Hey everyone got a 01 corolla with 291,000 on the body and about 150,000 on the engine. I am having some major idling problems. sometimes I can start the car and it will do ok. Other times the rpm will go to about 1800 then drop well below 1000 until it bogs out. When I put it in drive the immediate acceleration is very erratic. Almost like the engine is choking. It will die at almost every stop I make. I am also getting very poor gas mileage. I have had my mechanic work on it and he cleaned the tps and it helped some but not much. The only code that is coming up is p0420 which is the catalytic converter. Would that cause my problems? Any ideas are welcome this is my vehicle I commute to work with so I need it running soon. Thanks
The P0420 isn't really helping us with this problem probably. I haven't heard of a Corolla plugging up it's catalytic converter yet. Generally, they're just below the necessary 95% efficiency required for emissions so it puts up a code.
I've seen similar symptoms from bad MAFs and crank sensors. You'll need some live data to monitor these systems to get further along.
My MAF went after my catalytic converter did a couple years back, seperate symptom. Under a live scan, I saw that the MAF said the same amount of g/s were coming in no matter how I pushed on the throttle. So I had a "duh" moment that it was bad.
I usually see 2 to 3 g/s at idle and 30 g/s under moderate acceleration. Mine failed and was stuck at 90! lol Even with my short ram intake that lets a lot more air in can only get me up to 70+ g/s at full throttle, lol.
If it feels like the engine is choking that was a similar feeling to my MAF fail. Surprised it hasn't got you an engine code yet. When I cleared my MAF code it'd come back without even turning on the car...but then mine failed at 90 g/s! lol Still makes me laugh (I'm on my 3rd or 4th MAF, Toyota is really good, but they failed a bit on these, hopefully someone knowing your '03 better than me can say if it's a common failure.)
Sorry, rattled on longer than I probably had to, but it's a funny story...$93 at AutoZone? Not so funny at the time. I normally buy parts online, but with how bad it ran I couldn't wait, you know?
there is a valve that automatically adjusts the idle at start up and at idle (at stops) that is known to get fouled from recirculated oil spray from the EGR? I can't recall what it is called but it is attached to the throttle body. Many have taken it off and cleaned the valve and throttle body fixing the issue.
Right, sorry, he has a 2001, so I have the same engine. Yes the 1999 didn't have variable valve timing, but my car has a remanufactured title and a 2000 engine in it.
Anyway, no EGR on these cars, so no problems from it.
However, the PCV valve can get some oil into the intake and gum things up, just like a K&N filter eventually will at about 80-100k miles in my experience.
You're talking about the IAC or idle air control valve. While these do commonly fail on our cars, but with the symptoms being during driving and not just at idle, I think the IAC probably doesn't have anything to do with the problem.
Cleaning the throttle plate and revving it on engine start up to clean the throttle cleaner may help if the throttle plate is sticking from being gummed up. My car ran better after a throttle plate cleaning, but it made no difference to how it ran for these particular symptoms.
This video on cleaning a throttle plate on a Honda will get you far enough along to take care of this part, though I still suspect it isn't the problem as the symptoms are at idle as well.
Ok so the throttle body has all been cleaned and the from what I have read I can spray some cleaner in the port where the iac is located and it should clean it well enough to work. Now I have a confession on my maf sensor instead of getting a oem sensor I ordered a $20 one on eBay. ?BUT it has ran fine with that sensor in it for over a year. I had a similar problem to the one I have now but it was just the throttle body at the time. So could that give me the problem?
That's good maintenance even if it doesn't sound like the problem. Personally I pulled the IAC off to clean it.
It seems like there isn't enough space to remove it, but the threads that you pull nuts off of it also have tiny hex shapes on the end. Might be 6.5 mm so you can unscrew that off after the nut comes off. This is necessary to have the space to pull it.
Sure, you could go straight in with a stubby screw driver under there and pull the IAC component itself off, but that's so hard that if you do need an IAC you still won't need to undo those screws. They're that hard to take off.
Ok I pulled the pcv valve out and cleaned it really well. Car is idling but idling rough. Should I go ahead and replace the pcv valve and hose that goes to it? I will try to pull the iac in the morning and clean it really good
I removed the throttle body and gave it and all the sensors a good cleaning. After reassembling everything I drove the car and still would not idle properly. So I let it warm up and drove it for a while and it did fine. I took it back to the house and attempted to start it about an hour later with no luck. It will start but immediatly stalls out. I ran a diagnostic on it and got codes 0P300,0P303 and 0P304. What would be the next best step in this?
Disconnect the MAF and start the car.
Do a quick drive with it. WATCH OUT the engine WILL NOT go above 3000 RPM with MAF unplugged so do not attempt to get on a freeway OR pull out in front of traffic!
The engine will not even start without the maf plugged in. I pulled the plugs and they are really bad. I also had oil pooling around one of the plugs so I am replacing the valve cover gasket and plugs and will see if that helps
Ok drove it today it actually ran alot better I still had some erratic rpm a couple times. I got back to the house and ran another diagnostic. I still have a random misfire code and now I have a p0100 which I believe is something to do with the maf sensor. Should I replace it?
Unplug it and drive as stated above.
If the car runs awesome (Other than no revs above 3000) then yes replace it.
If car still runs like garbage then MAF is probably fine, and we need to look elsewhere.
Also what plugs did you use? These cars are VERY picky about their plugs.
Replaced maf this morning with a used one from a pull apart place. Cleaned it really well first then installed it. Car drives alot better still a couple issues though. I'm getting the p0100 and p0300 codes. Possibly a vacuum leak?
How bizarre...
My car runs like a champ with it unplugged. :dunno:
If a used one made it run much better, then just drop the cash on a new Denso OEM one.
Then see what errors come up, so then we KNOW you have a good one in there, if it was from a pick and pull place then it's probably really old just like your orig one was....
Placed and order for a new oem one today. I have drove the car to work the past two days and the only code I am getting now is the p0420 code. But I'm still getting hesitation and rough idle until the engine warms up but then it's fine.
Also noticed that the hesitation is only there when the ac is on. Ac works fine. But as soon as I turn it on the hesitation starts when it's off no problems.
Curious how your alternator is doing? If you can check the output with and without load using a voltmeter. See if your alternator is acting up. If you dont have the tools find a dark garage start the car and one by one turn on your ac, defrost, lights, fogs, stereo and see how dim your lights go. A little dim is normal at full load its only a 80a alternator.
Thanks I will try that next. I ran diagnostic on it this morning after driving to work and I got the p0420 but I also got P0440
P0441 codes. Something to do with my evap system. What causes this?
On a side note fixing the evap will not fix the 420 code or vise versa. You have two very different systems tossing codes so be careful this can get pricey if you just toss parts.
Well if the evap code is going to hurt the performance of the car I will work on it. If not I don't think I will put the money in the parts for it. But I will try to fix the p0420
Well if you need a smog test you will fail with the evap issues. Also ive read any check engine light will keep the car from driving in closed loop mode which is the most fuel efficient mode. I doubt you have a clogged cat its so very rare they break and clog so odds are its just 5% below efficiency and thus throwing the 420. New o2 sensors will improve your fuel economy and a new cat can too. So if you dont need a smog test and gas is cheap where you are id fix nothing.