Help Failed Emissions On Low End Hc's

[Scaramoche]

I'm not sure what to do now?

 

fill you in.

 

I have re-installed all emissions equipment to my rebuilt motor(all except aiv aka smogpump cause i cant find one). Either way some people i talked with said it wouldnt matter for the low end HC's.

 

Either way I PASSED everything else, including High rpm HC(hydrocarbons). The only thing i failed was low end (idle) HC.

 

My pathy smells "rich" when at idle, and only idle.

 

What am i missing? what "Leans" out my exhaust?

 

PLEASE HELP this is my only car and only have a month to fix.

[Kingman]

I've been driving on expired tag for over a month due to that same damn problem. I can't figure it out either. I've got the same motor you do...

[Precise1]

Check the function of all the smog valves/systems and vacuum lines/diaphrams. Scaramoche, how much did you fail by? Can you post a copy of the smog report??

 

Damn Tbi's...

 

B

[Alkorahil]

Did you see my reply to your other post?

[MY1PATH]

Check the function of all the smog valves/systems and vacuum lines/diaphrams. Scaramoche, how much did you fail by? Can you post a copy of the smog report??

 

Damn Tbi's...

 

B

 

Hey I smogged my TBI for @!*%s and giggles my CO failed by 0.17 because my idle was low (675-725 iirc) turned it up a little (850-900)and all was fine.

if you fail any of the idle tests by only a little bumping the idle by 100-150 may pass you. most states have a maximum idle of 1200 or something like that so turn it up as far as they allow and try again.

[Kingman]

Damn Tbi's...

 

B

 

I would agree, but that's a gramatical error so I can't take it seriously. There's no ownership being showed by TBI, only plural units.

 

I smogged mine too at school and it passed just fine. At the emissions place, the guy stuck it in the tailpipe and waited for a few seconds and yanked it out as the numbers were still rapidly falling and told me I failed. Pure laziness on his behalf. That number was way higher than the previous test for CO at idle, the first test was 2.XX (limit is 1.20) and the second test AFTER I RE-INSTALLED MY RETURN TUBE FROM THE CAT was 3.09. I had it passing steadily at .89 earlier that day, we also use the same machine at school that the DMV and every automotive shop uses.

[Scaramoche]

Ok here is are the values of my emmision

 

Make Nissan

model pathfinder

model yer 1989

type 1

engine size 3000

cylinders 6

transmission m

fuel g

exhauste single

 

odometer-(148027)not acual miles

 

Visual Results

cat PASS

V Smoke/emission: PASS

V Gas Cap PASS

 

Emissions Fail

Reading Limit

 

Hight speed RPM=2599 RPM

HC 72 200 pass

CO .64 1.20 pass

 

Low speed RPM= 0744 RPM

HC 3977 200 FAIL

CO .15 1.20 pass

 

My Smog box doesnt exsist anymore, it was completly trashed when i purchased PF. So I capped any vaccums to it. I was also told this would not make me run rich, ie hi HC's from a mechanic, but he did say he didnt know rubish about PF's.

 

Thanks!

[87pathy]

actually, the missing smog pump will cause it to fail at low rpm.

 

thats what is wrong with mine.

 

 

im golden at top end, low end.. NFG.

air box, solenoid and switch.

[Alkorahil]

IF you are failing at low spped the HC it may indeed be the PAIR valve:

 

The '91 thru '93 high-port engine had problems with 'port wall wetting', where the injector was far enough from the intake valve that some fuel was sprayed onto the intake port walls. When the throttle was snapped shut, the increase in port vacuum sucked this extra fuel into the combustion chamber and caused hydrocarbon emissions to skyrocket. In addition, low intake port velocity at idle also caused an increase in port wall wetting, leading to a similar condition. The PAIRV was there to introduce enough fresh air into the exhaust for the cat/con to burn off the excessive hydrocarbons.

 

The '94 and newer low-port engine moved the injectors closer to the intake valve and increased intake port velocity at low engine speeds. These changes were enough to allow for the elimination of the PAIRV. They were also responsible for the improvement in the engine's low-end power

[87pathy]

IF you are failing at low spped the HC it may indeed be the PAIR valve:

 

The '91 thru '93 high-port engine had problems with 'port wall wetting', where the injector was far enough from the intake valve that some fuel was sprayed onto the intake port walls. When the throttle was snapped shut, the increase in port vacuum sucked this extra fuel into the combustion chamber and caused hydrocarbon emissions to skyrocket. In addition, low intake port velocity at idle also caused an increase in port wall wetting, leading to a similar condition. The PAIRV was there to introduce enough fresh air into the exhaust for the cat/con to burn off the excessive hydrocarbons.

 

The '94 and newer low-port engine moved the injectors closer to the intake valve and increased intake port velocity at low engine speeds. These changes were enough to allow for the elimination of the PAIRV. They were also responsible for the improvement in the engine's low-end power

 

 

he has a TBI pathy, not a MPFI pathy..

 

i promise its the aiv crap.

[Precise1]

I would agree, but that's a gramatical error so I can't take it seriously. There's no ownership being showed by TBI, only plural units.

 

Funny, it looks like your TBI is owning you...

 

B

[BowTied]

Could a leaky injector cause this?

[MY1PATH]

Funny, it looks like your TBI is owning you...

 

B

 

[adamzan]

Can't you just put another vehicle on the sniffer and then put your truck into the computer.

[Kingman]

Funny, it looks like your TBI is owning you...

 

B

 

Indeed it is. Which is why I want to swap to a 300ZX intake...

 

[Alkorahil]

he has a TBI pathy, not a MPFI pathy..

 

i promise its the aiv crap.

 

thats what I said!

[Alkorahil]

Can't you just put another vehicle on the sniffer and then put your truck into the computer.

 

 

A large Ford dealership here in Dallas got fined over 400,000, almost $500,000 by the state for doing that.

[Scaramoche]

ok smog pump aka aiv.

 

Here is the problem, when i purchases vehicle mine was completely trashed, any alternative? other vehicles that may have same system?

 

Also I did a write up for forums a few days ago, and got a good understanding of all emission systems .....except 1, aka aiv. can someone please help me

a)understand it(from my understanding durring operation, specifically idol, the valve(reed type) allow for fresh air to be pumped into exhaust, allowing for better burn of fuel in exhaust).

 

b)how do i wire the thing up? ie what hose goes where?

[87pathy]

the other guy who posted on your thread.. aklo???

can supply you with a new aiv and a pair.

 

I have bought one of them from him and plan on buying the second as soon as money is available.