New, and need help!

[tjhooker66]

Did a search but couldn't find my problem...not sure if right thread or not but I recently bought a '94 Silverado 1500 5.7 tbi z71 5 speed, I believe it has the NV4500.
Here's my problem, truck runs fine. Idles fine starts up just fine doesn't run hot etc.
The thing has like ZERO low end power it will go down the road just fine, takes a bit to get up to speed but it's an old truck with maybe 200 hp when it was new. If there is any sort of incline at all it will rev up and you could red line it and struggle to go 35 mph, in 4th or 3rd. The guy I bought it from put new cap wires coil, not sure about plugs. Doesn't have factory air intake on it. It is high mileage but I'm not sure on the exact mileage. I've got air fuel and spark, not sure where to start looking next...
It's my $700 daily driver and don't have a ton of money to throw at it ( divorce, bankruptcy) first TBI motor I've ever had so don't know where to start...

 

[Oldblue98]

Cat converter plugged maybe !?

 

[tjhooker66]

I was doing some searching and that and the temp sensor came up, I will try the cat first when I get off work

 

[someotherguy]

When was the last time the fuel filter was changed?

Also, if you're curious as to which trans you have - the NV4500 is rare in a half ton though definitely was available; it has an L on the knob instead of 1 - it's a granny low gear first and you generally wouldn't use it unless starting out pulling a heavy load. The much more common light duty 5 speed (NV3500, 5LM60, etc. as well as other names depending on year) has a number 1 on the knob. The NV4500 also has rectangular bolt-on covers on either side that can be removed to attach a PTO; very distinct appearance: (1996 model pictured)

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Richard

 

[evilunclegrimace]

plugged cat and /or plugged fuel filter will most likely not let the engine rev to redline. I am more inclined to think that the clutch is slipping.

 

[tjhooker66]

I will give all of those a try, the only reason I was thinking NV4500 is if you take off in "1st" you can redline and go about 8 mph. The original shift knob wasn't on when I bought the truck.
Clutch seems good, the tranny does have some issues tho. I'm thinking synchros tho

 

[someotherguy]

Yeah 8mph in 1st does sound a little bit like NV4500 but it's easy to tell if you look underneath and see those covers on either side of the case. The only other trans you'd find in a GMT400 that has those is the SM465 granny low 4 speed that was available only for the first few years of GMT400's (and previous body styles.)

The NV4500 does suffer synchro (blocking ring) failures once they get some miles on them, but they also can suffer if people use the wrong lube. Too many "it'll be fine with (whatever brand)" posts out there that are bad information. The factory-installed carbon fiber blocking rings require use of the specified lube - GM Synthetic Manual Transmission Lubricant, part # 12346190 - or its Mopar equivalent. Other lubes you're taking an expensive risk. Now there are aftermarket parts that are just bronze and any appropriate lube for those can be used (check the GL spec for what is OK with "yellow metals") but only if you're sure you know what all is in your trans.

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Richard

 

[evilunclegrimace]

I will give all of those a try, the only reason I was thinking NV4500 is if you take off in "1st" you can redline and go about 8 mph. The original shift knob wasn't on when I bought the truck.
Clutch seems good, the tranny does have some issues tho. I'm thinking synchros tho

The synchros are only in play when you are changing gears once the tranny is in gear the synchros are just along for the ride, they cannot cause the engine to rev excessively

 

[tjhooker66]

It doesn't rev high on its own unless I'm trying to go up a hill but it's all pedal related.
But to go from 2nd to 3rd I have to--
Clutch in, shift to neutral, clutch out
Clutch in shift into 3rd.
To go from 4th to 3rd- clutch in shift to neutral get the rpms over 2500ish and it'll slip in. Anything other than that it'll grind as you shift it into 3rd.

 

[Schurkey]

If there is any sort of incline at all it will rev up and you could red line it and struggle to go 35 mph, in 4th or 3rd.

plugged cat and /or plugged fuel filter will most likely not let the engine rev to redline. I am more inclined to think that the clutch is slipping.

^^^ Winner.