darksheep85
Newbie
This will be a long post so, apologies in advance.
2 years ago I bought a 1993 suburban c2500 454TBI/4L80 that had 250k miles but was meticulously maintained. Southern truck so no rust. When I got it home, it didn't have very good oil pressure so I changed the oil pump hoping for the best. But it was actually the crank bearings were shot. So I had the engine and transmission rebuilt at the same time. The machine shop reused the cam and lifters because he said he didn't trust new camshaft metal. (I didn't know this till after I paid for it).
We then move from SC to NY
6 months later it wipes a cam lobe. So I replace the cam, lifters, rockers, and studs. Immediately upon startup it wiped the same lifter. So after being thoroughly disgusted with my situation, i bought a ATK reman engine at NAPA and had a local shop install it. So heres the rundown on new parts on the engine. NAPA brand distributor, coil, ngk iridium plugs, good wires, every sensor on the engine, no vacuum leaks, new fuel pump, timing set at 4°, tps set to spec. Ran great but had a slight miss and rpm would go up and down at idle. The miss was causing the tach to bounce when it would miss. And it would randomly miss at low rpm low load situations, like 60mph on flat road in overdrive. Ran it like that till it was time for my break-in oil change at the place that did the engine. They change the oil and go to back it out....no reverse. Great.
So now 1 year old transmission needs rebuilt again. Took it apart and found the plunger that engages the 1/R band had pounded itself into oblivion and something else in the transmission was cracked. So, full rebuild.
Still using the torque converter from 1st rebuild 2 years prior.
So now engine and trans are fresh and new again. What feels like a misfire is still there, so I've changed the NAPA distributor out for a Delphi. The bouncing tach and fluctuating idle have gone away, but this thing still feels like it has a miss at cruising speed (40-70+). But it's different. I don't know how to explain it. If you floor it from a dead stop, it takes off with no problem, bangs through the gears, and has plenty of power. But if you set the cruise at 60, it gets this random stumble that is driving me nuts.
I've thought maybe the ngk iridium plugs are just to much for it, but that doesn't really make sense to me. They should be fine, they just last longer. I've never had a vehicle with torque converter problems before, and I don't know if that's what this could possibly be. It's not making a "noise" of any kind. It feels like the engine dies for a 10th of a second.
I'm too far into this thing financially to just give up. I bought this to tow with and I need it to do its job. PLEASE HELP!!!
2 years ago I bought a 1993 suburban c2500 454TBI/4L80 that had 250k miles but was meticulously maintained. Southern truck so no rust. When I got it home, it didn't have very good oil pressure so I changed the oil pump hoping for the best. But it was actually the crank bearings were shot. So I had the engine and transmission rebuilt at the same time. The machine shop reused the cam and lifters because he said he didn't trust new camshaft metal. (I didn't know this till after I paid for it).
We then move from SC to NY
6 months later it wipes a cam lobe. So I replace the cam, lifters, rockers, and studs. Immediately upon startup it wiped the same lifter. So after being thoroughly disgusted with my situation, i bought a ATK reman engine at NAPA and had a local shop install it. So heres the rundown on new parts on the engine. NAPA brand distributor, coil, ngk iridium plugs, good wires, every sensor on the engine, no vacuum leaks, new fuel pump, timing set at 4°, tps set to spec. Ran great but had a slight miss and rpm would go up and down at idle. The miss was causing the tach to bounce when it would miss. And it would randomly miss at low rpm low load situations, like 60mph on flat road in overdrive. Ran it like that till it was time for my break-in oil change at the place that did the engine. They change the oil and go to back it out....no reverse. Great.
So now 1 year old transmission needs rebuilt again. Took it apart and found the plunger that engages the 1/R band had pounded itself into oblivion and something else in the transmission was cracked. So, full rebuild.
Still using the torque converter from 1st rebuild 2 years prior.
So now engine and trans are fresh and new again. What feels like a misfire is still there, so I've changed the NAPA distributor out for a Delphi. The bouncing tach and fluctuating idle have gone away, but this thing still feels like it has a miss at cruising speed (40-70+). But it's different. I don't know how to explain it. If you floor it from a dead stop, it takes off with no problem, bangs through the gears, and has plenty of power. But if you set the cruise at 60, it gets this random stumble that is driving me nuts.
I've thought maybe the ngk iridium plugs are just to much for it, but that doesn't really make sense to me. They should be fine, they just last longer. I've never had a vehicle with torque converter problems before, and I don't know if that's what this could possibly be. It's not making a "noise" of any kind. It feels like the engine dies for a 10th of a second.
I'm too far into this thing financially to just give up. I bought this to tow with and I need it to do its job. PLEASE HELP!!!
