Question about 1988 Cadillac Sedan DeVille

Open Question

My 1988 deville idles high and has high nox...help

My 1988 deville runs great after I got a complete tune up and oil change. I went to get a smog test and i failed. my service soon light stayed on and my engine idles high for some reason and won't go down. my nox # at 25mph was1269 and my cat converter seems to be alright so i don't know if it's my egr valve or the idle thats causing failure. I guess it sould be many things though....HELP!!!

Posted by on

  • thomas thompson May 11, 2010

    cheek for a vaccuum leak hose off. high nox is that there is to much heat in the combusting camber the egr vavle lets air in the cylinder to cool it off .check to see if the egr is working

×

6 Suggested Answers

justuscc
  • 360 Answers

SOURCE: CHEVY SUBURBAN FAILED SMOG BECAUSE OF HIGH NOX VALUES.

nox is from running lean..... its realy high temps that cause this.......... replace the o2 sensors this should cure that any more help let me know

Posted on Oct 24, 2008

  • 2920 Answers

SOURCE: I HAVE NISSAN SENTRA '97 MY PROBLEM IS, IT WON'T

id say you need to get them changed then so it will pass inspection

Posted on Feb 20, 2009

michigan man
  • 3533 Answers

SOURCE: the service engine soon light stays on i just change oil

you can try taking the positive cable off for about 3-secs and check in you owner manual to see if it tell you how and if you do have one try this website www.edmunds.com to see if you can download one for you car.

Posted on May 25, 2009

  • 15 Answers

SOURCE: Emissions failing with high NOx

You need to check the oxygen sensor. You car may be running lean and therefore giving you increased NOx levels

Posted on May 30, 2009

  • 7353 Answers

SOURCE: 1998 cadillac deville service engine soon code

P0420 is catalytic converter inefficiency, the cat is bad.

Posted on Oct 22, 2009

nvannoy
  • 234 Answers

SOURCE: My 1994 nissan altima nox high speed emission

O2 sensors, EGR or catalytic converter(s) may be malfunctioning.
If you've ever had a blown head gasket the coolant coming through could have clogged the O2 sensor and the cat.
EGR system could be out, do you hear any exhaust coming from the EGR pipe or EGR? also try and push in the EGR diaphragm, being careful not to damage the rubber
Also there are a few products you can buy at auto parts stores that claim to fix high nox, but I have not had success with these myself.

Posted on Jan 05, 2010

Testimonial: "Thank you very much for that info."

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

2 Answers

I have a 1994 chevy silverado c1500 v/6 4.3 litre and failed smog for high hc levels st idle . what should i do before i take it back to try and smog? ive already done complete tune up.


as long as you have no check engine light on change oil, air filter. pep boys sells a product called guaranteed to pass add to fuel make sure car is hot when you go back for emission test cold car has high hc levels it also helps to post the hc level you tested at and the limit on your receipt hope this helps

Apr 08, 2016 | Cars & Trucks

1 Answer

My Toyota echo did not pass smog high Nox what could be wrong?


Nox is created in the engine, and the hotter the engine the more Nox is created.Get your car to run as cool as you can,oil change.engine/rad flush,fresh coolant,tune it up etc.In addition a high nox number may be a sign that your catalytic converter needs to be replaced.The converter is where the nox gets neutralized. good luck

May 05, 2014 | Toyota ECHO Cars & Trucks

1 Answer

Cant pass smog!!! I know i know, too many people ask this same question. i know enough about my engine to diagnose it myself but this has me stumped. on first and second gear the nox is too high. im doing...


We do not have emissions testing here, so I can't give specific advice on reducing nOX, but the EGR can be tested with a handheld vacuum pump. Simply idle the engine and slowly apply vacuum to the valve. If the engine starts running rough, the valve is opening.

Feb 02, 2013 | 1990 Chevrolet Suburban

2 Answers

My 95 Lincoln towncar failed smog due to high nox at 15 mph


Your EGR is plug or is non operational,When the EGR is not plug and is in operational its job is to cool the combustion chamber thus lowering Nox.

Mar 29, 2012 | Cars & Trucks

1 Answer

High nox fail smog test any remedies? 99


NOX is created when the internal combustion temperature gets to high.The egr system uses burnt exhaust gases to line to cylinder walls.The purpose of this is decrease internal combustion temperature therefore reducing the amount of NOX created.Would look to a possible egr malfunction usually they will trigger the check engine light but not always.The 4.3L has been known to have issues with carbon buil up in the egr and the egr pintle not open and closing properly.

Jun 07, 2010 | 1999 Chevrolet Astro

2 Answers

I have a 1992 nissan sentra that failed the 15mph part of the smog test because of high Hc's and high NOx so what can i do to fix it.


get oxygen sensor checked,maybe get tune up see if engine is leaning off properly,could be air flow sensor,but needs sensors to be checked

Oct 30, 2009 | 1993 Nissan Sentra 4 Door

2 Answers

Emissions failing with high NOx


Change the lambda/oxygen sensor in the exhaust.

May 21, 2009 | 1994 Mitsubishi Galant

1 Answer

Failed smog


We had to have the calatic converter replaced. We did this after doing an oil change, air filter change, and new spark plugs and still hadn't passed smog. After changing the calatic converter it passed smog with scores of 25.

Mar 17, 2009 | 1992 Mazda Protege

1 Answer

CHEVY SUBURBAN FAILED SMOG BECAUSE OF HIGH NOX VALUES.


nox is from running lean..... its realy high temps that cause this.......... replace the o2 sensors this should cure that any more help let me know

Oct 24, 2008 | 1993 Chevrolet Suburban

Not finding what you are looking for?
Cars & Trucks Logo

Related Topics:

95 people viewed this question

Ask a Question

Usually answered in minutes!

Top Cadillac Experts

yadayada
yadayada

Level 3 Expert

60667 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

21936 Answers

Jeff Turcotte
Jeff Turcotte

Level 3 Expert

6811 Answers

Are you a Cadillac Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...