92 Tercel - Bad Mileage and Strange Running

[macboy91si]

Hi, I just bought a little 92 Tercel 4-dr sedan. Auto, A/C, P/S, Original 3EE with 225k miles on the clock. The car is in really good shape inside and out and for the most part runs OK. I commute in this car, and I have been getting about 22-25mpg in the thing. Now, I know it's an automatic and that it will be less than the 4 or 5 speeds, but it seems REALLY low to for this car. The car also does a few other thinigs that may or may not provide info.

Transmission seems to shift gears too soon, going into 3rd by 25-30 and L/U at 35 unless you're foot is in it 3/4 way. The transmission actually shifts fine however and there is no delay when putting the car in gear. Fluid is clean and full. I know it's an A132L but I don't know if that's electronic controlled or what. I had over 250k on my old Corolla A131L and this is the same family, so I think it should be still good?

When the car is in the mid-range RPM's, it sort of bucks, like it's trying to overcome some strain. It does this pretty badly when the A/C is on, but also does it with the A/C off, when the car hits 3rd and L/U it seems to do this the most and will continue throughout the driving range if heavy load conditions are present, but to a lesser extent with RPM and speed increases. The car has new NGK's in it and the cap and plug wires appear to be new as well. All of the vacuum hoses were connected properly.

This car smokes, like most 3ee's. Puff in the morning, and a light stream at prolonged idle. It's been using about 1/2 qt per week with 65mi round trip workdays. I don't know, but it doesn't *seem* that bad yet, I've seen some much worse.

The car has great low end response and starts right up all the time. The idle will seem to create more vibrations sometime, but the RPM's don't seem to drop much if any. This may just be the mounts not dampening vibrations well.

There is a strange vibration when the car revs around 3500 that sends the dashboard into a rattling frenzy. This also happens on the interstate at speeds over 75mph. I was thinking a motor mount or something that's gotten hard, the engine transmits a lot back to the car.

There is a squeak coming from the front of the engine somewhere, I think it's the P/S pump bearing. It's hard to pinpoint, turning the A/C on or off does not affect it, only revs and sometimes it stops altogether for periods of time. There is no noticeable difference in the P/S operation that I can tell and it's full of fluid.

The temp. gauge on the dash only goes up to about 1/4 the way. I didn't know where the gauge got the reading (ECM or switch) so I don't know if that's telling me something or not. The engine fans kick in at intervals once driving around and it doesn't seem to be overheating. Heater works well and seems to put out the proper temps there so I don't think it's actually over-cooling.

I really like this little car, and I don't think it has too much wrong with it. I would like to get better fuel mileage out of it than a V-6 S-10 though. I was expecting the 30mpg mark for combined highway/city. Most of the driving is highway though. I figured I would post everything that I know at this point and see what happens

Thanks

-Tim

Here are a few pics, and the temp gauge and fuel usage.

[96paseo]

Is that where your temp gauge normally is when cruising? Seems a bit low unless the engine was still warming up when you took the pic. Looks like a bad t-stat which will make the engine run poorly and explains the poor fuel economy. On a side note, check your pick ups and ignition coil to make sure they're still in spec. If the distributor and coil are original, they're nearing the end of their lifespan. Has the EGR been cleaned? A clogged EGR pipe is good for causing strange problems in the 2000-3000 rpm range. The valve guide problems with the e-series engines have little affect on compression. A recent thread here had near perfect numbers close to the 200k mile mark.

[Tercel GTS]

^ I tell y'all he's good with tuning. I look at the picture and see a speedo at 70. He sees a temp gauge way low.

I'd also expect much higher economy as mine was getting 41mpg with a 5speed and a stock engine. Even with the turbo and 3" exhaust I was getting near 30mpg. These numbers are with the air off btw. Turning the air on really hurts the economy.

[macboy91si]

The temp guage in the pic is from the highest that it goes. I haven't located the EGR on the car yet, but I will check that. I'm pretty sure that it's the original distributor on the car, and my Corolla experienced something sort of similar before I replaced the coil to I will certainly check the specs on that. If the thermostat was sticking open, would the engine still get hot enough to cycle the radiator fans on and off? Even with the A/C on and sitting in traffic, the gauge never goes higher. The A/C doesn't actually seem to affect mileage on the car. It noticeable puts a drag on the car, but I get 22-23 with it on and 24-25 with it off. When I got the car, the A/C's lowside charge port was leeking. I replaced the valve, vacuumed the system and charged with R134 and removed a branch from the condenser fan and it's been great for about a week now. The system was professionally converted in 2002 with a new condenser. I'm assuming the car bumped something as the driver's headlamp bracket is missing the grille support.

[Tercel GTS]

Confirm the gauge reading by either having a scanner check temp from ecu or (shadetree method) get a meat or candy thermometer for about $5 at a grocery store and check coolant temp. Make sure the thermometer reads at least 250F. You'd like to see around 210-220F

[macboy91si]

Well I went out and investigated the thermostat with what I had handy. I removed the cap, and started the car and instantly antifreeze started running over from the filler. After about a minute the antifreeze was getting hot and the rate at which it was coming out was picking up. I'm going to replace the thermostat either way, can't hurt, but I don't think it's supposed to do that unless it's open, and it may be stuck open. My Corolla didn't do anything like that until the thermostat started opening.

-Tim

[96paseo]

Originally Posted by macboy91si

Well I went out and investigated the thermostat with what I had handy. I removed the cap, and started the car and instantly antifreeze started running over from the filler. After about a minute the antifreeze was getting hot and the rate at which it was coming out was picking up. I'm going to replace the thermostat either way, can't hurt, but I don't think it's supposed to do that unless it's open, and it may be stuck open. My Corolla didn't do anything like that until the thermostat started opening.

-Tim

I'd be 99% sure you've got a stuck open t-stat. Drain and backflush the system while you have it apart. You can use a garden hose. It works great. Replace the stat and refill with fresh Toyota red. You'll be suprised how good it will run with a properly working stat. When the engine doesn't reach proper operating temp, combustion efficiency is affected. The coolant temp sensor also sees this and will not allow the ECU to lean out the fuel mixture for proper fuel economy.

[macboy91si]

I feel good about that, and it makes perfect sense. Amazing how something so rudimentary can cause such issues. I haven't dealt with many t-stats sticking open, usually sticking closed and causing all sorts of havoc. I was thinking the car was running rich, it smells like an old car with the choke stuck on, and if the ECU is never getting the signal that the car is warm, then it would run it in closed loop right? In closed loop the ECU isn't even monitoring all of the sensors is it? Also the car doesn;t do the bucky studder thing while the engine is actually cold, only after you drive it a bit.

Can't wait to try this.

Thanks

[macboy91si]

Where do you get the Toyota red antifreeze?

[96paseo]

Originally Posted by macboy91si

Where do you get the Toyota red antifreeze?

Thats dealer only. About $30 bucks per gallon. Buy the concentrate instead of the premix. Get yourself a gallon of distilled water and mix it 50/50. You'll get 2 gallons out of it since 1 gallon of the premix sells for the same price. IIRC, open loop is when the engine is warming up and sensor values are changing constantly on a large scale. Closed loop is when sensor outputs settle in to where the ECU can make fine adjustments.

[macboy91si]

I get them mixed up, I was trying to say the ECU isn't going into warm operation mode. I will have to getthe green stuff for now as the Toyota dealership is about 35 miles away and closed until Tuesday . I do have a flush and fill kit though, for now it'll be green Prestone. Getting ready to head up to parts store to get a thermostat now.

[96paseo]

Originally Posted by macboy91si

I get them mixed up, I was trying to say the ECU isn't going into warm operation mode. I will have to getthe green stuff for now as the Toyota dealership is about 35 miles away and closed until Tuesday . I do have a flush and fill kit though, for now it'll be green Prestone. Getting ready to head up to parts store to get a thermostat now.

Thats alright. So long as you don't have the two different coolants mixing together. Thats why the back flush is important.

[macboy91si]

Well, I changed the thermostat and still nothing, and what a charm it is to get to . The old one looked pretty new, but there was gasket sealer everywhere. I installed the new one, and o-ring and cleaned all the crap out of there. It needed to be done right and I installed the backflush kit. It had green in it, but it was very clean.

I found the sending unit for the gauge and I suspect it's the reason for the gauge not working, the gauge itself will make a full sweep with no resistance, so I'd say that may be an issue. The switch in the housing is the rad fan switch and it seems to work. I can't get the gauge sender very well because a TVV is in the way, but I did pull the ECU's temp sender, and using a chart I found on here, it seems to be within spec. On an old Festiva I used to have, the temp gauge sender went bad and did the same thing, I wonder what the chances are. Both look original. The ECU's temp sender was measuring 1.79k ohm at room temp after 30 minutes which is about 80ish degrees F and within spec in a boiling pot of water. I don't have a thermometer to be exact but I think it's working. There also appears to be no EGR valve on the car.

The coil looked new, and it was a Toyota coil, but I will check that and see what I find. There was black dust on the rotor button, but it was also newish. I don't know how bad the O2 is and if it would even cause this without throwing a code.


-Tim

[macboy91si]

Checked the ignition coil, and the primary was way out of spec. It's supposed to be 0.30 - 0.60 ohms and mine fluctuated slightly between 2.30 - 2.53 ohms. This is what my old Corolla did when it was running strange. The secondary was within spec on the coil though coming in at 13.0 k ohms, which was higher in the spec range but still within. Going to go fork out $50 bones for one of these and a temp switch. I hope this narrows it down!

-Tim

[lt1tyrell]

My 91 automatic shows about the same reading on the temp gauge on the highway but it will go up a little bit higher idling in traffic. I always thought it seemed kind of low on the gauge but in -30 winter weather it still throws alot of heat so I just left it. I get about 30mpg combined city and highway and as high as 40 hwy. My auto trans also shifts as you explained-it shifts very early if you accelerate lightly. I think the torque convertor locks up at about 80km/h (50mph). So I don't know if they are so designed to shift like that or if it has a kickdown cable that is slightly out of adjustment.