What do I need to fix?

[klloyd]

Ok, I have just found these forums, awesome! Been reading a lot! HERE is my deal... My 87 4wd wagon, is an automatic, 3 speed, push button 4wd. I see you guys getting insane mpgs on here, I AM LUCKY TO SEE 17!!!! Car runs pretty well, seems quite gutless compared to my 3 cly geo though. The geo is a 5 speed, and feels like a race car compared to the tercel. I thought it was normal until I found this site. I mean, at 65, its is screaming! Wound out pretty tight. I understand back in 87, 55 was the normal speed for places, so I can get that. Yet I'm seeing guys claim on here mpg in the 30s! I have a suburban, 350, 4x4, that gets better mpg than my tercel. Just let me know what I need to start looking at, and I'll start fixing, looking, something. I would kill to have this thing get in the 20's even. Man, how awesome that would be!

[dlb]

welcome, klloyd.

the automatics definitely get lower mileage than the manual transmissions, and that is normal for it to rev so high at hwy speeds. i put a dash cluster with a tach from an sr5 in an automatic and it revved around 3000 at 55 mph. i hate the auto transmissions. anyway, here is a good point of reference for you for fuel economy. this is the fuel log of forum member aubrey falconer. he has a well-maintained automatic t4 and appears to average 25 mpg.

http://www.fuelly.com/driver/aubrey/tercel

17 mpg is far too low. something is wrong. here is my go-to checklist when i find fuel economy is the shits:

tire pressure
wheel alignment
extra cargo weight
ignition timing
air filter
dizzy rotor
dizzy cap
spark plug wires
spark plugs
vacuum leaks
AAP diaphragm
dragging brakes

if you're not familiar with the vacuum routing for these cars, take a look at the factory service manual which is available here:

https://tercel4wd.com/forums/viewtopic.php?f=2&t=8103

make sure all your vac lines are routed correctly, and none are loose or disconnected or cracked or broken. also check all diaphragms (vacuum advance, choke opener and choke breaker) because if they are ruptured, they are also vacuum leaks. disconnect and plug the lines going to those things if the diaphragms do not hold vacuum. check the AAP diaphragm as per the FSM test. very easy to test, easy to replace too. it's a common culprit of poor mileage on these carbs but usually you will get some performance issues as well if it has ruptured.

good luck, let us know how it goes.

[klloyd]

You gave me some good points to start. My tires are new and pretty well maintained. Goes straight as an arrow down the road, I have nothing in it, ... Timing, that might be something I can look into. Air filter was changed with oil, rotor and cap, ..... got me there too. Cant remember doing it. Plugs and wires, yes, done last year. Brakes I'm pretty sure arent dragging. What is an AAP diaphragm? I never heard of it, so it could be bad!

[dlb]

the AAP is the 'auxiliary acceleration pump.' when the engine is cold, vacuum is supplied to the AAP, which pulls on a rubber diaphragms and enrichens the fuel mixture. once the car is warmed up, vacuum is no longer directed to the AAP so the diaphragm closes and the mixture leans out. if the diaphragm is ruptured, the car will run rich all the time, and fuel will also get sucked up the vacuum line to the TVSV (the little tree-looking thing at the front of the engine, where there upper rad hose connects to the engine) and throughout other parts of the vacuum system.

the test for the AAP is in the FSM on page 142 (or EC-54). super easy so give it a shot. if bad, it can be replaced without even removing the carb.

[xirdneh]

when all else fails try a different carb
i would grab one off a parts car somewhere
if you take the carb apart and re-build it
check the numbers on the primary main jet screw
should be 101 or 103 max
my experience with biggers numbers is lower mpg (but if car runs well, much more power)

[Petros]

Welcome to the list!

17 mpg is way too low, even for an automatic. DLB gave you a good list, but I have also found that the timing belt could also be off a tooth or two and still seem to run normal, but gets crap for economy. That is an easy check, take off the upper timing belt cover (you have to pull the fan belt and remove the water pump pulley, three-10mm bolts), and get the timing mark on the front pulley at zero TDC, and than inspect the mark on the front of the head through the hole on the cam sprocket (see the picture in the FSM). BTW, I would not necessarily trust that a mechnic got it correct, they can mess up too. so it is best to verify it yourself, after you have checked everything else out. If you have trouble getting the timing in the correct spot, that is a clue the cam timing could be off. Also, I have seen bad/intermittant spark to cause poor economy, even though it seems to run okay. Easiest to just replace the whole distributor assembly from a junk yard at a test (I always keep a spare one around just for that reason).

Good luck

[dlb]

you should also check the automatic choke to make sure it's wide open once wram. i have to add that to my aforementioned list.

[Mark]

I have an '84 auto and I get about 30 mpg on the highway and about 26-28 around town. I drive like a granny though.

[Mark]

I have an '84 auto and I get about 30 mpg on the highway and about 26-28 around town. I drive like a granny though.

Also, I removed and plugged the vacuum line to the AAP since the diaphragm in mine was leaking creating a vacuum leak and a rough idle. I don't notice any difference unless I try to accelerate quickly from a stop in cold weather. Then it hesitates and almost stalls unless I quickly let off on the gas pedal and try again more gradually.

[keith]

You all are forgetting the mechanical advance in the distributor. The weights get stuck after awhile and mileage drops like a rock. There is a little hole in the bottom of the distributor that you can spray some penetrating oil up into or you can remove the distributor and take it apart to make sure they get lubed and freed.

https://tercel4wd.com/forums/viewtopic.php?f=7&t=3700

The vacuum advance could also be shot, you just have to replace that with a new one.

[dlb]

You all are forgetting the mechanical advance in the distributor. The weights get stuck after awhile and mileage drops like a rock.

that would show up when he checks the ignition timing, which i mentioned. that's how i found a stuck mechanical advance on one of my tercs before.

[klloyd]

Wow! You guys have given a TON of things to look at. I am going to go with AAP thing first, as the car ALWAYS runs rich. So much so it smells flooded often. And I will also do the full tune up on it, as I dont remember when it was done last. I do no I've not changed the timing belt since I had it, so it may be a thing to do while I have it down.
As far as running, it "runs" perfect, if there is a such thing. Can get it up to 65-70, but its screaming. If you take a low speed hill, look out, you might have to get out and walk. It has less, WAY WAY less power than a 3cyl geo. Put it under load without having the rpms high, it will bog down. It may be getting too much gas. OR, not burning what its getting.... So many places to look. I will try and tear into it this weekend. I've got it down due to needed a new cv axle. I plan on putting it on next weekend or so. If this little care could really get above the 20's, WOW what a great little car it would be! I had lost hope until I found this site. Thanks!

[klloyd]

I have ONE more quick one... Which tercel do I show in all the auto parts stores to get the right parts? There is no 4WD that shows in any of the major chains.

[dlb]

no, i had the same experience with the automatic t4 i fixed up. thoroughly gutless. it starts out strong if you stomp on the throttle but that's it. everywhere else, it's a turd. hills in low revs were awful, highway speeds were wound out, generally just gutless. but if you're doing a lot of city driving or have a bum leg or if you simply never learned to drive manual, i think they have their place. i'm sure they're still awesome in the snow.

select '86 as your tercel when looking for parts. if you look up '87 tercels you will often not get the option for 4wd. other members have experienced this too. it's because even though toyota made 4wd tercs untill '88, they started making the tercs with the 3E engine in '87, so i guess 86/87 is the cutoff most parts places have for the 4wd.

[marlinh]

I drove an automatic for a while and hated it. The high revs was disconcerting. Unbelievable that Toyota couldn't have designed a three speed with an overdrive. I'd have to check my records but the mileage wasn't as high as my manual trans. When you are checking plugs, make sure the gap is set properly. That will make a difference in mileage. I know dlb mentioned plugs, but the gap does need to be measured.