should not change much w/ tune. Get us a vid or sound clip if possible.
GL

 

[roush360r]

well if your car sounds like a diesel then you need a motor. if its an exhaust leak thats worse under load and you drive it in the winter its pry a cracked exhaust manifold or broken studs. it could be detenation but i doubt itd be doing that on a factory tune unless you got some very very bad gas. esp since the factory tune is just for 87. leaking manifolds will make a ticking noise.

 

[Criscone]

im going to do a pair of header gaskets, buddies truck makes same noise but 100x worse and mainly under load. He said it was header gaskets on his 454. Any tips to doing just the gaskets? can i get away without removing K member like when doing longtubes?

 

[roush360r]

the factory gaskets generally dont go bad for no reason, ford uses metal gaskets. its pry a warped manifold with broken studs or a cracked manifold. you shouldnt need to remove the k member. thats just so you have room to fit long tubes in.