kdailey4315
NAXJA Forum User
- Location
- Pacifica, CA
For a first step, disconnect the brake vacuum line from the manifold and plug or cap the connector at the manifold. If idle now works then start hunting for brake problems.
Did this and the engine jumped up to 1500 RPMs and then shut off when I plugged the vacuum on the manifold.
Do you get any brake boost at all? Assuming a conventional vacuum booster, pump the pedal with engine off, then start the engine while you have your foot on the brake. Does the pedal sink at all? If not, you're not getting any boost. If it does, then at least some vacuum is reaching the reservoir. Check for changes in idle when you pump the brake (sign of booster problem), and also for smoke in exhaust when brakes are applied (booster leak pulling fluid out of master cylinder).
No change in idle when I pump the brakes but if I pump it once and hold it for a second when I let go a get a slight jump in RPMs. Maybe 20-30, from 750is to 780ish.
You don't specify a year
Check the check valve at the booster. It is a 1 way valve. To test just remove and blow into it. Should only be able to blow through 1 way.
....You still haven't reported whether or not you have boost.
If you did not test this, try again: With engine off, pump the brake pedal until it's good and firm, with no residiual boost. Now, keep your foot firmly on the pedal, and start the engine. If your brake booster is working properly, the pedal will sink noticeably when the engine starts. If this does not happen, your booster or the line to it is bad.
Try also plugging the vacuum line on the manifold with the engine off, then restarting, to see how it idles without the brake system in the mix. That way you won't be mixing up vacuum loss issues with the attempts of the engine to correct itself for a sudden change.
I did. I posted the results a few posts ago (in red).
When I pump the pedal while the car is off it goes down a very small amount. Not even half way.
When I unplug the vacuum hose at the manifold the idle jumps to 1500 then dies when I plug it up.
Maybe I'm not understanding your reply. When you hold the pedal down and start the engine, does the pedal sink? The change should be quite noticeable.
How does the idle act if you do the removing and plugging with engine off and then start the engine? Does it still stall, or does it idle?
Check the check valve at the booster. It is a 1 way valve. To test just remove and blow into it. Should only be able to blow through 1 way.