10-12inhg Vac at Idle after sitting for a while, runs fine?
 

So I have been getting back into the RX7 after I painted it last year. Trying to button up any loose ends so I can get it on the road for a few months this year. As I was messing around tuning the fuel maps for idle(rewired fuel pump) I noticed my vac reading seemed a bit low around 10inhg. I have the mech gauge and boost controller pulling the vac from the side of the intake manifold.

Aren't these supposed to draw about 20inhg at idle?

I have stock ports, low mileage engine at less than 5,000 total on the re-manufactured keg but not much action in the past few years. I have made sure to start it every few months and it starts and runs fine, solid idle around 1,000rpms. I might have a small vac leak still as some of the rubber vac caps have cracked but it idles smooth and doesn't loop or pop.

My main question is can th evac be low from the motor sitting for a while and just idling every now and then. Would it be wise to dump a bit of oil in the housings and do some light cruising to see if the seals might be sticking a bit?

Any advice is greatly appreciated!

Thanks and have a great day!

NJGB

10 is low mine idles at 20 vacuum and my engine was just rebuilt has only 200 something miles on it so far

Attachment 505436

Rotary > Pistons

Thanks. Yeah that's what I thought. I honestly don't ever remember getting a proper vacuum reading on this boost gauge so I am thinking maybe there is a leak in the tubing since both it and the EBC are reading low and they are plumbed on the same line- I should compare the reading to the live data of the Rtek and see what the ECU is reading from the pressure sensor since it's on a different line I guess. It looks like a vac leak but it runs like it doesn't have one.

That is weird.............my streetported engine idles at 18ingh and my big cut bridge does idle at 10.I have never had a rx7 pull 20 idleling at 20...well only if is idleling at 1200rpms or so.
Sounds like you have a vacuum leak or sticky seals.

I'm idling around 800 rpm, stock port rebuilt by rotary resurrection with like new housings.

Rotary > Pistons

Good update, I just hooked up the bluetooth adapter to the Rtek ECU and the stock MAP sensor is reading 16inhg on a cold start, much better right. I think there is a problem with the plumbing for my mechanical boost gauge and the EBC. And I think there are still a few small vac leaks from split vac caps that I am going to replace today.

cold vacuum isn't always a good indicator, vacuum will usually drop slightly when fully warm versus cold.

Go drive it! See what happens.

Yeah I am pretty sure we are okay, I had a couple tiny vac leaks that had developed and on top of the that the boost gauge wasn't reading correctly. Fixed the easy vac leaks and unkinked the tubing for the boost gauge/EBC and now it matches the stock sensor reading, was up to ~18, still need to replace a few vacuum caps under the UIM too, should get to that tonight maybe.

Just need to finish entering the timing values for one of Arghx conservative map based tables and dial in the EBC before we go cruising.

Thanks for the help fellas!