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%20Web/articles/Are%20The%20Secondaries%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
:cheers:

[innkeeper]

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?

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

Sent from my SM-N960U using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

[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 (http://r.tapatalk.com/byo?rid=90383)

[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.
:cheers:

[Hib Halverson]

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%20Web/articles/Are%20The%20Secondaries%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
:cheers:

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

[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.

[Young1]

Hmm. If the car has Marcs chip why is the OP messing with the key? Chip keeps it on full power mode all the time. BTW I know where there is an NOS power switch if needed.

[efnfast]

Key override is an option with Marc's programming, it's not a given.

[wfot]

I second that. there is a code/number Marc puts on his chips, if you call and tell him what it is, he can tell you exactly what he programed into it....

[kz098123]

Hmm. If the car has Marcs chip why is the OP messing with the key? Chip keeps it on full power mode all the time. BTW I know where there is an NOS power switch if needed.

The power key in 1990 only can be left ON all the time, so no need for a chip to do that. His chip doesn't do that for 1990 cars as far as I know. At least it doesn't in mine.

[Young1]

My 91 Marc chip is default power on so that is my reference. I was unaware of the different 90 configuration.

[Paul Workman]

After removing my SPT throttle plates and Marc reprogrammed my 90 to run on the secondaries full time, he warned me of the fact those 1990 FULL POWER switches were known to become intermittent and if it opens unexpectedly (or intentionally for that matter) half of the fueling (the secondary injectors) would shut off* resulting in a serious lean condition which could result in knock in the least, or worse (as I was to find out later!).

*in secondaries ON mode, the fueling (injector dwell time) is split between the primary and secondary injectors. With the full time modification, if the FULL POWER mode is not working, the result is to shut the secondary injectors OFF - running on the primary injectors only - BUT w/o increasing the dwell to replace the fuel from the secondaries. That is a BAD thing!

And, as it happened, I noticed my "FULL ENGINE POWER" light was intermittent due to the funky POWER switch, and later what seemed like a miss on one cylinder. A compression check showed a serious lack of compression on one cylinder which ended up the result of a burnt valve (after pulling the engine - and all of the ramifications that entailed - to get to the valve).

Never wanting to have an issue with that switch again, I hardwired the wires together which assures the FULL POWER mode is always on - far as the switch is concerned (at least).

Pete Polatsidis (co-member of the "FBI" (Fast Boyz of Illinoiz - Chicagoland ZR-1 group) replaced the valve after I took the opportunity to finish my porting project and port the heads (that after also fashioning a metal sleeve to insert inside that accordion hose (between the air filter and the intake horn). That was back in 2011-12 and the results transformed the Z into a different beast and runs making 432 HP at the wheels before the last bit of porting. That's over 100hp increase on stock cams and NO difference in idle or low speed manners! I highly recommend Marc's "510" package!!