lkollar

Have you checked the plug wires? I’ve had similar issues when the wires have gone bad—they just wear out over time. Thing is, they don’t always look bad, so you can’t just eyeball ‘em and call it good. One way to check: pull into a garage or shed and turn the lights off, or wait until night if you don’t have an indoor place. With the engine idling, spray window cleaner on the wires. If you get pops or the motor misses, the wires need to be replaced. Hey, it’s a cheap replacement. Just do them one at a time so you don’t get the wires crossed (you think it’s running rough now, try swapping a couple plug wires). The “check engine” light usually indicates a problem with the EGR (exhaust gas recirculator, might be called PCV on older vehicles). If it’s clogged up, it could also be causing rough running/power loss.

I thought I was having that problem at first, but it cleared up next time I tried it. I might have had something on my finger.

Definitely test-fit. For me, the replacement battery goes all the way to the left of the compartment, and just a tiny bit (maybe 1mm from the top..

For completeness, it should tell you to peel off the cover over the adhesive before seating the battery for real, even if it’s obvious. You can squirm the battery a tiny bit after taping it down if necessary.

You don’t need a lot of pressure on the battery while pulling the second strip. Just enough to keep it from popping off. If you’re worried about the battery taking flight, a fingernail along the bottom is enough to keep it in place.

The display will drop into place when it’s aligned properly. You can also lay the iMac down for this step if you don’t have the wedge.

Take out the two screws that hold down the right speaker, and push it up a little, before removing the logic board. It makes things a lot easier.

Also: there’s a cable on the right side of the logic board that isn’t called out. Nor are the two HDD cables that plug into the underside of the logic board.

I got it (also upgraded the HDD while I had it taken apart), but some steps are missing IMHO. Most crucial are the HDD cables that plug into the underside of the logic board. I had everything but the display put back together when I noticed the loose cables. They must have pulled out when I lifted the board out. There’s another cable on the right side that isn’t called out, either.

Apple doesn’t make this easy, to be sure, but I also took the opportunity to clean out 6 years worth of dust. That was probably one of the 5 hours I spent on this.

There are two connections underneath, where the HDD cables plug in. This should be pointed out; they pulled loose when I removed the logic board and I didn’t notice until I had most of it put back together.

The tab is at the far end of the connector, so you’ll need to reach farther than you might think.

The replacement battery came with the seal—but how do you put it on???

Looks like iFixit has fixed this issue by shipping the replacement battery with strips already attached. In this case, skip to step 7.