Erratic Fuel Economy - 1991 Camry SV21 / 3S-FE Manual Sedan

[iinmn]

I just purchased a cheap 1991 Camry (SV21) Manual Sedan, CSi model, 5sp manual with 3S-FE engine (car was made in Australia)

It drives very well, purchased it with 138,000km on the Odometer.

I always closely watch the fuel economy. I filled it up just after I purchased it and headed from the suburbs of Melbourne to South-West Gippsland where I live (150km away). I then had it serviced. On the first tank which included time when it was serviced I managed, 8.2 l/100km (or 12.2km/l), which I thought was rather poor. This was over 647km which included almost exclusively of long trips (normally around 60km return journey) and a trip to Melbourne and back. Nearly 100% country highway/freeway driving. Hardly any red lights or idling, or short trips (under 30km!). I drive very carefully and conservatively using 5th gear at close to 100km/h and going to 4th for some sustained climbs on the highways around here.

After I filled the tank a second time I went on a 100km return trip, which included a fair few hills and had 2 kids and an adult passenger as well as a whole lot of shopping on the return journey. I filled up the tank at the end of this trip using the same pump as before and filled it to the extent that some fuel overflowed. This time I had a ridiculously good fuel economy of 6.1 l/100km (or 16.2km/l).

I then filled it up again and drove it to nearly empty, this was mainly a few trips in the area (typically 50km-70km return journey) and another trip to Melbourne. It should be noted that most of my driving occurs in early morning and in the evening, when it is cold. On this tankful I got 8.3 l/100km (or 12km/l).

I then filled it up about half-way to Melbourne and filled it up again on my return. This time I got a respectable 6.9 l/100km (or 14.5km/l) [for 268km]. This was driving late afternoon and early afternoon the next day (i.e. during the warmer time of day), and about 30km of suburban driving in Melbourne.

The tank is nearly empty again and I have just passed 600km I don't think I will even break 9.0 l/100k (or 11.1 km/l). This time the 600km is made up of a series of trips in early morning and evening of around 60km return journey, like always at a steady and careful 100km/h no red lights, no idling, mainly on 5th gear, shifting to 4th on some sustained climbs.

I always reverse into the driveway when I come back home, and I do notice that the exhaust smells a bit rich, normally you would expect a car's exhaust to have no perceptible odor after a long trip (30km+) when it is fully warm. I talked to the local mechanic, he suggested that the Oxygen sensor might not me working and that it might be worth replacing, only to find out that that this version of the Camry, even though it was fuel injected did NOT have an oxygen sensor at all ! -> is that normal??

He also suggested that the air flow meter might be getting stuck, and suggested examining it and making sure it's flap was moving correctly.

Do other Australian Camrys SV21 (1987-1992) with 3S-FE 2.0 litre engine have an Oxygen sensor?

Can anyone suggest any other solutions, I live in the country and drive on highways with hardly any short-trips I would expect around 7 l/100km (14.3 km/l)CONSISTENTLY.

Is that a reasonable expectation?

I keep the tyres inflated at close to 32 psi (220 Kpa), and regular check the level of the oil and engine coolant. I don't keep the air-conditioner on (it's Winter now).

Any suggestions or ideas welcome.

[Tash]

I'm certainly no mechanic or expert but maybe a good injector clean out and perhaps new spark plugs would be worth investigating? The tyre pressure also sounds a tad low to me, I would be up around more like 34/36 PSI, especially if you're doing regular freeway trips. If you trust the mechanic you've mentioned it might be worth getting him to have a closer look at it, although I'm not that alarmed by your fuel consumption though it does fluctuate a bit, I don't think you're ever going to average a consistent 7 litres/100k all the time. Even in my Gen 6 Camry I've got fluctuating fuel consumption, anywhere between mid 7's to mid 12's.

[iinmn]

I'm certainly no mechanic or expert but maybe a good injector clean out and perhaps new spark plugs would be worth investigating? The tyre pressure also sounds a tad low to me, I would be up around more like 34/36 PSI, especially if you're doing regular freeway trips. If you trust the mechanic you've mentioned it might be worth getting him to have a closer look at it, although I'm not that alarmed by your fuel consumption though it does fluctuate a bit, I don't think you're ever going to average a consistent 7 litres/100k all the time. Even in my Gen 6 Camry I've got fluctuating fuel consumption, anywhere between mid 7's to mid 12's.

The car has continued to achieve poor fuel economy 8.6 l/100Km and 8.3 l/100Km (or 27.2 and 28.4 MPG) for the past 2 tankfuls. Again this was achieved with driving on 100% rural highways, as described before. For the last tankful the tyres were at 35PSI.

I took it to the Toyota dealer nearby, and got them to have a good look at it. They checked:

1. engine compression - OK

2. Fuel Pressure - OK

3. Throttle position sensor - OK

4. Cold start injector for leaks - none found

5. Engine temperature sensor (I assume they mean coolant temperature sensor) - OK

6. Ignition timing - OK

7. Check diagnostic fault codes - all clear

8. Checked Air Filter - OK

-->9. Air flow meter - Variable resistance not within Specifications

they also reported:

* spark plugs showing some wear

* Spark plug tubes need to be resealed - oil leaking into cavities

* Injectors may benefit from servicing

They quoted me a hefty A$600 (=US$520) to changeover the air flow meter (AFM) if it could not be repaired. They would send the AFM to a specialist first to see if it could be repaired, the $600 would be only if it had to be replaced.

Is this the going rate for an Air Flow Meter for an 18 year old Camry?

I will go ahead with the other recommendations as it won't cost much and the spark plug tubes will eventually give me some grief if I leave them. I just want to find out what the reasonable cost for the Air Flow Meter is before I go ahead with it.

The mechanic was not 100% confident that this work would fix the problem, but thought it was the most likely solution.

[Oybek]

I just purchased a cheap 1991 Camry (SV21) Manual Sedan, CSi model, 5sp manual with 3S-FE engine (car was made in Australia)

It drives very well, purchased it with 138,000km on the Odometer.

I always closely watch the fuel economy. I filled it up just after I purchased it and headed from the suburbs of Melbourne to South-West Gippsland where I live (150km away). I then had it serviced. On the first tank which included time when it was serviced I managed, 8.2 l/100km (or 12.2km/l), which I thought was rather poor. This was over 647km which included almost exclusively of long trips (normally around 60km return journey) and a trip to Melbourne and back. Nearly 100% country highway/freeway driving. Hardly any red lights or idling, or short trips (under 30km!). I drive very carefully and conservatively using 5th gear at close to 100km/h and going to 4th for some sustained climbs on the highways around here.

After I filled the tank a second time I went on a 100km return trip, which included a fair few hills and had 2 kids and an adult passenger as well as a whole lot of shopping on the return journey. I filled up the tank at the end of this trip using the same pump as before and filled it to the extent that some fuel overflowed. This time I had a ridiculously good fuel economy of 6.1 l/100km (or 16.2km/l).

I then filled it up again and drove it to nearly empty, this was mainly a few trips in the area (typically 50km-70km return journey) and another trip to Melbourne. It should be noted that most of my driving occurs in early morning and in the evening, when it is cold. On this tankful I got 8.3 l/100km (or 12km/l).

I then filled it up about half-way to Melbourne and filled it up again on my return. This time I got a respectable 6.9 l/100km (or 14.5km/l) [for 268km]. This was driving late afternoon and early afternoon the next day (i.e. during the warmer time of day), and about 30km of suburban driving in Melbourne.

The tank is nearly empty again and I have just passed 600km I don't think I will even break 9.0 l/100k (or 11.1 km/l). This time the 600km is made up of a series of trips in early morning and evening of around 60km return journey, like always at a steady and careful 100km/h no red lights, no idling, mainly on 5th gear, shifting to 4th on some sustained climbs.

I always reverse into the driveway when I come back home, and I do notice that the exhaust smells a bit rich, normally you would expect a car's exhaust to have no perceptible odor after a long trip (30km+) when it is fully warm. I talked to the local mechanic, he suggested that the Oxygen sensor might not me working and that it might be worth replacing, only to find out that that this version of the Camry, even though it was fuel injected did NOT have an oxygen sensor at all ! -> is that normal??

He also suggested that the air flow meter might be getting stuck, and suggested examining it and making sure it's flap was moving correctly.

Do other Australian Camrys SV21 (1987-1992) with 3S-FE 2.0 litre engine have an Oxygen sensor?

Can anyone suggest any other solutions, I live in the country and drive on highways with hardly any short-trips I would expect around 7 l/100km (14.3 km/l)CONSISTENTLY.

Is that a reasonable expectation?

I keep the tyres inflated at close to 32 psi (220 Kpa), and regular check the level of the oil and engine coolant. I don't keep the air-conditioner on (it's Winter now).

Any suggestions or ideas welcome.

Hi i purchased the same car with yours Camry sv21 manual 1989 sedan 3S-FE 2.0 motor, and consupmtion is about 8,9 L100km , i used to drive the same car but automatic transmission fuel consuption was 6.7, 7 L 100 km

[iinmn]

Hi i purchased the same car with yours Camry sv21 manual 1989 sedan 3S-FE 2.0 motor, and consupmtion is about 8,9 L100km , i used to drive the same car but automatic transmission fuel consuption was 6.7, 7 L 100 km

What sort of driving do you do? suburban or rural highway/freeway <- & what combination of the 2

Since my earlier posts I have had the radiator thermostat changed. I had noticed even after the car had warmed up, the temperature gauge would plunge after going down a decent hill. It was also generally erratic, but hovered around the 30% level (between cold and hot). This accounts for the previous high RPM idle, and I thought would fully explain the bad fuel economy as a cold engine is never as efficient as one fully warmed up, but this turned out not to be the case.

After the thermostat was changed the gauge sits solidly at the 50% mark (i.e. 12 O'Clock position) after a relatively quick warm up, even on long descents with the heater and fans on full blast.

The first tank fill up after the thermostat change I got a much better 7.5 l/100km (driving 90% rural highways / freeways with nearly 10% suburban driving), this was good but I was still hoping for a result closed to the 7.0 l /100km. I am using our second car more at the moment, so the Camry is hardly being driven at the moment, but I am close to filling it up again, but judging from the position of the fuel gauge and the number of km driven, I think fuel economy will be in the 7.5-8.0 l/100km range, so this is disappointing, but still somewhat better than before. It will be interesting to see if the warmer weather will start to make a difference.

Since my previous post, I had the fuel injectors cleaned and the spark plug tubes resealed, I also swapped over the AFM from a wreck, although the part number was not identical, I think there was 1 digit difference. I also treated the engine with Subaru Upper engine cleaner as per the instructions on the can.

So, make sure your radiator thermostat is OK, by watching the temperature gauge when driving, it should sit close to the 12 O'Clock position solidly, if it fluctuates get the thermostat replaced. Getting the fuel injectors cleaned doesn't cost too much, so it is worth a try, and give the engine a treatment with Subaru Upper engine cleaner (available from any Subaru dealer). Also like me get the mechanic to test: compression, fuel pressure, throttle position sensor, engine temperature sensor, Cold start injector for leaks (as per list).

Good luck and let us know the results.

[Ozzcaddy]

I agree with Tash regarding the tyre pressures. In olden days 32 psi was the norm, but in recent times it is 34 - 36 psi. Main reason for higher pressure as explained by tyre fitter, to prevent edge of tyres wearing out as quickly. The higher pressure may give a firmer ride, but your tyres won't wear out as fast and you might gain some fuel economy.

You've said that you filled up after various trips, but you haven't told us what fuel you fill up with. This may contribute to erratic fuel consumption, especially if you have filled up with E10. Hope the repairs that you have had done helps with the problem.

Ozz

[iinmn]

I agree with Tash regarding the tyre pressures. In olden days 32 psi was the norm, but in recent times it is 34 - 36 psi. Main reason for higher pressure as explained by tyre fitter, to prevent edge of tyres wearing out as quickly. The higher pressure may give a firmer ride, but your tyres won't wear out as fast and you might gain some fuel economy.

You've said that you filled up after various trips, but you haven't told us what fuel you fill up with. This may contribute to erratic fuel consumption, especially if you have filled up with E10. Hope the repairs that you have had done helps with the problem.

Ozz

Before the radiator thermostat was changed I drove over 5000km averaging 8.3 l/100km, I either filled up with regular ULP (0% ethanol) or premium, but there was no difference between the 2. I have never put in any fuel with ethanol in it. Also since the 2nd or 3rd fill up since buying the car I have put the pressures up to 36psi all around from the previous 32 psi, but this didn't help

[Ruxis]

I'm certainly no mechanic or expert but maybe a good injector clean out and perhaps new spark plugs would be worth investigating? The tyre pressure also sounds a tad low to me, I would be up around more like 34/36 PSI, especially if you're doing regular freeway trips. If you trust the mechanic you've mentioned it might be worth getting him to have a closer look at it, although I'm not that alarmed by your fuel consumption though it does fluctuate a bit, I don't think you're ever going to average a consistent 7 litres/100k all the time. Even in my Gen 6 Camry I've got fluctuating fuel consumption, anywhere between mid 7's to mid 12's.

The car has continued to achieve poor fuel economy 8.6 l/100Km and 8.3 l/100Km (or 27.2 and 28.4 MPG) for the past 2 tankfuls. Again this was achieved with driving on 100% rural highways, as described before. For the last tankful the tyres were at 35PSI.

I took it to the Toyota dealer nearby, and got them to have a good look at it. They checked:

1. engine compression - OK

2. Fuel Pressure - OK

3. Throttle position sensor - OK

4. Cold start injector for leaks - none found

5. Engine temperature sensor (I assume they mean coolant temperature sensor) - OK

6. Ignition timing - OK

7. Check diagnostic fault codes - all clear

8. Checked Air Filter - OK

-->9. Air flow meter - Variable resistance not within Specifications

they also reported:

* spark plugs showing some wear

* Spark plug tubes need to be resealed - oil leaking into cavities

* Injectors may benefit from servicing

They quoted me a hefty A$600 (=US$520) to changeover the air flow meter (AFM) if it could not be repaired. They would send the AFM to a specialist first to see if it could be repaired, the $600 would be only if it had to be replaced.

Is this the going rate for an Air Flow Meter for an 18 year old Camry?

I will go ahead with the other recommendations as it won't cost much and the spark plug tubes will eventually give me some grief if I leave them. I just want to find out what the reasonable cost for the Air Flow Meter is before I go ahead with it.

The mechanic was not 100% confident that this work would fix the problem, but thought it was the most likely solution.

hey this does seem kind of low, ive been driving my beloved sv21 '88 since i was on my L plates (3 years ago), ive monitored my fuel consumpsion every tank i have ever bought. i usually get 650 kms out of my 55L tank, this is driving on a 80/70 km/h for a 15 min trip twice a day with about 15 red lights usually get about 5 of them getting me.

have you tried different fuel aswell? i find e10 actually works best for me suprisingly. also my different driving techniques changed the economy too. my dad showed my a forum saying 4 cylinder engines have better fuel consumpsion if you get to 5th gear faster, i tried driving like gramps and driving it as a p plater should (gasing it off the line), which has shown a better result! and thats how i get the 650 kms every fortnight.