This is a post meant for the few on a.cc who know what they are talking about with cars.

Basically, what should be done in an engine overhaul/tune up? My celica has a (Toyota) 5S-FE engine, if that helps at all. Not much as far as maintenance has been done on the car (before I got it), and all I've done is dumped some fuel injector cleaner in the gas tank, done an oil change, and put a new air/oil filter in.

The car idles a little rough and sometimes feels like it has a lack of power. I'd think a tune up would help this situation out (there's nothing wrong with the engine aside from a small oil seep, which should be fixable by changing a gasket or something). Also, is it possible to adjust automatic transmissions at all? Something seems to shift aggressively, and usually it shifts before reaching 2500 rpms (unless I manually shift down or turn off overdrive), which also seems to cause crappy acceleration.

I'm not sure what could be done to tune up the engine to make it run a little better (some googling led me to taking the injectors out and having them cleaned at a dealership or garage, tightening up the throttle assy a little bit, and some other stuff like that).

General tips and advice are appreciated. I'll give cookies too.

Post in a car forum, i bet you'd get better advice from car nuts.

I figured it was worth posting here first, because we have at least a couple people knowledgeable about cars, at least it appears that way from the Deathwish threads we get into.

I would go first changing oil, spark plugs and air cleaner.

That worked great on my mom´s car. Was running like crap, and with those 3 simple things, started running great again.

You can do it on your garage (except for the oil change, well, you can, but what are you going to do with around 5 lts of old oil? better change it at gas station)

The ones already mentioned plus spark plug cables and fuel filter. A bad set of spark plugs is quite often the source of bad running. I replaced mine and now it feels like the engine (XU9J2, 125hp/177Nm) has 10hp and 20Nm more. If the car feels like it stutters when accelerating, replace the fuel filter. A clogged fuel filter drops fuel pressure in the supply rail (while increasing pressure on the pump side, stressing it unnecessarily) and fuel flow rate. That can cause lean burning, which can ultimately lead to the pistons melting.

Whatever you do, first make sure that your brakes can handle the improved speeds.

It's almost due for an oil change again and the air cleaner is only a few months old. I'll put a new spark plugs in next oil change (in a few weeks), and a new fuel filter.

And my brakes are good, so they can handle it. ;P

Are you old enough to drive on public roads yet? My, how time flies

Is there anything more you can tell us? What year is the car, how long have you had it, what's the mileage, how did the previous owners treat it, what general condition is the car in, etc.?

I forgot one important thing from the previous post:

DO NOT TOUCH IT! Take it to a proper mechanic. Automatic transmissions operate on half good faith and half black magic - that is to say they're too complicated devices for non-professionals.

if your lacking power that was there before. i would check the exsues system and the timing belt they have the most to do with power.

No, that would be the crankshaft, connection rods, pistons, cylinder liners and cylinder head. All the others are just accessories for those.

Yeah, you'll certainly know if the exhaust is leaking. As for the timing belt, if it's one notch out either way, the engine could theoretically run, but it would be as gutless as anything. So I doubt that's the problem. If you're not going to replace the spark plugs just yet, at least pull them out and give them a good clean. You can actually tell quite a lot about how an engine is running from inspecting its plugs, so have a look. You can supposedly tell if the engine (or a particular cylinder) is running too lean or rich, so perhaps that's a good way to tell how well the injectors are working.

well i took my Toyota Celica 1990 to shop the shop to get the timing belt change. when after i took after i took for test drive i told them it run but it dose not have the same power it used to have. then they redone the timing belt and it worked like a charm.

All there is to it.

Yes, I have been for just over a year.

Well.. it's a 1990 Celica GT, I've had it almost a year, it has about 142,000 miles on it, it was treated well and maintained (except I guess it (hardly?) never got new plugs or anything, according to what they said). It's in very good condition, and was garaged for a while.

I didn't know if it was a small tweak. Would tightening the throttle cable help at all as I read on a thread I found with Google?

One thing to note is that as the gas tank gets below a half a tank, you can feel a loss in power. If you go fill up the gas tank, it feels a lot more powerful.

The engine runs fine, just idles rough and, it's powerful enough, but it feels like it shifts before it hits the good power.

So, the general consensus seems at the moment to put new plugs in and see what that does?

[edit] I went outside to check stuff and it started raining again. I did look at the throttle real quick before coming back in. I'm not sure how it works, but there's a small wheel type thing, one cable on top, one on bottom (presumably cruise control?). The bottom cable is tight, but the top one has a little bit of slack. Should that be tightened to take the slack out via the adjustment?

Could be a crack in the fuel intake tube inside the tank or your fuel pump is its way out (the hydrostatic pressure of a full tank forces more fuel to the pump)

The wheel type thing is the throttle cable wheel, which the throttle cable rotates and which in turn rotates the throttle butterfly inside the throttle body.

If the cables both go in the same direction but on different sides of the wheel i'd guess the other cable actuates the kickdown. Or you could have a motorcycle-style dual throttle cable system which i doubt since i've never seen one on a car before. Usually there shouldn't be much slack in any throttle cables, however the throttle butterfly should rest on its stop, the cable shouldn't exert any force on the wheel at idle.

If they go in opposite directions (i.e. both cables would rotate the wheel in the same direction) then i'd be inclined to believe the other one is indeed for cruise control.

edit: See the attached image: Do you have the cables set up as if you had two of same color or one of each color?

It's done this from day one, but is there an easy way to see which it could be (without pulling the tank out to look at it)?

The cables are both on the same side of the wheel, one on top, one on bottom. They both rotate the wheel in the same direction, so I guess my guess on cruise control is correct.

There is a small amount of play on the cable, more so on the one on top than the one on bottom. The throttle rests at it's stop but I'm not sure how much i'd be able to tighten up the cable without exerting force.

[edit]
I'm not sure how the bottom cable is routed, but I'd say it my system resembles the orange cable on the left, and the blue cable on the left (but the blue cable follows more of an orange path).

I wouldn't know, it depends how they manufacturer has intended these things to be looked at.

For them to be throttle and cruise control cables they'd need to be on opposite sides or travel in quite an unusual configuration - the curved arrows demonstrate direction the wheel would turn if the cable of same color (straight arrows) would be pulled (in the direction of the arrow obviously). You should trace the cables to see where they go.

I'll go out and check after it stops raining some, or tomorrow, whichever comes first.

I don't know if anything can be found on google by searching for the car, but it's a 1990 Toyota Celica GT coupe, auto tranny, and I 99% sure it has the 5S-FE engine.

If the gas pump is weak it sucks. No, it doesn't.
As jhuuskon pointed out, the full tank helps with the pressure. But an empty tank might do the opposite. Do you notice a "Swooosssh" sound, when you open the cap to the tank? I used to have that sound on my Toyota Carina 1991, before rust made small cracks in the tank and the filler neck. I recently replaced the neck. Couldn't stand the gas smell, when I filled up the tank. I got back the swoosh sound. Now it's gone again.

Anyway, when pump sucks gas, it develops a great underpressure in the tank and that sucks!

If you are replacing the spark plugs and wires, you might take a look at the distributor cap as well. It couldn't hurt to replace it. As for the transmission, mine slipped the first few weeks I had the car, after replacing the spark plugs, the problem went away. Most likely unrelated, or may have been the engine being out of synch with the transmission due to the plugs.

I hear a swoosh if the tank is below about a half a tank too.

Thank God! I thought I had become crazy.

Try to just open and close the cap (and enjoy the sound) and drive on. Do you get the power back without adding fuel?

It seems to get power back after I let the pressure out, but I haven't test driven it yet.

Also, jhuuskon, the throttle wheel has the throttle cable actually on bottom, and when you open the throttle up it pulls on the top cable.

I was having trouble with my car running roughly a couple of months ago. I had started buying only 10% ethanol added gasoline at the time. I took it in for a tune up and the mechanic said that ethanol is much more sensitive to spark plug gap spacing and ignition timeing than normal gas. After the tune up it ran great.

So have you been using 10% ethanol gas?

Well, I got more power, but now the engine misfires like crazy (hopefully it's the 4 year old spark plugs in it). I have new sparkplugs here, just waiting for the engine to cool down and me to go find a spark plug gapper before I put the new plugs in.

[edit]
Nope, just regular gasoline. My car isn't flexfuel anyway, so I don't think i can run E10 (or whatever it's called).

What did you do to make it misfire!? Or was it doing that already...?

Tank tank pressure problems are easy, just replace your filler cap. or you can find the pressure-relief hole in your existing one and scrape out the corrosion and dirt.

bamccaig: I assume it was the spark plugs being old. The old ones were all the same color, they looked like the normal ones in the link posted before, and they all looked the same so that's good. And it runs a LOT better (and didn't misfire at all) and doesn't seem to run rough at all with the new plugs. I'll look into the tank pressure thing (it's NOT normal to build pressure like that?) and pick up a new cap if I can't clean the current cap.

When I drive tomorrow I'll see if it feels like it has more power.

I think its normal; I have the same car as you but in manual and when I take the cap off too put gas in, it release a huge vacuum .

Rust is normal, but not desirable.

Wrong, you can run up 15% ethanol on a stock automobile; ethanol can corrode rubber, but back in the 70's a law was passed that req'd auto manufacturers to build cars that can handle some ethanol.

The it's the kickdown actuator cable probably. Does your kickdown work normally? If it does, don't touch it. If it doesn't like it should, take it to a professional to have it adjusted properly (i still insist the home mechanic shouldn't touch anything that has a direct effect on the operation of automatic transmissions. )

No, your tank should have a vacuum relif valve in the filler cap (new regime) or somewhere in the filler piping (old republic). Ideally, when you open the tank, you don't hear any hissing.

Well, it will kick down unless it's in overdrive. When you are in overdrive, if you step on it, it doesn't kick back down unless the RPMs go down to like 1000 (going up a hill or something). It also likes to shift into overdrive early.

I just dropped my car today for the follow-up check after last month's failed inspection. It passed this time, but after i came home and added the costs to my maintenance log, i wanted to cry. For the reason, figure out the attachment.

Gunk built up in the throttle body can cause poor idle, don't go wild with the carb cleaner or you might melt some plastic gadgetry such as idle control motor valves. If the O2 sensor has 60k+ miles on it, you'd probably pick up some power and miles per gallon by putting in a new one.

Shifting too soon and harsh shifting sounds like some valves inside the transmission are hanging up on gunk inside, there's a slight chance that a fluid/filter change would help. Some people have told me that the Slick 50 people make an additive called TransX that can improve shifting.

It shifts fine, just goes into OD too soon, IMO.

I'll have to look at the throttle body too, because it also sticks in one spot.

jhuuskon: I can't read any of that.

You can read the sum in bold.