420SEL Lambda 99.99%? - PeachParts Mercedes-Benz Forum

redassag00 · #1 10-13-2010, 02:37 PM

Hi fellas,

Working on the 420SEL.

I have replaced a bunch of vacuum lines and hoses etc under the hood, chasing a rough idle and middle of the road vac gauge when warm. I seem to have eliminated most of the vac leaks, as the gauge is now mostly to the left except when the A/C is on.

I used my voltmeter across the Diag port,slots 2 and 3 the other day, and it was pegged at 99.99% as soon as I turned the key on (engine off). I remember that it should be 70% or 85% at KOEO to show if its a Federal or Cali Car right? Swapping the negative and positive on the DVOM yields the same results.

So KOER (engine Running) is 99.99% also. No change. I suspected the OVP may have been bad, so I used the voltmeter across the fuses to check for voltage. There was none. Fuse was good, So I picked up a new OVP, plugged it in. Same thing. 99.99 KOEO, and 99.99 KOER.

Any help?

Thanks in advance.

mbdoc · #2 10-14-2010, 09:31 AM

Does your voltmeter have duty cycle capabilities?

Have you tried measuring current flow(75Ma KOEO) to & thru the EHA?

Gilly · #3 10-14-2010, 09:45 AM

What are the readings across the OVP now that it's replaced???

How is the car running now that the vac leaks are fixed??? And the gauge?

Does it run better when warm when compared to cold?

Any warning lights on the instrument panel??

Gilly

redassag00 · #4 10-15-2010, 12:44 AM

Quote:

Originally Posted by M.B.DOC

Does your voltmeter have duty cycle capabilities?

Have you tried measuring current flow(75Ma KOEO) to & thru the EHA?

Doc,
thanks for the reply. The duty cycle was 99.99 on the DVOM.

So you recommend unplugging the EHA and measuring voltage across the plug to check for 75Ma, KOEO?

I will do that tomorrow.

Quote:

Originally Posted by Gilly

What are the readings across the OVP now that it's replaced???

How is the car running now that the vac leaks are fixed??? And the gauge?

Does it run better when warm when compared to cold?

Any warning lights on the instrument panel??

Gilly

Gilly, no lights on the panel. I didnt check the readings on the new OVP. I had the package on the door step when I got home, was too excited and swapped it out in dress clothes. The gauge used to stay in the middle as soon as you strated the car. Now its on the left in the black pegged, in drive with the air on and your foot on the brake, the needle is barely off the peg

The car runs fairly smooth when cold. The problem I have is the shaking when warm. O2 is about a year old.

Gilly · #5 10-15-2010, 05:52 AM

Well ya MIGHT want to see if there is voltage at the OVP fuse, that just might affect driveability, what with the ECU not receiving any voltage and all......

redassag00 · #6 10-15-2010, 10:24 AM

Quote:

Originally Posted by Gilly

Well ya MIGHT want to see if there is voltage at the OVP fuse, that just might affect driveability, what with the ECU not receiving any voltage and all......

I understand that.

As I stated, I got home from work and saw the box on the doorstep and just put the new OVP relay in. Didn't want to be leaning over the hood in a dress shirt and tie.

Will check and report back.