I have a 1999 Camry V6 with a peculiar problem. The engine runs just fine up until it gets hot (180 degrees F) Then it starts to miss when under load. For example when accelerating away from an dead stop it will miss and if I accelerate rapidly (like passing) it will miss. If I gradually accelerate I can get it up to speed and run all day long at 55 on cruise. But if I stop and start again it misses. I've taken it to two shops and the dealership without a fix. So far I've changes the CATs (Not the one in the header), O2 sensor, plugs, wires and all three coil packs. I've replaced the fuel filter, the PCV valve and the MAP sensor. I really don't know where to go next.

Any ideas!

 

Is the check engine light on?
Losing any coolant?
When were the plugs changed last?
How many miles on the car?

 

Thanks for the response.
No, the check engine light does not come on. I've put the code reader on it several times and nothing.

I changed the plugs the same time as the wires and coils. No change.

The car has 224,000 miles on it and it belongs to my son who can't afford another car. I really need to get it fixed.

Thanks!

 

Fuel system issues may not cause a code.

Do you have a code reader that can read out real time data?

 

Yes, I have a code reader that displays engine data. What do you suggest?

 

When the engine starts misfiring, you might be able to get a snapshot of the engine sensor data. Check the scanner manual for its ability to access data with engine running. Such as:

Bank 1 (rear cylinder bank) 02 data is the same or different from Bank 1 (front cylinder bank). If different then the problem may be more localized.

The engines fuel trim trying to lean or rich the mixture caused a real too rich or lean mixture.

Sensor output changing dramatically between engine cold and engine hot operation.

Not all systems are monitored by the computer but may show up in data.

"Real time" may be updating scanner data every 30 seconds. Check owners manual.

 

fuel sock if it has one in tank, something in computer maybe

 

Long story, my 2012 Camry needs a new engine bc of misfires and coolant in cylinders! Head gasket won’t help! Coolant was getting low, I kept it topped off, within 2 months the engine went!! Happened at 130,000 miles, was a trade in for my 2007 Camry which consumed oil!!! No more Toyota’s for me! I’m stuck with this one for 4 more years still owe $10,000 on it and now a $4000+ repair!!! Warning: your coolant should never leak!!! Checked engine light and traction light popped on and a week later my car was dead. I’m investigating with the dealer where I got it. I keep all my cars very well maintained and I’m the one that noticed the coolant getting low and had it checked by a trusted mechanic the first time around that sent me home telling me everything was fine. I’m telling people this to help others out, get an engine test or a compression test done!!!