New 1996 CCLB 3500 454. Help set my expectations on power or is there a problem

[brycebba]

Im new here and I just found a truck I have been looking for for quite a while. 1996 GMC Sierra 3500 Crew Cab Long Bed with 63k original miles and a 454 auto 4L80e. When I bought it I did a partial tune up including plugs, wires, fuel filter, pcv valve, MAF cleaning, EGR valve cleaning, bank 1 pre cat o2 sensor, new magnaflow XL, and a K&N filter which I am replacing after reading articles on here. I have driven diesels for the last 8 years and my current one I am selling is a 03 Cummins with 500rwhp and close to 1000ft lbs of torque, needless to say it is insane in comparison but I am sick of expensive repairs and everything being so tight and impossible to work on easily. I am happy to slow things down and move to my new 454 but because the change is so drastic in power I want some opinions on whether or not this acceleration seems normal for an auto 7.4 with 4.10 gears and 285 tires because to me it seems a little weak. I hammer hard on the throttle and it kicks down, at that point im full throttle till I let off. Other than a stumble at idle it doesn't have any obvious problems that I can see. My wifes 5.7 99 Yukon seems to be much faster but I know that doesn't mean mine is lacking power or anything necessarily

http://youtu.be/HNBNIA75c5U

I can shoot other videos or whatever, just let me know what may help.

 

[someotherguy]

How did the plugs look? At 63K they should have been fine; the factory platinums tend to last 100K in these engines.

What specific plugs did you replace with?

Have you checked fuel pressure? Spec is a little lower on the big blocks than small blocks, if you've got at least 55psi you're good - the big blocks will start and run on seriously low pressure, unlike the small blocks.

285 tires meaning.. 285/??/?? ? What specific size?

Richard

 

[brycebba]

Thanks for the reply Richard! They were mostly lighter tan which obviously could mean a lean mixture. They smelled pretty rank though like old stale fuel and the filter did too but I have run probably 10 tanks through with no change so I think it must just be age and not recent bad fuel. I replaced them with the NGK G-Power 3403 plugs and I read on here to reduce the gap from 60 to 45 so I did that. I plan on checking fuel pressure tomorrow so I can get you some numbers then. Sorry about the tire size, they are BFG All Terrain 285 75 16s

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[Blaine Davies]

How did the plugs look? At 63K they should have been fine; the factory platinums tend to last 100K in these engines.

What specific plugs did you replace with?

Have you checked fuel pressure? Spec is a little lower on the big blocks than small blocks, if you've got at least 55psi you're good - the big blocks will start and run on seriously low pressure, unlike the small blocks.

285 tires meaning.. 285/??/?? ? What specific size?

Richard

I agree, I wouldn't bother with anything other than ACDelco plugs, these trucks don't like anything else. Kind of an un-written rule with GMT's of any body style is when you're replacing factory parts and accessories stick to ACDelco parts, it's what GM used from the factory.

 

[brycebba]

Yeah with what I have read I seem to have jumped the gun on those plugs and will order the correct ones.

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[Blaine Davies]

Thanks for the reply Richard! They were mostly lighter tan which obviously could mean a lean mixture. They smelled pretty rank though like old stale fuel and the filter did too but I have run probably 10 tanks through with no change so I think it must just be age and not recent bad fuel. I replaced them with the NGK G-Power 3403 plugs and I read on here to reduce the gap from 60 to 45 so I did that. I plan on checking fuel pressure tomorrow so I can get you some numbers then. Sorry about the tire size, they are BFG All Terrain 285 75 16s

Sent from my SPH-L720 using Tapatalk

Have you seafoamed it yet? that stuff works wonders, and it's like $12 at any auto parts store. Worth it to try it out if you havn't yet. I would have a set of new plugs on hand to replace right after though. ACDelco Part number : ( 1 )

 

[brycebba]

I forgot to mention that. I did seafoam it prior to changing the filter and plugs and I didnt really notice any change in this case. I have used it in the past on other vehicles and it worked well on them. Looks like it just turned your part number into a frown. Is the 41-932

 

[Blaine Davies]

I forgot to mention that. I did seafoam it prior to changing the filter and plugs and I didnt really notice any change in this case. I have used it in the past on other vehicles and it worked well on them. Looks like it just turned your part number into a frown. Is the 41-932

hahaha! yeah I just noticed that! the part number that my parts guy gave me for my ACDelco plugs was simply just " 1 " lol pretty easy to remember! idk if its different from a 350 to a 454 though, hmm.. seafoamed, plugs done, wires, etc.. let me think and get back to you on that. now it's going to bug me too! when you cleaned the EGR out was there a fair amount of carbon built up in the intake?? i'm assuming you checked the EGR Valve to see it if's sticking and what not? Is it still burning a little lean? only thing that I could think of would be possibly a coolant temp sensor, maybe a MAP sensor? I'll ask a buddy of mine who has a 454 and see if he's experienced anything similar. get back to you in a little bit.

 

[brycebba]

cool thanks man! There was a fair amount of carbon that I could see though it was kind of dark so I cant say for sure. The EGR valve was black but the valve itself didnt seem to stick or anything when I moved the little piston in and out. I will try to get those plugs tonight or maybe tomorrow and then I can see what the coloring is on the current plugs.

 

[someotherguy]

AC Delco 41-933 are the current regular platinum plugs for these engines.

AC Delco "1" plugs are the RapidFire "upgrade" plug for TBI engines. If you wanted RapidFire for a Vortec then it's "12" but personally I'd stick with the regular platinum 41-933; they work great forever.

You need to check fuel pressure...it's easy.

Richard