1.5L L4 FI questions
 

I just inherited a 1990 STD Hatchback.
It is completely stock with no mods, doesnt even have tint on the windows.
It has 153K on the engine. The car sat for 8 months before I got it. I put in a new battery and it fired right up. Of course a couple miles down the road the right front tire blew out because the valve stem rotted in the sun... so it has 4 new tires on it.

Anyway, after having all the fluids replaced and getting it checked out by a mechanic, I drove it from San Diego to Tampa without any major issues. The only things that happened were:
1. I filled up with Shell gas in Pecos, TX and a short while later the check engine light came on. I figured it was because the car has california emissions and the Shell gas has a nitrogen additive in it that disagreed with the emissions. I refilled with different gas and had no more issues with the check engine light.

2. A few days after arrival in Tampa, the oil light started coming on when I took sharp curves rather aggressively. Turns out I was almost 3 quarts low... I didnt see any oil patches in the driveway so the engine is burning some oil. About 1 qt every 1000 miles, I guess that is to be expected.

Anyway, the car runs great, I want to restore what little body damage there is and possible do a little tweaking on the appearance and performance. (When I get started I will start a projects thread.)

My question is, what can I do to get max performance out of the existing engine, without spending a lot of money, and at the same time I want to get things that will enable me to upgrade the engine in the future, without having to upgrade parts I will be putting on the car for this engine. Meaning when If I put a performance exhaust on this motor, I dont want to have to buy another one if when decide to swap the engine later.

I intend to use this car as a daily driver, and let my daughter use it to get back and forth from school/work. I want it to be fast enough I dont get embarrassed when the stoplight turns green, but I dont want my daughter to go out and kill herself driving like a maniac either lol. When she gets her own car, then I will turn it into a beastly machine.

Also if someone could tell me some good online sources for various parts and accessories like headlights, performance parts etc.

Is the engine burning or leaking oil? This should be the first item to fix. Next, if you don't know when the timing belt was last replaced, this is your next job. A timing belt that slips or breaks may destroy the engine.

Click here for discount OEM replacement parts.

No leaks. Its burning oil. Timing Belt. Gotcha. Is that a DIY thing or do I need a mechanic? I'm pretty good with most mechanical stuff however I have not done much engine work.

You should do cylinder compression and leakdown tests to determine the source of the oil burning (click Compression link in my signature). Leaking valve seals won't reduce cylinder compression but bad piston rings or head gasket would.

Replacing the timing belt is a moderately difficult job, but with the right tools can be done by you. The hardest part is removing the dreaded crankshaft pulley bolt.

Timing belt info:

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Yeah I just looked in my Haynes Repair Manual. Looks like a real PITA. I will probably take it in for this.
Fortunately I have all the maintenance receipts since the car was new. I looked through them all and it appears it was replaced about 10 years ago. I would say it's definitely time to have it checked.