Yup, sounds more like a fuel filter or fuel pump issue. Get the pressure checked. You’ll need a gauge and most likely a special ‘tee’ or fitting to add a fuel port for the gauge. Most Toyota’s do not have a fuel pressure test port.
How random and how frequently does the failure to accelerate happen? If it doesn’t happen all the time, or frequently, that complicates matters.
“The loss of power came after the oxygen sensor was changed” [paraphrased].
Something isn’t right with that outcome. Wonder what. Maybe, that was just coincidental.
Since weather makes a difference, that difference in performance would be most effected by temperature change?
There are two sensors which tell the engine computer of temperatures: the engine coolant temperature sensor (ects), and the intake air temperature sensor (iat). If either sends the wrong temperature indication to the engine computer, the engine computer will command (erroneous) fuel injection based on that (erroneous) information. One can check either sensor with an electrical multimeter (ohms and volts). The instructions are in the repair manual.
When you depress the gas pedal, the throttle position sensor (tps) tells the engine computer that the throttle has moved. When the tps does not tell the engine computer of changes the computer doesn’t make fuel injection changes for, say, acceleration. The tps develops flat spots; which is shown when you move the throttle a little, and the ohms (or, volts) indication doesn’t change. There can be spikes and dips in the ohms and volts in the out put from the tps, also. These spikes and dips can be from “hairs” (slivers of metal) on the sensor contact surfaces. The volts and ohms should be progressive as the throttle is progressed (or retard as the throttle is retarded).
So, doing a few simple tests can save a lot of paper with dead Presidents’ pictures on them.
Since the OP told us that his Corrolla (sic) has a timing belt, I assumed that he actually knew what type of engine he has in his car. I guess that will teach me to assume such a thing.
After all, as the old saying tell us, “When you assume, that makes an ass out of u and me”!
OP? All I know is the guys at the Toyota shop say timing belt NOT chain.
The O2 sensor was replaced a couple of months ago in the dead of winter. I have often wondered if there is a connection with the current problem and the new O2 sensor (those were the guys that told me the fuel filter was made not to be replaced and is an integral part of the fuel pump located in the gas tank which is not correct according to what I have since read and heard from other mechanics).
When it was very cold outside the loss of power happened everyday several times a day and was so bad I altered my driving patterns to use traffic lights to stop traffic instead of pulling out into moving traffic as there was no way to tell when the loss of power would happen, how bad it would be and what sort of accident it might cause. Now that the weather is warming up it is happening less often and less severely. At this rate it may all but disappear until December.
Generally after the car warms up it happens less but there have been days when it happened all day long regardless of the engine or ambient temperature was.
(I answered your last comment as you were editing it so here’s the remainder of my reply)
I do understand what you are saying and thank you for treating me as if I have a brain and can learn rather than making sarcastic comments.
Fortunately the Toyota shop did not charge for the diagnostics they did (although they did say the car had a timing belt not a chain - now I will have to look into that as well - either way it needs replaced). They could not duplicate the problem. Certainly more testing is in order before throwing parts at the problem. Your information is very helpful. I used to work on my own cars when carburetors were the norm, but in recent years have gotten lazy as cars have become more complicated. I feel from this discussion more empowered to know what to look for myself and be better educated when dealing with mechanics who often treat women like they are unable to understand how a car functions let alone how to do more than fill the tank.
Thank you
Call several auto parts stores and tell them you want a timing belt for your 1.8L Corolla engine. Listen closely to their reply.
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Thats not true. I have never had to replace a fuel filter on any vehicle made since 1990. I have seen vehicles that did need a new fuel filter, but those were exceptions traced to an unusual event. Something got into the fuel system, bad gas or running out of gas and using a dirty gas tank.
1997 Nissan PU 152k miles
1997 Honda Accord 152k miles
2002 Saturn SL 186k miles
2003 Toyota Corolla 120k miles
None have ever had the fuel filter replaced or needed to be replaced.
Whether your engine has a timing chain or belt depends on which engine you have. If you have a 7AFE engine, its a belt. If its the 1ZZ engine, its a chain. Both are DOHC, 16V, 1.8 liter engines.
The problem you describe can be due to excess fuel and that could be due to a faulty fuel pressure regulator. Those usually fail completely though and are not intermittent.
Which O2 sensor was replaced, the front or the rear. If it was the rear, they are hard wired into the wiring harness so replacement requires cutting and splicing wires. If that is what was done, you could have a bad connection and that could well be intermittent. But it should also give you a check engine light, do you have one?
You should also get the codes checked even if you don’t have a check engine light. You could have a chronic pending code, one that is so intermittent that it doesn’t set the light. Many autoparts stores will check them for free. Post the actual code(s) here if you get one.
The front O2 sensor was replaced. The check engine light is not on. The codes were checked this past week by a certified Toyota tech. No codes were in the system.
The Toyota tech did offer some speculation when I pressed him as to what may cause this problem. As I said they were not at this time able to recreate the problem so this is speculation. He said it could be the thermostat causing an incorrect amount of fuel to be put through the system. Cars idle a bit high when cold but drop down to regular idle speed when warm. Perhaps it’s not getting the signal the car has warmed up and doesn’t adjust fuel accordingly. That was speculation. As the weather warms it seems to be less of a problem. The cars mpg did drop after a tune up last fall from 26 to 22 city. That has not improved. SO perhaps it is excess fuel.
OP = original poster
98-99 Corolla’s have a 1.8L 16V 120HP 1ZZ-FE engine with a timing belt.
00-02 Corolla’s have a 1.8L 16V 125HP VVT-i 1ZZ-FE engine with a lifetime timing chain.
Hope this clears things up.
I’m with you, Keith. I routinely drive my cars about 200,000 miles and have never had to replace a fuel filter. I have removed and inspected several of them and found no significant resistance to flow.
And this tidbit of info from my Haynes repair manual on my '04 Matrix (IZZ-FE):
The fuel filter IS a part of the fuel pump.
As BustedKnuckles said: There is no test port (Shrader valve) as is common on most engines.
A test kit with the necessary fittings and hoses and gauge hooks up between the fuel rail and the fuel feed line. (The fuel pressure test hose temporarily replaces the factory hose)
If the fuel pressure is higher than specified,(this test is done with the engine idling) replace the fuel pressure regulator.
If the fuel pressure is lower than specified, the fuel filter could be clogged, the fuel lione from the fuel rail to the fuel tank could be restricted, the fuel injectors could be leaking, or the fuel pressure regulator and/or the fuel pump could be defective (this is probably the most likely cause).
In this situation, it is recommended both the fuel pressure regulator and the fuel pump be replaced to prevent any future fuel pressure problems. Note: the fuel filter is part of the fuel pump assembly.
Anyone,
Autozone.com reformatted their Web site today. I am a registered user at there. I have a link to the fuel pump for the 1998 Corolla. I need to know if any un-registered person can access the link. Here is the link: http://www.autozone.com/autozone/catalog/parts/partsProduct.jsp?itemIdentifier=21938_45032_0_&skuDescription=Airtex+Master+/+Fuel+Pump&brandName=Airtex+Master&displayName=Fuel+Pump&categoryNValue=14999999&sortType=&store=1140&isSearchByPartNumber=&fromWhere=&fromString=search&itemId=prod10652&navValue=14900078&filterByKeyWord=fuel+pump&productId=21938&appQuestionText=&categoryDisplayName=Fuel+Delivery&parentId=cat10007&questions=[]
Hellokit
So, what was the final solution? I am having the same problem. Car power comes back to normal once I turn off and on the car!