Ok I have an 82' rx-7 GSL, I've been rebuilding the thing for that past 3 months. She runs, but doesn't want to idle at warm up. What I mean by that is she starts just fine, then whenever I let the car warm up, she'll start idling at 3000. Not like a steady increase, but a jump from whatever I'm at to 3000, and then the car just dyes, it doesn't sputter out or anything. The carb hasn't been tuned since I rebuilt it, and this is the only carb I've ever rebuilt. So, I could have screwed something up there. Also, I hear a hissing from the drivers side of th engine, but I think thats just a leaking booster. Any Suggestions?

 

sounds like a vacuum leak.. find the hiss and stop it from hissing...

 

Its still a little odd for a vacumm leak to start leaking only when warmed up

 

I think there is something in the FAQ about high idle.

 

I'm not really familiar with the emission control devices on these cars, but I know that on some cars they only activate once the car is warmed up. That could be a possible reason for a vacuum leak that only starts when the engine is warm.

Find that hissing noise and fix it. That is definitely the place to start...

 

start spraying the starter fluid. When it sounds good, thats where the leak is.

 

Check the bottom of the #2 anti-afterburn hose where it attaches to the intake manifold. It is directly above the exhaust and often melts.

 

You say you think the brake booster is leaking. Why? Do the brakes not work?
If your booster is that screwed up, then yeah, that would account for your idle problem.

 

I say the brake booster is leaking because it was hissing whenever I pump the brakes, there's alot of pressure being releived write after I turn off the engine, it hisses whenever the engine turns on, and its coming from that area. The brakes seem to work ok, the booster seems to help a little. I'll try all this stuff tonight or tom. thanks for your help. Ill keep you guys updated.

 

I dunno.
You'd definitely know it if the booster wasn't working.

 

Check that hose from the #2 AAV.
Find the hissing.
Test for Power Brake Unit:
1 Engine off, depress pedal a few times
2 with pedal depressed, start engine
3 If the pedal move down slightly immediatly after the engine starts , the unit is serviceable.

2ND step
1 start engine
2 Stop engine after it has run for at least 1 or 2 minutes
3 Depress the pedal with usual force
4 If th first pedal stroke is long and becomes shorter with subsequent strokes, the unit is serviceable.
5 If there is a problem, check for damage of the check valve or vacuum hose, and check for proper connection. Repair if necessary, and check again.

3rd Step
1 Start engine
2 depress pedal with usual force
3 Stop engine with pedal depressed
4 hold down for ~ 30 seconds.
5 If the pedal height does not change, the unit is serviceable
6 See 5 in step 2

If this is inconclusive, you need to do a check with a tester (vacuum gauge)

Proceedure found on 11-17 of mazda factory shop manual

 

As for the "leaking" brake booster. When you press the brakes hard something does hiss. This happened on my rx7(before i took it apart) and on my slightly newer (91) 4runner (which runs perfectly no issues with engine or brakes or anything).

However it could be a vacuum leak. But just thought i would throw that out there.