Pennock's Fiero Forum
  Technical Discussion & Questions
  failed emissions on hydrocarbons

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
failed emissions on hydrocarbons by wolf63
Started on: 03-23-2014 10:19 PM
Replies: 9 (199 views)
Last post by: wolf63 on 03-28-2014 09:43 PM
wolf63
Member
Posts: 265
From: Brighton Colorado
Registered: Aug 2007


Feedback score: (1)
Leave feedback

Rate this member

Report this Post03-23-2014 10:19 PM Click Here to See the Profile for wolf63Send a Private Message to wolf63Edit/Delete MessageReply w/QuoteDirect Link to This Post
so my 84 4cyl manual failed the Colorado emissions test. hydrocarbons at 4.55 with a 3.00 limit. it has a relatively minor miss at idle. the graph they gave me shows it spiking all over the place until it hits 50MPH then all the levels drop way down. i reset the timing and it seems a little better but it still has an occasional miss and i notice the timing mark moves around between 8 and 6, is that normal?. i switched the MAF? (the one on the side of the air cleaner) no effect. however, i did note that when i disconnected the EGR vac line nothing happens. finger on the port feels no vac at all. higher revs get a small vac but still not much. is that normal? appreciate any help.
IP: Logged
PFF
System Bot
Gall757
Member
Posts: 10622
From: Holland, MI
Registered: Jun 2010


Feedback score: N/A
Leave feedback





Total ratings: 88
Rate this member

Report this Post03-24-2014 07:56 AM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
I don't think it is normal. Is your idle speed around 900 rpm? If you pull a vacuum line does the idle go up? Is there oil in the air filter tray? There could be some carbon build up somewhere that is reducing the manifold vacuum, perhaps at the EGR valve.
IP: Logged
wolf63
Member
Posts: 265
From: Brighton Colorado
Registered: Aug 2007


Feedback score: (1)
Leave feedback

Rate this member

Report this Post03-24-2014 10:24 PM Click Here to See the Profile for wolf63Send a Private Message to wolf63Edit/Delete MessageReply w/QuoteDirect Link to This Post
idle is normal around 900ish, yes pulling a vacuum line raises the RPMs, yes it has oil in the air cleaner (some blow by but no smoke). however, pulling the vac line going to the EGR does not cause the rpms to change and a finger over the port on the throttle body does not register any vac at idle and raising the rpms only generates a very weak vacuum.
pull the throttle body and check for clogged port? net search indicates non functional EGR causes high NOx reading (and it isnt good but passes with 3.42 out of 4.5 allowed)
IP: Logged
Rodrv6
Member
Posts: 1897
From: Ball Ground, Ga.
Registered: Nov 1999


Feedback score: (2)
Leave feedback





Total ratings: 76
Rate this member

Report this Post03-25-2014 09:21 AM Click Here to See the Profile for Rodrv6Click Here to Email Rodrv6Send a Private Message to Rodrv6Edit/Delete MessageReply w/QuoteDirect Link to This Post
I had the same issue in the past when I had my 84. High HC with everything else within limits. It ended up being a bad catalytic convertor. A new one dropped the HC's way down and it passed easily..........

------------------
Rod Schneider, Ball Ground, Ga.
"You can't have too many toys!"
1988 Fiero GT
1987 Porsche 944S
1987 Corvette
1966 Porsche 911
2001 Chrysler 300M
Van's RV-6 airplane

IP: Logged
wolf63
Member
Posts: 265
From: Brighton Colorado
Registered: Aug 2007


Feedback score: (1)
Leave feedback

Rate this member

Report this Post03-25-2014 09:03 PM Click Here to See the Profile for wolf63Send a Private Message to wolf63Edit/Delete MessageReply w/QuoteDirect Link to This Post
thats the plan for tomorrow morning :-) getting the cat replaced and installing a new O2. we'll see how that goes.
IP: Logged
Marvin McInnis
Member
Posts: 11597
From: ~ Kansas City, USA
Registered: Apr 2002


Feedback score: N/A
Leave feedback





Total ratings: 226
Rate this member

Report this Post03-26-2014 07:11 PM Click Here to See the Profile for Marvin McInnisClick Here to visit Marvin McInnis's HomePageSend a Private Message to Marvin McInnisEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by wolf63:

... when i disconnected the EGR vac line nothing happens. finger on the port feels no vac at all. higher revs get a small vac but still not much. is that normal?



That is normal. EGR is active only during mid-throttle cruising, and it is disabled both at idle and near full throttle.
IP: Logged
wolf63
Member
Posts: 265
From: Brighton Colorado
Registered: Aug 2007


Feedback score: (1)
Leave feedback

Rate this member

Report this Post03-26-2014 08:18 PM Click Here to See the Profile for wolf63Send a Private Message to wolf63Edit/Delete MessageReply w/QuoteDirect Link to This Post
i found the EGR vacuum (or lack thereof) link using the pennock's search, so no worries there (thanks though)
so it now has a new CAT and O2 sensor. doesnt run any different although the sound is lower (kind of Evenrude-ish) :-)
i still have a random miss at idle thats driving me nuts, and worries me regarding the pending emissions re-check. ive checked for vac leaks (none). replaced plugs, wires, coil, swapped dist from my spare motor still have the same random miss.
next, lets talk timing. i set it as best i can to 8ish and that bothers me cuz it really is 8ish according to the timing light #1 is firing between 12 and 4 with it constantly moving. does that give anyone any ideas? i'm fresh out :-(
IP: Logged
armos
Member
Posts: 573
From:
Registered: Aug 2010


Feedback score: N/A
Leave feedback

Rate this member

Report this Post03-27-2014 08:38 AM Click Here to See the Profile for armosSend a Private Message to armosEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by wolf63:
next, lets talk timing. i set it as best i can to 8ish and that bothers me cuz it really is 8ish according to the timing light #1 is firing between 12 and 4 with it constantly moving. does that give anyone any ideas? i'm fresh out :-(


Do you have the A-B pins on the ALDL connector jumpered when you check the timing?
IP: Logged
Marvin McInnis
Member
Posts: 11597
From: ~ Kansas City, USA
Registered: Apr 2002


Feedback score: N/A
Leave feedback





Total ratings: 226
Rate this member

Report this Post03-27-2014 12:52 PM Click Here to See the Profile for Marvin McInnisClick Here to visit Marvin McInnis's HomePageSend a Private Message to Marvin McInnisEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by wolf63:

next, lets talk timing. i set it as best i can to 8ish and that bothers me cuz it really is 8ish according to the timing light #1 is firing between 12 and 4 with it constantly moving.



Assuming you have the two pins on the ALDL connector properly jumpered ... A couple of degrees of timing jitter, especially at idle, isn't unusual for a worn engine. Jitter can be introduced by a worn timing chain and/or gears, by a worn distributor drive gear, and by wear in the distributor itself.
IP: Logged
wolf63
Member
Posts: 265
From: Brighton Colorado
Registered: Aug 2007


Feedback score: (1)
Leave feedback

Rate this member

Report this Post03-28-2014 09:43 PM Click Here to See the Profile for wolf63Send a Private Message to wolf63Edit/Delete MessageReply w/QuoteDirect Link to This Post
woo hoo! dont know if it was the new CAT or the O2 sensor or both but it passed by a mile! HC dropped from 3.5something to .3something :-) thanks everyone for your help. Pennocks is a godsend :-)
IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock