high nox
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Joined: Jul 2002
Posts: 514
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From: ceres ca
St. Jude Donor '08
high nox
hi guys.
I just failed the roller "test only" test. It's an 88 with 106,000 miles. It has a fairly new high flow single cat. It did ok on most fronts but the HC was a little on the high side but passable. My problem is the NOx readings were double the max allowable. The car has only been driven a couple of times in the past year, but has been started every couple of days and allowed to run for about 10 minutes to keep things in working order. Any ideas on what gives.
Thanks
Randy
I just failed the roller "test only" test. It's an 88 with 106,000 miles. It has a fairly new high flow single cat. It did ok on most fronts but the HC was a little on the high side but passable. My problem is the NOx readings were double the max allowable. The car has only been driven a couple of times in the past year, but has been started every couple of days and allowed to run for about 10 minutes to keep things in working order. Any ideas on what gives.
Thanks
Randy
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
If you've replaced the exhaust system with larger exhaust tubes or headers, the reduced back pressure will have a large effect on the NOX results.
Also, check or replace the EGR valve, EGR solenoid, EGR temp switch, vacuum lines, O2 sensor and clean out the EGR passage in the intake manifold.
You can clean out the carbon in the EGR passageways with "Seafoam" available at Napa auto, just disconnect the brake booster vacuum line and stick it in the can of Seafoam and let it suck out a little at a time but, don't let the engine stall. Just follow the instructions on the can.
Also, check or replace the EGR valve, EGR solenoid, EGR temp switch, vacuum lines, O2 sensor and clean out the EGR passage in the intake manifold.
You can clean out the carbon in the EGR passageways with "Seafoam" available at Napa auto, just disconnect the brake booster vacuum line and stick it in the can of Seafoam and let it suck out a little at a time but, don't let the engine stall. Just follow the instructions on the can.
Last edited by GKK; Jul 10, 2005 at 09:38 PM.
