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If you still cannot find your issue, I recommend you take it to a shop that specializes in Asian makes that has a Toyota specialist… They can probably find the issue in less than an hour…
Not trying to insult you, but P0171’s are not usually that hard to fix on a Corolla, and even easier on the 98 and 99 because they were non-vvt and had no MAF sensor.
-Karl
Sorry guys, I have not done squad. Smog is due in January. Got to find some time to fix it. I know it’s probably something easy. There’s no vacuum leak. I suspect the O2 sensor. I need to get my hands on a scanner to check the switching data on the sensor. Does the upstream goes out more often than the downstream one?
Thanks.So I bought the Denso O2 sensor from Rock Auto, replaced bank 1 and the check engine light is back again. What is the next step? No exhaust nor vacuum leak that I could see. I guess only fuel injector and Fuel filter/pump in the gas tank.
My wife took the car to a mechanic and he said for $350 he could fix the code with something call fuel pressure relay. I wonder if he means fuel pressure regulator?
OK, I’m the new guy resurrecting the old topic.
I’ve been working on a 99 Corolla. I pulled the engine, replaced the rings, etc. The engine runs strong & doesn’t smoke. But it has the P0171 and is idling too high. I’ve replaced the PCV valve & most of the vacuum lines. I’ve tested for leaks with the carb cleaner trick. Nothing seems to indicate a vacuum leak. When I got the car it already had the catalytic converter removed and replaced with a piece of pipe. It also needs a muffler. The old one has some serious ventilation in it.
I have a decent Innova scan tool. It will give me live data. Part of the problem is I don’t know what the data means. I don’t have any way to know what the values should be.
Thank you for your input!
Sometimes you get lucky with a spray test, but to find vacuum leaks reliably, you need to smoke test.
What are your long term fuel trims at idle and at 2400-3000 RPM?OK. Here we go. I’ve been driving it a few days. Interestingly, the fuel mileage has increased from 20mpg to 25mpg. Here’s the current codes:
P0420
P0420 (listed again for some reason)
P0441
P0446
So, this is different than when I started.
ECT 169
STFT B1(%) @ 2900rpm bounces all over the place between +2.3 & -3.9, at idle (1900rpm) it’s pretty steady at -11.
LTFT B1(%) @ 2900rpm pretty steady at -3.1, at idle (1900rpm) it stays at 0.
MAP (inHG) 10
Spark adv 16.5
TPS (%) 10.2
O2S B1 S1 (V) bounces all over from 0.090 to 0.565
STFT B1 S1 (%) 19.5
O2S B1 S2 (V) pretty solid around 0.895
STFT B1 S2 (%) 99.2
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