Camry Stumbling

[Nick1994]

This started happening 2-1/2 weeks ago. I've been thinking it's the transmission, but now I'm wondering if it's a sensor or something else.

When accelerating from a stop with lots of throttle, it stumbles, almost acts like the transmission is slipping, but the RPMs don't shoot up. If I take off gently, it's fine. Once the RPMs are above 2,500 or so, it's fine. Driving at 40 mph or 70 mph is perfect, even under heavy acceleration.

I've also noticed when slowing down to a red light and I reach around 20 mph if the light turns green and I give it 1/2 throttle or a little more, it does the stumbling. But if I give it full throttle at that speed, it downshifts to where the RPMs are nice and high and it's normal.

I've also noticed when sitting at a light that it will also have a "miss" for a split second occasionally. All of a sudden it's a bump of it cutting out, hard to explain.

It does this with a warm or cold engine. I have no CEL and no pending codes. I bought the car August 2015 and have since put on a little over 30,000 miles. When I bought it I put in new OEM spark plugs, new spark plug wires, new PCV valve, new air filter, and a new fuel filter.

Here's a link to a video I recorded. I was at about 3/4 throttle. You can hear the RPMs climbing weird in the beginning and if you watch the tach you can see it get a little stumbly before 2,500 or 2,700 RPMs. The creaking sound at the beginning is the rear strut mounts, they're on the to-do list.

 

[Rolla07]

Aftermarket air intake or stock?

 

[SatinSilver]

How about some Gumout All in One Fuel treatment and some Shell gas from a newer, high volume station.

 

[JC1]

Is the engine a V6 or 4 Cyl?

Have you ever cleaned the IAC(Idle Air Control valve) and throttle body? Does the PCV valve have a hose on it? You should clean it out if it does.

What about the tranny fluid? Has it ever been changed? I would do a drain and fill on the tranny to see if that improves it. You could also drop the tranny pan and clean it up.

 

[Drew99GT]

If you're certain it's not in the transmission, try the usual things. Fuel system cleaner, spray out the throttle body with cleaner (make sure it's safe for fuel injection), clean the MAF sensor if it has one etc. Also, you didn't mention the cap and rotor. I'd for sure pull those; if they haven't been replaced in a while, they'll be a lot of carbon tracking.

 

[Lubener]

I always believe in testing first. Recheck the basics( even a coil breaking down), because you did it in 2015 does mean much.Some things I would check, if the fuel filter is due(you got 30k), I would change it, I know you did it 1.5 years ago but a bad tank of gas could do it in. I would check the TPS for a nice resistive response (with no dead spots at certain postions)while moving the throttle plate with an analog meter.Try disconnecting the MAF and see how it responds. I recently had issues with the EGR valve sticking and my car behaved in a similiar fashion.You might want to hang a fuel pressure gauge on it where you can see it while going on a test drive.

 

[Dan55]

Were The ignition coils ever replaced ? I think you are due, OEM Denso are a little over $100 from Rockauto. Also the EGR valve can also cause similar problems.

 

[goodtimes]

The first thing I check now are the two large hoses that go from the air filter to air box to the throttle body. Especially that age they get cracks. These look like a bellows. It fouls the whole system up if they get cracks as the air after the MAF sensor is inaccurate. I had stumbling on an 02 and this fixed it so it ran like new. I got the new ones from a Toyota dealer online.

 

[Danno]

Thinking coils as well.

 

[HerrStig]

The "before the cat" air fuel sensors can cause this problem if they get "lazy". The coils on my 99 I4 are currently at 350K. The throttle is a cable, not electronic. If the car can hold 80 mph on a level road it doesn't need a fuel filter.

 

[eljefino]

Originally Posted By: goodtimes
The first thing I check now are the two large hoses that go from the air filter to air box to the throttle body. Especially that age they get cracks. These look like a bellows. It fouls the whole system up if they get cracks as the air after the MAF sensor is inaccurate. I had stumbling on an 02 and this fixed it so it ran like new. I got the new ones from a Toyota dealer online.


This car has a speed density system, not MAF. My vote is for coils.

 

[OVERKILL]

Can you get access to a reader that will give you actual misfire counts? That would help you pinpoint a coil, wire, or failing plug. Since the plugs are newer, it would point to a coil IMHO.

 

[WobblyElvis]

More like an air leak to me. Mixture is not right due to a crack in a hose or an intake sensor is not reporting correctly throwing the mixture off. A bad coil will usually throw a code.

 

[Nick1994]

Originally Posted By: Rolla07
Aftermarket air intake or stock?

It is 100% stock

Originally Posted By: JC1
Is the engine a V6 or 4 Cyl?

Have you ever cleaned the IAC(Idle Air Control valve) and throttle body? Does the PCV valve have a hose on it? You should clean it out if it does.

What about the tranny fluid? Has it ever been changed? I would do a drain and fill on the tranny to see if that improves it. You could also drop the tranny pan and clean it up.
2.2L 4 cylinder. Haven't cleaned anything yet. The hose to the PCV valve was all gooey just from heat, I replaced the hose with one from the dealership about a year ago. I've done at least one drain and fill on the transmission. Maybe 2, can't remember. I have a new transmission pan gasket and filter for it that I bought last summer, just haven't gotten around to doing it yet.

Originally Posted By: Drew99GT

Also, you didn't mention the cap and rotor. I'd for sure pull those; if they haven't been replaced in a while, they'll be a lot of carbon tracking.
No distributor, it's got a coil pack.

Originally Posted By: goodtimes
The first thing I check now are the two large hoses that go from the air filter to air box to the throttle body. Especially that age they get cracks. These look like a bellows. It fouls the whole system up if they get cracks as the air after the MAF sensor is inaccurate. I had stumbling on an 02 and this fixed it so it ran like new. I got the new ones from a Toyota dealer online.
I replaced the intake hose last year, it broke from the heat.

The fuel filter is supposed to be a lifetime filter I think. I changed it because I think 200k miles was a little much. Wide open throttle and redlining the engine is fine merging onto the highway. I do this daily, this car is driven pretty hard.

 

[supton]

Every rubber hose on my '99 has been disintigrating. I wouldn't be surprised if you had an air leak. But I'd see about hooking up something to monitor O2, maybe Torq over the OBDII port. Or just hook up that cheapo Techstream.

 

[Nick1994]

Originally Posted By: OVERKILL
Can you get access to a reader that will give you actual misfire counts? That would help you pinpoint a coil, wire, or failing plug. Since the plugs are newer, it would point to a coil IMHO.
I've got a cheap code reader that I can read with my phone, I doubt it'll read that. A buddy of mine is a mechanic and he's got a pretty good scanner. He's pretty busy right now though, I might see if he can squeeze it in if I can't figure it out

Originally Posted By: supton
Every rubber hose on my '99 has been disintigrating. I wouldn't be surprised if you had an air leak. But I'd see about hooking up something to monitor O2, maybe Torq over the OBDII port. Or just hook up that cheapo Techstream.
Everything rubber on mine is disentegrating too. I found a broken vacuum line a week ago, I electrical taped it back together for now. Didn't change how it ran though. I'll check for more.

 

[OVERKILL]

Originally Posted By: WobblyElvis
More like an air leak to me. Mixture is not right due to a crack in a hose or an intake sensor is not reporting correctly throwing the mixture off. A bad coil will usually throw a code.


I'm not super familiar with Toyota's, but on a Ford, a failing coil rarely sets a code. The misfire count never gets high enough fast enough unless it totally defecates in the bed. Of the four coils I replaced on my Expedition, not one ever set a code. On my dad's, one, that failed outright, did. the other two didn't.

 

[Kuato]

If this issue happened suddenly, go back and check the most recent repair.

 

[Warstud]

It could be a number of things.

 

[Merkava_4]

MAP sensor or MAF sensor dropping out is what comes to mind. You'd need an oscilloscope to catch the drop outs. I've had both issues with my Buick at separate times.