I have this Toyota siennna 1999 model , it starts consuming fuel excessively gushing out black smoke, I was advised to change the air flow meter which I did but doesn't solve the problem, my mechanic later cleaned the throttle valve and some other things, the black smoke reduced excessively, but the fuel consumption still very high.
Following the advice on one of the threads on nairaland, I decided to go for scanning which reveals the following codes..:
P0325 - knock sensor 1
P0330 knock sensor 2
P0500 - speed sensor
P0773- transmission shift solenoid
My question now is , Will changing the knocks sensors reduce the fuel consumption?, what of changing the shift solenoid, how does this affect the fuel consumption as well. What do I do now because I don't ve money to waste...pls i just want the gurus to advise me on what to do next...
Thanks very much as I will be waiting for your responses..

sunylop:
I have this Toyota siennna 1999 model , it starts consuming fuel excessively gushing out black smoke, I was advised to change the air flow meter which I did but doesn't solve the problem, my mechanic later cleaned the throttle valve and some other things, the black smoke reduced excessively, but the fuel consumption still very high.
Following the advice on one of the threads on nairaland, I decided to go for scanning which reveals the following codes..:
P0325 - knock sensor 1
P0330 knock sensor 2
P0500 - speed sensor
P0773- transmission shift solenoid
My question now is , Will changing the knocks sensors reduce the fuel consumption?, what of changing the shift solenoid, how does this affect the fuel consumption as well. What do I do now because I don't ve money to waste...pls i just want the gurus to advise me on what to do next...
Thanks very much as I will be waiting for your responses..

those code are only for the auto gearbox they got no links with black smoke, black smoke is most linked with oil, oil must be linking into the engine

@ Zim drill...code P0325 and P0300 are not related to automatic transmission.. Only P0773 has to do with the transmission.although, there is oil leakage from the sump, I think that doesn't ve anything to do with black smoke from the exhaust..

i think you need to rescan the car, and make sure you use a generic scaner. therez absolutely no relations between the codes you have here and the black smoke. although the shift solenoid could make your car consume fuel because the gear ratio will not be proper. not by black smoke. but i tell you, dont guess and dont waste money, the fault can only be reveald by scaning.

@ o tech... Thanks very much for your contribution, the car was scanned twice and these are the codes :
0325 - knock sensor 1
P0330 knock sensor 2
P0500 - speed sensor
P0773- transmission shift solenoid

Maybe I should still go ahead to change the knock sensors..the black smoke reduced after cleaning the throttle valve..

Siena and ikena should please contribute..pls I am still waiting ...