[Edited for accuracy]

Some history first:

This is my first time on the forums, please correct & forgive me if I break any rules.

I just inherited a 2003 Mazda Protege from my parents because it doesn't start reliably. This started happening when my dad threw a battery in it, with the terminals backwards.

2/3 days, it starts fine. However, on the days when it won't start, the engine turns over VERY slowly, as if the battery is dying. I've tested it, and that's not the case. If I remove the key, reinsert the key, and try starting it again, sometimes it will start (after 3 or 4 attempts at this).

My suspicion is that one of the engine grounds was damaged when he put the battery in backwards, so I've been trying to find out how I can get a FSM (for less than the $300 that the stealership wants) so I can go through each of the grounds and replace them, one by one. If anyone could help me locate a FSM, or provide a diagram of the grounds, I would greatly appreciate it. I would also love to hear any other suggestions.


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Additionally, it gets very poor gas mileage. It's rated for 25 city, 31 hwy. I drive it mostly hwy, and I'm getting 24 consistently. I don't drive it like I stole it - it's a 2.0L engine - not much fun to be had there.

Once I can get it to start reliably, here's what I intend to replace to bring gas mileage up to snuff:

Plugs
Wires/Coil Packs
PCV valve
Air filter

Any other suggestions are welcome.

Thanks in advance!

 

No one? Bump please!

Also, I did a VIN lookup. It's actually a 2003 Protege ES with the 2.0 L engine.
I just replaced the spark plugs, wires, and PCV valve. I also replaced the ground wire between the chassis and the battery.

The engine now starts reliably. It also usually turns over normally now, but once in awhile it still turns over super slowly, leading me to believe that there's another bad ground elsewhere.

Can anyone point me to a diagram of the engine grounds? Pretty please?

Thanks!

 

I don't have a diagram. But I would check if the alternator is o.k. Maybe a diode got damaged. I' take the alternator out and have it checked at a parts store.