Newbie looking to buy a ZR1
08-04-2014, 08:50 AM
#41
Burning Brakes
Thread Starter
-The door ajar is the plunger switch on the door. It can be replaced, but a good cleaning with silicone lube or whatever sometimes gets them to stroke the contacts properly. Almost surely the driver side unit.
-The later 95,96 c4's (not ZR-1) had a vastly improved abs system, buy it is pretty typical to get an errant light over just the right bump on a drive. It also comes on at 4mph as a self test on the beginning of every drive. There is a yaw sensor in the middle of the car that tells it if you are in a hard corner- I think every now and the combination of inputs falsely activates.
-Rock chips...par for the course on any C4 with a few miles and no mud flaps. you could probably polish the dirt out of the pits and scratches to make it less obvious. I doubled my chipping on just one drive after a rain.
As far as the handling, I had good improvement by rebuilding the shocks. That took out some of the mushiness out of the chassis. Recently, I drove a low mile Porsche 968. My ZR-1 had less body roll, but the Porsche felt lighter and was easy to drive with less torque and good feedback (but hey- it has about 200 hp less). The LT5 is heavy and and doesn't respond to sudden steering inputs on hairpin corners as well as a normal coupe even. The saving grace is that the 32 valve engine has a more linear power delivery and doesn't just run away and blow the tires off like a modified 2v smallblock v8. Things still happen slow enough to recover. Unlike C5's and C6's, you don't absolutely need a computer to keep the car pointed straight. The limits are lower, but the driver involvement is still high.
the vacuum pump might be ok, just get a vacuum pump with a gauge and test the hoses. Do the secondaries still function (full power when you step on it?)
also- does the car have "a chip" or any other mods?
-The later 95,96 c4's (not ZR-1) had a vastly improved abs system, buy it is pretty typical to get an errant light over just the right bump on a drive. It also comes on at 4mph as a self test on the beginning of every drive. There is a yaw sensor in the middle of the car that tells it if you are in a hard corner- I think every now and the combination of inputs falsely activates.
-Rock chips...par for the course on any C4 with a few miles and no mud flaps. you could probably polish the dirt out of the pits and scratches to make it less obvious. I doubled my chipping on just one drive after a rain.
As far as the handling, I had good improvement by rebuilding the shocks. That took out some of the mushiness out of the chassis. Recently, I drove a low mile Porsche 968. My ZR-1 had less body roll, but the Porsche felt lighter and was easy to drive with less torque and good feedback (but hey- it has about 200 hp less). The LT5 is heavy and and doesn't respond to sudden steering inputs on hairpin corners as well as a normal coupe even. The saving grace is that the 32 valve engine has a more linear power delivery and doesn't just run away and blow the tires off like a modified 2v smallblock v8. Things still happen slow enough to recover. Unlike C5's and C6's, you don't absolutely need a computer to keep the car pointed straight. The limits are lower, but the driver involvement is still high.
the vacuum pump might be ok, just get a vacuum pump with a gauge and test the hoses. Do the secondaries still function (full power when you step on it?)
also- does the car have "a chip" or any other mods?
I will start checking the vacuum lines. The pump does work. I pulled the line off and put my finger over it and it stopped pumping. As soon as I let off it started up again. So there is a leak somewhere.
How would I know for sure if the secondaries still kick in? There is a huge difference in power between Normal and Full. Is that what you mean?
08-04-2014, 10:19 AM
#42
Safety Car
The car supposedly has a chip and borla cat back. I got a good look under the car and saw the Borla CatBack. It is just the cat's straight back to 2 borla mufflers. One for each bank. It sounds great. Not very loud at all.
I will start checking the vacuum lines. The pump does work. I pulled the line off and put my finger over it and it stopped pumping. As soon as I let off it started up again. So there is a leak somewhere.
How would I know for sure if the secondaries still kick in? There is a huge difference in power between Normal and Full. Is that what you mean?
I will start checking the vacuum lines. The pump does work. I pulled the line off and put my finger over it and it stopped pumping. As soon as I let off it started up again. So there is a leak somewhere.
How would I know for sure if the secondaries still kick in? There is a huge difference in power between Normal and Full. Is that what you mean?
you could have a leak, but not enough of one for the secondary actuators to stop working. there is a small reservoir, one way check valve, a solenoid and a couple of odd vacuum connections all under the plenum. generally this is an easy fix, but you might have to pop the plenum.
08-04-2014, 10:29 AM
#43
Burning Brakes
Thread Starter
yeah, it is pretty tame without secondary actuation- poops out at 5000 rpm. a good way to test this is turn the full power key off and see if the car is suddenly slower.
you could have a leak, but not enough of one for the secondary actuators to stop working. there is a small reservoir, one way check valve, a solenoid and a couple of odd vacuum connections all under the plenum. generally this is an easy fix, but you might have to pop the plenum.
you could have a leak, but not enough of one for the secondary actuators to stop working. there is a small reservoir, one way check valve, a solenoid and a couple of odd vacuum connections all under the plenum. generally this is an easy fix, but you might have to pop the plenum.
Is taking the plenum off on this car a huge job? I assume at that time I would want to change the plugs and wires? Would I need to do anything with the fuel injectors?
08-04-2014, 10:31 AM
#44
Burning Brakes
Thread Starter
At the Buick, GMC, Caddilac dealer by my house I asked about getting the coolant flushed. They quoted me only $119 to do the job on the ZR-1.
Can they be trusted or should I take it somewhere else?
Can they be trusted or should I take it somewhere else?
08-04-2014, 12:17 PM
#45
Safety Car
Taking the plenum off is a right of passage to owning an LT5. It isn't particularly difficult, but you do need to drain the radiator a little to lower the coolant to below the throttle body (since it has a water passage thru it). The rest is just torx 40 bolts. you do need to pop off the fuel line to get that one corner bolt in the rear. anyhow, a lot of people take the opportunity to replace ign components during this time. You may need to see if your injectors were already replaced, but if not you should replace them all. There are many posts on that topic as well as easy ways to measure their resistance. They usually act up when you have driven for 20-30 minutes when they get hot. hopefully the last owner handled that.
order the plenum gaskets a couple of days ahead of time.
order the plenum gaskets a couple of days ahead of time.
08-04-2014, 12:31 PM
#46
Tech Contributor
I will start checking the vacuum lines. The pump does work. I pulled the line off and put my finger over it and it stopped pumping. As soon as I let off it started up again. So there is a leak somewhere.
How would I know for sure if the secondaries still kick in? There is a huge difference in power between Normal and Full. Is that what you mean?
How would I know for sure if the secondaries still kick in? There is a huge difference in power between Normal and Full. Is that what you mean?
Finding A Vacuum Leak
Secondary Functional Test and Reconditioning the Secondary Actuators
Removing Plenum (including the 10 minute Plenum Removal)
Inspection, Testing and Reconditioning the Valley, Starter, and Coils
Electrical Reconditioning (including grounds and Alternator Connector Boot)
Last edited by Dynomite; 08-04-2014 at 12:35 PM.
08-04-2014, 08:51 PM
#47
Race Director
Taking the plenum off is a right of passage to owning an LT5. It isn't particularly difficult, but you do need to drain the radiator a little to lower the coolant to below the throttle body (since it has a water passage thru it). The rest is just torx 40 bolts. you do need to pop off the fuel line to get that one corner bolt in the rear. anyhow, a lot of people take the opportunity to replace ign components during this time. You may need to see if your injectors were already replaced, but if not you should replace them all. There are many posts on that topic as well as easy ways to measure their resistance. They usually act up when you have driven for 20-30 minutes when they get hot. hopefully the last owner handled that.
order the plenum gaskets a couple of days ahead of time.
order the plenum gaskets a couple of days ahead of time.
08-04-2014, 09:34 PM
#48
Burning Brakes
Thread Starter
Well I found where some air was leaking out of the hose that was connected to the vacuum pump. Now it runs for a second then stops, then runs, then stops. So I will need to go through all the vacuum lines, but it sounds like I better be ready for a huge job. Haha.
What is the normal checklist of stuff that should be done while the plenum is off? I would assume clean any electrical connections, replace all the vacuum lines(if possible), make sure that drain hole is clear, replace plug wires, and anything else? Should the coils be replaced? What about blocking any coolant from going through the intake manifold?
What is the normal checklist of stuff that should be done while the plenum is off? I would assume clean any electrical connections, replace all the vacuum lines(if possible), make sure that drain hole is clear, replace plug wires, and anything else? Should the coils be replaced? What about blocking any coolant from going through the intake manifold?
08-04-2014, 11:51 PM
#49
Safety Car
You can do all of that if you want, but I wouldn't go crazy on the vacuum lines- a lot of it is hard line and couplers. I'm even still on the original plug wires, but I'm not afraid to pop the lid off the engine so it's really an inconvenience, but hardly a big job. Some people have it down to 20-30 minutes.
I would do the ign wires, maybe coils, probably do a minor starter rebuild, clean up the general area and then finish with a coolant flush since you will have the radiator petcock already opened.
I would do the ign wires, maybe coils, probably do a minor starter rebuild, clean up the general area and then finish with a coolant flush since you will have the radiator petcock already opened.
08-05-2014, 03:21 AM
#50
Tech Contributor
Keep it simple
You can do all of that if you want, but I wouldn't go crazy on the vacuum lines- a lot of it is hard line and couplers. I'm even still on the original plug wires, but I'm not afraid to pop the lid off the engine so it's really an inconvenience, but hardly a big job. Some people have it down to 20-30 minutes.
I would do the ign wires, maybe coils, probably do a minor starter rebuild, clean up the general area and then finish with a coolant flush since you will have the radiator petcock already opened.
I would do the ign wires, maybe coils, probably do a minor starter rebuild, clean up the general area and then finish with a coolant flush since you will have the radiator petcock already opened.
Exactly as mike100 suggests......it is the vacuum couplers that leak which leaks are often because of the rubber connector shrinkage/hardening with age. You can often leave/get by with original plug wires (I change plugs) as well as leave the original coils unless you know one is bad. Original Injectors are usually not left as you will "usually" find a bad injector or two or three. I would restore the Starter Solenoid Starter, Starter Relay, Wiring Harness, Battery, and Plugs Tricks
Make sure the Valley Drain is cleaned and open as Z51JEFF explained
I also always install the Differential Drain Plug...and the Starter Solenoid. Item #4 and item #7 LT5 Added Systems
I would change ALL fluids (make sure you use GREEN antifreeze) LT5/ZR-1 Fluids
I always Block TB coolant at the Injector Housing. See item #4 LT5 Eliminated Systems
On the Zs I want to look stock (when blocking TB Coolant) I leave the hoses/tubing in place with a blocking connector going back to the passenger side of the coolant reservoir (follow the rubber/steel tubes along side the top rail of the passenger side plenum back to coolant reservoir). I block that runner line leaving the plenum about where the fuel lines are vertical on passenger side. But no one can tell TB coolant is blocked
I always clean the radiator of debree and install a debree screen. See item #3 LT5 Added Systems
Also see Minimum Restoration of a 1990 ZR-1
Last edited by Dynomite; 08-05-2014 at 03:51 AM.
08-05-2014, 11:55 AM
#51
Team Owner
Member Since: Oct 2001
Location: Do or do not there is no try YODA
Posts: 23,121
Likes: 0
Received 296 Likes
on
141 Posts
That is probably a great score...I have to revise what I said, for $10k there probably aren't a lot of cars out there in as good condition.
Fun factor/dollar factor ratio is very high on what you just got.
Fun factor/dollar factor ratio is very high on what you just got.
08-06-2014, 09:42 AM
#52
Burning Brakes
Thread Starter
The carpet is a little rough on the part right under the door. I don't know if I can replace those 2 pieces of carpet or I need to replace the whole thing.