how it going new guy here kool site! how would i find my bad codes i have 1995vette thankfor the help

 

What codes do you have?

What were your test #'s on your failed test?

Are you asking about the procedure for retrieving your stored DTC's?

I am sure it is a problem on my part, but i am not sure what you are asking us.

Greg N

 

HC(gpm)3.67 standard 0.80 fail CO(gpm16.5 standard 15.0 fail CO2(gpm) 505.6 standard NA NOx(gpm)5.40 standard NA

Tested it 3 times same numbers every time i have new LT1 motor only 2000 miles on it when i bought car motor was new with nos installedi have headers car was dynotested 402 hp with 100 shot of nos. service engine light just started to come on last week but never at test times guess my q is what is the way to find out if i got bad codes and how do i do that thanks for your help

 

Have you ever changed the O2 sensors?

What are your mods on this new motor?

 

Do you still have cats on this car? Did you drive around for an hour to allow the car to fully come up to operating temp PRIOR to going in for the smog test?

 

Is this a normal warmup procedure? Just wondering because the wife took it straight over, which is about a 5 mile drive. So I think I see where one of my problems is at. lol Well I guess it is my fault but she wanted to take it while I was at work so we wouldn't have to waist time when I got off. Thanks for that advice about the warmup.

 

There is a way to pull the codes with a paper clip, do a search on pulling codes. Better yet buy a scan tool and a factory sevice manual.

First take care of all of the code related issues.

Make sure that your o2 sensors that are between the cat and the motor are not slugish and have a good voltage swing, say from about .300 mv to .850 mv.

O2 sensors tend to get slugish or stick rich or lean with age. you also stated that this has a new motor in it, if the failure was due to a head gasket leak and the 02 sensors were not replaced, i would suspect them.

looking at your #'s i would say that also you have a convertor problem also. If you take care of all of the other tune up things and it still will not pass, but gets close, you will more than likely need convertors, even if they are lighting up. (by that i mean the temp is hotter after the convertor than it is before the convertor, we have seen many convertors that will light up, but will not bring the NOX down)

I hope this helps, and you did not mention if this car is stock other than the N2O and headers (camshaft?)

 

Is there a paper clip trick to see my bad codes?? i got the car like it is so i dont know if there were any mods other then headers and bbk thorttlebodyand 3 inch exhaust, does have cats still on it.oh yea got ram air induction

 

Do a search on pulling codes, it is there somewhere, i just have never done it that way, you can get so much more information with a good scan tool, like looking at the data stream.

The headers, ram air should not have and throttle body any effect on your emmisions.

I really did not under stand what your #'s were.

HC(gpm)3.67 standard 0.80 fail CO(gpm16.5 standard 15.0 fail CO2(gpm) 505.6 standard NA NOx(gpm)5.40 standard NA

were your Hydrocarbons 3.67 PPM and allowable was .80?

Was your CO was 16.5 PPM and allowable was 15.0 PPM?

On your NOX was it 505.6??? PPM and passing was 5.4 PPM?

Greg N

 

Yes, there is a simple way to pull the codes using a paperclip. Under the diver side dash is the Assembly Line Diagnostic Link or ALDL. By shorting the proper terminals with your paperclip you can get the Powertrain Control module (PCM) to flash the existing codes for you.

Your 1995 should be an OBD1 system. It will probably have an OBD2 ALDL connector, but that does not mean it is an OBD2 vehicle. Most all 95s have the OBD2 connector, but are still OBD1. OBD2 officially started in 1996 by Federal law, however it was not unusual or against the law to install OBD2 earlier. On the emissions sticker it will tell you what version OBD1/OBD2 you have in your Vette. Check under the hood on or around the radiator.

Here are some links to the procedure with an illustration of the ALDL.
This page: ALDL Types shows the many ALDL connectors used by GM2 including the 2 types of connector used by GM in the C4. Type No. 13 is for 1984-1995 OBD1 Vettes and No. 21 is the OBD2 connector used in all 96+ Vettes as well as some 95 and 94 Vettes. There is info there about which pins to jumper, based upon your specific ALDL connector and OBD version. You may also be able to find the method detailed in your owners manual.

The codes used in the C4s did vary somewhat from year to year, so the same code isn't always used the same way in an 85 as it would be in a 95. Here is a page that purports to show each model year specific codes. CODES There are other places on-line and in earlier Forum threads where you can find this info as well. Be sure to use the correct definition for the codes for your model year Vette.

One excellent CF thread on later model C4 code pulling is at http://forums.corvetteforum.com/showthread.php?t=1302584&highlight=pull+ codes&forum_id=48

Bogus has a web site where he posted some code pulling info for the 92 and 93 model Vettes that you might find useful. Go to Bogus code page to learn about the aditional computer installed in the Vette starting in 1990. In addition to the PCM for the engine, you also have a Central Control Module (CCM) that communicates with other sensors on the car including the ABS.

Before you buy a scan tool, do some research as many of the cheaper tools are just packaged paperclips so to speak. Look into getting a good scan tool if you are going to spend the money. Ask in the C4 Scan & Tune section for more excellent info on codes and scan tool usage.

 

For an emmitions test, you want to drive the car around for an hour or perhaps 30 minutes on the hi-way. The cats don't start working effectively until they reach a very high operating temp (needed for the chemical conversion reaction to take place) Otherwise when they stick a probe up your tailpipe, which is what they generally do for OBD I cars (those 95 & older) you will fail the test.

This is not something made up by me or found here on the forum. Here in Washington they have huge signs infront of the inspections stations telling people that if there car is not up to full operating temps they will fail the test. The tech explained the cat part to me.

 

CO2(gpm) 505.6 NOx(gpm)5.40 they dont give a standard for these they dont come into play on test here in chicago you had other right

 

Thanks for the information. I will drive it around for a while this weekend and then get it tested. Now I feel alot better. You just made my night.

 

for me, i always put new plugs and air filter in before i take a vehicle to emissions. in the past, just doing this has made the difference on a failed vehicle. and of course, as said, it has got to be hot.


frog.

 

You have something going on there.

It is either way to rich, or you have a miss fire.

With #'s like these in all probabilty you are going to need a new convertor and O2 sensors AFTER you get everything else corrected. Running that rich has probably poisoned the cat and the O2's

With the engine in a good state of tune it should come very close to passing with out the convertor, but probibly not close enough.

Remember, test first, then replace only what you can prove bad.

Greg N