New member, new car with problems

[GreyZ]

So I'm new to this site, I spent hours reading posts prior to buying my first ZR-1 which is also my first vette. This site has been very helpful to me in making my purchase, and I'm hoping someone out there can help answer some questions about my new ride. Some quick background on the car, 90 ZR-1, 36,700 mi, Borla exh w/ X-pipe, Doug Rippie Motorsports Chip, K&N air intake system, new tires, tinted windows, all else appears to be stock.

Q1- Oil pressure gauge stays pegged out on 80 psi while driving, occassionally dropping to 60-70 psi for couple seconds max, but always jumps back up to 80 psi. Needle does not sweep or flicker or go to 0 psi, stays steady. Is there a by-pass or something not working in the engine or is oil press. sending unit bad or??
Q2- With power key in full power position, the indicator light for it does not illuminate on the information panel. There is no obvious power difference when switching between normal & full power, and switching is done while in parameters rpm wise with owners manual and even shut car off, switched, and restarted. Car runs like a top and smooth through all rpm's, but it feels like it's running on about maybe 250 hp instead of 375 hp. There is an INFL REST light on the control panel lit up and seat belt light on while driving, will either of these or high oil psi lock out the full power function from working correctly. And there is NO Check engine soon light on or any other lights lit on the dash while engine is running, and coolant temp is at operating range as per owners manual.
Q3- When decelerating any speed, any gear. There is a what sounds like perhaps an electric kick down that engages instantly when throttle pedal returns to full upright position, stays on for 1 second, then off for 4 sec, then on for 1 sec and so on until car has slowed down. If you tap brake pedal, the noise stops as well as if push in clutch and down shift to a different gear.
Sorry that was allot of info. Any help on these items would be greatly appreciated. I'm excited to own my first Vette and am enjoying to car so far, but I'm beginning to freak out about if these are gonna be huge ticket items to get fixed. Thanks again

[Kb7tif]

secondaries are not working. This is common and completely fixable by you. Could be anything from a bad vac line ect. pry a simple fix. Mine was more complicated but wait until you feel the power difference, i almost lost control of mine first time they kicked in and I wasnt expecting it.

[WB9MCW]

Common problem

See >> http://www.zr1.net/forum/showthread.php?t=10134

also >> http://www.zr1.net/forum/showthread....9218#post89218

If this is not it then you need to do a complete vacuum testing.

>>> http://www.corvetteactioncenter.com/...0/002/article/

Did you run a check for codes?

Here is the main area for research >>> http://zr1.net/forum/showthread.php?...ight=solutions

jrd1990zr1 idea below is also another good one. Esp. if you did not have a high idle.

Good Luck and welcome to the ZOO

DYNO -- none of your links are working in the above post.

[jrd1990zr1]

I think I can address Q2.

Sounds like the contacts in the full power "valet" switch may not be making contact, so you may not have experienced "Full Power". If you jiggle the key does the light go on at all? I found my switch was not makng contact. The switch can be repaired but you need to pull the console covers to get to it. Could also be a vacuum problem but jiggle the key and see if the light goes on first.

The INFL REST light with a seatbelt light on lead me to believe your front impact sensors have lost ground. They can also be repaired relatively easily. See: http://zr1netregistry.com/ZR1_howto.htm for a write up.

Welcome to the brotherhood!

[GreyZ]

Wow, thank you both. I will check out all those links tonight. My oil pressure gauge stays on 80 psi when engine is shut off so that may help me narrow it down, sounds like it's supposed to return to 0 with key off and it's not.

Q3- I was wondering if it is supposed to make that noticable buzzing sound on and off when decelerating- or is something wrong?? It is definately activated by the cars computer to have the same persistance of timing of how it kicks in and out.

[GreyZ]

Out of town for a week, so will have to wait till I get home to do some more trouble shooting, and check for codes etc. I will wiggle the switch and see what happens.

I did also notice when pull up to stoplight engines idles couple hundred higher than normal for a few seconds then bumps down to normal idle speed. Thank you all for the input and links, it's very encouraging that I may be able to fix these items myself. Thanks

[PhillipsLT5]

Welcome, to the Brotherhood

[tccrab]

Originally Posted by GreyZ

I did also notice when pull up to stoplight engines idles couple hundred higher than normal for a few seconds then bumps down to normal idle speed. Thank you all for the input and links, it's very encouraging that I may be able to fix these items myself. Thanks

This is normal.
It's an emissions feature.
The idle drops to it's lowest after the speedometer registers "0" MPH. Depending on the calibration on the DRM PROM, the idle should be between 600-800RPMS, providing that you have no vacuum leaks.

Your Q3 question is intriguing.
Did the previous owner provide you with the original PROM for the ECM?
If they did, it would be interesting to pop it in and see if the car does the same thing.
One of the "Features" of some of the aftermarket PROMS is a modification that minimizes backfires when decelerating if you have an aftermarket exhaust system. Maybe this has something to do with it although my '90 with a Flowmaster exhaust with a Marc Haibec PROM does not do it.
It might also be a symptom of whatever is keeping you from going into FULL POWER mode.


The oil pressure gauge is a simple/quick fix. Pop in a new sensor and you should be golden.

TomC
'Crabs

[Hog]

For question #3, is this the DCFO(Deceleration Fuel Cut Off) coming into effect? Basically it cuts the injectors upon the throttle closing while at speed.
If you touch the accelerator at all during this period it should stop this noise.

Justa wild guess here, I'm not even 100% sure if these ECM's have DFCO as I use Tunercat OBD2, not OBD1 and havent looked at any LT5 calibrations.

peace
Hog

[GreyZ]

I'll swap out the stock PROM that the previous owner supplied and see if anything fixes itself. That's a great idea. I'll read up on here on how to do that swap
Called Napa, they have a oil pressure switch on the shelf. I'll read up on here and see if the # is posted somewhere to compare to Napa #, make sure I use the correct one.