Jax ZR1

I just bought a 1990 ZR1 with 9500 miles on it, since I got it home I'm having a few problems with it and wondering if any one can give me some ideas. 1 if I drive it hard and get the revs up around 5500 when I idle down I start to lose oil pressure, and my service engine soon light comes on let it sit for 10 minutes then its good again. Car was bought at an auction so don't know alot of the history of the car. Also just wondering about the throwout bearing seems to be noisy after the car is driven and sitting idle is that normal or am I looking at doing the clutch.

lgaff

make sure they put the right amount of oil in the car... takes way more than a normal 5.7 TPI

Paul Workman

with Lee (LGAFF) - first thing I thought too.

At only 9500 miles you shouldn't have an clutch issues, unless the car was used (a lot) for drag racing.

1990-92 ZR-1s factory Multi-tech injectors WERE NOT alcohol tolerant. If it turns out yours are original, that should be at the top of you list of things to bring her "up to speed" (so to speak). Do it NOT, and besides poor performance, you may be like me and end up with a burnt intake valve! Anyway, one of the symptoms of injectors going south is the idle being sketchy and you'll get a lot of knocking sounds from the dual mass flywheel.

For parts you'll want to get familiar with Jerry - Jerry's Gaskets. Jerry is a heck of a nice guy and very knowledgeable on parts (especially) and carries a wide inventory of parts (for the LT5 especially)..

You'll want to also go over and introduce yourself on the ZR-1 Net Registry forum. There you'll find a support group like no other and all the support you will need for yourself and you "Z".

Welcome to the "BROTHERHOOD OF THE BEAST"!

..

zrc3john

Congrats on the purchase....Was it a mecum or barrett jackson auction ?

Jax ZR1

thanks for the ideas the oil level is good when cold but shows low when hot but let it sit and then reads good, I believe the injectors are original because I received some paper work with the car for oil changes, new tires, weather stripping. The gas that was in it when I got it was bad and low so I top up with chevron supreme plus fuel, runs better but still idols rough so may have to look at those any way to test them? If any ones knows a mechanic that knows LT5 motors and lives in northern British Columbia, I would love to know about them. zrc3john it came from the Barrett Jackson auction in January. I think I over paid for it but every time I drive it, it buts a huge smile on my face. Love the car just hope it loves me back.

Jax ZR1

thanks for the advise. Oil level appears good on the dip stick when cold but low when warm but from what I've read that is normal. I believe the injectors are stock and the rpm goes up and down when idling, any way to test them or best to replace. Going to do a fluid change on motor, transmission, clutch, and rear end. Every thing seems to be working have a infl rest light on need to figure out the cause of that also. zrc3john I bought the car at Barrett Jackson in January. the few times I have got to drive it I love it. Should have done more research before I went there could have found a better one for less money but I always wanted one and now I have one so I will hope for the best. If any one knows a mechanic in or around northern British Columbia would be great to know.

FASTAZU

Welcome, could just be a bad oil sensor. As Paul suggests the ZR1 net you will find all the answer's, and lots of help to get it sorted out.

ccmano

Welcome and I second what Paul said. The “infl rest” Issue is a common C4 thing, your answer is here,
http://www.zr1netregistry.com/Inform...EST-light.aspx

Another great source is www.zr1specialist.com. Great information on his website and answer for the really tough questions.

Yes, the oil level issue is normal. Says right in the manual that oil level should only be checked when cold and sitting at least 3 hrs.

Are there any mods to the car that you are aware of? Post some pix so we can all see. Be aware, this can quickly become an addiction!
H

zrc3john

If the C4 ZR-1 is known as the " beast" then what would you call the C7ZR-1 ?

ZR1Bob

Lee is right but I might add that checking the oil on a ZR-1 is different from other cars. Due to complicated oil galleries, it takes a long time for oil to drain back down into the crankcase, so if you check the oil right after driving it will appear down about a quart or more. When I first got my first ZR-1 (the Quasar '93) I checked the oil on the way home and being ignorant of such things, over filled it. It survived but I since then I always only checked the oil in the morning before I started it up after it had all night to drain down. Usually waiting an hour will suffice to make a dipstick reading accurate.--Bob

Jax ZR1

Do I got the oil changed went for a drive oil pressure was good to start with but after it warmed up and can to stop at stop light car would idle down and oil pressure gauge would drop off to 0 then would come up as soon as you give it gas, no low oil light or service engine light came on so I’m thinking maybe a bad sensor. Stopped at the store on way home and then car would not start not even a click at the starter. Push started it to get home. ? Any ideas

zrc3john

I had that on my 91...No click, nothing when I went to start it....My starter needed to be changed..

ccmano

A 90’ does not have an oil level light, that didn’t come till 91’. Change out the oil pressure sensor and see what happens. Luckily that’s easy to do, it’s the tall one next to the oil filter. Oil pressure issues are very uncommon on these cars. I wouldn't sweat it at this point. Your starting issue is likely the starter, another very common issue. If no one has been under the plenum to do maintenance you’ll need to get in there anyway. It’s a right of passage for the ZR-1 owner. If not already done it’s wise to change out the injectors, check all the secondary throttle system components and of course change or rebuild the starter. On a car where none of this has been done previously injectors are virtually guaranteed to need replacement, as previously mentioned by Paul. Sometimes these low mile cars can be more problem than the high milers because they sit for so long. I would expect to change out the fuel pumps and filter as well. Keep us posted.
H

DRM500RUBYZR-1

"Beauty" ?

Marty

zrc3john

Lol.....Good one....

Jax ZR1

Ok, so looks like I have some work to do, will need to get a service manual, and does anyone know where I can find parts in Canada might be easier then shipping across the boarder. Thanks for the insight

LT5corsa

Very doubtful you need a clutch. Change the clutch fluid and bleed completely before considering changing the clutch. They are hard to find and a premium. Clutches can last 125k miles.

I bet your injectors are original and that’s why it’s having a hard time with accelerating.

CHANGE ALL FLUIDS. Bleed brakes and clutch completely. Owners never do this and this is one of the reasons they go so cheap! Maintenance makes the difference in performance 👍

cheers

David

wfot

another right of passage is that a new owner washes the engine itself. this is a bad idea as the starter is in the valley of the block and will flood which gets the starter wet and kills it. there is a drain hole for the valley, however the hole and drain tube is small and get clogged and this allows the valley to flood when the engine is subjected to a hose. This results in the key doing nothing but allows the car to be push started. the drain holes were made bigger in the 405hp motors, but it is not a good idea to give the LT5 a bath...
it can be rebuilt or changed out with ease once the plenum is off, haha and it is a right of passage to get into the club, lol

John

Jax ZR1

Thanks John, I haven’t taken the hose to it, but I’m going to pull the plenum replace injectors and rebuild the starter and check the secondary’s.

Aaron71771

zr1 Specialist has an under plenum service DVD that has lots of information on it and is worth watching.


http://zr1specialist.com/HAT%20Web/p...enum%20dvd.htm