'90 560SEL Sudden Loss of Power
 

Hello,

My 560SEL has been running perfectly for two years! It has 135k miles and maintained well. Yesterday, after running for 20 minutes at 70 MPH I had no acceleration but the car didn't stall. It came back to normal in 3-4 seconds....then did it again less than a minute later. I pulled off the freeway and shut off the engine and it restarted normally. I drove for another hour....freeway; stop and go traffic; 95 degree heat. Last night, after 20 minutes, the same symptoms.....sudden loss of power. I was driving in a 30 MPH zone...I placed in neutral and rev'd.....the rpm jumped to 4k with no problem. The power loss kept repeating for the next 3 miles home. I rev'd in neutral a few more times and if I let up completely on the accelerator the engine stalled sometimes. It always restarted normally.

It should be noted that the idle is smooth; starts normal and quick; does not stumble or sputter when power loss occurs; no backfire.

Thanks for your help!

Problem solved! It's a faulty E.H.A. Valve.

Great!
How were you able to isolate the fault to the EHA.
mak

I read a lot of postings....but I was ready to send an update! While the problem disappeared after disconnecting the EHA valve, it may have been a coincidence. My mechanic thinks it is bad gas (obtained from Kroger in Atlanta). I am bringing the car to my mechanic (Autobenz in Marietta) and have is diagnosed. I was told the EHA rarely fails.....usually leaks (mine shows no sign of leakage). I will report back.

Thanks for the advice everyone!