72corvette

I bought an 88 C4 from Florida and it has to pass Texas Collin County inspection to get it registered here. It failed the Emissions testing and they say I need to start by changing out the Catalytic converters and the EGR valve and then possiblly the Injectors. They say it has old style injectors which were not very good which they have since been replaced by inproved ones which you can purchase? Where should I start and how do I know what is bad or not bad for sure. I do not want to just replacing things that may be good. Please Help. Here are the Emission Test Results:

High Speed Emission Results (25 mph) RPM: 0

HC(PPM) Standard-152 Current Reading-140 Result-PASS
CO(%) Standard-0.97 Current Reading-0.25 Result-PASS
CO2 (%) Standard-N/A Current Reading-14.9 Result-N/A
02(%) Standard-N/A Current Reading-0.1 Result-N/A
NOx(ppm) Standard-1082 Current Reading-614 Result-PASS
DILUTION(%) Standard->6 Current Reading-15.2 Result-N/A

Low Speed Emission Results (15 mph) RPM: 0

HC(PPM) Standard-157 Current Reading-486 Result-FAIL
CO(%) Standard-0.88 Current Reading-1.31 Result-FAIL
CO2 (%) Standard-N/A Current Reading-13.8 Result-N/A
02(%) Standard-N/A Current Reading-0.3 Result-N/A
NOx(ppm) Standard-1184 Current Reading-1710 Result - FAIL
DILUTION Standard->6 Current Reading-15.1 Result - N/A

Gas cap integrity Test result: PASS
Safety Items: PASS
Overall Test: FAIL
Thanks
Gene (ingramg@yahoo.com)


[Modified by 72corvette, 11:01 PM 10/20/2003]

65Z01

First off "they" should not be telling you what needs to be changed, only in which areas your car failed emissions! Besides they obviously don't know anything about L98s.

You need to pull the codes to see if they are any stored trouble codes. If the EGR system failed, it will show up there; if so there is a diagnostic procedure on my site (link in sig. below) to isolate the problem area.

Use the diagnostic procedure on my site to see if the ECM is going into and staying in closed loop mode. If not, you either have a faulty O2 sensor or faulty coolant temp sensor (in the front of the block).

Actually replacing your stock cat with a 3-stage hi-flow Random Technology unit is a good idea. In that case also replace the stock front Y with it's two pre-cats with a 2 1/2" mandrel bent unit. This change will give you some added HP, better mileage and is 49-state emissions legal.

Check your spark plugs and, if needed, replace them with a set of AC Delco with cut-back electrodes (see my site for details) as this mod not only gives you a free 8-10chp boost but also provides for a cleaner charge burn (lowers emissions).

Don't worry about your stock injectors as they are quality units. If you don't have symptoms of leaking (hard warm starts, fast fuel pressure leakdown, or discolored spark plugs) don't service them. If you find a problem in that area, send the set (all 9 of them) to Rich at Cruzinperformance (link on my site). He does a complete rebuild in 48hrs for around $100.

When you return to your "friendly" EPA station make sure your L98 is fully up to normal operating temp. If you are waiting in line, bring up the idle occasionally.

Q1KSLVR

:iagree:

:bs If those guys knew how to fix cars, they wouldn't be sticking hoses in tailpipes!

If it is in Texas the way it is in NJ (where I'm from) there should be mechanic shops that are licensed inspectors that will diagnose and fix the car and re-inspect it in house so it'll pass. :thumbs:

85 Dave

I seem to remember that the EGR doesn't start working until the speed gets a little faster than 15 mph. Anyone???

SunCr

Kinda looks as if it was in open loop during the low speed test as the differences between 15 and 25mph are like night & day. Wish they would note the engine temp when they run these things. You might want to try a new O2 and make sure the air pump is functioning -