Need help getting 1991 back in operation

[dmaclennan]

Originally Posted by Ccmano

Yes, the nut has to come off. While it is the nut for the engine mount, it and the “K” member do not support the engine. After you have the O2 sensors in take it for a long hard drive to get the cats good and hot. Its likely the cats got a bit contaminated from that old gas, long inactivity and frequent startups without really driving it. When I still lived I CA I found that a few good full throttle runs to redline immediately before taking to the smog station brought the numbers down somewhat.
H

Thanks, it looked a bit scary. Will get to it tomorrow and plan to empty a tank of gas to clean everything out before the next smog.

Cheers,
Don

[Z51JEFF]

What part of California are you in? I’ve had to really work to get my bone stock 25,000 mile 91 to pass,it’s failed twice.

[dmaclennan]

Originally Posted by Z51JEFF

What part of California are you in? I’ve had to really work to get my bone stock 25,000 mile 91 to pass,it’s failed twice.

San Jose. Plan to go to the smog shop in Mountain View. I think they test the Corvettes for Northstar Corvettes. Any suggestions on what to do to get it to pass would be appreciated. I have 85k miles on mine but it is stock too.

[Z51JEFF]

I’m in Fremont,you need to start the registration process,get a temporary moving permit and put some miles on the car. I’ve got to get mine smogged in a few weeks. Send me a P.M. for some tips and I’ll give you my number.

[Z51JEFF]

Originally Posted by dmaclennan

Got advice from Marc and I'm in the process of changing the O2 sensors. Left one was easy. Got the right one out easily but i am having difficulty getting the electrical connector installed. Another older thread suggests removing the k-frame brace. There are 4 bolts attaching the brace to the frame and a nut that appears to be attached to the engine mount. Does this nut get removed too?

Any ideas on how to get the connector re-connected?

Planning a long run with CRC 05063 after the O2 sensor is re-attached then another smog.

Cheers,
Don

Getting the connector to seal is a real bastard. I used a long screwdriver,a wad of dumdum on the end of it,stuck to connector on the end of just to get the connector to line up with the other end. Once it’s lined up I used something long to oust it all the way on until it’s locked in place. Dumdum is that black seam sealer stuff used in the automotive trade.

[Z51JEFF]

Precision Motive in Hayward has experience with ZR-1s,if you have to take it somewhere that’s an option.

[Young1]

Take out the K frame to get to the right O2 . It is a brace only. It supplements the motor mount rigidity. It does not hold up the motor. Pulling it out does not affect motor position.
I bought another connector and made an extension for mine. Next time will be easy peasy.

[Z51JEFF]

Whatever happened with this?

[dmaclennan]

Originally Posted by Z51JEFF

Whatever happened with this?

Just got it smog tested yesterday - passed with flying colors. Here's what I did based upon input from Marc H.

1. Replaced O2 sensors - even though no codes.
2. Changed oil and filter. Might have helped hydrocarbons a bit.
3. Put CRC Emissions Systems Cleaner in 3/4 full tank and drove it in 4th gear for about 100 miles (about 3500 rpm) with some WOT exercises. Then normal driving for another 100 miles to finish off the tank of fuel. Filled her up and drove to the smog station. Passed with no problems. Note - this was a different smog test location from the previous one and he used lower gears for both the 15 and 25 mph tests. Interesting!! Hydrocarbons are now better than average and NO gases only slightly higher than average. Both well under max allowed.

Thanks to all on the forum for your help and a BIG thanks to Marc H for his advice.

On to fixing everything else now Tires, brakes, suspension.....

[XfireZ51]

After modifying my 84 Xfire, I spent a year trying to get it passed. The “clown” doing the driving kept lugging the motor in 4th at 20mph, so my HC numbers spiked on decel.