OK so my dad has an 87 corvette that will not pass emissions. He is about to just let the car sit for three years until he can purchase the historic tags. I really want to get the car to pass I know how much he would enjoy it. I have replaced the spark plugs and changed the oil and I'm not sure what else I can do. Changing the spark plugs and oil dropped its emissions a little but not enough to pass. If anyone has any knowledge to help lower the emissions it would be greatly appreciated.

 

try seafome

 

You need to scan it to take the mystery out of it. And if you post the test results, we can tell you what to look for.

 

I don't have a scanner and don't have the money to have it scanned. thank you for the suggestion. does anyone know just simple repairs that can help the car pass emissions.

 

You have to tell us what the test results were.

One suggestion was to seafoam it. Obviously not enough information. Don't know if search is working, but here are the basics.

Buy a can of "Seafoam" - yes that is the real name of the product its $8 - $10 from any auto parts store (I've even seen it at Walmart)
Remove the vaccum hose from the brake booster, start the car and wedge the throttle so it is running at about 2000 rpm. SLOWLY pour half the can of seafoam in the vaccum hose and watch the smoke show. Turn off the engine, re-connect the vaccum hose, pour the other half can in the gas tank. Drive the car until you need gas. Put fresh gas in it and see what the emissions are.

 

You have to tell us what the emission test results were before we can tell you what likely caused it to fail.

 

There is an excellent book written by Charles O. Probst called CORVETTE FUEL INJECTION AND ELECTRONIC ENGINE MANAGEMENT. It covers problems dealing with failing emissions testing. 400 pages. Good Read.

 

What state do you live in ?

When I picked up my 88 in Jan. it had problems passing the smog test, I just spend a few hours checking and doing these and I pass without any problem and numbers looked great afterwards:

- Pick up a FSM and follow the procedure on tuning and checking.
- Major Tune up (cap, rotor, plugs, wires, etc)
- Seafoam job (help out a lot)
- check and repair all vaccum lines and hoses (this was Key !)
- Check EGR and make sure it is clean and functions correctly
- clean MAF and check relays and connectors (fixed 3 codes)
- clean or rebuild the Throttle Body, replacing anything tha tis needed, Autozone has a cheap kit for the gaskets and seals. replace TPS, IAC if needed. (I had bad carbon build up, soaked it in a bucket of carb clean over night!)
- do a compression and/or leak down test to ensure that you got good compression and that there is no leakage in the rings and seals.
- Check the ECT (Edit, sorry was thinking of one of my other cars)sensor and replace if needed. (cause some idle problems and replaced it).
- Check the Resistance in the fuel Injectors.
- Change the Fuel Filter
- Have the back pressure checked on the CAT and replace if needed.
- Use a good brand and grade of Gas.
- Make sure the Cat is HOT when testing. take a quick drive at high engine RPM.

All of this costed under $200 and about 8 hours of work (yeah I work slow).. but the results were great. many of these items can be done cheap.. because all they are is just labor of cleaning and checking..

 

CO2-failures are usually a result of not enough air entering the engine.

NOX-failures are very high combustion temperatures which is usually a bad or non functioning EGR valve, plugged egr intake passage, egr temp switch, or bad egr solenoid (a plugged or damaged Catalytic Converter could also, cause high NOX).

HC-failures are a result of an incomplete burn in the combustion chamber as a result of a too rich or too lean air fuel mixture.

All these problems can be corrected with a Full tune up as stated above including, oil and filter change, spark plugs, wires, cap, rotor, air filter, O2 sensor, fuel filter, coolant change and thermostat.

I would also do the Seafoam treatment as mentioned, before anything else to clean all the carbon out of the engine.

 

Caution about Seafoam it works great but it will ****-off your neighbors. If you live in a residential area do it later at night (so they can't see all the smoke

When I did mine, I used a small tube and hooked up to one of the vacume ports. Even at idle it sucks in fast, so be careful; you don't want to hydrolock the engine. Oh ya the smoke doesn't stop when the bottle's empty either, the first pass or two down the street is good for keeping down the mosquitos

 

Yes.. be carefull. .I used a funnel on the end of my brake vacuum line, as I got near the end of pouring it in.. I got a little to close with the can and the funnel and WHAM.. it had suck the top of the can right into the funnel.. and the vacuum collaped the CAN like a beer and on your forehead !... LOL.. The power of Vacuum can be a lot more stronger and powerfull than you think ! .


And enjoy the smog show !..

 

sorry i haven't been able to get on in a couple of days. I live in Maryland so the emissions standards aren't that high. the results for hydrocarbons (HC) state standard:1.8000 car result:3.5069. (NOx) state standard: 2.8000 car result 3.7133. I have just changed the spark plugs with E3, oil, air filter, and pcv valve. After I have change the pcv valve i noticed there was a crack in the grommet and I don't know what size grommet will fit and the local auto shops didn't because the grommet isn't in their computer. What is the grommet size and where could i get it? Would the crack in the grommet effect anything? thanks for all of the help and I could still use more!!

 

You need a good seal there to prevent a vacuum leak. The grommet is available at your Chevrolet dealership.

 

on my 86, the thing seemed to run funny, and in checking all the items on the car, I came across the vacuum ports being clogged up with the egr residue.
Use a drill bit, and twist it with your fingers into the vacuum port tubes.
Use an 1/8 inch drill bit, it will be sloppy in the hole, but you can ream them out pretty easy.
Suddenly, I saw a change in how things were working, even the air conditioner worked better. The heater valve was finally being pulled shut!!!

 

Which part are you talking about.. or a picture.. ? Just checking so that we can all check the right one the next time we go under the hood !