Another ZR-1 Approved by the CA Smog-Nazi's!

[bdw18_123]

Went and got my Z smogged today. Was a little bit worried about whether it would pass or not because of hearing of all the issues some guys are having getting our cars to pass, especially with the newly reduced emissions limits in CA.

I needn't have worried though, my '90 Z passed the enhanced smog check with flying colors!

The smog place I went to is about 14 miles from my house by freeway, so I went that way and stayed in 4th pretty much the whole way to keep the RPM's up to get the cats good and hot for the test.

I don't know if this made a difference or not, but I also switched the power key to 'normal' and removed the key for the test.




To help out anyone else trying to get their Z to pass, here is the info on my car:

- About 1,300 miles on a recently "rebuilt" with all new gaskets from Jerry's Gaskets and thoroughly cleaned inside and out LT5. Not overhauled though, I only replaced 1 liner (because of a few small chips in the nikasil) and the piston rings (used) on the piston in that same cylinder. Rotating assembly still has 140K on it other than that one liner and used piston ring set I installed.

- Heads were completely cleaned & gone through, 5-angle valve job and valve guide seals installed on the exhaust valves ('90 heads came stock without seals on the exhaust valves).

- Intake cams are timed to the stock 114 degrees (which stayed the same for the rest of the model years of Z's), but exhaust cams are timed to 110 degrees ('93-'95 LT5 stock timing, '90-'92 LT5's are 114 stock on exhaust cams).

- IAT sensor relocated to under the front bumper.

- ~51K mile set of '91 exhaust manifold/cat assemblies installed, probably a big factor in why my Z passed so well (thanks to an awesome ZR-1 brother, Cliff, for the donation!).

- One new Bosch O2 sensor couple hundred miles ago (driver's side, the one that came with the car turned out to be bad), other side is also a Bosch, but was in the car when I bought it.

- New set of AC/Delco PCV valves at time of rebuild & entire vacuum system rebuilt and tested.

- Fresh spark plugs at time of rebuild, nothing fancy just the regular stock AC/Delco ones.

- Rebuilt Bosch II fuel injectors from FIC that had come with the car (gone through and cleaned by FIC before installation)

- Full tank of gas from Arco (been using that brand for years, never once had an issue with their fuel), 91 of course.

- Fresh Mobil 1 High Mileage oil at time of rebuild.

- I do not have any PCV oil catch-can installed.


Everything else is stock on the car.


I noticed a funny thing about the report though - the 'Functional EGR' test is correctly listed as "N/A", but the 'Visual EGR' is listed as "Pass-"! I wonder how they saw a non-existent EGR system on my car?

[mike100]

I looked over the previous owners smogs and the pre-test i did after repairs. Very similar HC and CO numbers depending on how warmed up it was, but my car's NOx went to hell sometime after 2006. There was a huge vacuum leak and bad injectors I fixed. The best I could do on the low speed ones was 400 ppm, but still well below the limit.

The HC was just slightly rich as I had just changed the chip at the smog station to try out a different cal. It didn't even have time to let it fully adjust the BLM and fuel trims totally, but it was just an exercise I went through to verify it could pass as the car was barely making it in the rural county (with the vac leak) it came from and would have failed in SD.

also, never under estimate the power of a fresh valve job on emissions- I've seen some really high combustion efficiency on fresh motors assuming the cat was still good.

I hate the worry our program creates. If you know your car is golden- fine, but if not, such a huge headache if you can't get the right cats.

[mike100]

On closer inspection... in 2005 the tech tested the 15 mph segment in first gear at 1800 rpm on my car- the NOx was low due to low engine load..ha! I wonder if that is allowed? The 25 mph test result was the same 6 years ago as it was this year. I guess the cats are in the same health as they were years ago.

It seems Nox conversion is just a function of how uncontaminated the catalysts are...that and combustion temps/pressure. It will fail eventually I think.

[mike100]

BTW, several limits are even lower than they were for the test I did in March.

In March, NOx was 545 for the slow speed and 502 max for the 25 mph. the co/hc are just slightly lower too. either your county has a special limit or they are continuing the squeeze. now your sheet shows 541/498

[bdw18_123]

With regards to the low RPM on the 15mph test - the guy at the smog shop said that CA requires that both the 15 & 25 mph tests be done in 2nd gear only. He said that this requirement has been around for awhile, but CA just never bothered to enforce it.

But he said they are making it a point to enforce it now because they found that some cars were only passing because of the lower load on the engine in first gear at that speed compared to second.

He also said the only way they are allowed to do the 15mph test in first gear is if when in 2nd gear, the RPM's are lower than 1200.

[sammy]

boy i feel for you guys that have to do this .sure glad inyo county doesn't have the bi-annual tests. we only have to test when we buy or sell

[tomtom72]

Just want to say a big Congrats to ya Ben!!!! Now go enjoy the fruits of your labor! Drive the wheels off of her!


Tom

[mike100]

Originally Posted by bdw18_123

...

He also said the only way they are allowed to do the 15mph test in first gear is if when in 2nd gear, the RPM's are lower than 1200.

I could see having a D44 and batwing assy with 4:30's just to beat the NOx on the smog test.

[bdw18_123]

Originally Posted by tomtom72

Just want to say a big Congrats to ya Ben!!!! Now go enjoy the fruits of your labor! Drive the wheels off of her!


Tom

Thanks Tom!

Oh you bet! I'll be putting over 700 miles on her this weekend and that is not even including the run itself!