Hayhayman Posted August 19, 2015 Report Share Posted August 19, 2015 Would the brake booster or brake master cylinder cause the RPMs to go up when you step on the brake? Quote Link to comment
datsunfreak Posted August 19, 2015 Report Share Posted August 19, 2015 It could be causing a vacuum leak? Haven't seen it happen myself, but I suppose it's possible... 1 Quote Link to comment
datzenmike Posted August 19, 2015 Report Share Posted August 19, 2015 Two things happen.. There is a load on the charging system when all the brake lights come on. This is not enough usually to do much more than drop a few RPMs from the added load. If the brake booster were faulty there may be an increased vacuum leak. Vacuum leaks don't make the idle speed increase unless it were too rich to begin with. Maybe the rear carb is out of sync with the front. Then the added air would burn with more gas and the revs go up. Clamp the large hose to the brake booster and see if this removes the increased idle speed. Quote Link to comment
datsunfreak Posted August 19, 2015 Report Share Posted August 19, 2015 What he said. Clamp the large hose to the brake booster and see if this removes the increased idle speed. Quote Link to comment
datzenmike Posted August 19, 2015 Report Share Posted August 19, 2015 Perhaps a third observation.... does it have cruise control? Quote Link to comment
Hayhayman Posted August 19, 2015 Author Report Share Posted August 19, 2015 Perhaps a third observation.... does it have cruise control? no Quote Link to comment
datzenmike Posted August 19, 2015 Report Share Posted August 19, 2015 Then... Clamp the large hose to the brake booster and see if this removes the increased idle speed. 1 Quote Link to comment
Hayhayman Posted August 20, 2015 Author Report Share Posted August 20, 2015 Then... did that, rpm still goes up. Ill probably be replacing the booster and master cylinder soon anyways. Quote Link to comment
Draker Posted August 20, 2015 Report Share Posted August 20, 2015 Why.. if it goes up with the hose clamped.. it's not your issue. Quote Link to comment
510farmer Posted August 20, 2015 Report Share Posted August 20, 2015 Is your car a automatic? Quote Link to comment
DaBlist Posted August 20, 2015 Report Share Posted August 20, 2015 By clamping the hose you understood that meant pinching the hose until it was totally closed off? 1 Quote Link to comment
datzenmike Posted August 20, 2015 Report Share Posted August 20, 2015 Or remove it and hold thumb over fitting on the manifold. Maybe the hose has a split too. 1 Quote Link to comment
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