New to this site, have a few questions.
 

I'm a proud owner, as of Tuesday of a 1999 Chevy Metro 2d Hatchback 3 cyl

Bought it in excellent condition w/ about 90k miles.


Now I've stumbled across a few sites like this and teamswift.net and I must say, from spending yesterday and today on these sites, I already feel addicted to the idea of modding my car to squeeze the most MPG I can out.

So I have a few questions.

First I want to do a tune up of my own. What type of spark plugs should I get? Are the Platinum +4 Spark Plugs any good? Also, as for a air filter, I read that the k&n filter is more of a waste of money then anything. I do need to replace the filter, it's absolutely filthy. I still need to check the pressure on my tires, was thinking about starting at 44 psi. Also was going to replace the fuel filter while I'm at it.

Anything else I should consider? I read replacing the O2 sensor can make a huge difference. What would be a symptom that I need to replace that?

Also, what octane should I be using? I live in Colorado at a altitude of around 5200 feet, if that matters. I read somewhere I should run 85 at this altitude on the 3cyl engine. Also, what type of oil should I use?


I'll be the first to admit, I know almost nothing about cars, but I'm handy with my hands and building things. (computers in general)The main reason I bought a Metro, is because I have a mint condition yellow 88 Fiero GT, that I want to do some work and/or upgrades on, but I know nothing about cars, which is why a friend recommended I get a Geo to learn and work on. Low and behold, it seems I found another side hobby I can devote some time into. :)

Yesterday I filled up the tank (87 octane) then drove, from southern Denver, CO, up North, about 70 or so miles, averaging about 55 mph most the whole way on the HWY, while trying to practice easy driving habits. Refilled my tank up after I was done to average out my MPG and it came to about 49.7 MPG.

Seems I can get a lot more from reading a few stories of various users on this site.

Guess I would like to start with some of the basic mods first, then go from there. :)

Any help would be appreciated!

Thanks!

Wanted to add, that while I was testing the car's MPG yesterday, the temps here never broke freezing and were around 20-25 degrees all day. So I'm sure that impacts my MPG a bit.

Welcome! I know the 3-cyl Metros can get great fuel economy.
The ~50 mpg you're getting sounds great to me!

In the "General Fuel Economy Discussion" forum, see the two stickies at the top of the page (if you didn't already). That information should help a lot.

You asked about air filter and oxygen sensor. I'd go with a fresh standard oem type filter.

For oxy sensor, the test procedure is pretty simple if you have a digital voltmeter (has to be a high impedance/resistance meter - read up on the procedure and you'll see). Google on "test oxygen sensor" and you'll find the method - that's what I did. Or you might find it in wikipedia. For that year car, I'd expect to find a simple 1- or 3- wire sensor, nothing complicated. I never did it yet but I've been meaning to.

I think if your FE is 49.x mpg the oxy sensor must be OK. But checking it now and then sounds like a good idea.

I'd decide if and/or how I was going to reroute the air intake before replacing the filter. I think a filter is a filter and the location there of is more important. I bought a new filter to go in the OEM intake but rerouted it to the exhaust manifold,so I needed a different type of filter anyway. The quicker warm-ups helped the MPG's almost as much as the higher tire pressure.

Don't buy Bosch spark plugs. You'll be better off with OEM.

Thanks for the suggestions!

What type of Octane do you all recommend for this altitude and car type?

Also, what type of oil should I go with? 0w20 or 0w30?

I'd go with w20 if oil burn is not occurring. Most say 87octane is best,but I use 93 myself. I've tried both and my car "seems" to be running smoother with 93 with slightly better mileage.Can't hurt to try both and decide for yourself. Also if you pick the higher octane, life is easier if you don't tell others( unless you like endless debates and reading assignments).

Thank you. :)

I would say to carefully record the mileage with 87 octane and also 93 octane then see whether or not the numbers work out. It could turn out that you do indeed get better FE but it may not be enough to cover the additional price/gallon.

I'm currently running 0W20 in my son's '99 Saturn SL2 and 0W20 as well in the Prius. As was mentioned earlier, if the car is burning oil you may want to go with the lightest/cheapest oil.

As for the Bosch +4's I'm not sure if the extra cost will justify their use. See my article on spark plug comparisons: https://www.gassavers.org/showthread....park+Plug+Test

Premium, unless called for (usually for higher compression engine or advanced timing), is actually harder to ignite (that is why high compression engines require it to fight detonation or pre-ignition). It does no good at all unless it is preventing detonation. Otherwise you want to run 87/89 octance (89 if you are getting some pinging under acceleration) to get complete "explosions". I know some will say different but that is the reasoning behind higher octane levels. Put in 87 octane and consider the savings added mpg$.

I need to clarify my earlier post. The only way that higher octane would improve your FE would be if your car has a knock sensor and is detecting detonation. As DarbyWalters mentioned, the only reason to use higher than 87(if that's what your car calls for) is if you have pinging on 87 in which case you likely have carbon deposits that need cleaning out.

Save your money and just go with OEM plugs, jack up the air in the tires, switch to 0-20 synthetic oil AND.....drum roll please........GET A SCANGAUGE!

IMO opinion the Scangauge is the best mod you can do as it will help you modify the one thing that most people overlook when making mileage mods ---- The Driver. You'll become fixated on your mileage. Try it and see.

I also went with the racing disc caps on my old Metro, but some people are opinionated about how they look. I love them though, and my opinion is the only one that counts - just kidding.

Noob problem!



I decided to replace the spark plugs today (OEM as suggested), since the old ones were filthy, but after doing so, the car won't turn over.

I made a dummy move and didn't pay attention to which spark plug wires went where, so I have a feeling I have them in the wrong spot.

How do I check where they are supposed to go?

I doubled checked the gapping, and they are correct.

It's a 3cyl engine.


Thanks for all the other suggestions guys, I think I will pick up a scan gauge so I can fine tune my cars MPG.

O and BTW, yesterday I discovered my tired were horribly under inflated. one tire was at 18 psi, the others between 20 and 22.

Pumped my tired to 40 psi (tire says max should be 35psi) and will see how my MPG fairs.

Even if you installed the new spark plugs in your ears [:D ] the car should still turn over. Spark plugs only fire the cylinder, not turn the engine over. Something in your starting circuit is amiss...[battery, starter, solenoid, cables, ignition switch, wiring, etc.]