New Injectors

[secondchance]

I finally pulled the plenum, removed all injectors, cleaned all nooks and cranies, checked all vacuum lines, installed set of reconditioned injectors from FIC, installed new PCV tubing, checked secondary actuators and vacuum lines w/ vacuum pump.
Vacuum lines and connections to rubber fittings were fine (dab of epoxy does work!). It was a check valve stem that had broken off. Good thing I followed the advice and bought two check valves from Discount auto.
I did not get into aluminum tubing because it was getting too late and I was borrowing my brother-in-laws garage - sorry...

I checked vacuum with a pump before buttoning up and it was hodling like 25hg.

I had to call Michael in Reston because I lost torquing sequence info I had - thanks David and Michael!

Buttoned her up and vacuum pump keeps running! I must have either pulled vacuum going to the gizmo mounted on the plenum or map. Either way, I will pull again tomorrow or Tuesday to track it down for SURE.

Despite not holding vacuum, high idle and excessive pinging disapeared!
And the car pulls much, much better.

I have a strong suspicion that one of my primary injector was gone.

80% of problem fixed - 20% to go and spic and span under the plenum.

Oh, the joy of LT5 goes on - I will have it running perfect before end of this week.

[secondchance]

I forgot to mention thanks to Jon Banner of FIC for making himself available on Sunday for silly questions.

Thank you Jon!

[USAFPILOT]

Those injectors go in easy, come with all necessary o-rings etc.

[secondchance]

Yes they do go in easy. Pu;;ing them out was a little tough after 15 years.

[secondchance]

I pulled the plenum again as soon as I woke up, checked vacuum from vacuum pump and found vacuum check valves I bought on Saturday from Advanced Auto Part had failed - both of them!
Went to a local Chevy dealer partsm replaced both check valves, went through start, shut down, restart cycle and she purrs like a kitten - smooth!
Moral of the story - be careful w/ cheap parts!

[jonszr1]

WTF is the above post???????????????

[secondchance]

Originally Posted by jonszr1

WTF is the above post???????????????

Well, I have been chasing this demon - pinging at around 2000 rpm part throttle for about 8 years.
Then recently, idle speed jumped to about 1100 w/o AC compressor on. When the compressor kicked in, rpm would drop to around 800 but the motor would shudder. Also, quite a bit of throw out bearing rattle.
So, finally I pulled all injectors (15 years old) and replced them w/ reconditioned Bosch units from FIC. And checked, resealed all vacuum lines and vacuum check valves.
It seems that real culprit was bad injectors gone worse recently (from simple pinging possibly due to partially clogged to completly clogged). Certainly leaky check valve did not help.
Finally the car runs better then ever - not shuddering and no pinging noise at part throttle.

[Scrrem]

Originally Posted by secondchance

Well, I have been chasing this demon - pinging at around 2000 rpm part throttle for about 8 years.
Then recently, idle speed jumped to about 1100 w/o AC compressor on. When the compressor kicked in, rpm would drop to around 800 but the motor would shudder. Also, quite a bit of throw out bearing rattle.
So, finally I pulled all injectors (15 years old) and replced them w/ reconditioned Bosch units from FIC. And checked, resealed all vacuum lines and vacuum check valves.
It seems that real culprit was bad injectors gone worse recently (from simple pinging possibly due to partially clogged to completly clogged). Certainly leaky check valve did not help.
Finally the car runs better then ever - not shuddering and no pinging noise at part throttle.

Glad to see there is a bunch of local experience at this task. With is 90 ZR-1, I think I may have this job in my future, may need some hand holding . Can you say "Plenum Pull Party"
Rich

[ZR1Vette]

Rich..
Bunch of us can get together and help you thru it...once you do the plenum pull, learning a few 'tricks', what is needed etc. it very easy. First time I was cautious, had great assistance and a little with the angst over exactly what to expect.

Let us know when you decide to do... will give you what you need to order etc. Also, we can run the diagnostic protocols for vacuum, secondary actuators etc.

Plenum Pulling Party PPP

[secondchance]

No worry Rich. I am out in Tyson's and will be glad to assist if needed.
Without prior discussion with those who had done the work before, I would have been frightened to pry and yank on the fuel rail to get the injectors out of intake port. It took some serious pursuation.

Also, I strongly advise having all necessary GM weatherpack connectors on hand. These things break at a touch after so many years.