# 88 5000 S failed Nox emissions. Help!



## tullio (Dec 4, 2003)

Hi all,
I had researched this and concluded that egr was be my problem. But my car doesn't have an egr valve. Here's the story.
Daughter's 88 5000 non turbo, auto, failed NOX emissions twice, but passed HC and CO. Numbers from latest test: HC 1.45 (limit 2.0) pass; CO 8.72 (limit 20.0) pass; NOX 4.49 (limit 4.0) fail.
First test had similar CO and HC numbers, but 4.8 Nox reading.
Second test was done after oil & filter change and a can of BG44K treatment (always works in my old Italian and British cars dammit!) after about 75 miles and then 30 mins on freeway prior to test. Nox reduced a little, but still failed as shown above. Tune up was done (not by me or during my ownership) about 10k ago. Car runs great, no stalling etc.
Fuel tank is full, but I just learned daughter filled it with 85 octane regular gas. Fuel filler door states 91 octane. Could this be the problem? Any other ideas? I can't hear pinging, but could be age (of the ears, not the car...)
Thanks in advance!
Greg / Denver


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