HELLLLLPPPPPP ME LT5 Brothers!!!

[mike100]

Mine was the purge line that goes between the purge solenoid and the throttle body. Its that hard plastic line with the 4" diameter curly-Q bend in it under the plenum (of course, where else would it be- everything is in there).

maybe backfires help those things slip out. I rough sanded mine to help keep in in the rubber connection better. It would never idle below 1400 except when cold.

the book over the throttle inlet verified this as it could still run on just the air leak. spraying some carb cleaner in the middle of the runners on the drivers side resulted in an idle speed change which verified that for me.

[C4Fanatic]

Well, just ordered a set of plenum gaskets from Jerry.
Have a trip to Chicago coming up next week, so it looks like I'll be "popping the top" here as soon as I get back home. Sounds like a good cold weather project.

I did the book over the intake trick and while the idle slowed some she kept right on running.

[C4Fanatic]

Well, I've been procrastinating and haven't torn the Skunk down yet, but the weather is supposed to be nice down here for the next couple days, so I may give it a go.

QUESTION: Where can I get new Crankcase Vent Hoses? I'd like to go with Semco, but not sure where to order them from.
Jerry got them??? I don't find them on his website.
Figured while I was under there I might want to replace them, talked to the previous owner and he said they had been brittle the last time he had the plenum off, but he didn't have replacements. I'm seeing some oil on the top of the engine between the intake runners, so I figured that was a possible source, that and a new gasket for the vent cover.

[LGAFF]

Gates - Molded Coolant Hose
Part Number: 22120

neon hose, cut it 2 makes both breathers

[C4Fanatic]

Thanks Lee!

Sorry I missed ya when I was in Chi-town earlier this month, turned out I was MUCH busier than I thought I was going to be.
I'll be back up that way in a couple weeks.


Got the hose in stock at the O'Reilly's down the street, sweeeeet!

[C4Fanatic]

OK, now I'm confused.

I was doing some basic checks before I tear this thing apart and was checking the vacuum pump...again....just in case.

I'm getting 11.4vdc to the pump, but I never hear or feel it run when I turn the key to the run position. I pulled the hose and it's not pulling anything, no suction against my thumb.

Am I doing it right? The thing should run for about 5 seconds or so when you first turn the key on, correct? I should be able to hear, or at least feel the pump run, right?

I bought a Mityvac vacuum check kit, pulled the main line out of the vacuum pump and pumped it up to 20 inches of vacuum. It took nearly 20 seconds to lose 1 inch on the gauge. Is that enough of a leak to be causing my problem?

That thumping sound is my head on my desk...

[C4Fan]

My '91 with 53,000 miles started having the same idle/running issues a few months ago right after I had the entire car serviced. While I am unable to offer any advice due to my lack of technical skills, I am anxious to hear what you finally learn about your ZR-1 C4Fanatic. I may be having the same problem and hope to narrow the field of possible cures. Thank you for sharing your experience on the net.

[sammy]

your pump is most likely either gone or the contacts inside are corroded.you can take the top off very carefully as there are wires inside . if your lucky the contacts will have that turquoise film on them .i know there is a thread on how to ck it somewhere here . do a search.or someone will chime in with the link . i dont know how to do that sorry

[C4Fanatic]

Well it's been interesting...

Did a few more checks, found that the secondary vacuum pump has died, but I'm not getting a code and that vacuum loop holds good vacuum. Seeing as the secondary's were removed by the previous owner, I'm leaving that alone for now.

In the mean time, I had to run to Chicago for business and had a chance to drop in on Mark and pick his brain. He was sure the vacuum pump wasn't causing my idle issue, totally different vacuum loop. So he pointed some things to check out when I popped the top.
Removed the plenum and NOTHING jumped out at me. Found one hose that was loose/ kinda half way off, but nothing completely off. Pushed every hose back on good and tight, zip tied any that seemed to need it. Replaced both of the crank case vent hoses as the old ones were hard as rocks. Put everything back together and crossed my fingers.
First couple times I fired it up it was still idling around 1800-2000rpms.
In a fit of madness...frustration...confusion....I shut it down and pulled the cruise control cable off. No change.
So, I pulled the throttle cable off.........SON OF A B*TCH!!! Thing fired up and idled right down to 800-900rpms just as smooth as ever.
Messed with the throttle cable, check the connection at the pedal, nothing seems wrong, it's smooth in the housing. Put it back on, fire it up...idles just fine, 800-900rpm on the tach.
SO, I don't know if it's the cable OR starting it up, shutting it off after having the battery disconnected maybe the computer was re-learning idle position. Thought???
We'll see what the next few days brings, weather is supposed to be beautiful, so I'll put some miles on it and we'll see what it does.
Keep your fingers crossed!!!

[mike100]

well, at least you know what make the top end on an LT5 tick...I guess everybody needs to dig into their car to make it their, so-to-speak.

probably the cable was jammed cockeyed or something. a scanner would have shown a high throttle position- might want to keep in mind if it happens again.