Hi, I have a Australian 2000 camry wagon. There is a very slight misfire when the the car is not working hard. e.g usually appears when the engine is warm and is on flat or slight decline, with just a little throttle (1500 rpm or so).
I have changed Plugs and fuel filters so far. This has reduced the misfire but has not resolved it completely. Should I try the ignition leads next? Any suggestions would be welcome. It is a 6 cyl, Auto, 170,000 km's.

Cheers

Dave

 

Plug wires can cause this issue.

If you know how you can clean the MAF sensor and throttle bore.

 

Thanks Toyo,

I tested the leads last night with my multimeter the readings were 14k, 16k, & 18k ohms. Does this seem OK or should I try changing them. What brands are good.

Also, What is the MAF sensor where is it located. Any help with the throttle bore cleaning would also be welcome.

Kind regards

David

 

Toyota states 25K per wire is OK. You might check the wiring by spraying a mist of water on the high voltage wiring and coil(s) at night. Watch for any signs of electricity arcing and determine if the engine starts missing.

See link below for photo of MAF sensor location:

http://alflash.com.ua/RX/658_.jpg

See link below for cleaning, the link is for a Lexus but the engine is the same.

http://www.lexusownersclub.co.uk/kno...d=152&c=11

Be sure to use alcohol or an electrical contact cleaner for the MAF. Carb cleaner, etc is too strong and will damage things.

For throttle bore cleaner see the recent thread on IAC valve cleaning in this forum. For this job might also try CRC Lectra-Motive electrical parts cleaner, has less of a chance to damage plastic. The idle air control valve is plastic.

MAF sensor is mass airflow sensor. It is located before the throttle plate and measures the amount of air coming into the engine. It uses in part a heated wire exposed to the intake air.

The computer measures the change in resistance of the heated wire as a result of more or less air passing by and cooling it. The computer can then use this info in part to determine the volume of air passing going into the engine and adjust the amount of fuel.
The computer typically has trouble codes for gross misfires.

 

Great Reply Toyo,

Could you post the link to the IAC cleaning thread.

Thank you kindly. Will keep you updated.

Cheers, Dave

 

http://www.lexusownersclub.co.uk/kno...d=152&c=11

Link is for Lexus but the 2 cars use the same engine.

 

Have cleaned Throttle bore, MAF sensor and EGR valve.
Still no joy. Any other suggestions.

 

I can only guess at this point.

If the throttle is opened slightly the MP is going to drop. The drop would effect all vacuum circuits connected to the throttle body that use MP to in part control them. These would be the EGR and fuel pressure regulator as both us MP to modulate them.

This engine may also have an acoustic control valve that opens or closes to add more or less air (don't claim to understand this system), and another fuel pressure sensor that ties into the vacuum system.

Perhaps one circuit is not operating OK and the drop in MP is causing a flutter in its operation.

But just a guess.

Check your private messages for a link to more detailed info on this car.