95 K1500 - Sluggish Acceleration And Other Issues

sonoramike · November 6, 2008

got the new beast home tonight after an almost 3 hour ride. pretty comfortable ride all in all, but clearly there are a few issues to deal with. stopped off at the local autozone and picked up a set of ac delco plugs (CR43TS), but all the plug wires are out currently of the looms and I'm wondering if anybody has a photo of how they are supposed to be routed?

2nd prob is sluggish acceleration from a stop, seems like engine really winds up but there is no snappy launching going on. the idea of the truck spinning the tires from a dead stop while on pavement would be beyond consideration at this point - any ideas on where to start on looking for better out of the hole performance?

don't have a service manual for it yet, so I have no idea on tuning specs. pointers to any tuneup info/specs/procedures much appreciated.

nonotme42 · November 6, 2008

Miles, transmission fluid condition, last tune up (air filter, pcv, plugs, wires, clean injectors, fuel filter), transfer case fluid age and differentials fluid conditions.

pennzoil29 · November 6, 2008

Miles, transmission fluid condition, last tune up (air filter, pcv, plugs, wires, clean injectors, fuel filter), transfer case fluid age and differentials fluid conditions.

These would be good things to do.

sonoramike · November 6, 2008

Miles, transmission fluid condition, last tune up (air filter, pcv, plugs, wires, clean injectors, fuel filter), transfer case fluid age and differentials fluid conditions.

153k, more red-ish than brown, no idea, no idea, no idea

will be changing all the fluids over the next week or 2. TB is pretty cruddy, going to clean it up as well

95Sierra2500 · November 6, 2008

I'd start with a full tune-up including an EGR valve (it's probably toast), change fluids, and swap out the fuel filter (careful here, you could crack a line if it's rusted). Then see how it runs. If it's still kinda crappy, you may want to seafoam the engine and run some through the fuel system, do another oil change and see how it runs.

If it's still not up to your desires, you may want to consider having the valves lashed, and a new timing chain installed - 200k is nothing to shake a stick at. Also have it re-timed (if you can do all this yourself, perfect, otherwise you're looking at a healthy labor bill, but the parts are cheap).

Something to remember is that the TBI 350's weren't all that powerful anyway - but my truck certainly feels like it can definately get out of it's own way until I get to higher speeds.

sonoramike · November 6, 2008

motor seems to run fine given it's age and unknown tune condition. it's the perceived issue with stepping on the pedal and having the truck move fwd in a relative manner given how far the pedal is down. the pedal to movement ratio seems out of whack, like I have to push the pedal down pretty far to get the truck to move. I know it's a 4800lb beast, but it seems off/mushy. not exactly sure how else to describe the problem.

Mike G · November 6, 2008

Next time you are at AZ, pick up one of their GM Trucks manuals, that should have all your specs. The wires that you buy to replace teh originals are generally about 1 foot too long on each wire... I route mine and just keep them off of each other and away from metal. I would comfortably say you will not get the tire spinning performance, especailly with the auto. That truck will be dependable though for a good many miles still. I just threw a rod bearing in my old buggy with 190k. Yes, if you have the throttle stick wide open, even for a second, it will happen.

--Mike

thecraft · November 6, 2008

I would comfortably say you will not get the tire spinning performance, especailly with the auto.

I beg to differ.

sonoramike · November 7, 2008

well, here is the latest:

oil chg and tuneup yesterday, replaced old autolite plugs with the stock ac delco's. the plugs were in only finger tight, never seen anything like that before. new NAPA cap and rotor. sprayed the TBI down pretty good, it was filthy on the injectors and surrounding areas but the bores and butterflies were pretty clean. smoothed it out a lot. turns out PO wasnt running an aircleaner, ugh. will change the oil at about 200mi, it was pretty mungy. adjusted the throttle cable end at the TBI to remove some cable slop. wire loom routing plastic is old and cracked, broke a few so the plug wiring is still a mess... so the motor is running pretty well but still think it could be better, and I too would expect a 5.7l to be able to spin the back tires on this (not that spinning them is what I'm after but it's a good gauge of ability to get power to the ground)

paid more attention to how the truck drove yesterday, and I think my "mushy" issue is coming down to transmission shift points. the 1-2 shift happens at 2k which seems kinda high to me. shifts are pretty sloppy too -- speaking of which, my column shifter is like a bowl of mashed potatoes, that'll need to be addressed.

are the transmission shift points programmable? going to dig in on replacing the 1-2 and 3-4 servo's and see if there is any negative impact on installing these in a high mileage stock 4L60e trans

more when I know it

95Sierra2500 · November 7, 2008

A 2k shift point is about normal for average driving out of a 4L60. Yours is probably NOT a 4L60E since you have a '95 with TBI, but it's not beyond the realm of possibility. In which case, the only way to 'program' the shift points is to put in a shift kit. It's very possible that your trans is getting wore out.

As for your column shifter, it's VERY common for those to get sloppy over time. The issue is they used a softer material for the shift clevis (the little part that the lever actually goes into) than they should have. Over time, it wears out to the point where you can actually defeat the BTSI system - or at least I can in my '95. Eventually I'll try to find that little part and replace it...but for now, I'm too lazy.

You also don't state if you have a 1/2 ton or 3/4 ton - we're all presuming you have a 1/2 ton. If you have a 3/4 ton, you may have the 4L80 trans, which, while handling more abuse with less issue, doesn't seem to have the get-up that a 4L60 truck would have.

sonoramike · November 7, 2008

A 2k shift point is about normal for average driving out of a 4L60. Yours is probably NOT a 4L60E since you have a '95 with TBI, but it's not beyond the realm of possibility. In which case, the only way to 'program' the shift points is to put in a shift kit. It's very possible that your trans is getting wore out.

will have to get under there and see if there is a harness, assumed it was an E given that... well, I just assumed

As for your column shifter, it's VERY common for those to get sloppy over time. The issue is they used a softer material for the shift clevis (the little part that the lever actually goes into) than they should have. Over time, it wears out to the point where you can actually defeat the BTSI system - or at least I can in my '95. Eventually I'll try to find that little part and replace it...but for now, I'm too lazy.

guy at the stealer, errr dealer, said the same thing. going to pull the column apart and see if the bolt/screw/pin has backed out

You also don't state if you have a 1/2 ton or 3/4 ton - we're all presuming you have a 1/2 ton. If you have a 3/4 ton, you may have the 4L80 trans, which, while handling more abuse with less issue, doesn't seem to have the get-up that a 4L60 truck would have.

1/2 ton/SWB Xtended cab