Hello, last week I replaced the spark plugs in my base model in an attempt to fix a miss fire (I found out that this car had the original plugs after over 200k). I thought my engine would perform better with new plugs, and there is some improvement, but it idles really weird, at least I think. It idles on the lower 1000 rpm, closer to 0. There's been a few times as well, when I'm letting the car run, waiting for someone of just sitting in a parking lot, that it'll just shut off. It has thrown a few codes (p0123, p0410 and, p0400) but from the research I've done I don't think those would cause it to stall out, maybe the rough idle. Idk, what do you guys think?

 

Three things:

1) Try this. Start engine, let it warm up (drive it 5 miles).
Park the car, leave it running and pop the hood. Yank the oil cap off.
Does the idle get worse? Does it get more unstable and rough? It damn well better get worse, if it does not get worse, you have a bad vacuum leak.
Fix that.

2) If you changed plugs on a car with 200,000 miles and did not change plug wires, grab a reasonably large baseball bat, hit yourself with it a few times - preferably in the head.

3) If the car does get rougher when you yank the cap, I'd suspect three things: Bad plug wire(s) or fouled up MAF sensor assembly or low fuel pressure (probably not if it runs good when running down the road, low pressure would make it worse as you accelerate).

 

I would agree with the base ball bat, but as it stands I'm broke, the plugs themselves ran about 170 and I almost put it off. Once I have the money i plan on replacing coil packs and wires. Ill try the oil cap trick, if i do end up finding out theres a vacuum leak, where do I go from there

 

THa'ts nuts. Needwings.com has 12 OEM plugs for $87. The wire set is around $210 (back when I did it in 2016, it was $290 for all, so prices have not gone up much since then).
I have no clue how you could pay that much for 12 plugs.

I do not understand why people fight about changing plug wires, but want to change coil packs. You already abused those OLD wires by yanking them off the old plugs, they should be replaced, NOW. BEFORE you throw money at the car.

A bad vacuum leak can be one of the three vacuum hoses from the breathers to the throttle body, I suppose even the oil cap could be the problem, or maybe the EGR valve.

 

thanks for the advice. I ended up paying that much because I didn't have a lot of options, I live in a small town with only a few parts stores, and it's my daily driver so I couldn't wait for Shipping. I'm the second owner and didn't even think to replace the plugs until I did, which I regret because it's one of the first things I should have done. Ill check needs wings and get the wires asap, I was going to change the coil packs just as an extra precaution, I'm pretty sure they're just as old and abused.