failing emessions, need advice.

Al's Chop Shop · 10-28-2009, 08:34 PM

81 pickup, 22r, engine is a fairly fresh rebuild (~30k), new stock carb, new plugs/cap/wires, new cooling system (not that that matters). 1500 miles on oil change.

my hydrocarbons are 2x and 4x what they should be. i ran it through last week on a faulty thermostat (it was running really cold) and it failed. i figured the cat wasn't getting up to temp so i got the stat switched out to a 195, now it runs perfectly in the middle of the gauge. but still no real change in hydrocarbons.

the numbers are last weeks test running cold, first number is first idle test, second number is the idle after revving to 2k rpm for 30 seconds. the second numbers are todays numbers, same test but it was running at normal temp.

first: 572, second: 752

first: 474, second: 836

hydrocarbon limit is 220 in both tests.

every other test (CO and CO2) are within limits.

the test page suggests a misfiring engine (unburnt fuel or oil), causes:
plugs/wires/coil/cap.
vacuum leak
EGR malfunction
timing
catalytic converter failure
worn valves, seals or piston rings
carb malfunction.

because the ignition and carb are new on a rebuilt motor (that nix's most of the list), so i'm thinking about the EGR, if not that then the catalytic converter.

any way to test the EGR to know for sure?

Al

This ad is not displayed to registered members.
Register your free account today and become a member on Yotatech!

rowdy235 · 10-28-2009, 08:47 PM

Valves Adjusted?

Other than that, i'd look to cat and EGR as well.

83 · 10-29-2009, 06:33 AM

FSM has proceedures for checking the EGR. I can scan & post if you want..

DerekWlumley · 10-29-2009, 07:54 AM

Have you considered o2 sensors.. they can be making it run rich or leaning it out depending on how they are reading. Might be a cheaper option than going with EGR and CAT. O2 are around 40 vs 70-90 on universal Cat thats cost on parts maybe alittle higher depending on where you go. On testing the EGR you can apply vaccum to it to see if it holds.. thats how we test them.

83 · 10-29-2009, 08:51 AM

Our trucks don't have 02 sensors.

84foyota · 10-29-2009, 09:23 AM

I would rule out the EGR as a cause for high amounts of hydrocarbon. EGR is designed to control Nox and not carbon. Sounds like you have a jetting issue or a non functioning cat or both. Has the carb had any modifications? Many of these trucks ran really lean at idle from the factory (especially Canadian or Cali spec) and people rejetted them to make them run smoother. Pull the carb and clean it. Make sure your choke linkage is working properly as this will cause a rich mixture for sure. Check the jet sizes and low speed air screw settings.

My 84 22r past the emission every year I needed it to. Somtimes I retard the timming a couple of degrees from stock before the test just for some extra insurance as well. This helps mostly with the NOX reading though.

DerekWlumley · 10-29-2009, 09:24 AM

Fair enough lol, Ive only been a yota owner for about 2 weeks.. wasnt sure when they started puttin o2s on vehicles prolli atleast has to be fuel injected otherwise the o2 wouldnt do much anyway.

Al's Chop Shop · 11-02-2009, 03:44 PM

the carb is new from what i understand. one of the PO's had a problem with bad carbs (kept letting the same idiot rebuild it) and when he sold it to the next guy he put a new carb on it (or maybe remanned) and everything ran great since.

but IF the knuckle heads rebuilds were running horribly rich, i suppose it could have burned up the cat.

Al

10-28-2009, 08:47 PM	#2 (permalink)
rowdy235 Registered User Join Date: Sep 2007 Location: Sweet Home, OR Posts: 1,567	Valves Adjusted? Other than that, i'd look to cat and EGR as well. __________________ The Daily Driver: 1998 Tacoma \| Regular Cab \| 4WD \| 2.7L \| 5-Speed Stick \| Mostly Stock The People-Hauler 1988 Grand Wagoneer \| SUV \| 4WD \| AMC 360 \| 3-Speed Auto \| All Stock The Dump Runner 1982 Pickup \| Regular Cab \| 2WD \| 22R \| 5-Speed Stick \| Custom Exhaust FER SALE! http://www.yotatech.com/f108/1982-sh.../#post51229916

10-29-2009, 06:33 AM	#3 (permalink)
83 Registered User Join Date: May 2008 Location: Montana Posts: 1,694	FSM has proceedures for checking the EGR. I can scan & post if you want.. __________________ Zach '83 Shortbed 4x4 L52HD Rebuilt & Mostly Stock

10-29-2009, 07:54 AM	#4 (permalink)
DerekWlumley Registered User Join Date: Oct 2009 Posts: 16	Have you considered o2 sensors.. they can be making it run rich or leaning it out depending on how they are reading. Might be a cheaper option than going with EGR and CAT. O2 are around 40 vs 70-90 on universal Cat thats cost on parts maybe alittle higher depending on where you go. On testing the EGR you can apply vaccum to it to see if it holds.. thats how we test them. Last edited by DerekWlumley; 10-29-2009 at 07:56 AM.

10-29-2009, 08:51 AM	#5 (permalink)
83 Registered User Join Date: May 2008 Location: Montana Posts: 1,694	Our trucks don't have 02 sensors. __________________ Zach '83 Shortbed 4x4 L52HD Rebuilt & Mostly Stock

11-02-2009, 03:44 PM	#8 (permalink)
Al's Chop Shop Registered User Join Date: May 2008 Location: Portland, OR Posts: 609	the carb is new from what i understand. one of the PO's had a problem with bad carbs (kept letting the same idiot rebuild it) and when he sold it to the next guy he put a new carb on it (or maybe remanned) and everything ran great since. but IF the knuckle heads rebuilds were running horribly rich, i suppose it could have burned up the cat. Al __________________ 81 Toyota pickup 22r, 5spd, 4x4, longbed on 33's... custom suspension in the works. 79 Cherokee Chief Widetrack "Kronk" TBI350, SM465, NP205, Hydraulic clutch, Hydroboost, Custom aluminum radiator, Flowtech headers, SOA D44HD w/ Hi-steer, D60, 36" TSL/SX's, LED tail conversion... 91 Chevy K1500 - The Hauler TBI350, built 700r4, NP241, awaiting 4" lift... 90 XJ - 5.5" lift, 33's, bushwhacker cutouts, sliders, bumpers, winch... 08 Mazda CX9 - Zoom-Zoom!

10-29-2009, 09:23 AM	#6 (permalink)
84foyota Registered User Join Date: Feb 2008 Location: Port Perry, Ontario Canada Posts: 5	I would rule out the EGR as a cause for high amounts of hydrocarbon. EGR is designed to control Nox and not carbon. Sounds like you have a jetting issue or a non functioning cat or both. Has the carb had any modifications? Many of these trucks ran really lean at idle from the factory (especially Canadian or Cali spec) and people rejetted them to make them run smoother. Pull the carb and clean it. Make sure your choke linkage is working properly as this will cause a rich mixture for sure. Check the jet sizes and low speed air screw settings. My 84 22r past the emission every year I needed it to. Somtimes I retard the timming a couple of degrees from stock before the test just for some extra insurance as well. This helps mostly with the NOX reading though.

10-29-2009, 09:24 AM	#7 (permalink)
DerekWlumley Registered User Join Date: Oct 2009 Posts: 16	Fair enough lol, Ive only been a yota owner for about 2 weeks.. wasnt sure when they started puttin o2s on vehicles prolli atleast has to be fuel injected otherwise the o2 wouldnt do much anyway.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search