My 1996 Celica GT runs rich. Please help!!, Otherwise the car runs great. Options

[JohanFer]

Hi everyone, I write to see if I can get some insight into what could be wrong with my car. I bought a BlueDriver scanner to see how then engine behaves and get information from the computer, get 0 to 60 data, and learn more from the data the car spits out, I am a scientist and am crazy about data handling. Anyway, I noticed that the short term fuel trim (STFT) goes negative, making the Long Term Fuel Trim (LTFT) push it to the negative limit of -14%. I have learnt what it means and realize that the car is running rich and therefore the computer is trying to compensate. The thing is that I don't know what could be wrong.

I was told that the problem could be an exhaust leak, since the car had some work on the engine head for it had overheated, this was also supported by a light click-clak sound when the engine was cold at idle and by a small cloud of white smoke when the car was started. So when I took it to the mechanic, he replaced the seals with new ones and brushed the exhaust manifold to clear the leak. The sound is gone, but I still get a now smaller cloud of white smoke when I start the car in the morning and after it has been off for a few hours. The car continues to run rich and I don't know what it could be. I get about 24 MPG and drive conservative.

Any ideas on what it could be? Are the any test I can do to check for possible problems. I know the O2 sensors work fine, since the voltages work as expected. Please help!!!

Oh, and I have a somewhat unrelated question: Is the 3SGTE engine OBDI or OBDII?

Thanks.

[Jmk91]

http://www.6gc.net/howto/reset_your_air_fuel_ratio

Try this... Also 3sgte is 1 or 2 depending on year and generation of the 3gste.

[Box]

Weak spark could cause an issue, leaking injectors could cause an issue, too high fuel pressure can cause an issue. The engine losing compression will cause a decrease in efficiency. There are many things that will just need gone through to find it. I would start with a compression check and then checking spark and the fuel pressure after the pressure regulator. Get someone to start the car with you behind it in the morning or after it's been sitting to see what the smoke is, it could be the injectors are leaking and the puff of smoke is fuel. If you've ever had it be hard to start and opening the throttle helped that would indicate such. Generally water is white, oil is blue, and fuel is black. Though it's been more in my experience that fuel is grey as for it to be black it'd be running like complete ****.

The Japanese market engines are JOBD, so technically neither.

[Jmk91]

Mr2 in the states came with 3sgtes as well tho. You can use a mr2 3gste in 6gc.

[Box]

They were the Gen II, which is what was also used in the 5th gen All-Trac. Good luck finding a USDM one though. You're also giving up 50 horsepower for a more complicated install. Plus it's still only OBD-I and being he's in California his only options will be to go with a V6 as it's a newer engine than the model year and is OBD-II.

If his was a '94 or '95 model year finding a USDM Gen II would be worthwhile since he's in California. Most here don't bother with the Gen II for a reason though.

[Smaay]

-14 is not that bad. its not maxing out. what was the driving condition when you were at -14 if you were idling thats normal. when you go full throttle it should be close to 0.

all USDM 3S-GTE were ODB-I and a 3S-GTE swap is not legal in CA. only a V6 swap is legal.

[Box]

Not even a '95 MR2 Turbo 3S-GTE into a '94 Celica?

Anyhow, the GT was rated at 22/28 new, so if you do mostly city driving with the A/C on 24 or so would be about right I suppose.

[JohanFer]

-14 is not that bad. its not maxing out. what was the driving condition when you were at -14 if you were idling thats normal. when you go full throttle it should be close to 0.

all USDM 3S-GTE were ODB-I and a 3S-GTE swap is not legal in CA. only a V6 swap is legal.

Oh, the -14 is pretty much constant. It happens when I idle and when I accelerate the car or even if cruise it, pretty much all of the time except when I accelerate hard, when it goes to close to zero. I heard that the long term fuel trim is supposed to be the memory saved and it is not supposed to change that often. I don't know, but I'll try different things to see what happens.

[JohanFer]

Not even a '95 MR2 Turbo 3S-GTE into a '94 Celica?

Anyhow, the GT was rated at 22/28 new, so if you do mostly city driving with the A/C on 24 or so would be about right I suppose.

I know, but when i go to the thread about MPG our Celica's give us, people boast about way higher gas economy, even with GT, I think. If you go to fueleconomy.gov my data is the only one for our car. It is 24.

[Box]

Make sure the tires are properly inflated and the brakes aren't dragging any. Also most of those numbers are people doing a constant 55 or 70 with no stop and go traffic. Which the auto was rated 23/30 new, so I don't know then. If your trans is slipping and if the torque converter isn't locking up in overdrive that'll kill your efficiency.

[richee3]

24 sounds about right for a 3S-GTE swap. The highest I've heard out of one has been 27 on the highway, and that one may have had an E153 bolted to it.

[cardshark525]

I have a 3S-GTE swap with an E153 and on a 200 mile highway run at about 75-80mph I got 29mpg.

24 is perfectly normal from my experience driving say... 70% highway 30% in town and actually punching it on ramp and stuff.

I think the absolute worst I've gotten in it was 19.




Edit:
When I still had my old '95 GT I would average anywhere from 23-27 just depending on driving style. Best ever was about 30 or 31, and worst ever was 20 I think.

This post has been edited by cardshark525: Mar 6, 2015 - 7:08 PM

[Box]

He has a 5S with the auto.

[cardshark525]

He has a 5S with the auto.

So 24 then wouldn't be unreasonable.

Is it mostly city driving?

If this is highway I would say there's an issue to be looked into, however if it's 24 city... that's..... that...

[Box]

I dunno, I alluded to it and he never said. 24 city with the A/C running 24/7 would be good, 24 highway with no A/C would be terrible. Being he's in LA I'm leaning more towards the first.

[JohanFer]

Hi guys, thanks for the input. I do city and highway driving, I would say more like 60 hwy and 40 city, plus traffic. I do turn on the AC a lot in the summer, but not in the winter, has it has been for the last months. Anyway, I bring up this issue because the car is running rich and I was wondering if 24 combined was OK.

[Box]

19/26 is the revised and apparently 22/29 was original, so 24 would be acceptable.