2002 Corolla plugs

The plugs are in the head, hiding under the coils. Each plug has an individual coil. Look for 4 coils evenly spaced across the head.

Wow, someone still here. Hi Ray. Happy 4th.

I thought the group was lost to the noise.

Yeah, I finally found a good page on this:

Why in the world did they design the cover plate and 4 coils like that?

To make it cost more to repair, and so more people would take it to them instead of doing it themselves?

I long for the days when engines were just engines, without all the added crap.

The cover plate is supposed to make the engine look as high tech as it actually is, and it helps keep water from splashing on the coils.

Having a coil for each cylinder or a waste spark system eliminates the need for a distributor which needs periodic replacement of the cap and rotor, needs adjustment, and which becomes a possible source or trouble as the engine accumulated mileage. Distributor assemblies are pretty expensive, they are a potential source of oil leaks, and they create drag on the engine. Having individual coils allows the ECM to more precisely control spark timing and duration, which improves fuel economy and lowers emissions.

A coil per cylinder is actually a pretty simple setup, it cleans up the engine compartment, and is a pretty reliable system. The only maintenance item is the plug itself, and the high tension wire if the system uses a waste spark. If there is a coil per plug, there is no distributor cap, rotor, or high tension wires to change, and you don't have to keep track of the spaghetti under the hood.

And here I was just wondering if it was time to do all that. :)

Well this car, weighing less than the 93 Corolla wagon, only gets about 3 MPG more, on average, so something didn't work out so well there.

Hard to see that, given my real life MPG experience with this car now.

But they say to be careful because the connectors are fragile?

Cool. :)

I'm gonna take a look and see if the plugs are iridium, and if not, put in iridium. It was a worthwhile change in the 93, helped has mileage by about

2 MPG and the pickup of the engine. ( not that this one needs any pickup improvement! )

But this engine has been running a slight bit rough at times, so I was wondering if the distributor cap & rotor needed changing. LOL

It also makes almost a deisel grinding sound when you first start to accelerate, but that may just be from the design of the engine, I'm not sure.

Do the transmissions of the 2002 Corollas tend to develop problems? I've noticed a slight sound from it, when turning corners sometimes.

I'd bet that the '02 has a larger displacement engine with better performance than the '93 while getting slightly better fuel economy.

If you are getting 3 MPG better with a larger engine and a heavy foot, I'd say you were doing well.

Just be sure to release the locks before trying to pry the coil off.

What do you mean by "running rough?" rough at ide? rough at cruising rpm?

Diesel sounds are generally not described as a "grinding" sound so it is difficult to imagine what the sounds are caused by. I drove a friend's Corolla recently and noticed a heat shield buzzing sound on acceleration. She didn't mention it, so neither did I.

2002 Corolla transmissions are not known for developing problems. Sounds when turning corneres are generally not caused by the transmission. More likely causes are wheel bearings, CV joints, and ball joints.

Nope. Both are 1.8L engines, but I assume the 93, being a wagon, weighs more. The 02 gets a few MPG more than the 93. My foot is the same on both, I'm a light footed driver. But I woulda thought the 02 would get more than

3 mPG more.

When we first got the 02, the first tankful got me 34 MPG if I recall, but then it started going down some, to the 29-30 range ( could be the AC in warmer weather now ).

But since finding this low oil problem ( last post - the oil had gone below the bottom of the dipstick ) in the 02, and getting the oil and filter changed, the MPG seems to be going up again. I cant for the life of me figure out WHY. How could oil affect MPG a lot?

No, engines are both 1.8L, same foot. But I hear the 02 is a completely redsigned, more efficient engine ( you guys said ) so I'd expect more than

3 MPG more with the 02 when the 93 is a wagon?

I'm an ET.

Very low oil.

I don't think there would be a huge difference. But also it will vary to the type of driving, and also things like how much air is in the tires, are the tires a low rolling resistance tire? And yes, even the oil can have an effect. I have the same 1.8 L in an 05 Corolla, and it uses energy saving oil, "5w-30", of which I use Castrol Syntec, and the car has low rolling resistance tires which is how it came from the factory. And I keep the pressure at 32 psi or so. The MPG will vary a good bit. City driving with the A/C on? Maybe 30 or a little higher if not a lot of stops. On the highway, I can get up to about 43 mpg doing 65 mph with the cruise on. A couple less if I do 70 mph. But it's pretty much a 40 mpg car on the road unless you drive like speed racer. I noticed on a Toll turnpike at a legal 75 mph, I'd get 37-38 mpg with the A/C on. But at night in TX, I can only do 65 mph. When I refill during my trip, it almost always calculates out to about 43 mpg at 65 mph. BTW, I wouldn't expect the older wagon to be much heavier. In general the Corollas of a few years back were slightly smaller than the 2000's models.

A 1993 Corolla Wagon with an automatic transmission has a curb weight of

2,403 lbs and its 1.8 liter engine developed 115 hp and 115 ft-lbs torque.

A 2992 Corolla LE sedan with an automatic transmission has a curb weight of

2,520 lbs, and its 1.8 liter engine developed 125 hp and 125 ft-lbs of torque.

So, the newer Corolla weighs more, has more horsepower and torque, and gets better fuel economy, even with a neglected engine - any fuel economy improvement is a pretty good deal.

In message , Ray O writes

A car 992 years in the future?

Hadnt heard of those before.

Also didn't know that synth oil saved enough in MPG to cover the extra cost of the oil.

I was all thrilled to get cruise in this 2002 but have since noticed that it drives far more aggressively than I do. When it hits a slight hill, it floors the throttle and downshifts many times when I would feel no need to, to maintain the same speed. Not good for MPG's.

Well we have lots of steep hills here, not flat like TX. :)

The wagon is quite a bit bigger, so I was expecting more difference.

It's probably not drastic. The main reason I use the synth blend is insurance against the dreaded gelling. That's not supposed to be a real issue on mine, being as it supposedly has the re-designed head, but I'd rather be on the safer side. It's good oil for city use, which is actually rougher than highway.

Mine does that too. I just manually keep the throttle up with my foot when I come to hills. If you keep the throttle up, it won't think it needs to downshift and will stay in higher gears. It's the cruise control that is making it think it needs to downshift. Not the tranny, and how it see's the load. So if you bypass the cruise with the foot on hills, it won't go through all that histrionic downshifting.. Which BTW, bugs the heck out of me when there is no real need for it.

That was in Oklahoma, which actually is pretty hilly in some places. Plenty of grades steep enough to cause downshiftitus. :/

But I don't normally take the turnpike. That was a one shot trip down to east TX. I normally take US 75/69 up to where I go. "Houston to Dallas to Eufaula OK area" Just under an 8 hour run if doing the speed limit at night. It's 450 miles which takes just at one tank of gas each way I think. I always stop and top off In Anna TX, which is maybe 50?? miles or so north of Dallas, and I'll have a half tank, and it usually takes me appx 6.7 gallons to top off. At that is at the 290 mile point. 43.2 mpg.. And that's fully loaded up with camping junk, chain saws, lawn mower, etc.. It seems to do about as good loaded down as it does fairly empty. And the A/C doesn't really make too much difference either. I do about as good in the summer with it on as I do in the winter with it off, and the windows up. Must be a fairly low drag compressor. If I make the trip in the day, which I often do coming back, I can do 70 the whole way, and I'll get 40-41 mpg or so..

Yeah I see that.

Yeah but this is the Denver area. If I gotta take over on every hill, I may as well not use the cruise.

And the tranny, speaking of that, is apparently electronically shifted? It slams when it shifts, unless I'm EXTREMELY light on the gas.

Would that they'd done a nice smooth hydrualic tranny.

By the way, I looked into those Low Rolling Resistance Tires today at Costco. The guy said they get maybe 1 MPG better mileage and it looks like they cost $165 EACH. I think that's about double what regular all season radials cost. NO thanks!

Mine is totally smooth.. No slams on shifts.

It's usually at least 2 mpg difference. And they don't have to cost that much. Many are about the same price as the regular tires. IE: the factory tire on mine was the Goodyear Integrity, which is low rolling resistance. It's about a $100 tire if you buy local. The Goodyear Fuel Max Accutread is actually a bit cheaper than the OEM tire in some cases. And there are a few others that are low rolling resistance but don't cost too much. I calculated it out, and they will pay for themselves over the life of the tire, vs a standard rolling resistance tire. But another plus, is most of those are fairly light tires, so you have less weight. Which makes the car seem a bit peppier on takeoffs, etc. I'm at 57+k miles and still on the factory tires.. But not for much longer.. They are getting thin, and both the front tires have leaks now, so I have to air them up every once in a while. Which gets old.. I'll be getting new ones pretty soon. I'm still trying to decide what I want.. But I'm kind of leaning to the Goodyear Fuel Max tires. They have pretty good reviews so far. Everyone seems to hate the OEM Integrity tires. They aren't very good in the rain, but other than that no real issues..

Oops! my bad

Shift shock or harshness doesn't have anything to do with whether it is electronically shifted or shifted by transmission pressure.

The transmisison has accumulators that act like shock absorbers to lessen shift shock, but a transmission that shifts crisply will generally have a longer life and better fuel economy. The effect of the accumulators on an automatic transmission is kind of like slippinng the clutch on a manual transmission - the friction surfaces slip more so there is more wear.

In message , Ray O writes

Everyone makes typo's, I should have said 982 instead of 992, perhaps I'm just very, very slow at replying:-)