My Corolla is possessed by a Demon!!!

[RXTech]

I'm a newbie and a blonde.... I accidently posted this in the "introduce yourself" forum... Maybe I'll have beter luck with it here... Have a great night ya'll!!

Jessica

Hey ya'll! I've only had my 2000 Corolla for about 4 months now, and my CEL has been on off and on for the last two months. The codes that my autozone guy and mechanic keep getting are "random multiple misfire". I've replaced the spark plugs and the ignition coils (ouch$$$) but that stupid light just won't go away! After one of the last trips to the mechanic leaving him scratching his head and my wallet empty, it's developed another cute little problem described to a T in a previous thread... However, whenever I bring the car into the shop to have that issue checked out it won't do it.

"In addition to the light, I have the follownig problem: When I start my car, the engine fires up instantly, but when I shift it into Drive or Reverse and step on the gas a little, it wants to stall. The car doesn't start rolling immediately. I need to let it run in idle for 30 seconds or so before it will move. It happens more often than not when the car has been out in the sun for a long time. Early morning I have no trouble with it but when I get off work, which is when the cars been in the sun all day, I have the problem without fail."

I was wondering if anyone had any suggestions? FYI, I am car illiterate, please use simple terms a girl can understand.... After reading through some previous threads I've determined that I need to change my air filter, fuel filter, and check my gas cap. Any other suggestions would be greatly appreciated.

Thanks!
Jessica

[gino_bambino]

its your oxygen sensors.

Have them check if your car has one or 2, change them. then change the air filter, and change the spark plugs for good measures.

This happened with my father's dodge neon. The problem wasnt resolved till I gave the mechanics a link to a website that shows that the old neon's came with 2 o2 sensors.

[RXTech]

the spark plugs were the first things I had replaced, then the ignition coils, and both mechanics I've taken it to roll their eyes when I ask about the O2 sensor, cause that's what my Dad thought was wrong. I've got a appoinment later in the week for an oil change and a new air filter, I'll make sure they add the O2 sensor to the list while they're at it.

Thank you so much for responding!


~Jessica

[ShawnM]

O2 sensors have nothing to do with engine preformance untill the car warms up a little. When you start the car first thing in the morning, it is in "open loop". In open loop operation the computer ignores the oxygen sensor readings because the engine needs a richer fuel mixture to run properly. Once it warms up a little it goes into "closed loop". During closed loop operation the computer looks at all the sensor readings and adjusts the fuel input accordingly. In other words if this is a cold start problem it has nothing to do with the O2 sensors. Several people on here have had problems with hard starting or long cranking on newer corollas, i think a new fuel pump solved their problems. Might want to try a search on that. Oh....and if your mechanic dosent know how many oxygen sensors your car has, then i suggest you drive away from his as fast as you can. (even if it is sputtering and misfiring)

[montreal]

Originally Posted by ShawnM

O2 sensors have nothing to do with engine preformance untill the car warms up a little. In other words if this is a cold start problem it has nothing to do with the O2 sensors. Several people on here have had problems with hard starting or long cranking on newer corollas, i think a new fuel pump solved their problems.

I agree about the O2 sensor not being part of the open loop process, but the computer does learn from the front O2 sensor during closed loop mode and alter the cold start fuel and bypass air motor trim tables to improve the open loop performance in cases where there is a perceived defect. We should assume the O2 sensor is accurate because there have been no O2 sensor codes reported.

If there is a fuel pump pressure problem, would this not affect the idle when the car is all warmed up as well?

If she's stepping on the gas pedal when the car is relatively cold and it bogs down, doesn't that sound like the ECU can't recognize that the throttle plate is moving (ie. TPS problem) or the MAF sensor is giving a bad reading for air flow, or the ECT sensor is reporting the incorrect temperature so the computer proposes the wrong mixture? What about an air leak in the vacuum hose?

She definitely needs a better mechanic who knows that it has been over 10 years since there was a car produced with only one O2 sensor.

[RXTech]

Thanks ya'll for your input. I am on my second mechanic now, the first guy was rather snobby. If I'd call and ask him about the light being on he'd tell me not to worry about it since the car was running fine and that he was booked solid for weeks, but if my boyfriend (who's from well known family in town) calls then all the sudden I'm the top priority and he'd do anything to help me out and how soon could I be there. After a few go rounds of that crap I decided I didn't want to go to someplace where I had to drop names to get treated with respect so I've switched to Good Year. OK OK before ya'll even start with me about Good Year being ok for tires and oil changes but not much else, I beg to differ. When ever my CEL comes on they tell me to bring it in to have it checked that day and don't treat me like an over reacting girl. If they can't fix or find the problem they don't charge me for the diagnostic and will call and follow up with me a couple days later to see if any new symptoms have popped up. I'm going to have them check out my fuel filter, air filter, fuel pump, and O2's on Thursday while they have it for my oil change.

At the risk of sounding naive and blonde, I'm going to say that I'm confused on the terminology "cold start". I don't have the hesitation issue when the weather is cooler, it's just when it's really warm out side, but my temp gauge tells me the temp is normal and my coolant level is full.

Oh, about the vacuum hose leak suggestion, my Dad's checked out all my hoses and couldn't find any loose connections or leaks.

Also, can someone please define: ECU, TPS, MAF, and ECT? I'm car illiterate and would like to attempt to sound intelligent when I tell my mechanic what to look at.

I just had a thought... I just had my serpentine (spelling?) belt replaced before I started having all these problems. Could they have not put in on right and jacked up my timing??

Jessica

[karugs]

Originally Posted by RXTech

If they can't fix or find the problem they don't charge me for the diagnostic and will call and follow up with me a couple days later to see if any new symptoms have popped up. I'm going to have them check out my fuel filter, air filter, fuel pump, and O2's on Thursday while they have it for my oil change.

Hi Jessica,

I just have to say this mechanic sounds much better than your previous one, basing my opinion on your story. Sometimes, getting the right mechanic will also fix your problems (and not add any to them). Also, when a mechanic tells you stuff like "this has to be replaced" etc... ask for an explanation, tell him you'll think about it or talk to your parents (any excuse would do) and run back here and report back. I'm pretty sure others will chime in what's right, and if your mechanic is honest or not.

Oh and when you say "cold start" you don't refer to the weather. Rather, you refer to the engine as "cold", meaning it's sat long enough to cool down well below operating temps. "hot/warm starts" means the engine has been warmed up and you start it again (like starting the car to go home from picking up groceries).

Can't help you with the terminologies though, I'm more of an old car guy

Goodluck!

[Flashmn]

Said reasons are why I dislike fuel injection... one sensor or wire somewhere grounding wrong, or causing problems renders the whole car undriveable.

[NDR008]

ECU, TPS, MAF, and ECT?

- Depends where you read them off :P

ECU - Engine Control Unit - always so
TPS - In manuals sometimes referring to Turbo Pressure Sensor (but on the ECU circuit the turbo pressure sensor is referred to as the PIM - called the MAP sesnor for Manifold Absolute Pressure), so I guess for you it would be Throttle Position Sensor (which in my ecu is called IDL and PSW ecu pins) - oh yes, and in business and marketing reference, TPS stands for Toyota Production System.
MAF - If i am not mistaken this is some sort of air pressure sensor - Mass Air Flow.

[ShawnM]

MAF= Mass air flow sensor The computer uses it to determine how much air is going in to the engine so it can put in the proper amount of fuel. You dont really have to go in and throw all these terms at the tech. Just describe the problem your having, be as specific as possible and let them figure out what could be the problem.

[rcmathis]

fo to your local toyota parts store ie the dealership and talk to one of them i find them helpful on ocasion.

[derfburg]

Alright Ill try a little bit on this one. I am a Air Cooled VW guy. So I know nothing about all there new fangled cars, but my Wife has the same car, make and model. It is doing the same thing, I chaged the plugs, no dice. So the best thing to do is change the air filter, gas filter, and oxygen sensors? Is that a easy process or is it going to take a PHD in new cars to change?

Stacey