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#31 |
Join Date: May 2007
Location: Chicagoland, IL
Posts: 9,696
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Pump is there to make up for problem.
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[SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX |
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#32 | |
![]() ![]() Join Date: Nov 2007
Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri
Posts: 6,493
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![]() Marc should correct me if I'm wrong, but I don't believe he's saying a short "OFF" cycle doesn't need attention, but rather if the leak is small enough that the vacuum pump can attain sufficient vacuum to reach pump cut-off threshold, then the the SPTs actuators will not be inhibited for lack of vacuum (provided code 61 is not triggered). (Referring to the diagram above) The SPT circuit is divided into two parts, partitioned by the SECONDARY PORT THROTTLE VALVE (switch):
So, IF the vacuum pump will cycle OFF - for even a second, then sufficient vacuum exists to operate the SPT actuators, at least up to the SPT VALVE (valve). Now, however, if the circuit on the actuator side of the (valve) is severely compromised to the point of triggering code 61 when the ECM calls for the secondaries to open, we know the actuator side of the circuit is what is severely compromised. Back to Scottfab's point about the short "OFF" cycling and pump longevity: If a pump is short (off) cycling, I wouldn't argue there isn't an issue to be attended to. However, most of the time the engine provides the vacuum sufficient to charge and maintain the reservoir side of the (valve). The pump doesn't run at all until there is a sustained load to raise air pressure above the point the pump is triggered "ON". This significantly mitigates the concern for pump being over-worked (but I'd want to run that down at the earliest convenience). But, then again, during the 24 hour run, I would think the pump ran (ed. as needed) majority of the time, especially at/near WOT! Of course one could perform the secondary delete mod and NEVER worry about this entire topic again...But, that is another debate.
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Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry Last edited by Paul Workman; 04-22-2014 at 08:13 AM. |
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#33 | ||||
![]() Join Date: Jun 2005
Location: CenCoast California
Posts: 899
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'Preciate the time to shoot a pic and post it but, you didn't need to do that. I have FSMs from 1982-2012 and have read that page a number of times.
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With 90-92, almost all time at WOT, the SPTs are commanded open and with 93-95 it's all the time. Thus, for most of the time the SPTs are open, while vacuum may be present to open them, there's little or no vacuum to keep them open, so the primary source of vacuum is not MAP but is, first, the vacuum tank, followed afterwards, by the pump. Quote:
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There was a so-called "touch the sky" test done during the final stages of ZR-1 development. I think it was done at the now-defunct Desert Proving Ground where a ZR-1 was run on the high-banked track at WOT for the duration of a tank of fuel so the aux. vac. pump will last at least that long in continuous use. Quote:
HIB, your post was moderated for "some" of its content. PM sent. Last edited by Blue Flame Restorations; 04-21-2014 at 11:42 PM. |
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#34 | |||||
![]() Join Date: Jan 2009
Location: Portland Oregon metro area (Washington side)
Posts: 3,207
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Getting above 15sec and in fact achieving 30sec or more cycle time on the pump is not hard. Attention do detail is the key. Really going after and fixing leaks and contamination is key (if you live in a heavy dust filled and/or dirt filled environment then all bets are off) Quote:
(marginal condition) Quote:
"key on engine off". Not a great concern because it is usually rare for key on engine off but it does happen. This is not a fish pump we're talking about. It is not intended to run 100% duty cycle 24/7. If a pump is cycling every 1sec with key on engine off, just fix it. Gezzz Quote:
![]() On each curve and WOT maybe it's on. Straightaways? dunno Quote:
I suppose it is. I mean the block is still there. Back in 99 I came up with a solenoid actuator replacement that pulled a cable. I was convince it would be a permanent solution. However about that time I ended up actually fixing the secondary system and it has stayed fix all of these years, save the time the rebuilt pump failed (poor selection of replacement diaphragm material) . At that time (99) I announced I would, upon another secondary system failure, put that solenoid in and make public the part numbers etc. So far it hasn't come to that. I do still have all the parts etc in a box. I think ripping out the secondary is out of the question for me for several reasons. eh, but then that's just me. I still keep the spare tire and the owner's manual too ![]() Respectfully submitted:
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Scott ![]() Vett owner since 1979._It's about the car and the people |
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#35 |
![]() Join Date: Jun 2005
Location: CenCoast California
Posts: 899
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Guys...the Record Run engine was throttle stopped so there was always vacuum present in the plenum. If that engine had port throttles, which I suspect it did because the it came right off the LT5 Line at Stillwater, it's likely the pump didn't run that much.
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Hib Halverson Technical Writer former owner 95 VIN 0140 current owner 19 VIN 1878 |
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#36 | |
![]() Join Date: Jan 2009
Location: Portland Oregon metro area (Washington side)
Posts: 3,207
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Do you know or suspect what the thinking was to put the stop in?
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Scott ![]() Vett owner since 1979._It's about the car and the people |
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#37 | |
![]() ![]() Join Date: Aug 2009
Location: South Dakota/California
Posts: 3,791
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![]() If the vacuum pump cycles 5, 10, 15 seconds or at all....the vacuum system is NOT TIGHT but normal and functional for the age of the vacuum system with components not replaced with NEW LINES AND NEW RUBBER (soft) CONNECTORS. Disconnect the drivers side center plenum vacuum source and hold your finger over the rubber connector disconnected (Engine OFF but Key ON). IF THE SECONDARIES (Secondary Canisters) FUNCTION AND HOLD POSITION WHEN TESTING SECONDARIES WITH PLENUM IN PLACE (Key on) Verifying Secondary Actuator Operation with the Plenum in Place END OF DISCUSSION ![]() I will think further on this but for now I am busy planting corn and beans ![]()
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Left Clickable links ![]() -Solutions- LT5 Modifications/Rebuild Tricks Low Mileage ZR-1 Restoration 1990 Corvette (L98) Modifications LT5 Eliminated Systems LT5 Added Systems LT5/ZR-1 Fluids 1995 LT5 SPECIFIC TOP END REBUILD TRICKS Last edited by Dynomite; 04-22-2014 at 10:04 AM. |
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#38 | |
![]() Join Date: Feb 2014
Location: AZ
Posts: 860
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#39 | |
![]() Join Date: Jan 2009
Location: Portland Oregon metro area (Washington side)
Posts: 3,207
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Scott ![]() Vett owner since 1979._It's about the car and the people |
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#40 |
![]() Join Date: Feb 2014
Location: AZ
Posts: 860
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