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Discussion Starter #1
Okay,.. I have a second problem, this is a new one,.. and thankfully it's getting worse - I'm hoping it will give out entirely soon and make it easier for me to solve :facepalm:

I was driving to work today, stopped at a stop light, it turned green, I hit the gas and the car barley moved.

I gave it more gas, and still it barely creeped.

Hit the gas further, it sputtered a little.

Then I floored it.

The car coughed and took off.

It stumbled once more while going up a hill - but the rest of the drive to work went fine.

Right now I'm guessing maybe Throttle Position Sensor (Do Corollas have one of these? Does anyone know how to test it?) Or maybe Fuel pump not keeping pressure up I have a gauge for that and need to test it. What numbers for fuel pressure am I looking for?

Do Corollas have a Fuel Filter? I can't find one down by the frame rails, if it does, where is it? The previous owner said that he never replaced it,.. so that's a possibility too if there is one.

Thanks for the help!
Whiskey
 

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Discussion Starter #3
Plugs are less than a week old, wires are 30,000 miles old.

It is intermittent - most of the time it's okay,.. constant speed it seems okay,.. maybe a little jumpy, but It's mainly when the engine is under heavy load (Such as steep hills) that it acts up, or on acceleration but once again it's intermittent sometimes it accelerates fine. It idles great, there is no check engine light.

Thanks,
Whiskey
 

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Fuel filter is inside the gas tank - part of the fuel pump assembly. The "sock" you can get to easily, the filter itself, you'll have to partly disassemble the pump.

TPS is a possibility, though unlikely. Question, when it stalled the first time, was the ground level? Have you ever noticed it stalling in that manner if the front of the car is pointed downward. Could be a bad pump or faulty pressure regulator. Could also be a clogged injector or bad coil pack - those can be intermittent in nature, so it can be tough to pinpoint and nail down.
 

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Discussion Starter #5
It has never stalled entirely - only sputtered and failed to accelerate, once I let off the gas it will idle normally. It never misses at idle, the idle is smooth.

The nose of the car is always flat, or pointed up - but I think that's simply because going downhill I don't ask as much from the engine.

This fuel system does not appear to have a return line - so the pressure regulator is electronic and part of the fuel pump assembly right?

Thanks for the ideas! Is there a good way to rule out a clogged injector or bad coil pack?
Whiskey
 

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found a great video.

Run your car 'let it warm up and run at a stable idle'

Unplug a spark plug and note the change in 'sound\rpm' plug it back in and move on.

When you get to the cylinder that has little effect on the engine whatsoever that is the one having problems.

However if your problem is intermittent it is likely to be something else. possibly electrical or funk in your tank?


See: fishexpo101
 

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Discussion Starter #7
Yeah,.. that's great for diagnosing a miss at idle,.. but that's the weird thing - it always idles perfectly fine. It's only under load, and intermittently at that when it surges, shudders and struggles.

Whiskey
 

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out of my league.

It is to diagnose weak cylinders.

Not foolproof but gives a good idea.

I'll leave this solution to the experts, sorry for not being of much help.
 

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Discussion Starter #9
I appreciate the advice! Thanks for commenting. I'm stumped too :(

I'm still guessing fuel delivery including maybe clogged injectors, or throttle position sensor, I just don't know how to confirm or deny that :(

Is there any good way to clean injectors and make sure there clean?

Whiskey
 

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I had a prob like this not too long ago but mine would be the first time I tried to accelerate out of the driveway once starting the car it just completely bogged down. It ended up being the MAF sensor. But no one could tell me what it was before it got really bad and the CEL came on
 

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yeah, could try o2 sensor.

there should be one on your exhaust manifold as well.

Maybe one went bad?

possible grounding out on your ignition only on occasion? or maybe an injector is grounding out on occasion?
 

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Discussion Starter #12
The 02 sensor is brand new - I had a bad fuel economy problem and I replaced that in hopes of fixing it.

I was able to take it out for a 100 mile freeway drive and get 36 MPG - so I called it fixed, but now I'm thinking it's not.

Unfortunately I don't have a MAF sensor, only a MAP sensor - and those can't really be cleaned.

It's possible that things are grounding out - but I've inspected the wiring and all that pretty carefully and it all seems good.

I pulled the efi fuse so that I can reset the computer because you never know. Tonight I'll get some tools so that I can test fuel pressure.

Whiskey
 

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Discussion Starter #13
Hey,.. does anyone know if the rubber fuel line under the hood can be removed? I know the part on the firewall can be disconnected,.. but is that round swivel thing on the engine side a connector?

Thanks,
Whiskey
 

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I had an injector grounding out on a mudding vehicle we have and it shorted the electrical when it would hit.

popped the hood because it wouldn't start and a wire was bright red almost white, very obvious scorching so if you cant see anything similar then probably not a short.

Hopefully the reset did you some good.
 

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Discussion Starter #15
The Reset didn't help - the car was actually acting up all the way home today which is kindof a first, usually it's much more intermittent than that.

So! I checked the fuel pressure. 45 - 50 loading the enigne didn't make it drop much, looks good.

I checked fuel flow. It really squirted out of there. Check!

I checked the TPS - even climb and decline in the ohm reading, no jumps anywhere perfectly smooth. That sounds good.

I unplugged the MAP and verfied that the symptoms remined so that kinda rules that out.

Idle air thing is ruled out because it idles fine.

Plugs are new, and wires are 30K old, but I don't see arching anywhere. I couldn't find any trace of vacuum leak.

I tested the coil on every injector, they were fine.

So finally I put some super concentrated fuel injector cleaner into the injectors - let that soak, then put enough cleaner to treat 20 gallons of fuel, into 5 gallons - drove the car around like it was a race car for 20 miles and by the end of it there were no bogging issues.

However;
It's really intermittent, so I won't know if it's gone for sure for another week.

I was considering just replacing all the injectors because they do have 200K on them, and it has to be more effective than some injector cleaner,.. but then I learned that injectors are $250 EACH. Ouch.

Whiskey
P.S. If you didn't at least chuckle at my fuel volume test result, I can't help you ;)
 

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I lol'ed at many of your items on your check list.

I liked the 20gal treatment in 5gal then raced around.

Glad to hear you cleared it up.

I ran 2bottles of STP in a 1\4 tank to rid my car of hesitation, it fixed it =D.
 

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Discussion Starter #17
Always happy to spread a smile! :)

Well - It's still not fixed - it's doing it less often, but it's still doing it. I put 20 more gallons worth of fuel treatment into what is probably around 2 gallons now - I'm going to burn that out, then fill it up.

I'll be putting 1,000 miles on the car this weekend - so here's to hoping it's nothing serious!

Whiskey
 

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I have been having the same issues with my 01' Corolla with 105k miles too. The CEL came on a few weeks ago and it was P0133 (Bank 1, Sensor 1). I reset it and have put about 500 miles on it and it hasn't come back on yet but I still noticed today it almost fell on its face when the light turned green on my way home from work. I floored it and it came around but its definitely not a steady thing where you can feel the lack of smoothness during acceleration. Idles great and doesn't die but runs like crap. I am considering cleaning the MAF and maybe replacing the sensor but did you find anything else new with yours that may have been causing it?
 

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Discussion Starter #19
Yeah,.. ummm sortof.

I think my issue has been mainly caused by the switch to winter gas. I live in CA and they do a pretty major changeup of the gas formula adding a bunch more alcohol to meet the stringent winter smog rules here. I didn't live here last winter,...

I also think that part of the issue is my drive to work is lots of up and down,.. with stoplights at the bottom of hills.

My Jeep was getting 14 MPG on this drive,.. now it's getting under 10,.. so the corolla dropping from 30 to 24 doesn't seem bad. One thing that seemed to help me was using 89 octane - got some MPG's back but it's a little pricer so I go back and forth. I just had it out on the freeway for a trip and I was getting 32 again, when I went to AZ and back I was up to 34.

It still falls on it's face a little bit from time to time, but I just push the gas a little further and away she goes. I just passed smog in San Diego so the car can't be running bad,... I just don't think it deals with the Achohol very well.

For you,.. What was the code? That's 02 right? Replace it,.. 02 sensors are so important to a properly running engine if it throws a code it's probably super lazy at least even if it's not quite bad enough to set the code again. Basic tuneup would be a great idea too,.. plugs wires etc if there getting old, and some good injector cleaner. Might fix it, might not, but not a terrible place to start. You may gain some info by looking at the old plugs too.

HTH,
Whiskey
 

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They do the same thing to us here in Denver with the winter gas and I do use the cheap stuff so an upgrade in octane to 87 might be a good idea. I have the same kind of drive to work with the hills and lights all the way and of course on the highway it seems fine. I think I am getting 35 MPG right now. I am planning on replacing the O2 sensor after the holidays too since it's probably due but right now trying to save $$ til after the holidays. Got to replace them struts too I think. ~ugh~
 
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