Can't pass emissions, Help!

[Jackie Mac]

I have a 1986 c-10, 305 v8. My readings have been #1.HC-270-6.25. #2.hc--675. #3. HC-702. #4 HC-813. The Co2 Readings have been low. They have averaged around--co-0.20 and co2 around6.50. I have changed spark plugs wires and Rotor cap. cleaned pcv valve. I put on a new catalytic converter. I recently had my trans rebuilt and I am wondering if the guy may have let my distibutor hit the the wirewall and move it. I think I will check the timing(I have never done it, any tips appreciated!), I am also going to check each and every vaccum Line. This model is does not have the california emissions stuff on it(o2 sensor ect.)I want to thank you all in advance for any help you can offer. Joe

[dieseldawg142]

probably not the answers your looking for, but we have to deal with Air (s)Care emission tests too. back in the day my '68 gm 1/2 had a 383 with a monster cam & carb that would wilt flowers at 50 feet, no hope of passing. i bought alum. header collector gaskets & would loosen off the bolts. always passed, no one noticed, actually got complimented by staff how well tuned it was (almost scored a zero)! nowadays with a truck you can up the gvw & be air care exempt, although the fee is twice the cost of the emissions test, but my current truck (big block crew) like my '68, probably would not pass

[rfmaster]

Originally Posted by Jackie Mac

I have a 1986 c-10, 305 v8. My readings have been #1.HC-270-6.25. #2.hc--675. #3. HC-702. #4 HC-813. The Co2 Readings have been low. They have averaged around--co-0.20 and co2 around6.50. I have changed spark plugs wires and Rotor cap. cleaned pcv valve. I put on a new catalytic converter. I recently had my trans rebuilt and I am wondering if the guy may have let my distibutor hit the the wirewall and move it. I think I will check the timing(I have never done it, any tips appreciated!), I am also going to check each and every vaccum Line. This model is does not have the california emissions stuff on it(o2 sensor ect.)I want to thank you all in advance for any help you can offer. Joe

@Joe

So let see

Test
#1----HC 270 PPM
#2----HC 675 PPM
#3----HC 702 PPM
#4----HC 813 PPM

These are high sky numbers if that's what measured (please check your reports)! You should be well below 150 ppm with a three way converter. If these are actual values I would check ignition system and check engine for low compression. When one or more cylinders are misfiring raw fuel gets dumped into the exhaust. Sniffer picks this as high sky HC levels. Another common cause for high sky HC reading can be attributed to leaky valve stem seals. Oil gets into exhaust flow and spikes HC readings. How many miles you have on your engine??

//RF

[Psycho_SWB]

I just passed the California emissions yesterday in my '83 C10 (305). I read in other forums that you should drive your vehicle on the highway for about 20 minutes to get the catalytic converter nice and hot before taking your vehicle in for testing. Retarding your timing by a couple of degrees also helps to reduce emissions for testing.

My HC (PPM) was:
15 mph -- 14
25 mph -- 11

NO (PPM):
15 mph -- 176
25 mph -- 174

[Jackie Mac]

Thanks, Hey RF master, yes those numbers are correct, the truck has 160,000 on her.the truck seems to run good with no misses, esp. after I tuned it up and put a new cat on it. I am stumped. Thanks for all replys

[Jackie Mac]

Oh yea, just to add, this truck has always passed emissions, Its odd that right after I got my trans fixed, it wouldn,t pass. Thanks

[rfmaster]

Which trany you have in your 305 - 700R4 or THM350C? IRC THM 350C uses vacuum modulator - a leaky one may suck trany fluid into intake. Yet another source for unwanted HC.

Justing thinking out loud here....

[naphtali5725]

Originally Posted by rfmaster

Which trany you have in your 305 - 700R4 or THM350C? IRC THM 350C uses vacuum modulator - a leaky one may suck trany fluid into intake. Yet another source for unwanted HC.

Justing thinking out loud here....

X2^^
i've seen the same thing many times, blown vacuum modulator, but usually the engine smokes a little out the tailpipe when that happens....could be a minimal leak though, if your tranny has one it's worth chking it out...

[camok10]

If you've had a trans swap this may be worth looking into.I'm speaking from experience here..... I had a 91 wrangler with a 350/700r4 combo. The person I got it from swaped a th350 for the 700 and hooked the modulator line from the 350 to the 700's vent on top of the trans. The jeep would burn 1 1/2 qts of trans fluid a week till I found this and never really smoked anything noticeable.
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[INSIDIOUS '86]

You can run a thick oil to help with valve seal leaks and such. Lower the initial timing to as much as 4-6* timing. The engine just barely likes this but it won't hurt nothing. This will help with overall emmissions. Also run it and get it nice and warm. A hot engine burns fuel better. Also tune your carb. Don't try and make it leaner that actually makes emissions worse so just get it dead on with the distributor in the test position. Once you run timing back up after the test re tune the carb
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[INSIDIOUS '86]

Also run low octane fuel. It burns quicker
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[motornut]

maybe a hotter plug would help?
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[Malo83]

My routine is to change the oil, new air filter, spray down the carb with Gumout and spray down the throats with the engine running at high RPM, and new plugs,cap and rotor and O2 sensor. a bottle of Guaranteed to Pass is put in the tank a week prior to the test just for luck. As everybody stated earlier a good long fast run down the highway is best to get everything HOT and then straight to the testing station. With 216K miles on the 83 she hasn't failed an inspection yet, (knock on wood)

[motornut]

this is what is recomended to warm it up here
you must have to do that too?

Step 1: Make sure the vehicle has been parked for eight hours without a start.
Step 2: Start the engine and let it idle in Drive for two-and-a-half minutes with the Air Conditioning (A/C) and rear defroster on.
Step 3: Turn the A/C and rear defroster off. Drive the vehicle for 10 minutes at highway speeds.
Step 4: Drive the vehicle for 20 minutes in stop-and-go traffic.
Step 5: Your drive cycle is complete. You can now go in for your test

[KrazyRay]

Put 8oz of Lucas Oil fuel injector cleaner with about 5 gallons of 87 octane and do all the other stuff. The Lucas helps seal the valve train a bit. My Chevy went from a gross polluter to passing with just the Lucas.

[Chevydude56]

Originally Posted by motornut

this is what is recomended to warm it up here
you must have to do that too?

Step 1: Make sure the vehicle has been parked for eight hours without a start.
Step 2: Start the engine and let it idle in Drive for two-and-a-half minutes with the Air Conditioning (A/C) and rear defroster on.
Step 3: Turn the A/C and rear defroster off. Drive the vehicle for 10 minutes at highway speeds.
Step 4: Drive the vehicle for 20 minutes in stop-and-go traffic.
Step 5: Your drive cycle is complete. You can now go in for your test

I think this is for OBDII ?

[Coboyle04]

i dont know what rules you have out there but in oregon here is one way to work it out.
here you can pay to "transfer plates from any vehicle to any other vehicle. doesnt matter if the one your transferring to has expired tags.

so if you can and have another car available you can essentially just swap plates every time you need to renew. a wonderful legal loophole.

[motornut]

Originally Posted by Chevydude56

I think this is for OBDII ?

I didn't see it said for after 97

[JellyBeanDriver]

Originally Posted by rfmaster

@Joe

So let see

Test
#1----HC 270 PPM
#2----HC 675 PPM
#3----HC 702 PPM
#4----HC 813 PPM

Yeah, those numbers are insanely high.
I've read that burning oil does not raise HC #'s. Don't think your #'s are due to burning oil but instead either running too lean or too rich.

Why did you replace the cat?

[LynnJr]

I live in california and smog every two years.With those numbers none of the tricks will work.Put a new catalytic converter on it and it will pass with flying colors.

[INSIDIOUS '86]

My old mans 454 dually passed with no converter. So did his tri power 427 72"corvette with side pipes. Cat converters help but a good running engine don't need it.
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[Jackie Mac]

Thanks a million for all the info. I am gonna dig in and try to find the problem. My trans is a 350 lock up and I am gonna check the modulator out. I will also check carb adjustment as well as the other reccomendations.

[LynnJr]

The OP doesn't have a good running engine or it would have already passed.My old motor would put out over 1300 on the hydro-carbons and with a new cat I was getting 13.
If the motor is tired get a new cat and pass the test.Once you have passed pull the cat back off the truck or you'll burn it up.
Please post what actually works on your truck.

[JellyBeanDriver]

Originally Posted by INSIDIOUS '86

My old mans 454 dually passed with no converter. So did his tri power 427 72"corvette with side pipes. Cat converters help but a good running engine don't need it.
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Ditto with our ranch truck. Carb'd 454, no catalytic, dual exhaust. Does have air injection pumps though. Last #'s were cleaner than my passenger car with EFI and a catalytic.

I think they were around 15 ppm for HC's !



With #'s as large as the OP has, it's not the cat, and I don't think it's burning trans oil either.

Do you have 'normal' spark plugs in there or some fancy ones? I've seen problems with fancy spark plugs.

[JellyBeanDriver]

Originally Posted by LynnJr

The OP doesn't have a good running engine or it would have already passed.My old motor would put out over 1300 on the hydro-carbons and with a new cat I was getting 13.
If the motor is tired get a new cat and pass the test.Once you have passed pull the cat back off the truck or you'll burn it up.
Please post what actually works on your truck.

He already put in a new cat.

They work over a narrow range. He's pretty far out of range - not sure it is even contributing to taking care of the HC problem.