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Ok so I failed my emissions test. I know I need a tune up. However, what could cause the vehicle to be running too lean?

2006-06-20 17:44:29 · 7 answers · asked by mwmn35 3 in Cars & Transportation Maintenance & Repairs

7 answers

you need to specify what year/make/model/engine size. each car has its different possibilities for running lean. for instance, if its a ford 4.0l overhead cam engine, the intake manifold gasket is common to cause this, and could be fixed for free at the dealer due to a recall. give details, and maybe i can give good info.....besides the obviouse causes such as low fuel pressure, vacuum leak, stuck egr, dirty maf sensor........

2006-06-20 18:22:00 · answer #1 · answered by Anonymous · 9 0

Bad oxygen sensor in the exhaust-not likely, cause they normally fail open, which causes it to run rich, but easy to replace

too high octane-or fuel additives, most likely cause

bad EGR valve-normally adds exhaust gasses to cool chamber, second most likely cause

engine running hot-enough to notice

PCV valve-stuck open sends crankcase emissions into intake, reducing burn, easy to replace, very cheap, but not likely

fuel pressure regulator-third most likely cause, not too expensive, but difficult to replace

2006-06-20 17:59:51 · answer #2 · answered by Rockstar 6 · 0 0

Check the Exhaust/Muffler or the Heads/Exhaust Manifold

2006-06-20 18:32:34 · answer #3 · answered by Anonymous · 0 0

Yup, thats what hypertech does. decrease back at the same time as they were actual chips the dept shops used to eliminate them and save them. Now its in simple terms saved on your ecm. you pick to get it reflashed to inventory then after smog it you are able to reinstall the hypertech software.

2016-11-15 01:27:20 · answer #4 · answered by dethlefs 4 · 0 0

CLOGGED INJECTORS, FAULTY SIGNAL FROM THE ECM & ISSUES WITH THE 02 SENSOR TO NAME A FEW,GET A DIAGNOSTIC TEST BEFORE YOU GO AND REPLACE PARTS REMEMBER THERE'S AN EXEMPTION CLAUSE DEPENDING ON THE STATE YOU ARE IN GET MORE INFORMATION, IT MAY SAVE YOU MONEY HONEY!

2006-06-20 17:51:12 · answer #5 · answered by MRS.HOTWHEELS 2 · 0 0

Carburator adjustments

2006-06-20 17:56:34 · answer #6 · answered by AL 6 · 0 0

there a number of things that could be a problem intake leak o2 sensor throtle position sencor etc.

2006-06-20 17:55:02 · answer #7 · answered by Robert F 7 · 0 0

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