Longshot08

Picked up an 88 GTA (TPI 5.7) last week. Previous owner couldn't get it pass emissions. Has a new cat, distributor cap/rotor, and coil looks new too. Anywho the emissions report said it was emitting about 3x the allowed amount of NO. Read the manual and did some research on here all which led me to suspect the EGR was bad.

EGR- Took it out and tested it. Holds vacuum and valve moves when vacuum is applied on both ports (mouth vacuum). Good valve.

EGR temp switch- Got my voltmeter and tested it cold. No circuit when cold. Heated it over the stove and lookie lookie closed circuit. Cooled off the switch and open circuit. Repeat a few times to be sure. Good switch.

EGR solenoid- Got my 9volt and hooked it up. Heard the click and blew through the ports and felt the air come out the vent side. Removed battery and air flows through the ports. Repeat. Good solenoid.

So now I'm confused and look at the results from the emissions test again. I see that it also failed the Fuel Evap test. How did I miss that? Well I have a few days to stew on it because I dropped a bolt for the coil/solenoid bracket behind the engine and that thing is gone forever, so I need to make a trip to Lowes to match my remaining bolt with a new one.

I'm open to suggestions and/or sarcastic comments.

Bob88GTA

iTrader: (2)

Make sure all the vacuum lines going to the EGR and Solenoid are up to par and hooked up.

Fred SS

iTrader: (3)

High NOx is due to excessive combustion temps. Application of EGR cools the combustion process. I agree with Bob88gta to make sure the vacuum lines are ok. Also, make sure your timing is at the stock setting of 6 degrees BTDC. I have heard time and time again that TPI cars will not pass emissions test with timing set higher than stock. The failed Fuel Evap test may mean you need a new charcoal canister or something wrong with the vacuum lines. Good luck.

thtanner

iTrader: (1)

The EVAP system tests tanks ability to vent fuel vapor into the EVAP canister instead of into the atmosphere. The system consists of fuel vapor hoses running between the gas tank to the charcoal canister, through a purge valve and into the intake manifold.

If any of the hoses or the purge valve in the canister is bad, she'll fail that part of the test. Another thing to look at is if your tank is cracked where the filler neck attaches. This is apparently common and will not allow the tank to hold any pressure, and thus fail the EVAP test as well. You'll notice some fuel smell when you have a full tank around the rear of the vehicle if this is potentially the case.

Your timing is at least within 2 degrees of 6BTDC because the CA test checks timing and will fail you on that too - check and make sure it's on the money though.

I just did this song and dance and luckily passed, just to have the engine develop a light bearing knock leading to a rebuild at the end of the month. Hmmph.

paulo57509

The EGR valve and solenoid can test OK, but you need to be sure to check the EGR passages for blockage.

High NOx can be caused by a lean mixture (vacuum leaks are the most common cause for lean mixtures), which in turn raises the combustion temperatures.

In what state do you reside? Is the test performed on a dyno or is it just a tail pipe sniff test? Does your state measure and give you a read out of the five gasses (CO2, O2, HC, CO and NOx)? Post them up if you have them.

mk1431

is the car running hotter than normal coolant good? high milage car? is the motor clean inside under valve covers sludge etc injectors spray proper pattern? air fuel mixture good compression ok o2 sensors reading correctly coolant temp sensor ok fuel pressure ok try cooler sparkplugs run cooler t-stat try retarding timing a few degrees if possible sooooo thats prob why previous owner sold it it could be really anthing thats why most people sell when wont pass smog good luck let us know what your findings are and see if we can help i got more but this should get you started

Longshot08

The EGR passages you are referring to are the port on the intake and the valve correct? They both have carbon build up on them but otherwise clear. I'm going to clean the EGR valve and intake passage with some carb cleaner tonight or tomorrow.

I'll check all lines again just to be sure. The lines that run from the solenoid under the intake to the EGR valve and TB are good for sure though. It splits off at the TB and runs to the passenger side to a connector which has pretty gummed up lines. They go into what appears to be the canister but I need to recheck my reference manual to be sure.


Haven't tested a car here in Cali yet but the report has an idle measurement and a 15 mph measurement so I assume it's a dyno test with a tailpipe sniffer attached. I'll post up the actual report later tonight. for reference.

Longshot08

Hmmm. Haven't checked the timing but I will add that to the list as well for this weekend. The cap and rotor have been replaced by the previous owner so the timing being off is a very likely possibility.

Longshot08

Here are the results from the last emissions test.

Getting the bolts in the runners along the bottom right now. Not as much of PITA as I thought it was going to be so far.

thtanner

iTrader: (1)

A concern of mine is the Cat Converter being marked as modified. That's an instant fail no matter what numbers the car produces.

Is the new cat that was installed 50 state (CARB) legal?

-=Z28=-

iTrader: (3)

Wow, So not to be a giant butt muncher here, but Man am I glad we don't have emissions in MN anymore. Why are they so strict in CA?

RamIt

The reason is that we had horrific smog in the past that used to make me sick when I was younger. I am glad they have the smog program but have issues how they implement it.

thtanner

iTrader: (1)

If you saw LA in the 80s you'd know!

To be honest, it's not that hard to pass if your car is put together properly, stuff is functional, fairly clean, etc. The problem is we often inherit these cars from previous owners who neglected them, or had no idea what they were doing and made things worse.

Now if you're modifying your engine it's a tad more difficult and a different story.

-=Z28=-

iTrader: (3)

Too many friggen people in a area. Sorry to hear it made you sick. That alone would make me move. Yes, I agree, Glad they monitor pollution too.

paulo57509

Because your car has evidence of tampering or outright failure for visuals it really is difficult to know why your car is out of spec for NOx. We can talk in generalities but until the visual fails are addressed it's just a guessing game at this point.

Unfortunately the visual portion of the results just show pass/fail and no detail as to why it failed.

I think your next steps would be to address the visual fails and re-test to establish a baseline and then go from there.

There is the option of a referee station but I doubt they would sign off on something that fails visual or shows signs of tampering. Even if they sign off, I believe the exemption is only temporary. You will eventually have to repair the car if you want to continue to drive it.

CA also has financial options where they will help pay for repairs but this too isn't a slam dunk.

https://www.dmv.ca.gov/portal/dmv/detail/vr/smog

Good luck. I hope this doesn't turn into a money pit for you.

Longshot08

Cant say with any certainty. Previous owner had it done. I don't know how they identify a aftermarket cat. Self report?


The car is almost thirty years old so if it was still an original cat it's guaranteed not to be functional.

Longshot08

No equipment is missing. That's one of the reasons I jumped on this thing.




I'll just take it on Monday to the local smog shop and see what happens. It seems to run better with all the vac. lines replaced and actually hooked up so. Hopefully I'll have some better data to work with.

thtanner

iTrader: (1)

If they fail you on the cat as modified again, ask why. It'll probably be lacking Cali compliance text if so.

Longshot08

Update on my emissions issue.

Changed the O2 sensor because of an earlier thread I read on here where the car (88 L98 Iroc) had the exact same issue as mine back in 2012. O2 sensor was $20 bucks at autozone. Replaced it and passed emissions no problem.

After the tech turned the car off the heater bypass valve blew and spewed all the coolant out. Luckily a NAPA autoparts was next door and i was able to purchase the valve and coolant and replace right there.

I live in the desert with 114 degree temps so ive wired the fans in parallel so that both come on when the ecm tells the primary to kick on.

Didnt help that the P.O. had nothing but water in the cooling system( found that out the 1st time i flushed the system) so that just plugged up the heater bypass valve and was a timebomb waiting to blow. Glad it didnt blow on the road.

Longshot08

Next is the headlight gears, turn signal stalk (broken right off), and fix the fuel guage sending unit and then ill start preppin for paint.

Currently white but im going to paint it back to its original color ( the maroonish factory color)