I barely passed my emission test today. The state max HC limit is 85 ppm @15mph and 40 @ 25mph but I came at 85 and 47 respectively. This isn't the first time that happened. It happened the same thing 2 years ago too. All my ignition systems are fully tuned up. The wires, spark plugs, pcv valve, fuel filter, rotor, distributor cap, etc... has only 20K on them. The Cat has 10K. I just changed my O2 sensor cuz I thought that was the culprit but it didn't lower HC a slight bit.

My NOx level came in at 191/73 vs the max limit at 695/717. This is telling me my EGR is working fine.

CO was measured at 0.06/0.05 vs the max limit at 0.5/0.47. Which is very low comparing to HC. Something is telling me ignition is f***ed and burning rich. Any ideas of what could be the culprit that is causing an extremely high HC output?

 

oh yeah, when I moved to CA they don't sell 93 octanes gas over here. So I lowered my timing from 15 to 10 BTDC so I could run on 89 octane gas. Could this be the reason? It's only 5 degree differences.

 

Your not burning rich, your hc's were high, but your co was low, indicating that your getting too much air and running lean.

 

wait a min, but my CO was very very low and my HC is very very high. That doesn't make sense for the car to burn rich even though it appears that way.

 

I have already replaced all of my vacuum lines. The air filter is a K&N, checked, cleaned and was looking good prior to emission test. ok, if this is air related, what else should I replace?

 

VGs are made to run on 87 octane and 15BTDC. I run 18deg on 87 or 89oct depending on my wallet size.

~Alex

 

ok, I'll put it back up but I don't think that could be real reason for high HC low OC and crappy mpg though. btw, do you have the car manual, not fsm, the kiddy manual? What gas grade does it recommends? someone posted here a very long time ago said VG works with 89-93 octane but Nissan recommended 93. 93 is kinda high b/c not every part of the country has such high octane fuel. I'm starting to feel a little skeptical that Nissan would rec 93.


I think wunfstmax might be right, what about a CAI? would that do anything good? or that will ruin everything?


I'm thinking I might have to change the ignition coil pack? I haven't taken it apart so I don't know how it looks like. How many coil pack do we need? Is there one coil pack that distribute charges to all 6 plugs or do we have one for each plug?

 

please note, my car doesn't have any hesitation or rough idle problems. So, high HC + low CO = lean.... I could smell a lot of unburned fuel crap getting dumped in the back pipe. humm.... CAI or coil pack?

 

Its your timing - the fuel mixture is not getting enough time to burn up. therefore low power and bad mpg and unburnt fuel in the exhaust.

 

BV- like I said Nissan recommends 87 for the VG, only the VE needs 91+ for best performance. You can run it on 87, but thats only if the knock sensor works and you like worse mpg. Jimbo is right as is the fuel doesn't have enough time to burn

Can you smell raw fuel coming out of the tail pipe when the car is hot?

~Alex

 

In the owners manual of my 91 SE (VG) it recommends a minimum octane of 87. then it says "For the best performance and efficiency Nissan recommends a minimum octane rating of 91."

 

thanks fellas, I'll jack it back up then. On 89 octane, Alex you said 18 works best for you? Yes, I do smell unburned gas coming out of the tailpipe. I was wondering that and high HC mystery for a while. So, now it makes sense. On 89 octane, what other btdc mark did you guys advanced your timing to?

 

I have a ve auto, I've been getting 12mpg city, when I start my car sometimes it goes to start, jumps to 500rpms, then dies to 200rpms, then up to 500rpms all within a split sec, then I have to restart it and it always starts then, when this happens i get a black puff of smoke at the tailpipe and smell fuel....I notice my muffler gets coated black alot quicker than it should, im guessing unburned fuel. My car seems to have a smooth idle, and power seems there where it should be. within the last 3 years I have replaced the o2 sensor, spark plugs maybe 6 months ago, knock sensor, injectors taken off and cleaned ( 1 was leaking after a while, I took off and replaced o-rings), new tps sensor. I'm not sure what it could be, I dont have the papers with me now, but last emissions test I had I passed by 1 on the HC... not sure what other readings were. I'm guessing im running rich for some reason.

Ive looked on the plugs to see if they are wet with fuel, but none are. Don't have a timing light but I think I have it at about 15-17degrees. Could my O2 of crapped out on me from the previous leaky injector I had, not sure how long it leaked. I dont smell any fuel at all when the car is fully warmed up tho....seems to only burn excess fuel when cold... I know it does burn more fuel when cold, but smelling it at the tailpipe on start up and when it doesnt start on first crank then seeing black smoke on 2nd crank when it does start seems to me I have a problem somewhere. Any ideas?

 

Jake, I don't have any smoke coming out of the tailpipe. My emission results of low NOx, low CO, and HC told me that I'm getting enough air. Guys here then confirmed that I don't get enough compression, so timing might be the cure. For your "black smoke" case, it sounds to me your engine is burning oil.

are you getting high HC and CO at the same time? if so, then your definitely burning rich. It sounds to me you have changed everything, how about your spark plug wires and air filter?

if you smelled more fuel coming out the tailpipe in cold weather, that's normal. It's not rich, it's lean. Unburned fuel are being dumped. I have seen that's happening to many cars.

 

ok guys, I fixed my timing. It's been a while since I messed around with timing. Could someone please tell what I'm doing is correct?

Using ProLite advance timing inductive gun, I set my timing mark on the gun to 18 degrees. The best I could set my BTDC on the crank pulley was 16 degrees. When I lower the gun to 15 degrees, my crank pulley read 18 degrees. Does that sounds right? Argh weird. This is confusing me. And my distributor was rotated all to way toward its max clockwise position. I can't move it anymore. Is it because I'm using UDP? I thought those UDP marks are the same as stock crank pulley.

 

its cold weather now, but IIRC burning oil is blue smoke....I am going to go spend the $15 or whatever and get another emissions test to help diagnose if I have a problem, I dont remember what my co was

 

Coolant temperature sensor maybe? Is your ECU throwing any codes (not CELs, but actual codes from doing the diagnostic test)?

 

my buddy works at a garage shop and they have this fuel system/intake cleaning machine. Its like a $120 service, but he only charged me 40. I forget what chemical it was but jesus h christ....you thought seafoam worked good? I took off my intake tube, pulled the TB back and inside my intake it was gunked to hell...after they had my car running about 30 minutes and with this cleaner through the intake, it blew out more white smoke than ive ever seen. I drove it around afterwards and it almost seems like a new car....it ildes higher now, ill have to adjust it, i assume its from being so gunked, and now clean. But it gets up quicker, better throttle response, and even sounds better.

At the shop I noticed my O2 wire got cut...my car is lowered and it got snagged on something...not sure how long it was like that, but we respliced the wires....Im thinking that was my original problem, having the system cleaned was a bonus.

p.s. I pulled the intake tube off and opened the throttle body, looked in with a flash light...it looks brand new inside, all that gunk is just gone. I was so amazed.....anyone else had this done before?

 

you could just get a new o2 off ebay for around $50 shipped. They're all made by NTK, don't worry about which brand you get. I have gotten Bosch, Beck Arnley, and some other with their name printed on the box but the plug has NTK labels on it.

so how does this chemical stuffs works? Will it melt 1 cm layer of carbon deposit? that sounds pretty cool if it could do that cuz last time when I did my injectors, I had to scrape and melt those carbon deposit with throttle body cleaner detergents. is that stuff you used safe?

 

only the VE has coil on plugs the vg uses a distributor and coil system as for spark plug wires on a VE there are no plug wires the wires you see on the VE's are signal, power, and ground wires to power up each individual coil on plug as the VE's are distributorless igition systems usuaing a photocell sensor on the front right camshaft.

 

Does this mean your maxima isnt cali-spec? Is this the first time you have done an emissions test in CA?

 

The o2 sensor still works and wired back up now everything seems fine...1 out of 10 times the car wont start up right away but starts very soon after on next try.

I think the chemical was called BG or something...but ya it should clean all of that **** out, if its reall bad they may have it running for up to an hour to burn all that carbon build up out. Call around a few shops and ask them about "intake cleaning" or something along the lines.

 

I got my vehicle from NY so it was obviously NOT cali spec. I don't know why are they forcing me to comply to their stupid law. Any one here from Cali or have moved into Cali with your purchased vehicle from another states know of any way to escape these greenhouse crap laws? thanks

 

I like the smog laws here in Cali., they help me breathe easier. As far as gettin around em basically if it doesn't pass emissions, it's not getting registered, unless you find somebody who sells illegal certifications.

 

Well all my maximas have been cali spec just my first one I bought in CA and I wanted complete part interchangeablity. Plus they have more advanced features.
The only thing I could think of is trying a CA spec ECU in your car, even though it would have all the extra functions, and you will most likely get a CEL. I would think it would still do SOME to help lower you emissions.
Ive mentioned this before, but Im so proud Ill say it again. My Cali spec 89 VG with 220K miles and no engine work, just got a "quick pass" (I didnt have to complete the full 15 minute dyno, just 2 minutes) because the emissions were so low.

BTW, I know the cali spec cars have EGT sensor and altimeter (to adjust for air density) but does anyone know what other features they have over the federal spec cars?

 

Nice! How would you mount that EGT sensor and altimeter? I don't think these regular federal versions has places to mount them or we can modify it? I don't think so, right?

 

Im not sure where the altimeter is located, but the EGT is on the EGR and is easily swapable between fed and cali spec.

EDIT: Actualy, I believe the EGT became standard equipment on the 93 & 94 maximas, so you likely have it. See if there is a sensor (with two wires) in your EGR assembly

 

Yes, my EGR has a small sensor attaching to it.