E30 engine knock under load?

[bfraser30]

The last few weeks Ive been trying to track down a knocking noise under acceleration in my 89 325ix. It sounds like a knock/pop sound that will happen a few times per second while on the throttle when I accelerate hard at any point in the rev range. When I go in deep snow as soon as I lose momentum I get the same noise and have power loss. Without pushing the car it drives and sounds normal. No idle issues. 

From what Ive found online Im assuming its either a spark problem or possibly air/fuel issues. I changed all the plugs yesterday and they all looked fine, and all matched. The distributor was replaced 8 months ago, and they plug wires not long before that. I checked them all anyway and everything looks fine. At this point Im going to check where the plug wires go into the distributor for cracks, and change the fuel filter. After that the only thing I can think to check is injectors.

Basically I wanted to know if anyone has personally had this issue, or any advice on things to look for. I think Im on the right track, but engine knocks scare me and Id like to get this resolved as quick as possible.

[B C]

Run 93 and see if it still happens

[jc43089]

Yea try high octane, if it goes away then i would look into fuel system issues that would cause a lean condition, clogged filter, low fuel pressure due to fpr, could be an injector but I would start with easy stuff.

Sent from my potato phone

[AvusHatesCones]

Any chance its not engine related? It could actually be your front driveshaft spines beginning to go? I had a similar knock under heavy load in my IX and it was the splines jumping.

[bfraser30]

I just put the 93 octane in this morning and it doesn't seem to make a difference. It might delay the sound a little bit but it's hard to tell. I do normally run 91 octane though so is it possible the 93 isn't a big enough change to make the engine change?

I never thought of the driveshaft actually. The sound seems to be coming from the passenger footwell so I figured either an axle or the engine. When I put the driveshaft in last summer I made sure I lubed it correctly, hopefully that's not the case but I'll check into it.