Those are the symptoms my wife is describing. She says once she gets up to speed it’s fine.
The important thing is that this began yesterday, after she drove through some pretty deep water in the morning. So I would have to think it’s connected to water getting into the system somewhere.
I took out the air filter, which was dry, so it’s not like water went in that way. The oil dipstick looked very normal, as did the transmission fluid dipstick.
The only other possible clue is that the check engine light has been going on and off intermittently. Truth is that it’s been doing this for the past several years, but the pattern has been “on for a few days, off for a month or two …”, and now it’s been going on and off during the same drive.
Any thoughts? In particular, is it likely that whatever the problem is would become worse from driving around before fixing?
Make, model, engine, year, are always helpful. Cars have differences.
Downstream from the air filter is a MAF sensor. Mass Air Flow. It is probably in the air filter housing or nearby where some wire plugs in. They can get dirty or the screen can get plugged. Look at, but don’t touch it. Get a can of MAF cleaner and spray it clean if you think than may be the problem.
It is possible that the exhaust system is full of water? That could cause issues.
The fact that your check engine light has been coming on and going out is a concern. Sometimes a fault will be detected and then after a certain number of engine cycles without the fault, the light will go back out. It is possible that whatever issue is causing the light is getting worse. Code readers are great but hey only point you to the direction where something may be wrong and not the actual cause.
Cars are complex but the still need just air, fuel, and spark to run.
I had a longer post that got eaten by an error code.
chances are if it was water ingestion into the engine, she would have noticed it by the car stopping dead in its tracks. If this behavior began right after going through the water, then it’s likely that water got into a connector or some module and is causing an electrical fault. at idle and just at throttle tip-in, the idle air control (IAC) circuit is controlling engine air intake. Once you’re up to speed the throttle itself is handling that, so poor idle and stumbling on take-off makes me think something happened to the IAC valve, IAC motor, or the associated wiring.
So my wife brought the car (2001 Prizm) home, and I did a couple of things. 1) drove it a bit myself and 2) ran an OBD scan with a cheap scanner I have.
The major symptoms are as described above. The only thing I have to add is that while in idle, it depends on which gear the transmission is in. When it’s in park or neutral it seems fine. When it’s in reverse or drive or one of the lower gears, you get some shaking and rough idling.
The scan codes which came up are: P0300, P0303, and P1349. The first two seem to indicate a cylinder misfire, in Cylinder #3 specifically. The third is apparently a VVT solenoid malfunction. And apparently a VVT malfunction can itself cause a cylinder misfire, which in turn causes the problems along the lines of the above. So that’s my guess. (Though I don’t know if there’s any connection to the water, in that case.)
Key question is: are we damaging the car by driving it around meanwhile?
Generally when engine misfire is severe enough to cause damage, the check engine light will flash. The damage will first be to the catalytic converter, which is expensive to replace. Prolonged driving with a flashing check engine light could result in internal engine damage, which is REALLY expensive to fix.
I’ve seen poor running caused by an oxygen sensor that got well splashed by driving through a puddle, without setting a code.
The other suggestions getting tossed out are certainly easier to check, but I’ll add in the possibility of a failing fuel pump. I’ve had similar issues where an older truck I have would mostly be okay, but if you gunned the engine it was stumble, pretty bad too. A new fuel pump cleared it right up.
I’m not sure what pressure your car runs on, but the truck requires IIRC 63psi to run. Anything less and it won’t run or have a very difficult time. For that reason, on this truck, it can be tough to hunt down the cause since the pump still works, just not properly. In other cars, this isn’t as big of an issue.
In any case, if you can find out the PSI the injectors need, you can rent a fuel pressure tester from the auto store (usually for free) and test it yourself. If your car has a test port, it’s pretty easy.
The VVT fault may be a clogged oil control valve filter. You didn’t say how many miles are on the car, but the VVT filter is a 100,000 mile service item. Believe the Prizm’s engine is actually from a Toyota Corolla, so searching for the fault codes will turn up results for Toyota and Lexus models as well as Chevy/Geo.
So I brought it to a mechanic. According to him, it was coil/plug #3. ($200.)
[I’m not 100% clear on this, because this guy is a good and honest mechanic, but his organizational skills are very lacking, and he’s usually overwhelmed at any given time, so it’s hard to get more than a few disjointed words out of him, especially on the phone. But that seemed to be what he was saying.]
I had very similar symptoms about 10 years ago in a 1995 Nissan XE 4-cylinder pickup. Symptoms were most severe when idling or driving at low speeds, and diminished greatly at highway speeds.
It ended up being the ignition coils. If memory serves, they were tucked up underneath the distributor cap, and the entire assembly – cap, coils, wiring, etc. – was replaced. Ran great afterward. I recall that the repair was only about $250 at a Firestone shop (in 2009) … so your $200 quote sounds really reasonable.
The irony is that I myself know how to replace a spark plug and ignition coil, and could have done it for far cheaper. Where I’m lacking is in knowing how to diagnose it correctly, which is where this guy is really earning his money.
