Vacuum pump confusion

[MuRCieLaGo]

Hi,

I had a Code 61 for exactly 3 seconds this afternoon. So I tried to figure what is the problem.

When I put the key ON, I don't hear the vacuum pump. So tonight.

1st of all, I unplugged the vacuum pump and test the connector with a multimeter. Ground is OK, however I don't get any signal from the brown wire. I asked somebody to put key off/on while I read the multimeter, still nothing.

2nd of all, I opened that vacuum pump. What a mess! I don't think I can fix that now. It was full of rusty water.

http://i841.photobucket.com/albums/zz332/TiGarsRotatif/20151110_191438.jpg
http://i841.photobucket.com/albums/zz332/TiGarsRotatif/20151110_191630.jpg
http://i841.photobucket.com/albums/zz332/TiGarsRotatif/20151110_193849.jpg

So I put everything back on, I know for a fact that vacuum pump doesn't work.

I then went for a strong 10 miles ride, car runs like it should. Very strong at high RPMs. No SES light (erased previous Code 61).

Now I am very confused.

1. Why I don't have any current coming in the connector?
2. Why is the car running fine without the vacuum pump working?

[Paul Workman]

I do believe I have my pump that I removed when I removed the SPTs. It's yours, if you want it (and I can find it!!)

Paul.

[MuRCieLaGo]

Wow yes I'd buy it instantly. But I really can't understand why the car runs perfectly without it running...

I hate when I don't understand.

Thanks a lot Paul!

[RIP]

That vacuum pump isn't in use until the engine vacuum goes to almost zero. This happens at wide open throttle. Engine will run the same until you don't have vacuum to hold the 8 secondary throttles open.

[MuRCieLaGo]

That vacuum pump isn't in use until the engine vacuum goes to almost zero. This happens at wide open throttle. Engine will run the same until you don't have vacuum to hold the 8 secondary throttles open.

But I gave the car a strong 10 miles ride afterward (multiple WOT pulls) without any problem...

[A26B]

The vacuum pump provides supplemental vacuum to the secondary port throttle (SPT) system. Vacuum is also provided from the engine during normal operation. If your SPT system is tight, i.e. no vacuum leaks, it will hold the SPT system open for a short romp. When you let off WOT, engine will again provide vacuum.

With vacuum leaks, SPT will not open at all or slowly close, depending on severity of leak.

[We Gone]

WOW.. Looks like water intrusion for sure. You may want to check all electrical connectors, clean and apply some dielectric grease to them.

[Gunny]

ditch the secondaries, get a new chip from Marc, problem solved :thumbsup:

[MuRCieLaGo]

The vacuum pump provides supplemental vacuum to the secondary port throttle (SPT) system. Vacuum is also provided from the engine during normal operation. If your SPT system is tight, i.e. no vacuum leaks, it will hold the SPT system open for a short romp. When you let off WOT, engine will again provide vacuum.

With vacuum leaks, SPT will not open at all or slowly close, depending on severity of leak.

But I swear it doesn't run at all and I have done at least 8 WOT runs until 7k RPM and there's no issue. I thought that in these conditions the ECM would block my RPM to 3k...

WOW.. Looks like water intrusion for sure. You may want to check all electrical connectors, clean and apply some dielectric grease to them.

I knew there was something wrong when I opened it and it was full of rusty water...

ditch the secondaries, get a new chip from Marc, problem solved :thumbsup:

This!

I own a RX-7 and I removed a lot of systems. Made everything easier.

I would like to remove that secondary system.

[Dynomite]

I am the Contrarian here ;)

I love the Secondary System operating and it is very easy to maintain if you block TB Coolant at the Injector Housing ending up with the 10 minute Plenum Removal.

I really like the FULL ENGINE POWER light on the panel on the 1990s. On the 1991 you only have the green tiny light by the Full Power switch which on my 1991 I have eliminated the secondaries :p

because...because on the 1991s they eliminated the FULL ENGINE POWER light on the panel :D

http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite13/IMG_5021_1.jpg (http://s287.photobucket.com/user/dynomite007/media/Dynomite13/IMG_5021_1.jpg.html)

[MuRCieLaGo]

I am the Contrarian here ;)

I love the Secondary System operating and it is very easy to maintain if you block TB Coolant at the Injector Housing.

I really like the FULL ENGINE POWER light on the panel on the 1990s. On the 1991 you only have the green tiny light by the Full Power switch which on my 1991 I have eliminated the secondaries :p


Hi Dynomite,

I remove all these, plus I install a chip from Marc Haibeck, and that's it? And when I'll be done, I simply block the vacuum nipples from the plenum?

http://i287.photobucket.com/albums/ll142/dynomite007/LT5/SecondaryVacuumSys.jpg

What will happen performance-wise if I remove the system? There will be no more difference between "Normal" mode and "Full" mode?

I own a '91.

Thanks!

[We Gone]

I am the Contrarian here ;)

I love the Secondary System operating and it is very easy to maintain if you block TB Coolant at the Injector Housing ending up with the 10 minute Plenum Removal.

I really like the FULL ENGINE POWER light on the panel on the 1990s. On the 1991 you only have the green tiny light by the Full Power switch which on my 1991 I have eliminated the secondaries :p

because...because on the 1991s they eliminated the FULL ENGINE POWER light on the panel :D

Makes me wounder what it would take to add an operating bulb to the dic of the 91-up???, Could you tie it to the switch light or even to come on when the sec are open...?

[Dynomite]

Makes me wounder what it would take to add an operating bulb to the dic of the 91-up???, Could you tie it to the switch light or even to come on when the sec are open...?

You guys are missing out on the best interior feature that exists on the 1990s :D

http://i287.photobucket.com/albums/ll142/dynomite007/Dynomite13/IMG_5021_1.jpg (http://s287.photobucket.com/user/dynomite007/media/Dynomite13/IMG_5021_1.jpg.html)

Hi Dynomite,

I remove all these, plus I install a chip from Marc Haibeck, and that's it? And when I'll be done, I simply block the vacuum nipples from the plenum?
What will happen performance-wise if I remove the system? There will be no more difference between "Normal" mode and "Full" mode?
I own a '91.
Thanks!

You do not need to block the passenger side vacuum nipples from/to the Plenum (you block the Drivers side vacuum nipple between the Plenum Runners only). That vacuum nipple on the passenger side of Plenum is Cruise control and HVAC which you leave in place.

Your tiny green light will stay on all the time by the Full power switch (Haibeck Chip secondaries removed) and you are ALWAYS on FULL ENGINE POWER Mode.

See Item #2 Vacuum Systems 90' and 91' (Secondary and Cruize/HVAC) (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581460752)

This is a 1991 with Plenum Vacuum Drivers Side Blocked

http://i287.photobucket.com/albums/ll142/dynomite007/Blingzz.jpg

[Paul Workman]

Like many of the "FBI" gang, I removed my SPTs - the entire harness, butterflies, throttle rods, pump, vacuum lines - everything. Maybe someone has the # handy for the Dorman freeze plugs that are inserted in place of the throttle rod bearings. (And, for good measure, I put JB Weld around the edges of the plugs before I installed them for a permanent seal.)

I NEVER missed them for a single moment. The input valves both get washed constantly and so they don't have any coking buildup going on. And, talk about instant throttle response!

IMO, there is NOTHING not to like about pulling the dang things. However, it is a moot point now, as my "FBI" porting exceeds the stock diameter significantly.

Parts that don't exist never break. And, they don't cost much!

[MuRCieLaGo]

Alright so now I definitely have an issue regarding that failed pump. When I hold WOT in a hill for example, SES light comes on after a while until I reach the top of the hill.

I'd like to go ahead but I need to buy Haibeck's chip, and before I do that I'd like to put some headers and an exhaust system.

Is there someone with a used vacuum pump who would like to sell it? If I can't find one I'll store my car for winter time and do the removal of secondary system as a winter project.