Wierd knocking/popping sound

[klaxed]

Ok, I hope this is the right place for this. But today when I was driving out to Stevens Pass (and also on the way back), my car made this knocking noise. It started up at about 2500 rpm and when I would back of off the throttle, it would almost entirely go away by 2000 rpm and would sort of fluctuate above 2500 rpm. This noise occurred with the A/C compressor on and off so I don't think it's that (I could be wrong though).

Any ideas?

[asc_up]

It could be rod knock...
How bad of a knock was it?

Was it faint or did it sound like a hammer hitting something?

[klaxed]

The noise was less than that of a hammer hitting something. Very noticable. But the thing is, is that it isn't a constant noise. It varies with the rev's and it comes and goes. It happened once on the way up to Stevens (1 hr 20 min drive) and twice on the way down (1 hr 20 min).

[smh0101]

Is it like a click click click click?

THAT would be lifters. If it was... Have them replaced with solid mechanical ones out of a 97 2.2L... And forget the hydraulic stuff.

[klaxed]

It was sort of a click, but harsher, and it wasn't constant. I have had lifter click previously but that mostly went away after I changed my oil a couple of weeks ago.

But still, replacing the lifters might not be a bad idea. Is that hard to do? Maybe it might be something for the summer.

[altron23]

its pinging, mine did every day for about 3 months this last winter. started puting midgrade in it about 2 weeks ago, stoped doing it. they dont like hills with the shitty winter gas we get in the PNW.

[klaxed]

Meh, I drove my car numerous times up to the pass in december on the cheapest gas I can buy (from shell) and never had this sound before.

[altron23]

weird, well its a good place to start, just try some good gas and see what it does. it sounds just like pinging though.

[555BCTurbo]

Meh, I drove my car numerous times up to the pass in december on the cheapest gas I can buy (from shell) and never had this sound before.

cold = less ping

[klaxed]

Meh, I drove my car numerous times up to the pass in december on the cheapest gas I can buy (from shell) and never had this sound before.

cold = less ping

Yeah. But my car wasn't pinging. And since that day (it was a week and a half ago), I haven't noticed the noise, but want information that I can use so that I could fix it if it comes up again. Hopefully my engine won't self destruct.

[Herm99]

Did you by any chance have the Defroster, def/heat, or AC on during any of this?? I just read an interesting tidbit in my haynes manual. The AC Compressor IS running when the Defrost, def/heat, and AC(obvisouly) are selected. I experienced a similiar noise that baffled me, it only happened when I selected each of the 3 modes, surely enough it was my AC compressor going south.

It sounded like a pretty nasty thumping or "hollow pounding" noise, and its pretty consistent with the throttle. Not entirely different sounding from a knocking rod!

[klaxed]

Yeah, that was a thought that my brother had as his ac compressor isn't working the greatest. But the noise also happened when the everything that uses the ac compressor turned off. It wasn't constant just at random times.