2000 Avalon's engine complaining; diagnosis unclear

I’ve got a 2000 Toyota Avalon XL with 115,000 miles on it. I was driving to class on Friday (college student) when it seemed to take the right turn into the campus a little rough, and the check engine light came on. Starting it up after my exam, the engine light was gone, but it re-appeared within a few minutes. Pulling up to stoplights, I noticed the car was “shuddering” noticeably while at the light, and it started having slight hitches and a bit of trouble while accelerating.

Took it to a shop early the next morning. The guys there checked out the error codes and told me that there were four being generated: one from each of the cylinders on the right (I think) side of the car, and one from whatever system controls their firing. He did a little searching through the possible causes of the error code, and figured it might be work it to try and run the car hard for a little while, since debris and dirt clogging the valves was a potential cause. I had my misgivings, but eventually gave him the go ahead. Lo and behold, fifteen minutes later the car felt good - started up snappy and accelerated properly.

Didn’t drive it again for a couple days after that (unemployed student on winter break - I haven’t got a whole lot of driving need, at present). Next time I get in my car is Wednesday night. It’s much colder than it was last time I drove the car (30, vs. 65 previously). I don’t know that that fact is necessarily relevant, but a few minutes after the car’s been on, the problem resumes: the idle suddenly becomes rough, and acceleration is touchy. Check engine light comes back on.

Strangely enough (to me, anyways), when the engine idles for a length of time - so, at stoplights, or in neutral or park - the check engine light will start blinking on and off. After getting the car back in gear and revving up for a few seconds, though, the light comes solidly back on. I’ve driven it one more time since, and the problems remained pretty much the same.

A few other things I figure are worth noting: the battery needs to be replaced. I’m going to do that (probably tomorrow) regardless of whatever other problems; its voltage was tested as okay, but CCAs weren’t up to snuff. When they checked the rest of the engine, the mechanics both specifically mentioned that my oil seemed very clean - despite that it hasn’t been changed in almost 3,000 miles. I’m curious if that might have anything to do with what’s going on?

My trusted mechanic from my hometown is suggesting that I try to take the car back to him, but he’s ~100 miles away. D’you think the car will be okay driving that far? The problem feels slight when above about 25 or 30mph, though it’s definitely there. It seems most prevalent at idle and while getting out of first.

Thanks in advance for any thoughts or advice!

I’d be hhighly reluctant to drive a car on a 100 mile trip with the CEL blinking. On the other hand, you clearly need a new local shop.

Ask your friends, and even professors, if they can recommend someone local that’s good.

Or go to the local parts store, gete th aactual codes downloaded, and post them here.

I’m learning, as I read more into problems that Toyotas in this age range tend to have, that engine sludging is fairly to very common. Could something like that be causing the problem? I’m also curious why the oil still appears clean.

Thanks for your advice; I’ll get the specific error codes for you as soon as I can.

If you haven’t done it yet, do replace the battery before taking the car back home to your mechanic. You might have a few stalls along the way, and need a strong battery. Otherwise, you don’t mention non-starting, overheating, loud engine noises or anything that might cause the car to breakdown altogether. The flashing CEL light while idling does concern me, though. The CEL will flash as a warning, to get your attention to pull over immediately. It would flash if the car was overheating, for example.

Does the car run well enough to reach and maintain highway speed? If so, use as much highway as possible during the trip, and leave after rush hour to avoid traffic. You want to plan the trip to avoid a lot of stops and to make it in a short amount of time.
I would leave mid-morning so you have all day to deal with any problems.
I assume you have a cell phone and someone from home you call for help. If you have AAA, some plans allow up to 100 miles tow coverage.

I haven’t attempted highway speeds, but 40-45 mph seemed okay. Am I right to understand that a flashing CEL indicates MORE trouble than a solid one?

I do have Triple-A, but I don’t think I’ve a plan that gives me that kind of tow distance, unfortunately.

Thanks for your advice.

You should not drive a car with a flashing check engine light. It typically means a serious misfire.

And you do just need a new mechanic - now.

Get the actual codes if you can. (Like P0301).

Alright, attempting to synthesize all the input so far into a plan of action. Going to put in face time at a local parts shop tomorrow in the interest of getting the error codes, and finding a trustworthy local Toyota-specialist shop.

Any stabs at the prognosis for the state of the engine now? I definitely don’t want to over-drive it in the state it’s in now, or partake in any sort of behavior harmful to it.

One of the most common causes of misfire is just old spark plugs & wires. If all of yours are original at 115K they are well past due.

Okay, here’s a question for you:

When was the last time any work was done to your car, and what was that work?
Has anything happened to the car recently? (crashed into a snow bank? hit by a truck? went for a swim in a pond?)

Your engine oil won’t cause the engine to stutter and set off a flashing CEL unless there wasn’t any oil in the engine. You would get those symptoms right before it shuts off for good.

If you have some tools, you can try removing the negative battery connector for about 5 minutes, then hook it back up, and see if that resolves it, in case it’s corrosion on the terminal related. If you were more mechanically inclined, we could recommend other procedures, like remove the spark plugs, and check their condition, and also cleaning the MAF sensor on your car.

Since you are a college student, you HAVE to know someone at school who is good with cars, and might be able to help you look at the car, for the price of lunch. They might have all the tools needed, and even know how to get the diagnostic codes for us to be able to help you better.

Ask your friends, and other kids in class.
Someone is good with cars, and is hungry.


Replying to the most recent question: the most recent work on the car was replacement of an alternator (I think) belt. Nothing weird or damaging has happened to the car recently, unless you count college students swinging their doors into other people’s cars.

So I took the car in to a local parts shop to get the battery replaced (as I said, it needed it), and was fortunate to get someone really helpful there, who pulled two different sensors out to check out the error codes for the problem.

Four “nonspecific” misfire codes - P0300, 0301, 0303, and 0305 (Firewall-side cylinder misfires?) - appeared with the first pass, and the more advanced reader additionally picked up a P1349 (VVT System Malfunction) error.

Am I right to think, then, that replacing the oil control valve(s) would be effective in solving this problem? Also, how hard are these systems to access? The guy at the parts store is apparently a mechanic when he’s not working there, and said he’d be happy to help if it were possible. I get the feeling it’s not going to be that easy, though…

Thanks again.

Find out what the actual code was autozone does engine light code reading for free
the car battery has nothing to do with the check engine light going on
you most likely need to replace your spark plugs

Those WERE the actual codes. Or is there something I’m still not getting here?

I know the battery wasn’t related - I just said I replaced it as well, because it was needing to be replaced.