Is there ANY reason the TPI EGR wouldn't run fine on manifold vacuum instead of port?
#1
Is there ANY reason the TPI EGR wouldn't run fine on manifold vacuum instead of port?
Turn out my BBK 52MM "CA Exempt" throttle body's port vacuum nipple is non-functional thanks to their design and gasket. Their older TB's had the port vacuum, like the stock TB's. I was able to notch the gasket up to the bore and reassembled so now that nipple has manifold vacuum. I also verified driving around with a vacuum gauge on the valve that my EGR system is functioning as it should be when I drive.
The only thing I can think of is that port vacuum MAYBE allows a smoother introduction of vacuum once the EGR solenoid opens but even then the valve diaphragm is large so I don't see this making a big difference.
OR, it's a failsafe if the EGR solenoid fails, stuck open, the EGR won't be open at idle.
Welcoming any ponderings.
The only thing I can think of is that port vacuum MAYBE allows a smoother introduction of vacuum once the EGR solenoid opens but even then the valve diaphragm is large so I don't see this making a big difference.
OR, it's a failsafe if the EGR solenoid fails, stuck open, the EGR won't be open at idle.
Welcoming any ponderings.
#2
Re: Is there ANY reason the TPI EGR wouldn't run fine on manifold vacuum instead of p
Depending on the year, the timed port can also serve the EVAP purge solenoid valve. I believe you are correct, that this is a redundancy in case the solenoid control system fails in some manner. You are also correct that it probably make little difference, specifically for the EGR since it is likely a negative backpressure valve, and that would probably create a more significant idle problem if the solenoid fails.
#3
Re: Is there ANY reason the TPI EGR wouldn't run fine on manifold vacuum instead of p
Thanks. So the car did finally pass CA emissions using the manifold vacuum, but I still replaced the BBK TB with a factory unit and car runs like new. Also, I think you are correct. I believe the evap cannister purge solenoid taps off of that port vacuum as well.
#4
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Car: '91 GTA, '92 T/A Convertible
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Re: Is there ANY reason the TPI EGR wouldn't run fine on manifold vacuum instead of p
I've had issues passing smog for years because of my EGR solenoid. So before I head to the smog station I disconnect the vacuum line from the bottom of the TB and from the EGR valve and plug the lines before I tuck them in under the manifold. Then I run a vacuum hose from the TB under the plenum and connect it directly to the EGR valve. It idles a little rough, but it passes every time when I do this.
I may be wrong, but I am pretty sure that the evap cannister does not use the vacuum from the port under the TB. I believe it uses one of the vacuum ports/hoses from the passenger side of the TB.
I may be wrong, but I am pretty sure that the evap cannister does not use the vacuum from the port under the TB. I believe it uses one of the vacuum ports/hoses from the passenger side of the TB.
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