hello yall can anybody tell me what a bad brake booster will cause engine to surge when you hit brake pedal? ive been chasing this for almost a year its got a new master cyl. the engine idles and starts fine .thanks to anyone who can help.

does it happen when you have a/c on only or all the time

no it dont do it with ac on it does it some when you hit brake pedal and after it warms up good you can stab gas it will do it also .

I'm not sure about a bad booster's effect, but a common cause of "brake surge" on a 22RE equipped vehicle (and maybe the 3.slo V6) is the idle RPM set too high. Check your idle RPM and adjust it down to spec if it's too high. The spec is on a sticker under the hood.

wow, u had this problem for a year? hopefully things didnt get worse over the course of time. Why would it have anything to do with the A/C?

Because the idle will go up when the AC compressor kicks on and back down when it goes off.

thanks guys i checked idle and turned it down problem went away!

You're quite welcome, glad I could help.

I have the same problem and lowered the idle (how do you know what your idle is at when the dash lacks an RPM gauge?) and it fixed the surging when applying the brakes at idle. However, when depressing the brakes AND turning the A/C on, it reappears. What's the issue?

BTW, thanks for the information. I just saved myself the money of having to replace the brake booster as suggested by my mechanic.

Having the AC on will cause a periodic RPM increase or "surge". Use of the brakes might make it more noticeable.

This happens in any gear, at any speed, the more bumpy the road (thus more foot input to the throttle) the worse. At cruising speeds around sweeping corners in tight traffic this can be unnerving.
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