bad stutter at 2000 rpm, only power key on

No, you can do it with out removing the plenum. Have a service manual?

[Spanky1965]

no, amazon?

www.helmsinc.com or www.ebay.com & I would imagine yes at Amazon as well.

[billybaloneey]

Originally Posted by Spanky1965

no, amazon?

eBay has them from time to time also...most of them offered there will be used and much cheaper than new.

[tccrab]

How to check injector coils without removing the plenum:
http://www.zr1specialist.com/HAT%20W...Resistance.htm

TomC
"Crabs"

[Spanky1965]

thanks guys, but since I have an all original 90, that sat, does not stutter on normal power, and the 2nd port system is working, then am I wrong to assume it must need new injectors?

[Dynomite]

Seems to me that if the The ECM drives the secondary vacuum solenoid valve by grounding the electrical circuit that maybe the ECM is not grounding like it should if the issue is with the ECM or input to the ECM regarding secondary opening Except here the issue apparently happens exactly when the secondary kicks in (indicating the secondary is in fact operational).

I guess you can open secondary at 40% throttle around 2000 rpm from the diagram below.

So....I guess you are assuming that since it stutters at 2000 rpm that it IS in fact caused by opening secondary (40% throttle) which the injectors/fuel supply are not functioning causing the stutter with the change in air flow? Just trying to learn the diagnostics.

Kb7tif provided this:
http://www.corvetteactioncenter.com/...diagnosis.html

[Spanky1965]

see thats what I was thinking, that is why i asked before could I just ground it and try driving her?

[Spanky1965]

oh and the ecm has a sticker on the back of it that says it has been replaced by GM

[Dynomite]

Originally Posted by Spanky1965

oh and the ecm has a sticker on the back of it that says it has been replaced by GM

Ha...ya...but after thinking...it would not stutter unless something happened at 2000 rpm....which as you can see...secondary can open at 40% throttle around 2000 rpm and since you do have a stutter then....secondary prolly DID open correctly leading to Jeffvette diagnostics of injectors and fuel starvation (too much air).

If the secondary did NOT open at 2000 rpm there would be no reason for a stutter right at that moment. Seems to me it would run poorly at rpms above 2000 also after the secondary is open.

Or.....the secondary did NOT open and the injectors gave it more fuel anyway at 2000 rpm (too much fuel).....LOL...........I am not sure how that works with the secondary and primary injectors. If I ever run into this problem, I am going to just disconnect the injectors and open up all primary and secondary, stick two Holly Three Barrel Carbs on it and GOOOOOOO!!!!!!

I am like you....just trying to figure out how the experts are diagnosing this so I know for future reference