failed emissions

Grumpy · Aug 10, 2015

corvette455 said:
My 1987 Corvette won’t pass emissions. The hydrocarbons are high.

I hooked up an AutoXray diagnostic tool and it said the car was running lean.

I brought it to a professional mechanic who put it on his “professional” test equipment and he told me I needed for starters a new Oxygen sensor. $285 later including his diagnostic fee, he says I need new injectors and new catalytic converters. He said that in one of the fuel banks I had an injector which was running lean which must be telling the computer to add more fuel which was the reason the car had high hydrocarbons. I asked him if he could flush the injectors and/or replace the one bad injector. He said his injector flush equipment didn’t work and he couldn’t isolate which injector was bad. By the way, he said the compression was good in all cylinders.

Please help me figure this out. Here are the issues.
1) High hydrocarbons, which I know is correct because I can smell un-burnt fuel out of the tail pipes.
2) On a cold morning (below 55 degrees) the car sometimes refuses to start. The engine will start and immediately stall. This can happen 15 times. The way I get it to start is to start pumping the accelerator and tons of carbon come out of the tail pipes. The last 2 times this happened, the service engine light came on. I hooked it up to the AutoXray Scanner and the code was 42 (wiring, spark control module, ECM). Being this is summer, I am not having this problem. But could this be somehow related to my high hydrocarbons?

A tech at Wells told me to buy a stethoscope and listen to the injectors and if any sound different then that one is the issue. I have done this and they all sound identical. The Well’s tech said then the injectors are fine. He also told me how to test the TPS (which I did) and he said my results were normal.

I looked at the spark plugs (which were new when I first tried to pass smog 6 months ago) and they all look clean and dry.

The problem feels like it is electrical. A bad sensor or something because when I first put in the new spark plugs, the car ran great for 2 days. On the 3rd day it ran rough as hell. On the 4th day, it ran great. Sometimes when I start it and it runs rough, I turn off the car and restart it and it runs fine.

Please help me figure this out. Is there a step my step process of checking each sensor? I can’t afford to buy parts I don’t need or pay mechanics to experiment. Is there something obvious I should be checking?

BTW: this is my daily driver.

Thanks for any assistance!

buy a CHEVY SHOP MANUAL FOR YOUR YEAR CORVETTE!
you always need a base line to start from, on a TPI corvette.
a logical step by step approach and keeping accurate notes helps.
youll NEED a multi meter, a shop manual and a timing light and fuel pressure gauge at a minimum,
set and verify your ignition timing, pull trouble codes,set your tps and iac,, then check for vacuum leaks on the lines and intake,then get out your multi meter and verify all the sensors, chances are good its a defective heat sensor or defective o2 sensor, a logical step by step approach will lead you to the problem, youll be amazed at what youll learn reading links. use of a shop manual and multi meter can be very helpful
there are soft ware programs too down load to a lap top computer that give real time data logging on engine performance and sensor output, engine temps, fuel ratios,ignition exavance, plemum vacuum, exhaust temps etc.

http://www.harborfreight.com/5-in-1-dig ... 98674.html
put a fuel pressure gauge on the fuel rail on the shrader valve,

a vacuum and fuel pressure gauge is useful

performance issues or troubles like you describe, generally fall into 5 basic groups

MECHANICAL--things like worn cam lobes , badly adjusted valves ,vacuum leaks, rusty distributor advance weights and springs,

FUEL DELIVERY-- things like clogged fuel filter or defective fuel pump, bad fuel pressure regulator, wrong power valve or jets, defective fuel pumps and accelerator pumps in carbs

IGNITION-- things like incorrectly set,timing advance curve or bad wiring , old spark plugs , burnt ignition wire, the wrong plug gap, cracked distributor caps etc.

SENSORS,computer controls and electrical connections, too sensors and computer controls

Improperly input or corrupt software when you have the option of changing the data

the basic tools youll need, are common mechanic hand tools plus....

the correct matching SHOP MANUAL
TIMING LIGHT
IR TEMP GUN
VACUUM GAUGE
MULTI METER
FUEL PRESSURE GAUGE
COMPRESSION TEST GAUGE

http://www.professionalequipment.com/ex ... ermometer/
Wide temperature range from -58 to 1832Â°F (-50 to 1000Â°C)

viewtopic.php?f=55&t=109

Grumpy · Aug 14, 2015

auto diagnostic software for laptop computers

http://www.totalcardiagnostics.com/toad/

https://www.autoenginuity.com/products/scan-tool.html

https://www.scantool.net/obdwiz/

http://pro.innova.com/Support/TroubleshootingDetails/92676814-3f73-49ae-a0d5-ec401ead3bc0

http://www.jbtoolsales.com/autel-ds...stem-w-free-maxitpms-ts401-al319-code-reader/

http://garage.grumpysperformance.co...r-engine-with-lap-top-computer-or-i-pad.6323/

http://garage.grumpysperformance.com/index.php?threads/c4-c5-corvette-trouble-codes.2697/#post-69239

the only problem I see is that every time I buy a scanner or scanner soft ware I find that within 6 months theres something new that far exceeds the old choices and usually at a similar or lower price, Id suggest you also look at software you can download and an AdL cable too connect to your cars computer access port

lots of related info

viewtopic.php?f=27&t=3096&p=18612&hilit=scanners#p18612

viewtopic.php?f=50&t=6323&p=19860&hilit=computer+cable#p19860

viewtopic.php?f=50&t=8136&hilit=obdII

http://www.haltech.com/product/platinum ... /sport-gm/

viewtopic.php?f=32&t=2697&p=8434&hilit=computer+cable#p8434

viewtopic.php?f=2&t=3074&p=8155&hilit=computer+cable#p8155

viewtopic.php?f=32&t=9202&p=33208&hilit=computer+cable#p33208

viewtopic.php?f=80&t=728&p=9217&hilit=+sensors+location#p9217

failed emissions

Grumpy

The Grumpy Grease Monkey mechanical engineer.

Grumpy

The Grumpy Grease Monkey mechanical engineer.