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Shade133

HELP! need to pass emissions by the 16th!

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:bulb:Hey. Im new to the forum (post wise) ive read a lot of stuff on here over the last year, never had to post until now LOL.

So hello,

Anyways. i have an issue with my 78 280z l28 (cold air intake, 2.25 exhaust glasspack muffler) 5 speed (straight gears).

It is an arizona car and i need to pass emissions here so i can get my plates and registration.

I can get the car to run great under a load and WOT with no miss or studdering.

but my issue is idle.

It has a rough idle. clearly a miss and rich exhaust.

Ive taken it to emissions twice.

The first time i took it was bone stock. no cold air intake, no exhaust. nothing done to it. and it passed everything within spec at the load speeds.

BUT didnt pass at idle.

it failed only with high hydrocarbons. pass is around 250 and it was putting out 890.

so did a full tune up. plugs 45 degree gap, wires, cap, roter, cold air intake because my boots were broken and leaking air after the AFM. and 2.25 inch exhaust same cat (exhaust guy said it was still good) and same muffler (glasspack).

did some tinkering with timing (which i cant get the white mark on the pulley to show up on the scale on the block so i assume the timing chain jumped, stretched, or someone did something wrong in a repair) and replaced one of the coolent temp sensor connectors (one closer to driver side) because it was totally destroyed.

also tinkered with that big screw that is on the throttle body that lowers or raises the idle (also seams to make it idle smoother the higher the idle is, more rough the lower the idle is, its at about 1200rpms right now for the smoothest idle.. still has a miss and rich exhaust)

i took it back to test again and it failed WORSE. passed everything under a load just like last time, but at idle instead of it failing at 890 PPM's HC it failed at 1300 PPM's.

Please help me with any suggestons. i dont have a lot of tools or work space, and not a lot of money to take it to a mechanic.. if there is something i did wrong, or something i missed that is easy to check or needs a cheap tool to fix, adjust, or anything please let me know.

I have to get this thing passed by the 16th or i cant drive it! and its my only vehicle..

Thanks in advance!!!!

Edited by Shade133

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forgot about that. put seafoam in the engine and gas tank?

ive ran 2 bottles of valvoline injector cleaner in it a while back before the first test.

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i have messed with that a lot and it doesnt seem to make much of a change. sometimes it will iddle lower or higher and sometimes it wont do anythign. i have messed with that for a hour or more trying to get it to make a difference.

is there an effective way i can use a volt metor (i have a old school analog one) to test it and adjust it the right way?

ive also read something about taking it apart and re adjusting the points inside of it.

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You don't have to take it apart to adjust it. Do you have a factory service manual? The procedure is in the Engine Fuel section.

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no ive yet to buy one.. i cant find one here in the normal parts stores so when i get paid i plan on buying one online.

should the car run better if i unplug the tps? maybe send it in a limp mode or a guess mode

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awesome! thanks a bunch. one other question. could i fix this issue by maybe a leakie injector. or possible my cold start injector. i was reading another post and it makes sense that my cold start injector could be leaking even when unplugged (which its unplugged)..

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These cars aren't sophisticated enough to go into a computer controlled 'limp mode' or reduced performance mode. Either they run right or they don't based on condition/adjustment of the components.

EDIT: I would think that if an injector or CSV were leaking you'd have mixture problems in all ranges, not just at idle.

Edited by sblake01

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These cars aren't sophisticated enough to go into a computer controlled 'limp mode' or reduced performance mode. Either they run right or they don't based on condition/adjustment of the components.

good because i hate it when comptuers go into limp mode. if they dont it leaves for better trouble shooting. like disconnecting sensors and reconnecting them to see if they work!

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I agree with Mr.Blake-however, being in Phoenix,you will lose nothing by pinching off the CSV line.It is POSSIBLE(however remotely)that the CSV could be dribbling just enough to screw up the idle

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What was your CO reading? CO is a direct indicator of mixture. Lower Co = leaner mixture. Too low and you will have a lean miss and high HC. Unburned fuel due to the miss. Too high and you'll get high HC. Too much fuel for complete combustion so the left over fuel goes out the pipe. The cat likes a relatively narrow range of mixture to perform correctly. Too lean or rich and it won't light.

Steve

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Question,

does it have a catalytic converter? I have been "advised" on this site that the 49 state models did not come with one. (I personally never saw any post 76 car that didn't have a converter, but that is beside the point.)

That may alter the strategy regarding making it comply.

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yes it has a cat and its was said that it was still in good condition from the exhaust guy.

and the co was in passing range when i took it to emissions.. i dont know the exact number (im at work) so in a while when i get a few moments ill walk down to the car and grab the paper.

but i do know it was in passing range when the hydrocarbons were up 1300 (around 250 pass)

which is why im so stumped because ive never seen hydrocarbons up so high and not have the CO off also.

ill post the actuall ratings in a few

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I agree with Mr.Blake-however, being in Phoenix,you will lose nothing by pinching off the CSV line.It is POSSIBLE(however remotely)that the CSV could be dribbling just enough to screw up the idle

sorry for the double post, just saw this.

what is the CSV?

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ok the last emissionstest numbers are as fallows

(they only test HC and CO here in phoenix i guess)

LOAD READING

Hydrocarbons in PPM 210 (standard is 250) pass

Carbon Monoxide in % 0.94 (standard is 1.50) pass

IDLE READING

Hydrocarbons in PPM 1334 (standard is 250) Fail

Carbon Monoxide in % 0.10 (standard is 2.00) pass.

(EDIT)Here are the emission readings from before i did all the work on it.

LOAD

HC PPM 220 (250)

CO% 0.43 (1.50)

IDLE

HC PPM 828 (250)

CO% 0.06 (2.00)

SO from what you guys are saying and what the readings are saying, at idle i have a LEAN missfire, correct? at load everything checks out but at idle the CO is WAY to low.. sooo i either have a vacume leak or another intake leak?

or is there other things that might be wrong like a bad valve? or weak valve spring? or maybe valves need to be adjusted?

the mechanic wants me to spend 100 bucks and have him look at it, which isnt bad, but ill be mad if i pay him 100 bucks for something i could of fixed with a 2 dollar hose. or a new hose clamp. or a 10 dollar sensor, or connector, i just dont have the money to waste right now.. if i can be efficiant with it. which sucks because id love to have the mechanic go all through it and make it pur like a lion again!

so what do you guys think?

BTW here is a picture of it. just for fun. it even has a aftermarket moon roof! (sunroof without the hindges attached LOL..)

post-22033-14150811544669_thumb.jpg

Edited by Shade133

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ok the last emissionstest numbers are as fallows

(they only test HC and CO here in phoenix i guess)

LOAD READING

Hydrocarbons in PPM 210 (standard is 250) pass

Carbon Monoxide in % 0.94 (standard is 1.50) pass

IDLE READING

Hydrocarbons in PPM 1334 (standard is 250) Fail

Carbon Monoxide in % 0.10 (standard is 2.00) pass.

(EDIT)Here are the emission readings from before i did all the work on it.

LOAD

HC PPM 220 (250)

CO% 0.43 (1.50)

IDLE

HC PPM 828 (250)

CO% 0.06 (2.00)

SO from what you guys are saying and what the readings are saying, at idle i have a LEAN missfire, correct? at load everything checks out but at idle the CO is WAY to low.. sooo i either have a vacume leak or another intake leak?

or is there other things that might be wrong like a bad valve? or weak valve spring? or maybe valves need to be adjusted?

the mechanic wants me to spend 100 bucks and have him look at it, which isnt bad, but ill be mad if i pay him 100 bucks for something i could of fixed with a 2 dollar hose. or a new hose clamp. or a 10 dollar sensor, or connector, i just dont have the money to waste right now.. if i can be efficiant with it. which sucks because id love to have the mechanic go all through it and make it pur like a lion again!

so what do you guys think?

BTW here is a picture of it. just for fun. it even has a aftermarket moon roof! (sunroof without the hindges attached LOL..)

Looks a little lean at idle to me. I'd look for vacuum leaks first. If the AF meter needs adjusted I'd suggest letting a pro do it. without a gas analyzer you'll be shooting in the dark.

Steve

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awesome. ill Severely check for intake and vacume leaks. ill need a few cans of carb cleaner for this :)

and i know to check for intake leaks and vacume leaks on the intake manafold and all componants and vacume lines but is there anything else i can check, like those little vacume pods (about the size of a quarter) that are on some vacume hoses? if so how do i check those. and are there any vacume componants i can check that lead to vacume lines or provide/use vacume?

if i check all this and it still misses then i will take it to the mechanic, because he said with that 100 dollars he will first hook it up to a gas analyzer and adjust the AFM and adjust timing and idle, then move on to check sensors and connectors and what not.

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Ask the mechanic if he minds you watching while he earns your $100.00. It could be an opportunity for you to pick up some valuable information and save yourself lots of aggravation. Just a thought and you would also make your deadline, if he is successful.

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thats a good idea. and with the deadline, i dont have the money until the 21st when i get paid so i wont be able to make it :(

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who is the mechanic??

and a little secret, you can get a 1 time 30 day temp registration at www.servicearizona.com or just a 3 day temp registration. Do you still have the out of state plates??

Edited by az240z

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Not familiar with him. Go to DZA site and check the member discounts for shops that specialize in Z's.

Also I bought the $1200 car but the owner didn't have the title notarized so I gave him a $100 deposit and was to get the car the following morning. He called me at 7:30 in the morning telling me he sold the car for more than what I paid him. Said he was sending me a refund. I'm not holding my breath.

But it was a nice car for the money. Had a great interior and ran well. don't know if it would have passed emissions. As for your car I would check all the vacuum lines as they go bad here in the desert.

Enjoy today and the 115 degrees.

Edited by az240z

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