110 - High Fuel Consumption And Slow Pick Up

[slash_lk]

Hi Guys,

I've been following AL for sometime now but this is my first post Not that happy about it being another thread about fuel consumption but I really need the help from you guys.

I have been using a 1999 Corolla AE110 (1500cc petrol AT) for about 5 years now and the current milage is around 155k KM. From the very first day the consumption hasn't been that good (around 8 km\l) but I didn't care much about it since it's an old vehicle, an auto and my first vehicle (i.e. not very driving style). But with time I was feeling that the pick up was getting slower and I have to accelerate a lot to get the vehicle up to speed, which in turn wasted more fuel. First I tried with things like fuel system cleanup and fuel additives but that didn't help. So last year I went to A$N* to get a tune up. The guy there also felt the low pick up and I got the injectors and throttle body cleaned and air filter and spark plugs replaced. There was an improvement in the pickup (though only for a few months) but no change in the consumption (in fact I think it has gone even lower now, around 7). Now after about one year the pickup is slow again and I took the car to a baas in Kesbewa and he cleaned the throttle body again and said if it doesn't help the next option is to check the fuel pump because the problem may be related to low amount of fuel coming from the pump (the reason why I have to accelerate a lot). Meanwhile I checked with T*y*t* L*n*a about whether a checkup would help, but a guy there said the problem is probably due to the age and the milage of the vehicle and if there are no warning lights no use plugging to the computer, and even a tune up may not help as I have already done it.

Now my last options are checking the fuel filter and pump but I'm not sure whether that will help either. Do you guys have any opinions about what more I can do? If this is really due to the age then I might as well have to live with it, but I know other vehicles of this model do at least 9-10 within city.

Any help is much apperciated!

Thanks.

[Crosswind]

Welcome to reality

[Fixzit]

155,000 kms for 15 year old car? Hmmm i doubt it. My 2005 IST has done 140k already.. so considering the age of your engine and transmission i wouldn't be surprised if you are getting 7 or 8 kms per liter in city driving conditions,but if this is in low traffic out station or highway economy,then you need to worry.

Still..fuel economy depends on so many factors so it's very hard to get a fixed value as your normal economy specially in driving conditions in Sri Lanka. Driving style makes a big difference too.

If there is no check engine light and no trouble codes a proper tune up and a transmission fluid change with new spark plugs should usually give you better economy until you get to a stage where you get bad fuel economy due to a worn engine and a worn transmission..

[slash_lk]

Thanks for your answer. I too have the feeling that 155K is too low, so it could be that the meter has been adjusted somewhere. On the other hand I usually drive within the city (Mount Lavinia - Wellawatte) daily so the usage there is somewhat low.

I have changed my driving style over the years and I'm getting something around 12-13 in my wife's A-Star (it's a manual though). And now I'm extra careful not to floor the accelerator and try to pickup as smooth as possible.

About driving at low traffic, what I have noticed is that the consumption is even higher when driving at high speeds. I have seen this while driving at Marine Drive and obviously due to this I'm reluctant to put it to any highway due to the fact that I might need more than one tank fill up to drive in that speed for 100KM.

One thing I missed to mention is that I've changed ATF also more than an year ago. The guy at A*N* said the engine is worn out because the plugs were burnt and asked me to fill Lanka S*p*r engine oil next time which lasts longer. I haven't changed oil after that, and the guy who checked the car recently said (after checking the dust inside the silencer) that engine is OK and there's no need to put any special type of oil. So now I'm more confused

Edited October 14, 2014 by slash_lk

[Chanaka Gunawardena]

I also have doubt about the mileage. Your mechanics idea is not so bad since fuel pump and fuel filters might cause this since due to its age.

[Rumesh88]

If a mechanic cannot find a fault without it being shown up in the form of an error code on a scanner display, then that's absolute BS. Your problem could be in one or more of the few sensors in addition to things you have already mentioned. How is your cold start RPM. Then as you drive and after the engine is warmed up does the RPM come down to around 800 without AC? If so does the car maintain same idle RPM during the rest of driving (ie whenever you slow down in traffic the idle comes down to 800) again without AC. Why I say "without AC" is to maintain some consistency for with the AC on the compressor may kick in time to time resulting in different RPM values. However, do you observe erratic idle RPM with AC on (like RPM going up as you slow down)? Also by now your wheel speed sensors may have gathered up enough dust to impair its proper operation. Get the two front ones cleaned (rear ones are built into the hub I believe). If you have erratic idle get your Throttle Position Sensor (TPS) checked with a simple multi-meter for a resistance value continuously and linearly through its entire movement range. Other sensors (MAF, O2) cannot be tested like this but at least if you can eliminate the simple ones then you can narrow down the problem. I don't think your engine is worn out to cause significant problems. Does your engine oil level drop between services?

Edited October 14, 2014 by Rumesh88

[slash_lk]

@Rumesh88, the problem is my car doesn't have a tachometer so I have no idea how the RPM changes during different scenarios. What I have noticed is that even though I have to accelerate too much to get the vehicle up to speed after a few seconds then I don't even have to accelerate, the vehicle just moves on. So what I do is I take the foot out of it and just let it go, especially when in medium traffic (maybe this is normal with AT). Btw it gives a high level of noise even in idle mode.

Regarding oil levels, I had some problems with engine oil seals sometime back and I had them repaired. After that I haven't noticed anything abnormal about it.

Do you know a place that I can go to get these things done, near Colombo south area?

Edited October 14, 2014 by slash_lk

[Rumesh88]

@Rumesh88, the problem is my car doesn't have a tachometer so I have no idea how the RPM changes during different scenarios. What I have noticed is that even though I have to accelerate too much to get the vehicle up to speed after a few seconds then I don't even have to accelerate, the vehicle just moves on. So what I do is I take the foot out of it and just let it go, especially when in medium traffic (maybe this is normal with AT). Btw it gives a high level of noise even in idle mode.

Regarding oil levels, I had some problems with engine oil seals sometime back and I had them repaired. After that I haven't noticed anything abnormal about it.

Do you know a place that I can go to get these things done, near Colombo south area?

If that is the case then the most likely cause is a faulty TPS with a blank position some where in between the idle and wide open throttle. This can be tested and if faulty can be replaced. (I believe your TPS is a four wire device but the same theory applies for three wire ones as well). In fact you don't really need a tacho to subjectively identify high or low revs. You can just listen to the engine "purr" and determine if the speed is high or low. There is a guy in Moratuwa whom I can recommend and if you are interested send me a PM.

Edit: Just thought of leaving a note further explaining the condition of some of the sensors in these cars which are now over 15 years old and done well over 150k kms. TPS being a mechanical sensor tends to under go usual wear and tear just like the volume control of an (old analog) audio amplifier (remember the intermittent cracking noise when you turn a worn out volume control). ECU determines the idle cycle based on the TPS reading at the home position and the Vehicle Speed Sensor( let's leave the things like ECT, AC and electrical loading aside). This is why you need to take a look at both TPS and VSS if you have problem with your idle/fuel consumption particularly if the car is over 10 years old and done over 100k kms. But most of the time our mechanics concentrate on the throttle body, MAF, ECT and O2 sensors ignoring the other simple ones.

Edited October 15, 2014 by Rumesh88

[slash_lk]

Update: I showed the car to the guy at Moratuwa that Rumesh88 suggested. He found out that the set of plugs fitted during the last tune up was not the correct type and that the engine oil has become 'chocolate' like. He suggested to do another tune up because otherwise it's difficult to find the real reason for the problem. I went ahead and then it seemed like the distributor condenser has become black, so that also was replaced. After that was done and the plugs replaced, he did a compression test and found out that first cylinder had low compression (around 8). And there were air bubbles coming out from the radiator inlet also. So it seems like there is a problem with the gasket and I need to have it repaired. He said there is no problem with the TPS or the O2 sensor and that he has advanced the engine a bit, so not the pickup should be OK. It seems a bit better so far and I have to drive a few days more to see whether the efficiency has improved. The guys is quite knowledgeable and attentive, if the situation has got better I will give his details on the other thread.Meanwhile I'm planning to show it to another mechanic to confirm whether there is really a problem with the gasket, and if so get it repaired.

[aps]

Rumesh88 like to know the contact in moratuwa, i have long standing TPS issue which not fixed with new.

slash_lk

do you see any mayonnaise color cream in your oil cap ? also little water drop in radiator

[Rumesh88]

Rumesh88 like to know the contact in moratuwa, i have long standing TPS issue which not fixed with new.

PMed you the contact.

@slash_lk - thank you for giving a feedback. However, you need to do a few more things it seems.

[slash_lk]

@aps: couldn't see anything abnormal on the oil cap. Coolant level has been dropping for sometime though. There was a leak that I got fixed but still it's going down slowly. Guess it's the gasket leak.

@Rumesh88: Yes unfortunately