bucking and surging
 

04 e55 with 84k. Car has run great no problems. Start car after work and head home hit gas and the car hesitates hard and slowly accelerates. Car is stock

I checked fuel pressure with the car off and holds around 60psi for several minutes.

With the car running fuel pressure does not drop much when under throttle.

logged some data and while accelerating it generates 8ish pounds of boost and accelerates very slowly.

It looks like timing is pulled to -26 degrees

outside temp is 68 ish and IAT temp is 100 before a pull.

I know that the IAT is high and I have ordered an updated bosch pump. I have pulled all of the conectors from the coils, inspected for corrosion and put electrical grease before reassembling them. No engine codes and I have pulled the battery to reset the ECU.

Is this a common problem with an easy solution?

Check the sc clutch if it is engaging.and then slipping.

what is stock boost in these cars? I am going to log some data and come back. it looks like the o2 voltages are consistent between both banks pre and post cat.

It looks like 60 psi is too low a fuel pressure and 55 idling is way to low. I removed the rear seat and the covers for the fuel sending units.

Can anyone explain the setup. does one feed the other? are there two pumps on one side and the filter, level sensor the other?

There is a heavier gauge wire going to the passenger side

similar just happened to me but it turned out to be the idler tensioner pulley as if broke and car went into limp mode and accelerated like a snail. once replaced all was fine though

ok so both pumps are on the passenger side. I opened up the unit on the passenger sideand removed one of the connectors and turned the key to hear if the pump would prime it did then tried the other. I wend back and forth a couple of times cause it sounded a little different.

Reached in the tank (full of gas) and felt the connections on the pump and the negative connector on the pump had a poor connection. grabbed my crimpers and tightened the connection and voila.

Fast car again I can only imagine what the dealer would have charged me and replaced

nice work my friend, good to know