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loss of torque...wtf?
'97 crew cab, 4wd, 4:10 gears, 168K miles, 3" down pipe
last year I completely gutted my cat. then I got a 4" exhaust from the (gutted) cat back. Nice turbo whistle. tons of low end torque...i thought.
I don't tow much. Sold my big *** boat a couple of years of ago, kept the truck. I had the opportunity to tow about 2K pounds yesterday up and down some 7 and 8 percent grades in the Colorado mountains. In town she runs fine. Very little smoke. She just runs.
Going up the mountains (empty at this time) she was struggling to stay at speed, constantly down shifting, up shifting, then back again. And tons of smoke.
When I hooked up to the trailer and 2 ATV's it got worse. The truck fought even harder to just get going. At one point going up an 8 percent grade, she only managed to hit 45 mph and I was in it. I pushed in the tow/haul button and when she down shifted the EGT's hit 11,000, even more black smoke, and just barely moved. I let off the accelerator til the EGT's backed off. By this time we had crested the top of the pass. Going down hill the EGT's were normal (well, yeah, no load) and going up the next hill I had momentum carrying the truck and trailer so she did OK, but once momentum was gone and I had to accelerate, she lugged hard with a **** ton of black smoke.
Once we were out of the mountains and back on flat ground she did fine. A couple of hills here and there but nothing to speak of.
I noticed a lack of high end torque as soon as i gutted the cat last year. And then a bit more when I got the 4" exhaust. So what happened? Do I need some back pressure? Should I get a performance muffler to add some back pressure? That would be a hell of lot cheaper than a new cat. I really don't want to go back to a cat...unless that is what is needed.
I just want to know what happened and how to correct it. These trucks are capable of towing an incredible amount, but I was having trouble with only about 2000 lb's. Please advise.
Thank y'all so very much