revs up when i put brakes on!!
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Joined: Nov 2002
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From: Southeast Texas
revs up when i put brakes on!! When im cruising under 2k rpm's and i hit the brakes, it raises up to 2k until i come to a complete stop and when im at the light,the car revs from 1k then goes to 1,500 back and forth the whole time, what could this be?? i made sure the hose for the brakes behind the intake was on tight ..i got a code but its to late to go see what it is... any ideas on what i could check?? ill try just about anything....thanks, dwayne
Brakes make the converter clutch unlock on an
automatic. This probably accounts for the RPM
jump. What accounts for it not coming right down
to idle, is probably a vacuum leak. Presuming you
aren't one of those TB-hole-drillers. I would look to
be sure some of those plumbing mods didn't leave
a little vacuum path; also PCV system. The surging
seems to be common with lightweight torque
converters and a twitchy idle mixture won't be
helping that any. Slow O2s aggravate the loop
and once O2 lag exceeds the control loop time
constant it can get unstable (oscillating at very
low frequency). If you had the ability to watch
O2s in real time you'd be looking for fast (several
per sec) bouncing from like .2 to .7; old cold
crusty ones will hit the floor and the ceiling and
do it more slowly (and, if in time with the idle
hunting, this is your donkey).
automatic. This probably accounts for the RPM
jump. What accounts for it not coming right down
to idle, is probably a vacuum leak. Presuming you
aren't one of those TB-hole-drillers. I would look to
be sure some of those plumbing mods didn't leave
a little vacuum path; also PCV system. The surging
seems to be common with lightweight torque
converters and a twitchy idle mixture won't be
helping that any. Slow O2s aggravate the loop
and once O2 lag exceeds the control loop time
constant it can get unstable (oscillating at very
low frequency). If you had the ability to watch
O2s in real time you'd be looking for fast (several
per sec) bouncing from like .2 to .7; old cold
crusty ones will hit the floor and the ceiling and
do it more slowly (and, if in time with the idle
hunting, this is your donkey).
