The emissions of my Z are somewhat high. Over here the tests are done at idle!
The results are:
HC at 437ppm (which is more than double than allowed)
CO at 1.21
CO2 at 12.15 (should be lower than 12)

Only changes are adj. fuel pressure regulator, hedmann shorties, catback, EGR not connected to dual-converters.

We replaced the o2-sensor with no change.
I have no codes or ses-light. Engine running at normal temperature.

During driving I have a little hesitation/stumbling when getting on the gas below 1500 rounds.
Also gas smell when standing still at a light or so.

Any help is greatly appreciated!

 

no idea?
anyone?

 

Can you access data from the ECM while it is running? If you can watch the data stream you can read/report the BLM values to see if the ECM is trying to trim fuel, how much, and in which direction.

 

Based on the info you have posted, check your fuel pressure. Should be about 43 psi at idle with vacuum hose disconnected. Prior to an emission test, change your oil and filter. Old oil has HC dissolved in it that will slightly increase emissions. Verify your timing. It should be 6 degrees before TDC. At 437 PPM HC, you are way too rich. You said that you can smell fuel when stopped at a light and you have hesitation and stumbling. Something is wrong. The last time I had my vehicle tested, my HC was 80 ppm a idle, and that is high. I've seen some members get as low as 22 ppm HC. I suggest you ohm your injectors, maybe even check you plugs. You may have a bad injector. Time to get back to the basics. Check your ignition system, cap, rotor, plugs and wires. Check your fueling, proper pressure. Air filter been replaced, etc. Good luck

 

If the engine still has the OEM Multec injectors in it, it is time for new ones.

RBob.

 

My 89 LB9 still has them. Which replacement injectors do you recommend?

 

Thanks for the answers! I will go step by step. Too bad that I'll be on vacation next time. I'll post an update later when I'm back to tell what was the problem!

 

So far we changed the cap and rotor. It was all corroded inside!
I really should drive my car more!
The emissions are much better now, but not where we want to have it. Timing and fuel pressure are ok. Now I will drive some more and then we will check the emissions again.