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Extra vacuum plug on Renix TB?

jaytee79

NAXJA Forum User
Location
Maryland
So I swapped out my original from 1988 MAP sensor tonight in an attempt to cure the low idle when cold, high idle when warm problem. I went ahead and swapped out the vacuum line for it as well, the one that connects to the throttle body, since my old one was pretty ugly. When I did this, I noticed that where it plugs into the TB, there is another unused vacuum connection just above the one where the MAP plugs in. The two connections share a rubber grommet, but the unused one is a little bit larger. I didn't know if it was supposed to be this way, or what it might go to, so I just plugged it with a wood screw.

Is this important? Should I open it back up? Is there something important that is supposed to be there? This truck is still new to me, it's my first Renix, and I didn't test drive the rig afterward, but I did start it up and run it, the idle seemed unchanged but I didn't let it get warm (not that it ever does, at least not above 160-180 or so, but that is another thread.....)

and next, on to the TPS......
 
One of those holes is a blind hole to nowhere.
What RPM is your high idle, it may help narrow down the possibilities.
Before you buy any parts, check your vacuum lines and your intake manifold bolts, being really careful not to snap off the studs.
Clean all your grounds down to bare metal, especially at the firewall and the dipstick holder.
The motor runs best above 200 F, you may have a thermostat issue. If it runs too cold, many of your sensors may not kick into the equation at all.
Clean most all of your connectors (except the big one on the firewall, save that one for the future), really well, forget about die electric grease in the connectors. Some of the sensor signals are a fraction of a volt.
Read the "Renix files".
 
One of those holes is a blind hole to nowhere

My '90 shares that feature. The vac connection fits in there and does nothing except adds grip, and not mcuh of that.

Possibly used for some other state or country's emmissions, not anything for me.
 
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