Car Talk thats not a Fiero - Aircare questions

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Aircare questions

Printed From: West Coast Fieros
Category: General Car Chat (Not Fiero Specific)
Forum Name: Car Talk thats not a Fiero
Forum Description: If your car is not a Fiero and you are not part of the PPPCC and you need to bring something up, this is the place for it.
URL: http://www.westcoastfieros.com/forum/forum_posts.asp?TID=967
Printed Date: 13 June 2025 at 6:29pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com

Topic: Aircare questions

Posted By: marcelvdgn
Subject: Aircare questions
Date Posted: 03 November 2008 at 7:33pm

Ive been reading latest comment from all about passing or failing and learning lots as i go....... so ill ask you guys about my gmc S15 pickup powered witha 2.8ltr V6 throtle body with 5speed standard.

Passed laste year perfectly....... this year failing on the driving nox.

allowable was 1498ppm.... mine was 2045ppm. which was 5 time thevalue the year bfore.

only hint i have of a problem was the speedo CABLE broke either minutes before or durring the test.

ecm probably didnot see a vehicle speed signal.

Waiting for any comments

Marcel

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Marcel 86SE V6 Auto
85SE V6 Auto
85 2m4
soon to be sleeper 3.8sc 5 speed

Replies:

Posted By: Dr.Fiero
Date Posted: 03 November 2008 at 8:25pm

Well, if you need a cable and it's the same as my '86 4*4's you're welcome to come and rob it (parting the whole truck).

But - yeah, that COULD effect the NOX, since it only kicks in above a certain speed (I think!) and throttle.

Of course, since you say it's been going up... your EGR passage could be blocked (yours is TBI right?). I had to pull my EGR pod and TBI unit off, then dig out the passage with hard wire. Then blast it clean for ages with carb cleaner. Horrid messy job.

Posted By: Capt Fiero
Date Posted: 03 November 2008 at 8:58pm

Yep craker is right, 9 times out of 10 high NOX is caused by a fault in the EGR system. Yours was close to passing, and if you want to try and cheat, you can go buy a liter of methyl hydrate and pour that in, then fill your truck with 94oct from Mohawk and go re-take the test.

NOX is caused by high combustion chamber temps.

The methyldrate burns cooler than gas causing the combustion chamber temps to be lower reducing the NOX.

However the correct way is to repair the EGR.

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Capt Fiero
88 Fiero GT 5spd V6
Eight Fifty Seven GT V8 5spd.

Posted By: marcelvdgn
Date Posted: 03 November 2008 at 10:12pm

John.... Thanks for the cable offer but bought a new one or 14.00 at lordco.

ill check for blocked passage by pulling up on the diaphram while running to see if the rpm falls.... if rpm falls at least its not blocked

ill check vacuum line aswell

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Marcel 86SE V6 Auto
85SE V6 Auto
85 2m4
soon to be sleeper 3.8sc 5 speed