Failed Emissions - Very High CO and HC

[Andy123]

Car seemed fine when i bought. A 98 GST stock. 118000 km on the engine. I did a few things, such as cleaning out the throttle body. Oil change. New spark plugs. Recently noticed that the cars exhaust smells and in the car it can also be smelt. Not sure what it can be. Any suggestions? I checked certain things for leaks but noticed nothing.

Car scored 5.0 in CO
Not sure of the HC, but i do remember it being high.

Thanks so much!

 

[talon187]

running at least 91 octane? have you checked the cat? any fuel mods or anything like that?

 

[Andy123]

ran 94 first. filled with 91 yesterday. No mods, bought the car from a older person. The cat is there. Could it of gone bad?

nevermind, my buddy found a hole in the exhaust mid way. Could that be the culprit?

 

[talon187]

is it before or after the cat? i dobut it but its pssible sounds like it could be the cat. are all your emssions things hooked up? i dont know if that will matter tho because i passed with my egr dissconnected

 

[Andy123]

found one hole. after the cat. only seen that one. but we didnt check before the cat.

 

[Jeff99GS]

Do you have any Check engine lights on?

Did you warm the car up for at least 20 minutes? I would drive it on the freeway and give it a chance to warm up and clear out the exhaust.

 

[Andy123]

used throttle body cleaner... not too long after the check engine light came on. Said that the fuel was lean/rich for more then ten seconds. dont know if it was because of the cleaner..

That was the only code that came up.

Took it on the highway, it still smelt.

 

[talon187]

check engine light still on?

 

[Andy123]

no we checked the code earlier today. hasnt come back on since. Drove on the highway for twenty minutes. No difference. Inside or car builds up with the smell really quick.

 

[Jeff99GS]

SO you sprayed Throttle body cleaner in the throttle, then took it to get the emmisions test?

If so I BET that's why you failed.

I would drive that car around for a few days to clear it out, and then try the E Test again.

What Number was the code P0____?

 

[Andy123]

oh ok thanks. No my friend doesnt remember the code. It had to do with the car running lean/rich though.

 

[Andy123]

car smokes white on idle.. when my brother started to drive it smokes blue a lot. Seems to drive perfectly fine though. Wonder if my turbo is going.

But than would that cause me to fail emissions?

Thanks

 

[Jeff99GS]

Yeah that would make it fail as well. Take off your intake fiter pipe and check the shaft play of the turbo. Check the Up/ Down and In/Out shaft play.

 

[Andy123]

oh ok. ill check that out. thanks

 

[EvilutionaryTSi]

does it burn white smoke or blue smoke? If its white after the car is warmed up and its not a cold day, then it could be a bad headgasket. Blue smoke means your loosing anitfreeze through the snail. see if your coolant level is staying the same

 

[cano86]

A high HC reading is the result of poor combustion. The most typical cause is a poor ignition system. HC is nothing more than fuel that makes it out the tailpipe without being burned.

So, your first step on the way to compliance will be a complete ignition tuneup: plugs, wires, caps and rotors. These parts are quite reasonable at any of the Big Three suppliers. The only exception to that might be the wires-- still "reasonable" but maybe just a little price shock. Resist the urge to spend on exotic multi-electrode plugs too; their only purpose is to provide extended life on new cars. The Bosch platinums will work just fine. Don't succumb to the temptation to get "bargain" wires either. The care and time required for wire replacement make installing good wires the best investment. Some folks have replaced aging ignition coils as part of the process too, while everything is out and accessible.

The CO reading tells you about the fuel mixture. For the most part, HC and CO are unrelated, unless the mixture on a cylinder is lean enough to cause a misfire. Lean conditions result from vacuum leaks at hard/cracked/broken hoses, leaking gaskets and boots around MAF/MAS sensors, and partially clogged fuel injectors. Old vacuum and emissions hoses undoubtedly need replacing just due to age on many cars, so getting all new ones and installing them in one session is not a bad way to go.

A poor oxygen sensor might cause a lean condition severe enough to create a misfire, but an engine with reasonable ignition will easily fire with that slightly lean mixture.

So, your marching orders would read ignition tuneup as described above, a visual inspection of hoses for vacuum leaks, followed by a listen and spray, and finally a test with a good high-impedance DVM for output from the oxygen sensor.

You should also be aware that excessive HC passing to the exhaust is death on a catalyst. They are only rated to react a certain mass of fuel, so extra fuel translates to extra heat, which leads to (hopefully just) a failed substrate, but too often also results in a fire. (!!) No matter-- if you have the high HC readings at the tailpipe, new catalysts are in your future if you want to have the car clean. Often, a carefully tuned 928 will pass without catalysts working, so start off with the basics and see how you do in pre-test mode at the smog check station. Then do the cats as your budget allows. You'll breathe easier.

Many owners will tell you that it's a good idea to do a wholesale replacement of maintetanance items when you first get the car. It gives you a new baseline for everything, and will help you avoid a lot of the sniggly little problems that often plague aging cars no matter what the make. The hoses and belts and fluids all fall into this category. If you don't have a solid history of timing belt replacement, now's the time. Don't forget to change the brake fluid too.

Good luck

 

[Srt4RacerDave]

Before I gutted my cat out I had that bad half-burned fuel smell in the car. After the cut was gutted out, the smell was gone. I guess after a while it just gets clogged up and can't filter nearly as good as it needs to. Granted I had a high flow cat.

 

[looking4it]

I don't have a cat, just a full 3" exhaust from the turbo back. I just held back some fuel @1000rpm (SAFC II) before I went into the emissions test, and it passed with no issues at all.

 

[Boosted_out]

I failed my first time around when I had 2.5 exhaust and a high flow cat. I seafoamed my car went back and passed!!

Now I know I will fail with a 3inch straight through exhaust.

 

[Andy123]

car seems to be running fine now. at shop. he said the car had some black smoke.. said fuel was running rich? how can i fix that, o2 sensor?

So i guess it could have been the throttle body cleaner.

 

[3tcpower]

When did it have black smoke? At idle? Under load?

Don't know if DSM's are the same way, but the GT4's from yota would spit black smoke when the bov was vented to the atmosphere. That was just when coming out of boost

 

[Andy123]

at startup.. for the first couple of secs..20 secs or so black smoke came out

 

[jaysonatticus]

How old is your O2 Sensor? i had the same problem as you with emissions. The two culprits for me were a faulty ISC and the O2 sensor. Might want to look into those two things as well.

 

[Andy123]

o2 sensor doesnt appear to have been changed. looks old. plus no service records or anything of a new one being put in