2001 Corolla - Poor Acceleration/Power

[m.salah]

Alright, so my Corolla is sitting at 210K+ miles and for the past year or so, the car has been hesitating at acceleration. Later found out it was a random engine misfire when it started to get bad (holding up traffic).

I ended up getting all the spark plugs changed as well as the valve cover gasket (I think that's what it's called) since I heard that was one of the cheaper options. It ended up helping, but only by a little. I'm still going really slow when I'm coming out of a stop and sometimes it struggles with changing from first gear (sounds like RPM gets really high and then finally switches, which jolts the car back a bit). Anyway, I'm wondering what my options are since I'm on a really tight budget and although I can't afford to spend a ton of money on repairs, I also can't afford to lose this car.

I've been running some Chevron fuel system cleaner (on the third cycle) and I haven't seen any difference in performance. Oddly enough though, when I went to Auto Zone to get my computer scanned (engine light hardly ever works), it came up with P0171, P0125 and P0150. Just a month and a half ago I went and it came up with a Cylinder 2 misfire. I don't know how that went away seeing as the car runs exactly the same.

My car also makes a really loud sort of gurgling/rattling sound whenever I accelerate. It seriously sound like death. This didn't start happening until a couple of months ago. It sounds pretty bad in idle as well but not as bad as when I'm accelerating on the road.

So TL;DR

- Had a random engine misfire
- Changed spark plugs and valve cover gasket
- Then it became a Cylinder 2 misfire
- Started applying fuel system cleaner
- Now have P0171, P0125 and P0150 but no misfire (even though car runs exactly the same as when I had a misfire)

What are my options here? I definitely want to get my MAF cleaned since I heard that's cheap. O2 sensors I hear are expensive so I'll save that for last. I have a weird suspicion that my fuel injectors suck but now that the car isn't even giving me a misfire reading and I'm using fuel system cleaner, I don't know what to do about that. I read somewhere that if the car has 200K miles, you need like five cycles of fuel system cleaner to see results but I don't know if that's true or not.

I have a ton of questions since I don't really know too much about cars so I'm sorry for the inconvenience. Thanks in advance.

 

[Kev250R]

It's hard to say for sure, especially since you didn't mention which engine you have but I'd start with the basics:

You had the plugs changed but did they change the plug wires? If the wires are worn (nearly impossible to tell just by looking at them), that can cause a mis-fire condtion. You should be able to check the continuity of each wire using a VOM.

Unfortunately changing the Valve Cover gasket won't fix the problem you're describing. I'm not sure that adding fuel injector cleaner will do much either.

The rattling noise could be a timming chain (if your engine uses one) which is nearing the end of it's life or (more than likely) the timming chain tensioners which when they fail (a common Toyota problem on some of their other engines) cause the timming chain to flop around a bit which makes a fair amount of racket.

Of course rattling could also be ignition timing which is off.

When was the last time the air and fuel filters were changed? A clogged fuel filter could cause some of the symptoms you've described.

Kevin

 

[Scott O'Kashan]

m.salah - To correctly address the problems you are having with your car, first we need to stop replacing parts, immediately. Don't replace anything. Stop.

Diagnose.

Randomly replacing parts is an extremely expensive way to try and address problems with a vehicle. The trash can gets filled up with perfectly good parts, your wallet gets vacuumed empty of money and the employee's at discount auto parts stores laugh when they see you coming.

We don't want any of that for you.

Whatever auto center replaced the spark plugs in your car without doing any diagnostic work and instead just took a random guess, don't ever return there. They either don't have your best interests at heart, are incompetent, or both.

Google'ing your trouble codes reveals a lot -

P0171 - http://engine-codes.com/p0171.html

P0171 Toyota - Air/Fuel Mixture System Lean Bank 1


Possible causes
- Intake air leaks
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection


Tech notes
If the P0171 is combined with the P0174 code, it's very likely that the problem is caused by an intake leak. If there are no intake leaks, the next step is to replaced the air filter and clean the air flow meter. If the problem persist the front oxygen (O2) sensor may need to be replaced.

There is a factory service bulletin for the following Toyota models:
2005–2007 Toyota Avalon
2007–2008 Toyota Camry
2005-2007 Toyota Avalon, 2007-2008 Toyota Camry Service Bulletin OBDII Code P0171

2005-2006 Toyota Corolla
2005-2006 Toyota Corolla Service Bulletin OBDII Code P0171


When is the code detected?
- Fuel injection system does not operate properly.
- The amount of mixture ratio compensation is too small. (The mixture ratio is too lean.)
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Excessive Fuel Consumption
P0171 Toyota Description
With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. The Engine Control Module (ECM) calculates the necessary compensation to correct the offset between the actual and the theoretical ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the ECM judges the condition as the fuel injection system malfunction and light up the MIL (2 trip detection logic).

Read more: http://engine-codes.com/p0171_toyota.html#ixzz3C55VdROD
​

P0125 - http://engine-codes.com/p0125_toyota.html

P0125 Toyota

P0125 Toyota - Insufficient Coolant Temperature for Closed Loop Fuel Control
Possible causes
- Low engine coolant level
- Leaking or stuck open thermostat
- Faulty Engine Coolant Temperature (ECT) sensor
- Engine Coolant Temperature (ECT) sensor harness is open or shorted
- Engine Coolant Temperature (ECT) sensor electrical circuit poor connection


Tech notes
There are factory service bulletin for the following Toyota models:

2003 Toyota Corolla
2003 Toyota Matrix
2003 Toyota Corolla and Matrix Factory Service Bulletin OBDII Code P0125

2004-2007 Toyota Prius
2007-2007 Toyota Prius Factory Service Bulletin OBDII Code P0125

When is the code detected?
The Engine Control Module (ECM) monitors the ECT signal voltage after engine start-up. If, after sufficient time has passed, the sensor still reports that the engine is not warm enough for closed-loop fuel control, the ECM interprets this as a fault in the sensor or cooling system and sets a Detected Trouble Code (DTC).
Example:
The ECT is 0C (32F) at engine start. After 5 minutes running time, the ECT sensor still indicates that the engine is not warm enough to begin active feedback control of the air-fuel ratio. The ECM interprets this as a fault in the sensor or cooling system and sets a DTC.
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P0125 Toyota Description
The Engine Coolant Temperature (ECT) sensor is used to monitor the temperature of the engine coolant. The resistance of the sensor varies with the actual coolant temperature. The Engine Control Module (ECM) applies a voltage to the sensor and the varying resistance of the sensor causes the signal voltage to vary.

Read more: http://engine-codes.com/p0125_toyota.html#ixzz3C5531JZA


​

P0150 - http://engine-codes.com/p0125_toyota.html

Possible causes
- Faulty Front Heated Oxygen Sensor Bank 2
- Front Heated Oxygen Sensor Bank 2 harness is open or shorted
- Front Heated Oxygen Sensor Bank 2 circuit poor electrical connection
- Inappropriate fuel pressure
- Faulty fuel injectors
- Intake air leaks may be faulty
- Exhaust gas leaks


Tech notes
Replacing the O2 Sensor 1 usually takes care of the problem


When is the code detected?
The response of the voltage signal from the sensor takes more than the specified time.
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- High Fuel Consumption
- Excessive Smoke from Exhaust
P0150 Description
The front heated oxygen sensor (or O2 sensor 1) is placed into the exhaust manifold. It detects the amount of oxygen in the exhaust gas compared to the outside air. The heated oxygen sensor 1 has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1V in richer conditions to 0V in leaner conditions. The heated oxygen sensor 1 signal is sent to the Engine Control Module (ECM). The ECM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from 1V to 0V.

Read more: http://engine-codes.com/p0150.html#ixzz3C54gfxSS
​

 

[Scott O'Kashan]

Each and every one of the possible causes for each of the symptoms listed must be checked/diagnosed, step by step and corrected as needed. There is no one easy answer.

Parts are not diagnosed by replacing them. They are visually inspected, or tested.

It is usually less expensive to have a professionally trained automotive technician to correctly diagnose your vehicle than to just randomly replace parts hoping it will fix the problem. You may spend $100-$200 for a Toyota trained automotive technician to diagnose the problem you're having with your car, but that's preferable to spending money on parts that don't need replacing.

 

[Kev250R]

I don't disagree with what you're saying Scott however if the car has been neglected and is behind on maintenance (such as a fuel filter which may never have been changed) getting it caught-up on those maintenance items may correct some (if not all) of the problems this guy is having, plus they should be done periodically anyways of course.

Kevin

 

[m.salah]

It's hard to say for sure, especially since you didn't mention which engine you have but I'd start with the basics:

You had the plugs changed but did they change the plug wires? If the wires are worn (nearly impossible to tell just by looking at them), that can cause a mis-fire condtion. You should be able to check the continuity of each wire using a VOM.

Unfortunately changing the Valve Cover gasket won't fix the problem you're describing. I'm not sure that adding fuel injector cleaner will do much either.

The rattling noise could be a timming chain (if your engine uses one) which is nearing the end of it's life or (more than likely) the timming chain tensioners which when they fail (a common Toyota problem on some of their other engines) cause the timming chain to flop around a bit which makes a fair amount of racket.

Of course rattling could also be ignition timing which is off.

When was the last time the air and fuel filters were changed? A clogged fuel filter could cause some of the symptoms you've described.

Kevin

My bad, I should've said that the replacement of the spark plugs was to address the engine misfire (which was the code I was getting until I went today and got these). If the valve cover gasket doesn't do anything for the engine misfire, then that sucks since he said it could. He told me that the wires were fine but I'm not sure if he tested them or not.

As for the fuel injector, I read that a misfire could be from bad spark plugs or bad fuel injectors so since I tried the spark plugs, I thought I would move on to the fuel injector. I know there could be more things wrong but I went with the cheap stuff first.

Anyway, it seems the misfire is somehow gone so I guess that other stuff is irrelevant. Thanks for the info on the timing belt though. I'll definitely have to look into that.

I'm not sure when the air or fuel filters were last changed. I got the car two years ago from an uncle but I'm not sure if he did or not. I'm gonna lean on the "no" side though. The place where I get my oil change offered me to clean it but I don't know if it was because it was actually dirty or not. I haven't done it in the two years I've had it though.

Again, thanks for the help.

 

[Scott O'Kashan]

Yes or course, however that might not be causing the problem the car is having. The poster stated he doesn't have a lot of money, so I'm recommending diagnosing instead of replacing parts in order to save money, time, frustration and headaches.

Also for someone that has no training and very little experience working with vehicles, replacing parts can lead to a Pandora's box of other problems caused by the part not being installed correctly, further complicating things.

 

[Scott O'Kashan]

My bad, I should've said that the replacement of the spark plugs was to address the engine misfire (which was the code I was getting until I went today and got these). If the valve cover gasket doesn't do anything for the engine misfire, then that sucks since he said it could. He told me that the wires were fine but I'm not sure if he tested them or not.

As for the fuel injector, I read that a misfire could be from bad spark plugs or bad fuel injectors so since I tried the spark plugs, I thought I would move on to the fuel injector. I know there could be more things wrong but I went with the cheap stuff first.

Anyway, it seems the misfire is somehow gone so I guess that other stuff is irrelevant. Thanks for the info on the timing belt though. I'll definitely have to look into that.

I'm not sure when the air or fuel filters were last changed. I got the car two years ago from an uncle but I'm not sure if he did or not. I'm gonna lean on the "no" side though. The place where I get my oil change offered me to clean it but I don't know if it was because it was actually dirty or not. I haven't done it in the two years I've had it though.

Again, thanks for the help.

What?! An, "automotive technician", actually advised you that a leaking valve cover gasket could cause an engine misfire?! Really?! You're not kidding, are you?!

If they actually said that, run far, far away from that person as fast as you can!

An air filter will not cause an engine to misfire. Neither will a fuel filter.

To check the air filter, hold it up to a strong light and if you can see light through the filtration media, it's fine. If it looks plugged up, it's time for replacement. If the air filter hasn't been replaced in two years, it's likely it needs replacing.

To check the fuel filter, visually look at it and if it looks very dirty and rusty, that means it hasn't been replaced in a long time. Replacing the fuel filter can be dangerous, as fuel does leak out. Make sure you know what you are doing before attempting to replace a fuel filter. The fuel filter for most cars is located in the fuel line on the left/drivers side of the vehicle, normally in front of the rear tire along the frame rail and is about the size of your fist. It looks like a little coffee can with a metal tube sticking out of each end.

 

[m.salah]

m.salah - To correctly address the problems you are having with your car, first we need to stop replacing parts, immediately. Don't replace anything. Stop.

...

Yeah, I wasn't planning on replacing anything at all. I failed to mention that I brought the car to the mechanic specifically to have the spark plugs and spark plug seals replaced because there was oil in them. He said to also replace the valve cover gasket for good measure (to prevent more leaks?). Don't know how I forgot to put that in the original post.

As for getting it diagnosed, I took it to Toyota about four months ago and the said they'd charge $500 to get it diagnosed (because they had to take out the engine?) and then they said from what they suspect, it'll be a $2000 fix. My car is worth $700 at the moment so I politely declined. If that's my only option, then I suppose I have to just drive it until it stops working then. I mean, it's at 210K miles and I don't think the previous owner gave it top notch maintenance. I'm not sure how I would test each any every potential cause for each code at the budget I'm at.

Thanks for the help.

 

[Scott O'Kashan]

Are you serious? There's no need to take out an engine to diagnose drivability problems. You've to to be kidding, or else those people were playing a huge joke on you.

Did they recommend repainting the car too? :blink::laughing:

What is the name and phone number of this Toyota dealership?

With the symptoms you've listed, along with the very high mileage of the car and the trouble codes you posted, it would seem the oxygen sensor should be replaced.

 

[Kev250R]

I agree, that Toyota dealership was playing a game for sure!

Looking at the engines in my '10 Corolla and the one in my friends '03 it looks to me that all minor (and probably many major repairs such as a headgasket) could be done with the engine in the car. Short of a complete engine or transmission rebuild I can't think of a situation where the engine in a Corolla would need to come-out.

FWIW I wasn't suggesting that a clogged fuel filter could cause a misfire, I agree that it won't but it could cause a hesitation. The rattling noise concerns me too. The poster needs to have a qualified tech determine what the source of the noise is be it detonation or an issue with the timing chain. With 210K on the clock changing the oxygen sensors would be a good idea anyways.

What state are you located in?

Kevin

 

[Donabed Kopoian]

I third the upstream O2 sensor. They should be replaced every 60k anyway for maximum fuel efficiency.