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What things can be done to improve chances of V6 passing emissions? by Timpilot
Started on: 09-02-2012 06:51 PM
Replies: 17 (174 views)
Last post by: Dennis LaGrua on 09-03-2012 06:34 PM
Timpilot
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09-02-2012 06:51 PM Click Here to See the Profile for TimpilotClick Here to visit Timpilot's HomePageClick Here to Email TimpilotSend a Private Message to TimpilotEdit/Delete MessageReply w/QuoteDirect Link to This Post

My daughter's '86 GT needs emissions test this month. I plan to help her clean the throttle body (TB) and Idle Air Control valve (IAC) and to add fuel injector cleaner to the tank. We will also have a look at the air cleaner.
The car has 140K miles and the exhaust leaves black, sooty deposits on the back bumper. Otherwise, it starts and runs great.
What else can we do to improve the odds of passing the smog check?

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tuggajb
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09-02-2012 08:08 PM Click Here to See the Profile for tuggajbClick Here to Email tuggajbSend a Private Message to tuggajbEdit/Delete MessageReply w/QuoteDirect Link to This Post

Take it to apache junc air test never had prob there the test station on greenfield? Shoed me they don't know s... T bout Fieros

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armos
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09-02-2012 08:28 PM Click Here to See the Profile for armosSend a Private Message to armosEdit/Delete MessageReply w/QuoteDirect Link to This Post

I'd replace the O2 sensor. As they age their accuracy degrades and they lead the engine to run more rich than it should. They should be replaced every several years or so. Don't use any grease on the electrical connector - it actually vents outside air through that wire to use as a reference.
If you're getting plainly rich exhaust and no check engine codes, then I suspect your O2 is in bad shape. It's responsible for detecting that condition.
Denso sensor costs less than $20 shipped from RockAuto and has a good reputation. Some people have had problems with Bosch so I'd avoid that one.

If there's any check engine codes, they need to be resolved.
Make sure the ignition timing is correct (remember to jumper the ALDL connector when doing this). Put in fresh ACDelco R42TS plugs before the test. Also look at cap/rotor/wires.
I've read it can help to retard the timing but I think that's mainly to reduce N2O, I'm not sure if it helps with HC (unburned fuel). I'd just stay with factory recommended 10BTDC on the first try. Then if it fails look at the details of the test to decide what to do next.

Run the car for about 30 minutes cruising on the highway before the test, this heats up the catalyst and maybe cleans it slightly. A hot cat will work better.

You could end up needing a new catalyst, but don't consider that until you're confident everything else is in order. Rich exhaust can overheat and ruin a catalyst.

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Dodgerunner
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09-02-2012 08:39 PM Click Here to See the Profile for DodgerunnerClick Here to visit Dodgerunner's HomePageClick Here to Email DodgerunnerSend a Private Message to DodgerunnerEdit/Delete MessageReply w/QuoteDirect Link to This Post

Might add new plugs and plug wires. One misfiring cyl. could cause a bad test also.

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TopNotch
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09-02-2012 08:42 PM Click Here to See the Profile for TopNotchClick Here to visit TopNotch's HomePageSend a Private Message to TopNotchEdit/Delete MessageReply w/QuoteDirect Link to This Post

Retard timing to 6 degrees for the test, and then restore it to 10 afterwards.

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Timpilot
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09-02-2012 09:12 PM Click Here to See the Profile for TimpilotClick Here to visit Timpilot's HomePageClick Here to Email TimpilotSend a Private Message to TimpilotEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by armos:

I'd replace the O2 sensor. As they age their accuracy degrades and they lead the engine to run more rich than it should. They should be replaced every several years or so. Don't use any grease on the electrical connector - it actually vents outside air through that wire to use as a reference.
If you're getting plainly rich exhaust and no check engine codes, then I suspect your O2 is in bad shape. It's responsible for detecting that condition.
Denso sensor costs less than $20 shipped from RockAuto and has a good reputation. Some people have had problems with Bosch so I'd avoid that one.


Great info. I didn't know that about the O2 sensor. I probably need one on my '88 Formula as well as my daughter's '86 GT. I see AutoZone has two Denso O2 sensors, P/N 234-1000 for $13.99 and 234-1001 for $19.99. The warranties and descriptions seem identical. So, I don't know what the difference is...

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NetCam
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09-02-2012 09:42 PM Click Here to See the Profile for NetCamClick Here to visit NetCam's HomePageSend a Private Message to NetCamEdit/Delete MessageReply w/QuoteDirect Link to This Post

Funny but it looks like Rock Auto carries both the Denso and Ultrapower sensors under the same 2 part numbers 2341000/2341001.

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Timpilot
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09-03-2012 12:00 AM Click Here to See the Profile for TimpilotClick Here to visit Timpilot's HomePageClick Here to Email TimpilotSend a Private Message to TimpilotEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by TopNotch:

Retard timing to 6 degrees for the test, and then restore it to 10 afterwards.


What's the theory on retarding the timing to help with the smog test?

[This message has been edited by Timpilot (edited 09-03-2012).]

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NetCam
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09-03-2012 12:09 AM Click Here to See the Profile for NetCamClick Here to visit NetCam's HomePageSend a Private Message to NetCamEdit/Delete MessageReply w/QuoteDirect Link to This Post

My guess would be that if the plug fires earlier in the cycle you will get more complete burn of fuel in the cylinder, giving you cleaner exhaust. You would of course get less compression so performance would suffer, but that's the point of this exercise

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Timpilot
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09-03-2012 12:48 AM Click Here to See the Profile for TimpilotClick Here to visit Timpilot's HomePageClick Here to Email TimpilotSend a Private Message to TimpilotEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by NetCam:

My guess would be that if the plug fires earlier in the cycle you will get more complete burn of fuel in the cylinder, giving you cleaner exhaust. You would of course get less compression so performance would suffer, but that's the point of this exercise


Ten degrees before top-dead center (BTDC) is earlier in the cycle. Six degrees is closer to top-dead center (TDC). Seems to me at 6 degrees, the fuel/air is compressed more than it is at 10 degrees - if that makes any difference in how complete the burning is.

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NetCam
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09-03-2012 01:11 AM Click Here to See the Profile for NetCamClick Here to visit NetCam's HomePageSend a Private Message to NetCamEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by Timpilot:


Ten degrees before top-dead center (BTDC) is earlier in the cycle. Six degrees is closer to top-dead center (TDC). Seems to me at 6 degrees, the fuel/air is compressed more than it is at 10 degrees - if that makes any difference in how complete the burning is.


Yes, you are correct, 6 degrees is closer to TDC, so I'm not sure if doing this would help. The longer the fuel has to burn (the earlier in the cycle the spark takes place) the more complete burn you would have (but less compression/power). Soooo... I'm thinking that going to 6 degrees would actually make the emissions worse, but that's just me thinking it through in my head, not any practical experience. I'll gladly defer to somebody with a bit more experience on this one.

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crashyoung
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09-03-2012 01:29 AM Click Here to See the Profile for crashyoungClick Here to Email crashyoungSend a Private Message to crashyoungEdit/Delete MessageReply w/QuoteDirect Link to This Post

Keep the timing set at factory, the ECM controls the spark from the base timing. Any deviation from there makes the engine run worse.
If you get to the test station, and you have to wait over 10 minutes, your cat will cool down and not work well until it reaches operating temp again.
If you can, drive around the block to warm it back up, idling does not heat it up fast enough.
Good luck!

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firejo24
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09-03-2012 03:04 AM Click Here to See the Profile for firejo24Send a Private Message to firejo24Edit/Delete MessageReply w/QuoteDirect Link to This Post

Retarding the timing shouldn’t help if the Emissions system is working as it should. The O2 sensor is monitoring the air/fuel mixture so even if you can get a longer burn the ECM is going to add or remove fuel depending on what it see’s from the sensors. Best bet to get past emissions is to make sure all of the sensors are working within specs and then read what the BLM is. An ideal BLM reading is 128. If the BLM is above 128 the ECM is adding fuel (covering for a lean condition, vacuum leak, etc…). If it’s below 128 it’s leaning out the fuel (covering for a rich condition. Leaking injector, etc…). If the BLM is right around 128 and the cat converter is good (which it won’t be with 140K on the car) the car will pass emissions.

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Australian
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09-03-2012 08:24 AM Click Here to See the Profile for AustralianClick Here to visit Australian's HomePageClick Here to Email AustralianSend a Private Message to AustralianEdit/Delete MessageReply w/QuoteDirect Link to This Post

If your rings leak dump the oil and put some thicker oil in for the test then ditch it after the test.

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TopNotch
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09-03-2012 12:39 PM Click Here to See the Profile for TopNotchClick Here to visit TopNotch's HomePageSend a Private Message to TopNotchEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by Timpilot:

What's the theory on retarding the timing to help with the smog test?



I guess the theory would be that it makes combustion temperatures cooler. But it's not just theory -- my car wouldn't pass until I did it.

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88FieroGT TTops
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09-03-2012 01:09 PM Click Here to See the Profile for 88FieroGT TTopsClick Here to Email 88FieroGT TTopsSend a Private Message to 88FieroGT TTopsEdit/Delete MessageReply w/QuoteDirect Link to This Post

I was failing on catalytic on my v6 dakota--my mechanic said to put a can of seafoam in--drove the tank dry twice and passed emissiongs--no new cat needed---
just my 2 cents

------------------
Pat Jones

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Timpilot
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09-03-2012 05:54 PM Click Here to See the Profile for TimpilotClick Here to visit Timpilot's HomePageClick Here to Email TimpilotSend a Private Message to TimpilotEdit/Delete MessageReply w/QuoteDirect Link to This Post

 
quote
Originally posted by 88FieroGT TTops:

I was failing on catalytic on my v6 dakota--my mechanic said to put a can of seafoam in--drove the tank dry twice and passed emissiongs--no new cat needed---
just my 2 cents



Thanks, Pat!
We picked up some Seafoam and put 1/2 can in a full tank of gas. Will use the other 1/2 on the next tank of gas then go for the smog test.

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Dennis LaGrua
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09-03-2012 06:34 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post

I've been using Fuel On power to spike the gas for emission testing and haven't missed yet . That additive causes more complete combustion and dramatically lowers emissions.
http://www.fuelon.com/fuelonpower.html
------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 09-03-2012).]

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