So, I recently bought a 2004 Montero Sport LS. It had 155,000 on it, so I was expecting a few issues. One of the things I’m having problems with is the way the car behaves going uphill.
When I’m driving up hill, SOMETIMES (maybe 1/5 hills) the car surges up and down about 200 RPM. Basically, at, say, 1/2 second intervals, the engine will rev up and down between 1500 and 1700 RPMs, despite the gas pedal being depressed at a consistent pressure. This is also coupled with, say, one in every two hills, I’ll start to lose acceleration on my way up the hill, and then I’ll push the gas, it will hesitate for a split second, then jump from, say, 2500 to 3100 REALLY fast, then it shifts and the shift is sort of rough. I can’t describe it as jarring, but more just a generalized bump in the car that you can feel. And it only does this occasionally.
The engine recently threw a P0455 code. I changed the gas cap to no avail, so I figured maybe the purge valve was sticking and I changed that. No luck.
So I can’t figure out exactly what it is. And it does it in any gear I’m in. For instance, if I’m driving slow-ish up a real big incline, and I’ve got it in 3 instead of D, and it needs a little more power, it’ll downshift into second and produce the same hesitation, surge, and then bump on the downshift. It also did this in 2. It most commonly does it in D, but that’s probably because I am most commonly driving in D.
Now, I don’t think it’s a transmission thing. It’s not like a jarring feeling when it shifts. If I’m accelerating on flat ground, it is perfectly fine and shifts completely smoothly. There are no problems downshifting when I’m decelerating, although sometimes I do get the same response trying to pass somebody. Given that I’ve still got this P0455 code lingering around, I can’t help but feel like it’s something in the EVAP system.
If I were to go PURELY on speculation and conjecture, it feels sort of like when I step on it, it’s not delivering more fuel to the engine right away. Then, when it surges, it feels like the engine got blasted with fuel and the hard shift comes because the tranny is trying to act quickly to catch back up. But I’m really at a loss at this point.
Also, I should note, although I don’t imagine this is relevant, that I noticed after replacing the purge valve (probably just because I wasn’t paying attention before that) that there’s a VERY faint clicking sound when I accelerate that sounds almost exactly like a playing card in a child’s bike spokes, only really really faint.
Any ideas on this? Does it sound like a transmission issue or something else? Dear God do I hope it’s not a transmission thing.
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