ZR191

The injectors are brand new, and the railings of the secondaries are free, I tested them with a vacuum hose and they retract perfectly opening the secondaries wide. Could it be the Ignition Module? Remember I replaced cables plugs,coils, injectors, the ECM was tested in other Z and rand strong also the sec solenoid was replaced as well as the vacum pump!

ZR191

New coils, new cables ,new secondary solenoid, new Delphi injectors,new vacum pump, new plugs ,ECM tested on another Z, it was fine, all vacum hoses checked for leaks, and still the same as before ...runs good without the power key on. When the key is on is like a shutter type rev limiter . Anybody has replace the ignition module? is the only thing I have left...ANY IDEAS?

Mr. Gizmo

you might try gordon killebrew's action line. he is the expert on diagnosing these cars.

The only other thing i can think to check is fuel pumps. I am not sure this would have this effect. To check the primary fuel pump - pull the secondary fuse - thats under the dashboard on the passenger side - you have to dig to get to that one. then power the car ignition on / engine off and see what pressure it builds. then to test the secondary fuel pump, pull the primary pump on the fuse panel on the side. (of course install the secondary pump fuse.

each independent of one another ignition on engine off should put out about 45lbs as i recall. - i also had a bad secondary pump.

but before you go throwing more money on parts i would try gordon.

He will charge you for the advice, but it is worth it.

Good luck and let me know how it goes

http://www.gordonkillebrew.com/

ZR191

The fuel pump was replaced 2 years ago, and the fuse of the secondaries is fine. When the fuel pump fail it was a different symptom, the engine as it rev up would starb for gas and slow down and pick up again! when gas reached the injectors again.

Mr. Gizmo

Are you getting any codes stored? even though I have sold my 91 zr1, i still have the complete set of helms manuals. they are at my Dad's house. Tomorrow i will go by dad's house and get them I will look at the symptom charts to see if there is a diagnostic to follow on a symptom of rough running with the power key on.

ZR191

In the next couple of days I will conect the car to the teck1 and I will make public the codes. What about the ignition module?

Mr. Gizmo

I do not know about the ignition module. If the car behaves normally with the power key off and revs freely and does not shudder - i would think the ignition module is ok. If it were the ignition module, i think it would behave the same regardless of if the power key is on or off. But i am not an expert and do not want to steer you wrong.

What part of the country do you live in?

ZR191

I wonder if anyone had problems with a faulty seconderies injectors relays?

TommyL

I did have 2 bad new injectors from GM.

_twisted_

my vote is definitly secondary fueling - the stock chip brings them on right around the 4k rpm you have the issue - also tps sensor has to meet the parameters as well. but that is my wag

dallas916

Have you checked you vacuum check valves for the secondaries? I had to add additional valves on each side because even new ones were not holding.

Mr. Gizmo

On the old Teamzr1 list server, i remember a few guys back in the day were either removing the secondary butterflies or defaulting them to always be open. -(while leaving the secondary injectors themselves operational as designed by the factory).

I do not think this would cause this problem here.

I checked my helms service manuals for a description of this problem to trouble shoot and came up with nothing.

These helms manuals have a lot of info, I will keep looking through them to see if i stumble across something - worst case its good night time reading to make me fall asleep.

I sure hope zr191 solves his problem. I do have a fond place in my heart for these LT5's

Aurora40

You don't need a Tech-I to read the codes, a paperclip will do the trick. Does your "check engine" light come on though? You haven't said it does.

If you suspect the ignition module, there is a tester specifically for it. However, tracking one down might be tricky? If you can find someone with one, send them your IM and get it tested. Better than just throwing more money at the problem without diagnosing anything.

Where are you located?

DDSLT5

Have Julio diagnose it! He won't let you down!

ZR191

I am in MIAMI, who is Julio, phone number?

94ZR1

When mine did that it was just a vacuum line that broke

ZR191

Anybody know a good ZR1 mechanic in Miami or close to Miami?

ZR191

Solution found. Thanks to Marc Heibeck, who via telephone help me a lot to debug the problem....it turn out to be in the ignition module. When the plenum was removed it turn out that one of the needles in the connector was bend up a little, not making contact with the connector. After fixing it the car ran perfectly. If anybody of you up there have a bug in your car I strongly recommend Mark Heibeck....his knowledge of zr-1 is second to none! Thanks Mark...


Marks phone is 6304588427

P.S>Mount your plenum carefully...specially the conector, make sure it meats straight not at an angle because it will bend the needles, causing big issues. Thanks