Newbie Question on Power

[innkeeper]

Sorry, I know I'm a newbie. Just picked up a 1990 ZR1 with following mods.
Billy Boat exhaust, Marc Haibeck chip, aftermarket intake (k&n?)
Anyway - car pulls strong to 5500 and then seems to fall off? Is this typical? Or is it just my imagination. What are the optimal shift points for peak acceleration. Thanks sorry if this is a dumb question....

[Z51JEFF]

The intake bellows can collapse under acceleration also make sure it he secondary vacuum pump is working. That's just for starters. The bellows is the large coupling between the airhorn and air cleaner.

[wfot]

ummmm, Sorry I have to ask, is the power key "on" to allow full power?

I believe on the '90 has a "full power" indicator light on the panel above the radio. If you do not have full power on, then it will feel like a normal vette.

any codes?

John

[Ccmano]

No, that's not normal. It should pull like a freight train all the way to 7200 rpm (red line). Either your secondaries are not functioning or, as has been noted, the intake accordion connector between the air filter housing and the throttle body is collapsing at full throttle. First remove the connector and drive the car without it. If that solves your problem get the connector reinforcements from Haibeck (www.zr1specialist.com) or a heavy duty connector from www.JerrysGaskets.com.

If not, you will have to go through the secondary injector system diagnostics. The first step is simple. Turn the ignition on but don't start the car. Does the secondary injector vacuum pump in the right front fender well (under the head light) run a) constantly b) not at all or c) cycle on and off every few seconds. "C" is normal, anything else and there is a vacuum issue with the system (the most common type of issue). Let us know what happens.

This is a must read on the subject to understand what is happening.
http://www.zr1specialist.com/HAT%20W...%20Working.pdf

Further diagnostics will require some specialized knowledge (available here) a factory service manual and ideally a Tech1 or similar scanner. Use the search function and do some reading here the subject. Also at the top of the Tech section are the "Solutions" stickies. Read up on the issue there.

Let us know what you find on your car. Many, if not most, of us have gone through the same thing.
H

[Hib Halverson]

Originally Posted by Ccmano

No, that's not normal. It should pull like a freight train all the way to 7200 rpm (red line). Either your secondaries are not functioning or, as has been noted, the intake accordion connector between the air filter housing and the throttle body is collapsing at full throttle. First remove the connector and drive the car without it. If that solves your problem get the connector reinforcements from Haibeck (www.zr1specialist.com) or a heavy duty connector from www.JerrysGaskets.com.

If not, you will have to go through the secondary injector system diagnostics. The first step is simple. Turn the ignition on but don't start the car. Does the secondary injector vacuum pump in the right front fender well (under the head light) run a) constantly b) not at all or c) cycle on and off every few seconds. "C" is normal, anything else and there is a vacuum issue with the system (the most common type of issue). Let us know what happens.

This is a must read on the subject to understand what is happening.
http://www.zr1specialist.com/HAT%20W...%20Working.pdf

Further diagnostics will require some specialized knowledge (available here) a factory service manual and ideally a Tech1 or similar scanner. Use the search function and do some reading here the subject. Also at the top of the Tech section are the "Solutions" stickies. Read up on the issue there.

Let us know what you find on your car. Many, if not most, of us have gone through the same thing.
H

Generally that's good advice, however, if the ECM cal is stock, the rev limit is 7072-RPM and the power curve will flatten before that.

You also want to change the fuel filter then road test.

Inspect the air filter, replace as necessary

[innkeeper]

Originally Posted by wfot

ummmm, Sorry I have to ask, is the power key "on" to allow full power?

I believe on the '90 has a "full power" indicator light on the panel above the radio. If you do not have full power on, then it will feel like a normal vette.

any codes?

John

Yes key is on full power. Not that much of a newbie lol.

Sent from my SM-N960U using ZR-1 Net Registry mobile app

[innkeeper]

Wow, thanks guys. - key issue, was on full power but no dash light. Messed with it and able to get light on. Took car for a drive and holy crap, what an angry monster. Loving it

Sent from my SM-N960U using ZR-1 Net Registry mobile app

[TX '90 ZR1]

When you have a chance you should probably pull the power key switch out and add some tension to the contacts. The issue you had is not that uncommon.
I believe there is info on this in the "solutions" sticky.
Glad you got it going for now.

[dave885]

I need to stop reading these posts! Took mine out for a quick spin to pick-up dinner yesterday and experienced the exact same issue of power loss at 5,500 RPM's. Power key was on and lit up. Service engine light came on when I tried to stay in it and then went off when RPM's dropped back down. Got a few things to check now.

[wfot]

haha, no insult intended, but sometimes the obvious is the thing is it.
I am glad she is running.