1996 Collector Edition Corvette

[wxo]

I started the engine again today. At first, it wouldn't fire up. Just on a hunch, I jumpered the new oil pressure switch and the fuel pump started immediately. When I hit the starter, the engine came to life. It appears as though the new oil pressure switch is bad.

Well, it wasn't and neither was the original. When I received the replacement for the presumed bad sender, it too, appeared to be bad. Oops, time to revisit how this startup works. After pouring over the diagrams and reading the descriptions of the startup scenario, I noticed something that I had missed the first time around. The fuel pump gets a signal from the ECM when the key is turned to the start position. Only after the engine cranks is the switch in the oil pressure sender closed at about 4 psi of oil pressure. So now I had to check the wiring diagrams to see how this circuitry works. The first thing I noticed is that there are two fuel pump fuses. One is located in the fuse box at the passenger end of the dash and the other is over on the other side near the battery and ECM. The first one checked out good, but the other one was "MISSING". I didn't have a replacement but Maverick took the initiative and built me a circumvention consisting of a 20 amp blade fuse with jumper wires to allow it to plug into the 20 amp Maxi fuse slot. This did the trick. Now the engine starts with just the key (no VATS problems, yet) and the clutch to the floor. A minor, but significant victory! By the way the new hydraulic clutch system works just fine for now. I will know more when the wheels touch the ground sometime in the future. I still have a short list of items on my list before that can happen.
PS: VATS = Vehicle Anti-Theft System.  You may have seen GM ignition keys with a resistor embedded in them.   I really like the concept, but they can be very trouble prone and if that happens the vehicle stops running at the most inopportune times.

[wxo]

Since my two of my three plans to travel have fallen through for various reasons, I have been picking at my punch list of items to get this car on the road. Nothing big, but moving forward nevertheless. I received the replacement clutch pedal retainer in the mail and managed to get the new one installed and everything under the dash buttoned up.

The power seats are all verschmeckled. I have to spend more time working on them. The passenger side used to work, but the drivers side is stuck all the way back. Now the passenger side is also stuck in place and nothing works. I believe the switch is part of the problem, but everything is interrelated.

Let's see, some good news...the Seafoam I added to the oil seems to be working. I start the engine and warm it up at least once a day. Now the tapping has virtually gone away. There was another engine noise, more solid sounding than the tapping, but with a "poit poit" character to it that has become the dominant noise at startup. It reminds me of the noise the exhaust makes when you run the engine without any headers attached. I can't detect any header leaks, though. It goes away as the engine warms.

I've started replacing the plug wires to address the off idle bog I'm still experiencing. Man, what a tedious job! I finished the right side and the coil wire and after several hours yesterday, I have all the left side wires out. In the process, I had to remove both the idler pulley and the tensioner to be able to see and touch the wires attached to the Opti-Spark. This is another blessing in disguise. Both pulleys are bad. No wonder there was such a racket at first startup. The good news is that the alternator bearing seem smooth when turning by hand. Now I'm waiting for parts before I can close this chapter. I've been measuring the resistance of each plug wire as I remove it. The old ones all appear to be good, so I'm not overly optimistic about this as a solution to my bog. Wheels on the ground seems to be eluding me for now.

I plan to soon change the oil in the ZF S6-40 6 speed. My research shows only two recommended motor oils. The first has a GM part number and is discontinued and the other is Castrol Formula RS Synthetic. I opted for the Castrol at $27/quart via Amazon. The tranny takes 2.2 qts, so I had to buy three quarts to fill it. Since the car is still on jack stands, this shouldn't be too tough a job. Next, waiting in the wings is the replacement of the O2 sensor. I'm not looking forward to that. It is very inconveniently located, as is everything else, on this wonderful car. Just another day in the "Last Chance Garage".

[Maverick]

You're knocking the issues off one or two at a time. Good news! Congats on the clutch linkage and tapping noise. I'd like to hear the other noise. How 'bout inviting me over sometime when you're going to start it.

[wxo]

Whew! Boy! I finished installing the spark plug wires today. This has been, by far, the worst of all the things I've tackled on this car to date. I would love to start it, but I'm still waiting for the serpentine belt idler to arrive.
In addition, Randi and I sanded off much of the rust from the power steering pulley. I inserted a long allen wrench in the pulley hub and Randi held it while I used a strip of sandpaper from a belt sander to clean off the heavy rust. I will be installing a new belt soon and thought I should do what I can to help preserve it. I'm expecting a noticeable reduction in overall engine noise on the next startup.
Looking for a solution to the off idle bog, I tested the MAP sensor and it looked like it should work. First, I used a multimeter to view the voltage change while applying vacuum. Then, to make sure the ECM was also seeing this voltage, I watched it with my UltraGauge and both agreed.

[wxo]

Seems time for an update.
1) I ran into a problem installing the new serpentine belt. I couldn't get it over the rim of the alternator pulley, so I called in Maverick to help. Both of us working together were unable to get the belt on. I checked the belt using two different sources and it was the correct part number for this engine (Dayco 5060670). Finally, I took the old belt and this Dayco to NAPA for see if I could find a solution. Ultimately, I ended up buying the next two longer belts. The Dayco belt with the correct part number is 67 9/16" long. The next bigger belt is 3/16" longer at 67 3/4" and it went on without a problem (NAPA 060672). I'm not sure why the right one wouldn't go on but the new, slightly longer one seems happy on there. All is riding quietly now.
2) I finally tackled the O2 sensor on the right side. It was a bear to get out of there, but this car has tested my patience all the way. With some help from Randi, I was able to get the new one installed and working. I have the left side upstream sensor on order. It looks a bit more accessible than the one I just changed.
3) I also installed a fuel pressure gauge on the test port of the fuel rail and saw that the fuel pressure is lower than it should be. At Maverick's suggestion, I pinched off the return line at the tank and ran the pump. I got 90 psi at the fuel rail so the pump is good so that leaves the fuel pressure regulator as the source of the problem. I just ordered a Holley adjustable fuel pressure regulator. I'm expecting it next week. Perhaps more fuel pressure will fix the stumble. Fingers crossed.
4) I changed the oil in the tranny and the engine oil. The SeaFoam I added to the oil really loosened a lot of crap in this engine. It fixed the sticking lifter and quieted things down. The drain oil was very dirty. I filled it with Costco's full synthetic 5W30. I think it's going to like it when this thing hits the road...someday...maybe...

[wxo]

Today I ran out of parts to install.
I got the driver's side O2 sensor installed and it was pretty easy. I'm waiting for the new Holley fuel pressure regulator which is coming next week.
Next big sub-project is getting the power seats to work. I will be picking at it as time permits.

[Maverick]

Great to hear you're running low on sub-projects!

[wxo]

The new Holley adjustable fuel pressure regulator was in the mail waiting for me when we returned from the beach last night. I couldn't wait for the morning to come, to get it installed, adjusted and tested. The off-idle stumble appears to be gone. I believe my fuel pressure gauge is inaccurate, because I had to set the pressure higher than stock to get the engine to respond without hesitation.
BOFORE:

AFTER:

Time for wheels on the ground. Soon, very soon. It's been over 10 weeks sitting on jack stands.

[Maverick]

So glad to hear you've solved the stumble. Good work!! Are the wheels back on yet??

[wxo]

Yep. Wheels are on it:
https://youtu.be/g9SIyW9tBAY
https://youtu.be/mZ8K_iAqzfg
https://youtu.be/E3AP3FMOqsY

[MostMint]

Nice to see its ready to do some driving!

[wxo]

Now for the not so great news. It kinda runs like crap. I was able to get most of the stumble out of it by adjusting the fuel pressure regulator before I took the first drive, but a every slight stumble off idle was still there. When I took it for a drive, the slight stumble was amplified. In addition, the engine is not running cleanly. If you listen closely on the videos, you can detect it. Surprisingly, there are still no trouble codes showing up. I think it might be time to do some serious engine diagnostics like for instance Maverick's suggestion to do a cylinder leak down test. The Opti-Spark is always in the back of my mind, too.

[wxo]

Today is another day. I went out and tweaked some more on the fuel pressure and now it drives fine. I drove over to Maverick's and we talked about it and now we both agree that there is one cylinder that is having a problem. It presents itself as a quick shudder just off idle. However, it was not bad enough to prevent me from watching the tach needle hit 6 grand on the way back home. I think I better get some tags on this thing before I get myself in trouble.

[MostMint]

Good. what I read is the later opti spark like yours were not problematic like the prior models

[Basement Paul]

As I'm reading back through your posts, I was unable to determine which fuel injectors are currently in the car. Sounds a little like a dirty injector IMO based on your description of what's going on.

You've done a LOT so far! Cool that you get to drive it and spin the tach a little.

-BP