Loss of power when braking
05-04-2016, 10:15 PM
#1
On The Tree
Thread Starter
Loss of power when braking Hey guys, here recently I've been having some strange issues when I apply the brake. Lights dimming and drop of rpm, twice to the point of the car dying at red lights. This morning on the way to work sometimes I'd mash the brake and the odometer lighting would go out. As soon as I removed my foot from the brake it would light back up. On the way home this afternoon the car died on me at a red light. My test when I got home was pulling the ebrake in the garage and putting the car in drive; I repeatedly pumped the brakes and as soon as I quit the interior light would dim and the rpms would drop almost to the point of stalling the engine. It is a v6 don't really know if it would make a difference but it might. Any help would be appreciated because it is a daily driver and very unsafe that it might just shut off out of no where. It's only happens twice to that extreme but it always seems to start struggling when brakes are applied.
05-05-2016, 11:36 AM
#3
if you have or can get a handheld scanner that shows real time data, specifically manifold pressure. at idle it will be low (high vacuum) around 30 kpa. as you hit the brakes if you see that manifold pressure number rise significantly then look for a a vacuum leak at the brake booster... i'm not knowledgeable about the v6 setup but if you can remove and plug the plastic vacuum line going to the brake system thus disabling the brake booster, and if that solves the problem then you know where the problem is. be aware you don't want to go drive anywhere without the brake booster hooked up because that effectively disables your brakes so don't go drive down the road. but doing so while keeping the car in park idling would be fine, or if you're in a safe area on a flat street/driveway rolling less than 5mph.
05-05-2016, 03:46 PM
#5
On The Tree
Thread Starter
Originally Posted by 1 FMF
if you have or can get a handheld scanner that shows real time data, specifically manifold pressure. at idle it will be low (high vacuum) around 30 kpa. as you hit the brakes if you see that manifold pressure number rise significantly then look for a a vacuum leak at the brake booster... i'm not knowledgeable about the v6 setup but if you can remove and plug the plastic vacuum line going to the brake system thus disabling the brake booster, and if that solves the problem then you know where the problem is. be aware you don't want to go drive anywhere without the brake booster hooked up because that effectively disables your brakes so don't go drive down the road. but doing so while keeping the car in park idling would be fine, or if you're in a safe area on a flat street/driveway rolling less than 5mph.
05-05-2016, 05:49 PM
#6
When these things happen on an auto - the first thing I always check is for a bad torque converter. Next time it happens, put the car in to Neutral. If the problem goes away instantly - you'll know the problem is there and not in the engine compartment. (If the torque converter starts to bite when it shouldn't, it will cause the engine to bog.)
05-06-2016, 02:07 PM
#7
parts stores usually only read DTC, but i would ask you might get lucky.
i have an innova 3160b, cost $200 amazon, i don't really recommend it. you might be able to find one at harborfreight for $100 or less that will show some real time data, but even then it might not show it fast enough to see the manifold pressure value changing. my 3160b has about a 1 to 1.5 second update rate.
i think autozone sells readers, the Actron brand, and there are models that will show real time data but they cost $200 or more.
i have an innova 3160b, cost $200 amazon, i don't really recommend it. you might be able to find one at harborfreight for $100 or less that will show some real time data, but even then it might not show it fast enough to see the manifold pressure value changing. my 3160b has about a 1 to 1.5 second update rate.
i think autozone sells readers, the Actron brand, and there are models that will show real time data but they cost $200 or more.
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05-06-2016, 03:13 PM
#8
On The Tree
Thread Starter
Originally Posted by 1 FMF
parts stores usually only read DTC, but i would ask you might get lucky.
i have an innova 3160b, cost $200 amazon, i don't really recommend it. you might be able to find one at harborfreight for $100 or less that will show some real time data, but even then it might not show it fast enough to see the manifold pressure value changing. my 3160b has about a 1 to 1.5 second update rate.
i think autozone sells readers, the Actron brand, and there are models that will show real time data but they cost $200 or more.
i have an innova 3160b, cost $200 amazon, i don't really recommend it. you might be able to find one at harborfreight for $100 or less that will show some real time data, but even then it might not show it fast enough to see the manifold pressure value changing. my 3160b has about a 1 to 1.5 second update rate.
i think autozone sells readers, the Actron brand, and there are models that will show real time data but they cost $200 or more.
05-06-2016, 03:21 PM
#9
this would work: $100 http://www.autozone.com/test-scan-an...?checkfit=true
this looks like it'll show at least the MAP value, says it shows maximum 2 live values:
$70 http://www.autozone.com/test-scan-an...er/554465_0_0/
whether you can buy one of these from autzone, carefully open then repackage and return it an hour or two later saying you bought the wrong one...
this looks like it'll show at least the MAP value, says it shows maximum 2 live values:
$70 http://www.autozone.com/test-scan-an...er/554465_0_0/
whether you can buy one of these from autzone, carefully open then repackage and return it an hour or two later saying you bought the wrong one...
05-06-2016, 03:27 PM
#10
the free way is this, if you have a 2nd person inside to press the brake pedal
http://www.agcoauto.com/content/news/p2_articleid/129
and if you find brake fluid inside the brake booster, then the brake master cylinder is leaking and you should replace that also.
http://www.agcoauto.com/content/news/p2_articleid/129
A ruptured diaphragm also allows, atmospheric pressure to enter the intake manifold. This creates a vacuum leak and causes the fuel/air mixture to lean out. Other than hard braking, another symptom is an engine misfire at idle, when we depress the brake pedal. Atmospheric pressure lowers the engine vacuum, by leaking through the diaphragm. It is simple to test for this. We can unplug the hose at the brake booster and block the end with our thumb. If temporarily unplugging the booster and blocking the hose solves the misfire, it shows a leaking booster.
05-06-2016, 04:39 PM
#11
On The Tree
Thread Starter
Originally Posted by 1 FMF
this would work: $100 http://www.autozone.com/test-scan-an...?checkfit=true
this looks like it'll show at least the MAP value, says it shows maximum 2 live values:
$70 http://www.autozone.com/test-scan-an...er/554465_0_0/
whether you can buy one of these from autzone, carefully open then repackage and return it an hour or two later saying you bought the wrong one...
this looks like it'll show at least the MAP value, says it shows maximum 2 live values:
$70 http://www.autozone.com/test-scan-an...er/554465_0_0/
whether you can buy one of these from autzone, carefully open then repackage and return it an hour or two later saying you bought the wrong one...
