Hi everyone, I have a 1998 ML320 with 225000 miles. On the way home from work thursday night I floored it to go around someone and the check engine light came on. My ML started runnning rough and had no power. yesterday I borrowed a code reader and came up with the following codes.
PO460 - fuel level sensor A circuit malfunction
The fuel gauge has been erratic for sometime now.
PO301 - cylinder 1 misfire
PO303 - cylinder 3 misfire
PO300 - random multiple cylinders misfire
PO700 - trans control sys malfunction
The car idles rough and misses badly above 4000rpm. If I shut the car off and then restart it, it runs normally (except for the miss above 4000rpm) for a few minutes then looses power and runs and idles rough.
From looking at some previous threads, I tried a few things. I cleaned the connector at the right side of the trans, no help. I have noticed that the throttle has been non linear lately, so I did the turn key on 5 second reset proccdedure, didn't help, though i didn't expect it to. Now that I think about it, the fuel filter hasn't been changed in a while. fuel starvation at higher rpm's? I changed the plugs about 10000 miles ago.
Anyway, any thoughts would be appreciated.
Thanks,
Howard

 

Hi Howard,
I have a same problem even after replacing plugs, coils, wires, crank position sensor and fuel rail with injectors. I tought my cat. converter is bad on one side of cylinder bank.
Now, after reading through W163 Star Manual I've found out that these codes will show up when throttle body (valve actuator) is not working correctly.
Go to your local library and log onto Alldata (damage code 14 031 73) "Usually no DTC is stored. In some cases DTC P0300-P0308 may be stored (A-misfire)"
Take a mirror and check label on your TVA (throttle valve actuator), production tolerances exceeded with date 662XX to 769XX are affected.
Three things to check:
1. CPS (crank position sensor)
2. TVA (throttle valve actuator)
3. CC (catalytic converter) clogged on your R (right) cylinder bank

I hope member chassis221 will reply to this thread, I would like to read his experience and opinion on this problem!
Regards,
Bernard

 

Hi Bernard,
Thanks for the reply. After checking some more threads last night, the threads with my symtoms all seemed to point the cps. I changed the cps today and it didn't help. If I turn off the truck then restart it, it seems to run okay untill it gets above 4000 rpm where it misses badly. The cel comes back on and it runs rough, idle etc. no power. Today I rechecked the codes and got .p0300, p0301, p0303, p0460. I guess cleaning the trans connector worked. Yesterday I had codes for every cyl execpt #6.
I assume that you have to join alldata because I couldn't find any info on damage code 14 031 73. I also couldn't find how much $ on their web site. Is the tva on the firewall just outboard of the coolant tank? Is there a way to test it?
I can't complian too much, with 225000 miles nothing major has gone wrong. I learn something new with each problem. Thanks again.
Howard

 

Hi Howard,
TVA is under the coolant tank screwed into back side of the intake manufold. Follow the air tube from air filter through air mass sensor right into it. Whole assembly cosists from 4 wiper style carbon surface potentiometers determining the position and one geared motor for opening the valve.
You don't have to join and pay for alldata info, it is all free but only through computers at your local library!
I have a new tva assembly but with newer style connector (01 and up). I was able to place mirror behind engine and read all tag info off of throttle body. I have same simptoms as your vehicle. When prolong misfire is detected, it will shot down the effected cylinder and reset it all back after turning off the engine (ECM). Normal driving will never trigger the misfire but my iddle is not as smooth as it should be. I have seen the inside of throttle actuator and I will clean the potentiometers as soon as I have some time too see the difference. Or I will make my own adapter to be able to connect the new style TVA to my engine's electrical harness. Good luck,
Bernard

 

Hi Bernard,
I will check out alldata at the library. Throttle valve actuator, another term to learn. If you would have said throttle body I would have understood. Thanks again,
Howard

 

this is what you need to do you need to reset youy adaptations of your crank position sensor. on a mercedes ckp sensors will not make yor car run rough by being defective that will not let your car start. therefore there either good or there bad. go to your local dealer and have them reset your adaptations. not your trans adaptations your m.e. adaptations. you have said you replaced all your coil wires and plugs as well?

 

I tought you don't have to reset anything when you replace crank position sensor (plug and play type of a repair).

Howard,
Sorry for my terminology, Mercedes is calling it in every literature throttle valve actuator, everybody else throttle body. So you better search for valve actuator when you log to alldata files for ML320.
Regards,
Bernard