Smog test Failed on my '86 420SEL????
Here's the background:
107K on the Odo.
New Copper core plugs, 91 Octane gas, 4 year old cat-back Time Valve Exhaust system.
Had the plugs changed to the coppers back in December, since that time the Tuna Boat has has a slight lope to the idle (800rpm+/-).
Two weeks ago I had a Lambda test done, just checking to see if any error messages came up.....shop owner tells me that on my year 420 the Lambda won't show any error messages????
He said, "I checked the "sweep" and it appears to be in the proper range. O2 sensor checks out OK!"....hmmmmmmm?????
Here's the real issue: Went to have the smog test done today, passed the idle, but failed the high speed(rpm) side of the test!
Looked under the hood, saw that the hose from the vacuum control valve to the throttle assembly was NOT connected!!!
On the test, the Tailpipe HC ppm reading @ 2500+/- 300rpm was 258. (No smoke!) And the CO% reading was 5.24. Yet, when he did the 4 gas test it passed?
Did a second test...the readings were 222 & 5.44 respectfully!
Is the hose disconnect the reason for the failure
p.s. - O2 sensor dash light is NOT lit.