PCV valves helped idle

[Aurora40]

I replaced the two PCV valves today. For some reason someone before me zip-tied the PCV valve assembly together. Maybe the hose was blowing off. Both valves seemed original, as they had "AC Spark Plug" stamped on them, not AC Delco.

I started the car up afterwards (I changed the fuel filter about two days ago too) and it idles very very smooth now. Just a hint of vibration to it, you can see it in the plug wires shaking barely, or if you put your hand on it, but it's much better. Plus, this was a cold idle with the AIR pump chuffing air into the exhaust.

The old PCV valves rattled, but a sort of gummy mushy rattle. If yours are old, you might consider changing them.

[tomtom72]

That's the first thing I did when I took delivery of my car...checked all the "tune-up" parts. I found that I had all the OEM stuff still in the car after 15 yrs!!!

So I went to the chevy store & bought all new stuff. The OE PCV's did just what you described. I thought it was rather neglectful for the orig. owner to leave all that stuff in there that long!

I figure that changing out the A/Filter, PCV's, F/filter every yr. should be standard maint.?? Okay the OE plugs were still good but 15 yrs! Maybe I'm wrong but wtf if you keep up with the small stuff I figure it goes along way to enhancing less trouble from the small things.

My PCV's had small hose clamps on them & I thought it might have been that way from the factory, since nothing was touched!?

Did you get a scan on the car??


Tom

[Aurora40]

Hey Tom, mine also has the little hose clamps. Those seem stockish. This was a zip-tie (plastic) that ran vertically, squeezing the hoses onto the PCV valves. I'm not sure why that would need to be there, the PCV would be under vacuum, not pressure. I'm pretty sure that's not stock, the Helm's book doesn't show it.

I have not scanned my car. I would very much like to get a scanner, but for now it's not in my budget. I think the suggested visual inspection of the injectors with fuel pressure will help me get a handle on whether they need to go or not. I'm shooting for the plenum pull this weekend, but we'll see. I've got all the parts I think I'll need, just need to pick up a longer torx bit from the local Advance Auto, and some coolant.

Unfortunately the idler pulley on my wife's supercharger (Regal GS) blew up. So that takes precedence, but hopefully it'll be a quick fix.

[tomtom72]

Hi Aurora, I hope the pulley R & R goes smooth for you! The Zip tie might not be a 1/2 bad idea...my PCV holders do seem loose. The top piece is easy to pull off, no effort at all...maybe the previous owner had something there?

Yes I hear you about the $ of a scan tool. I got lucky one of the residents in my building is a MTA mechanic & is into cars & he had a snap-on MT2500 he let me use to do my car! Ofcourse if it's just the secondaries they would not show up till you get the rpm's up. My problem was the primary coils mostly & that you could see at idle in "closed loop" on the scanner.

Hey man good luck in your mechanical endeavors this weekend! If you need to know anything feel free to e-mail me, thomastom72@aol.com. If I know the answer you know I'll get it to ya!!

Tom

[Tom]

Zip ties, hose clamps, and various other things were required on early ZR-1's to stop numerous small leaks in the plumbing. I bought my 90, #672, in May 91 with 2100 miles on it and I've zip tied the pcv valves and done several other small changes on my 90 to stop the small leaks. GM made changes later on to some of the plumbing and rubber fittings to prevent these nuisance leaks. Another interesting thing is if you leak at the radiator hose clamps, the early cars used screw type hose clamps whereas later cars used the typical GM spring type hose clamps.

[Patton]

My '94 has screw type clamps on the radiator hoses.

[Tom]

I first noticed the difference in hose clamps after I bought my 90 ZR-1 used in mid 91. Going to Corvette shows I noticed that the early 90's had the screw clamps and the later ones had the spring clamps. These were all on low mileage cars that were supposedly just like they came from the dealer. I am the third owner of my car and I bought it with around 2100 miles and it was supposedly just like it left the factory. It sure looked like new, the front spoiler hadn't been scraped on anything and the car had never seen rain. A couple of collectors had owned it and they both decided they would rather have something else. Noticeing the different clamps made me wonder how the NCRS people will handle these cars when they get older and they want the car to be just like it was when it left the factory to get the most points. I wonder if they will be able to document when the factory changed from one type clamp to the other. When the original hoses are replaced I imagine most people would switch over to the screw clamps.

[tomtom72]

I remember reading a TSB on the coolant leaks. It's at the NetRegistry site. I think the NCRS people will have a good handle on when the factory changed the clamps. Mine, #2233, delivered in June has the sprung steel clamps.


Tom