fuel cleaner now surges on acceleration

[rojeho]

Have only put about 150 miles on new to me 92 E36 M42 with 109k miles.  I drove it 500 miles to the house, then I changed plugs, and ran about 1/4 tank of gas.  I then refilled the tank and added a bottle of Red Line fuel system cleaner.  After driving through approx 1/4 of the tank, I now have a rough idle (never close to dying and needle doesn't bouce, but it'll shake every few seconds) and surging through acceleration.  It seems to be not as bad if I accelerate hard and hold shift to 4000-4500 rpm.  Once I get to speed it is smooth, but with any additional load (pressing more on the pedal) it is surging and not smooth.

I need to check codes, and I searched here and found suggestions all over the map.  I am curious about how this started after the addition of the fuel cleaner.  Any thoughts related to this or just coincidence?

[monko141]

I would say drive it like you stole it tomorrow, when you get home disconnect the battery overnight and let the dme reset.  Reconnect it in the morning and drive it normal and get back to us with your results.

[DesktopDave]

The fuel system cleaner might have loosened up some of the vac hoses.  They're notorious for failing.

You might also want to clean the AFM, clean the CPS, check the ICV or check the CCV.  All are trouble spots with the M42.  None of these is too expensive to do, and it's wise to be familiar with their condition.

Also, if you've just washed the car, the DME might have flooded.  Check the firewall drain on the passenger side.