I just can't pass emissions!

[Edmond]

I haven't been able to pass for the past two years.

The state requires a standard of .80 while I'm reading a 1.9 measured in GPM on hydrocarbons.

Standard of 15. on carbon monoxide while I'm reading a 26, measured in GPM.

What is going on here? Why are they reading so high?

In the past two years, I have replaced:

all 3 cats
EGR
PCV
plugs
wires
distributor cap
distributor rotor
charcoal canister

Only things I can think of are getting the injectors cleaned and the air pump. I hope it's not the injectors because taking the plenum and all that other stuff off to get to the injectors will be a PITA.

I need suggestions. Should I check the plugs again? They're 2 year old Bosch +4's. What plugs do you suggest?

This is getting very frustrating. ad

 

[JonM]

How about your O2 sensor and the Temp sensor...how old are they? They are very important componants that tell the ecm what to tell the fuel system to do. Have you also removed the return line from the cansiter and gas tank and tried to blow compressed air through it...Mine was block up so bad I needed to replace it. Just a couple ideas.

 

[1995 RedVette]

I would consider the O2 sensors. As they age, their response time goes away thus not allowing the computer to compensate for lean or rich conditions in time to be useful.

Brett

 

[Edmond]

Oops, forgot to put down that I did change the O2 sensor on Saturday. It's a brand new sensor.

As for the temp sensor, I haven't touched that. Where is it located at?

 

[JonM]

Oops, forgot to put down that I did change the O2 sensor on Saturday. It's a brand new sensor.

As for the temp sensor, I haven't touched that. Where is it located at?

On mine its on the front of the passenger side head.

 

[Edmond]

On mine its on the front of the passenger side head.

I'll check to see if mine is there on the passenger side as well. This is frustrating! :eyerole

 

[ErnieN85]

How long has it been since you changed the oil?

usually a fresh oil change and the PCV valve also helps.
Aside from that the bosch 4 plugs aren't the greatest .
get it good and hot befor the test and don't let it cool down any more than you have to. Do you have the stock thermostat (195) or are you set up to run cooler. cool hurts emissions!

 

[Edmond]

How long has it been since you changed the oil?

usually a fresh oil change and the PCV valve also helps.
Aside from that the bosch 4 plugs aren't the greatest .
get it good and hot befor the test and don't let it cool down any more than you have to. Do you have the stock thermostat (195) or are you set up to run cooler. cool hurts emissions!

Ernie,

I changed the oil at the end of July. I haven't even put 1500 miles on it since that time. The PCV was done a few weeks before I last changed the oil.

I'm still running the stock thermostat. The coolant temp was in the 226 range and I it was kept running for a solid 30 minutes with 25 of those minutes driving minutes.

I'm questioning the Bosch +4's. I may pull those and see what kind of shape they're in. I may switch back to Delco. Do you think Delco's are better off?

I went to an exhaust shop. He really couldn't tell me much without hooking the car up. I'm not going to pay him $94 to hook the car up. O2 sensor is new and no codes are showing. He did comment that it's running rich.

 

[bossvette]

there are three temp sensors on early TPI's one under the Plenum for air temp and two in the intake one for coolant temp and one that tells the cold start injector to fire a quick trick is to up your idle speed as much as you dare and then lower it after testing.
Goos luck
Craig sr.

 

[ErnieN85]

Edmond, looks like you have a lot of the bases covered.
check the base timing. if it's off that will mess it up. also fuel pressure. if you have an adjustable regulator or a bad one and pressure is high it will run rich. the tip tp speed up the idle is a good one also with a tpi its more difficult to do but might work

 

[Vettefan87]

I went to an exhaust shop. He really couldn't tell me much without hooking the car up. I'm not going to pay him $94 to hook the car up. O2 sensor is new and no codes are showing. He did comment that it's running rich.

How did he know it is running rich if he did not hook the car up to a scanner?

Do you think Delco's are better off?

I like AC Delco's a lot better, I don't have information to back them up if they are better or not, but they are the factory replacement plugs.

I hope you get it fixed man, I know how stuff like this goes. The fuel pressure regulator I have on my car now is set right at 47 lbs per the instructions that came with it. and the car idles great, I haven't had a chance to drive it yet still waiting............... Hope this helps.


Justin

 

[ocrick]

What is your fuel pressure? Where is the base timing set?

 

[taegdh]

Did you run a couple of bottles of Fuel Injector cleaner through the tank with 93 octane gas?


That's what I used to do. Even on Honda's and Dodges, and four letter american made vehicles.

Worked for me!

 

[-=Jeff=-]

Edmond,

Are you running the stock chip for emissions? I would not suggest my chip for emissions since it helps the car run cooler which is not a godd thing for emissions

 

[G Winter]

I won't use anything other than AC Delco in my GM cars. Diff brands have funny heat range overlaps. If your gap is set at .035 you might want to try setting at .040 or even .o45 could help the emissions,they light a bigger fire with a bit wider gap. The down side is , under hard load-high cylinder pressure they might missfire a little easier. Do you drive the car enough to keep fresh feul in it? Some additives can cause emission problems.

 

[Alloydude]

Hey Edmond. High hydrocarbons (HC) and carbon monoxide (CO) are usually the result of unburnt fuel. Possibly a vacuum leak somewhere. Not sure if they test for nitrogen oxide (NOx) in your area but if that’s high it’s usually caused by a bad EGR. Living in California I feel your pain man!!!! ad Good luck.

 

[Edmond]

Hey Edmond. High hydrocarbons (HC) and carbon monoxide (CO) are usually the result of unburnt fuel. Possibly a vacuum leak somewhere. Not sure if they test for nitrogen oxide (NOx) in your area but if that’s high it’s usually caused by a bad EGR. Living in California I feel your pain man!!!! ad Good luck.

No, they do not check for nitrogen oxide, yet ad

The idle is fine so could it be a vacuum leak? I just changed the EGR 2 weeks ago.

 

[Edmond]

Edmond,

Are you running the stock chip for emissions? I would not suggest my chip for emissions since it helps the car run cooler which is not a good thing for emissions

Jeff,

I put the stock chip back in and drove it for a good 50 miles before I went in for the test. The coolant temp was running in the 226 area while I was on their dyno during the emissions run.

 

[Edmond]

How did he know it is running rich if he did not hook the car up to a scanner?

I like AC Delco's a lot better, I don't have information to back them up if they are better or not, but they are the factory replacement plugs.

Justin,

I don't know how he assumed that it was running rich but his quote was (pointing at the high reading on the report certificate), "high hydrocarbon and carbon monoxide readings are the result of running rich."

I'm thinking about going with the Delco's. But first I'm going to take one plug out at a time to see what condition they're in.

 

[Edmond]

Edmond, looks like you have a lot of the bases covered.
check the base timing. if it's off that will mess it up. also fuel pressure. if you have an adjustable regulator or a bad one and pressure is high it will run rich. the tip tp speed up the idle is a good one also with a tpi its more difficult to do but might work

Ernie,

I have the stock regulator on there. But I will check the fuel pressure and see what it says. My book says that it should read somewhere in the 35-39 PSI area. Is that correct?

Is incorrect fuel pressure usually the result of a failing fuel pressure regulator?

I really don't want it to be the injectors and have to take all that stuff off. I mean, I can do it because I've done it before but that doesn't mean I enjoyed doing it.