Car shakes on startup, clears up if I rev the engine

So I’ve had ongoing issues with this car that no mechanic seems to be able to diagnose. It jerks when I accelerate and decelerate pretty badly. It sometimes lets out a big cloud of smoke right when I start it. Now, it has developed some pretty violent shaking when I first start it up. It will only do this if the engine is completely cold and car has been sitting overnight. I feel like all these symptoms are related somehow. I have changed all the spark plugs and cleaned the throttle body. I’ve also had all the motor mounts replaced. I really wish the engine light would come on but it will not and never has.

It’s really annoying that it only happens on startup so when I take it to the mechanic, well, they can’t replicate it.

Any ideas on what to try?

2002 Toyota Camry LE V6
136k miles

Any Coolant Loss In Reservoir Or Radiator?
If Not, My Vote Is For A Leaky Fuel Injector.

What color is the smoke? White means coolant in cylinders. Black is unburned gas due to a too rich fuel load. I suspect white smoke and you have a blown head gasket. Blue smoke is oil in the cylinders.

white smoke. I can’t see any coolant loss or oil loss. Blown head gasket,I hope not. Guess I’ll get it tested. It only happens when I start the car and it’s not every time. It happens maybe once every two weeks. The shaking is every day though.

Start up shaking only when cold, maybe the temp sensor. Have you tried cleaning the Idle Air Control Valve and MAF sensor. Use sensor safe cleaner on the MAF.

I cleaned the MAF but not the idle air control valve. My idle has seemed strange as well. Every mechanic seems to think it’s off but for some reason they have no idea what to do about it.

Any advice on using a combustion leak detector kit? I bought one but my radiator has a very strange cap. I drained a bunch of coolant out of it but it still overflows at the cap so I can’t test it without drawing coolant up into the tester. Here is a picture of the setup, I have never seen a radiator cap set up this way.

oh, it looks like there is no actual idle control valve to service on my model. I can’t find it, it’s definitely not where any videos show it but none of those videos are for the model I have. Other people online say there is no mechanical part for it’s and it’s all software driven.

Hm, you can do it through the overflow reservoir? Might as well try it. Strange the instructions don’t mention that.

The funnel gave me an idea though. I think I will test it from the funnel but seal it up around the tester instead. I don’t think the reservoir will give accurate results honestly.

Apparently your overflow reservoir is acting as a water tower and keeping fluid too high to use the tester at the radiator cap. That is as it should be. The reservoir MAY have some hydrocarbons there for the tester to "see’, but I’ve never tested it that way.

I rigged something up that did the trick. Test came back 100% negative. Also tested the reservoir just to see but negative as well. If it is a blown head gasket I don’t see any evidence of that. I think there may be something to a bad fuel injector. The jerking it does when accelerating is like “not smooth”. It feels like something just squirted a ton of fuel in and made it jolt. I’ve been saying it could be fuel injectors since day 1. I wish there was some easy test but I’m going have to take it in and get them checked out I think.

Pull the spark plugs and see what they look like.
Get a compression test.

got around to getting a shop to look at it. Compression test was fine. Plugs are fine. Fuel injectors are fine. They don’t know what it is just like every single problem I’ve had with this car. So annoying. 9 mechanics now have looked at this car and can’t diagnose a single problem I have with it.\

It seems like mechanics these days just 100% rely on a computer to tell them what is wrong and are completely clueless if it doesn’t throw any error codes.

What does the car do when you put the gear selector in Drive like a normal person?

it doesn’t do anything unusual

This mechanic claims my transmission has issues and is causing the jerking when accelerating/decelerating. I simply don’t believe that is necessarily true though. I told him it does it when in a fixed gear like L or 2 but he told me it’s still shifting and the computer just ignores that. He claims it jerks when shifting but I know it doesn’t. Maybe it is the transmission but what they’re telling me doesn’t make any sense.

Has the tranny fluid and filter ever been changed? If not, take it to a dealer and have them do it. That way you get Toyota fluid. It only cost me around $90. It was cheaper than buying the fluid and the filter. A big bonus was that I didn’t have to get under the car for once.

Does it need to crank longer to start than it used to? I am thinking fuel injector cleaning and or testing. Leave it overnight at the mechanic, best option.

I had a similar problem with a Ford Aerostar some years back. It would run roughly for 30 seconds to a minute after I would start the engine after it sat overnight. It turned out that coolant was getting into one of the cylinders due to a cracked cylinder head. The Code dealer first replaced the head gasket, but the problem reoccurred. After stripping the engine down the second time, they found the crack in a cylinder head. At this point the engine was,replaced because enough coolant had gotten into the cylinder to score the cylinder wall.
You might let the engine sit overnight and before starting the engine, remove the spark plugs…If you find coolant on any of the plugs, you’ve found the problem. Sniff each plug and see if any plug smells like antifreeze.

There’s a technical service bulletin for coil issues on Toyotas of this vintage. I don’t think that it applies to your year model car (could be wrong) but just because it may not apply does not mean the car does not suffer from the same problem.

TBSs are just like Recalls; the stated problem may encompass a greater number of cars than the bulletin or Recall applies to.

Did you check inside the coil boots for any corrosion? Any corrosion or scale can cause problems like this.