92 pickup won't pass emissions
05-27-2015, 11:40 AM
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92 pickup won't pass emissions
Hey guys, hope this is in the right place but anyway I recently took my 92 22re to emissions. It failed due to high NOx. First place I checked was EGR saw it was bad off so I replaced it. Took it back to emissions and it failed again. NOx was better this time but still high. So today I went to clean the air flow sensor and I don't know if the wire attached to the throttle body came undone on the inside but now my truck will turn over but not fire up. I'm not sure on why not and could use some help. I appreciate all the help!
05-28-2015, 06:50 AM
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Your air flow sensor (VAF) is on the other side of the engine bay from the throttle body. If the wire to the VAF is broken or disconnected, it will cause the fuel pump to shut off AFTER the truck starts (so it will run for a few seconds then quit). Does that describe your problem?
The purpose of the EGR system (its ONLY purpose) is to reduce NOx, so you started in the right place. There are several parts to the EGR system, so I don't know what you replaced. It's worth doing the FSM diagnostics to avoid wasting time. http://personal.utulsa.edu/~nathan-b...18egrsyste.pdf
The purpose of the EGR system (its ONLY purpose) is to reduce NOx, so you started in the right place. There are several parts to the EGR system, so I don't know what you replaced. It's worth doing the FSM diagnostics to avoid wasting time. http://personal.utulsa.edu/~nathan-b...18egrsyste.pdf
05-30-2015, 04:13 PM
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05-30-2015, 05:27 PM
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I did the big no no of unscrewing the plug. I ended up replacing the maf. Got the truck back running. Still failed emissions. I replaced the egr valve. I have never cleaned the ports out could that be it? It still is reading high NOx. Ive also heard it could be the CAT or O2.
05-30-2015, 05:34 PM
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go directly to step 6 in the link that scope provided... it's a poorly written and confusing document, step 6 should be step 1.
where it says "apply vacuum directly to the egr valve with the engine idling"... unplug the short vacuum hose on the top of the egr, but unplug the end where it's plugged into the hard line only, and suck on the hose.
if the motor stumbles, your egr is working, and it's probably going to be something else.
where it says "apply vacuum directly to the egr valve with the engine idling"... unplug the short vacuum hose on the top of the egr, but unplug the end where it's plugged into the hard line only, and suck on the hose.
if the motor stumbles, your egr is working, and it's probably going to be something else.
Last edited by osv; 05-30-2015 at 05:39 PM.
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