Ok my truck has a new noise now, whopeeee NOT!!!!!! I ran some fuel injector through my truck today, helped i guess but something inside the engine didn't agree with it. I ran some cyclo fuel injector cleaner through it(yea I know cheap sh--) It makes this noise when you just first acclerate from a deap stop and when your acclerating hard but not floorin it. I understand the fact that it's hard to tell w/o actually driving the truck but any advice is very appreciated.


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1991 FORD F-150 XLT LARIAT
4.9 L 6
4X2
EFI
GLASSPACK EXHAUST W/ STOCK CONVERTERS
2 1/4" BALL HITCH
DARK SANDSTONE/LIGHT TAN
FIBERGLASS CAP
265/75/15 TIRES(TOO BIG)
CAST ALUMINUM RIMS W/ BEADLOCKS
3.08 REAR AXLE???



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FUTURE MODS:
PERFORMANCE AIRRAID SYTEM
ELECTRIC FLEX A LITES
HIGH FLOW CATS W/ FLOWMASTERS
AMSOIL BY-PASS SYSTEM
BIGGER INJECTORS( P.S.I NOT SURE SIZE YET)
WHITE LETTERED TIRES





F-150_91

 

any chance it could be the cat?

 

Please post here when you find out what that noise is. My 2000 Lightning has done that exact same thing since day 1. The dealer can reproduce it but since they can't find a tech bulletin on it they said I have to live with it. Grrrr. It works exactly like your sound. Part throttle, no noise, WOT no noise, 1/2 throttle just before it shifts I get this rattle like noise from what sounds like the engine compartment. I would give anything to find out what causes that noise. I have posted before and it seems like no one has had a similar noise .

 

Ping maybe?

 

I would rev the truck while you are under the hood, listen to the injectors. See if you get the noise from them.

 

JA4x4 what makes you thinkn it's the cat? I'm not mad or nuthin just sayin Ive never heard of of a cat rattling while driving. I just hope it's not something like a bearing or something going out

 

Could it be a abnormally noises PCV valve. I can hear mine rattle like hell sometimes while at idle with hood up. You can also hear it if yo uslightly blip the throttle while under the hood. I was able to really listen to the PCV vlave and the injectors by using a cheap stephescope that we had hear. You can buy the mechanic type that has long rod to it to reach more places.
Also check all your drivebelts and pullies. A loose pulley/bearing or fan clutch can create rattles.

 

how do you know its not a lifter? does it sound similar to a noisy lifter? it could be a loose rocker arm or bent pushrod. just some ideas, good luck!