I'm hoping someone can assist with my issues following a transmission fluid change and motor / transmission mount change @ 95,000 miles.


Several days after the service I accelerated hard and the car stopped engaging the wheels, showing the BAS ESP light.

It stayed in drive, but it just revved without moving forward. I moved to the side of the road, turned the car off and back on, then it drove normally with the BAS ESP light no longer on.

I took it back to the mechanic that day and they could pull no codes, either with the motor or transmission. They also test drove it without issue.

Several days later it did it again, this time the check engine light came on. When I got home, I noticed the coupling hose from my NeedsWings single CAI was disconnected at the throttle body.

The codes showed as P0505 (Idle Control System Malfunction) and P0101 (Mass Air Flow (MAF) Circuit).

I reattached the CAI and checked all the vacuum hoses then reset the codes.

I'm now only getting code P0505 and the car does idle faster than normal, especially after being driven awhile. Shifting into reverse also makes a clunky sound.

I checked the intake manifold gaskets by spraying starting fluid on the seam, but the engine did not increase RPMs

My Sprint Booster was also removed in case that was the issue or contributing to it, but the P0505 code still appears.

I've also tried the Throttle reset procedure several times without any change to the behavior.

What am I missing?

 

Trans low on fluid or conductor plate or connector

 

Would replacing the conductor plate require my auto shop to basically redo the transmission service they just completed?

I’d hate to be charged again for the same service 2 weeks later.

 

If it's a non-Benz shop, my first thought would be that they didn't fill the trans correctly. Do you know how they checked the fluid level, or did they just replace "x" quarts of fluid ?
It's based on temperature, then I'd be looking at the conductor plate connection, then the conductor plate.
Classic symptoms of low fluid level, considering the car was shifting fine before the service

 

They are a well-respected shop specializing in European nameplates (90% Mercedes or BMW) that swear they checked the level correctly with the specialized dipstick tool.

I cleared the P0505 code again last night and so far has not returned after 30 miles of driving. But I have a call into the shop to drop it off tonight for further evaluation

 

Well the shop couldn't find the issue without asking for another $300 or so for a longer analysis, so I picked it up yesterday.

When I was shown a picture of the transmission fluid level, I noticed there are 3 separate brackets on the indicator:

The lowest bracket which is about 1/4" wide between the bars, a middle area which is around 1" wide, and a high level bracket also around 1/4" wide.

My level shows at 2/3 up on the larger middle bracket, it that filled enough to prevent the issues above?

The mechanic said that's the level they fill Mercedes 722.6 transmissions and never have high idle issues or P0505 or P0507 codes afterwards.

They also claim the Conductor Plate and connections from it checked out fine, there were no vacuum line leaks, and they cleaned up the Throttle Body.

Codes pulled off of Mercedes diagnostics were:

P20A2 - Idle speed control implausible:check system for unmetered air

P202B - Idle speed control implausible: (P0507) Short circuit to ground / open circuit (P0102)

Thoughts?

 

The height the oil level varies according to the oil temperature, cold oil = low oil level, hot oil = high oil level.
So the temperature of the transmission oil has to be taken into account when looking for the correct oil level. I’ll add a diagram in a while.
I use an infrared temperature gun on the oil pan or refill it when the engine has cooled long enough to be at the surrounding known air temperature.
The temperature has a large effect on the level also oil will be scattered around inside the tranny case and slowly trickle back to the oil pan.
It is not rocket science though.
It is covered in the owners manual quite thoroughly, you do have an Owners Manual I hope. ( OOPs I found this not to be true)

 

Thanks,

I ordered a transmission level dipstick today and will check it against the chart when it arrives on Monday.

Would you recommend measuring it in the morning when the temperature should be in the bottom area of the graph ?

 

Well the transmission fluid was about one quart low, which I remedied.

It seemed to have helped somewhat, but when the car tries to lower the RPM's to around 700 (In Drive at a stop light) it quickly goes back up to around 1,100.

Also, on the freeway, RPM's do not decrease below around 1800 when I take my foot completely off the pedal.


Last night I took off the Needswings single CAI and the throttle body to completely clean it and sprayed the connections in that area with electronic parts cleaner

Then re-installed everything tight.

The shop says there's a very small vacuum leak where the hose comes out of the intake and goes to the brake booster.

I checked its slip-style connector and it does move in and out fairly easily, but they claim the leak is tiny and wouldn't be enough to affect the idle.

Thoughts?

Do throttle bodies ever go bad?

Or could this be the gas pedal itself needing replacement?

 

How was the O ring on the TB ? Did you replace it ? Are you sure it is seated correctly ?
My stepson bought a smoker recently, not too expensive, sure is easy to find vacuum leaks with it.

 

The gasket / O ring on the Throttle Body looked great, the shape was good and it was still soft and pliable.

 

OK, good. Just know that when I did the swap from 68 to 74mm the old O ring was toast !

 

Well it turned out to be the Throttle Body itself.

The new mechanic was able to test the ohm level and it was out of spec.

(Sure wish I would have known how to test it, as they charged me $800 to install a used one)

But it's running perfect now.

 

good to know, glad you got it sorted, AND, came back to the forum to post the solution, which helps us all !