[RESOLVED] Engine stalls when brake is applied at idle

[eclipsed2g]

Hi, I searched all around but I cannot find a reason for this. I have a 90 tsi awd, when my car idles it idles fine at about 700 rpm. I was trying to do a test to see why my brake pedal was so stiff and I couldn't complete the test because when I pressed the brake pedal the car would sputter and die. I check the hose off the booster to the intake and it seemed to be fine. Has anyone else had this problem? Any help is appreciated, and again I have searched but I couldn't find any answer. Thanks in advance.

 

[dimon2000]

the first thing i would check is the vacuum lines you most have a leak some where. when you apply the brake that uses vacuum and if you have a leak your car will stall.

 

[eclipsed2g]

I checked it for connection but ill have to wipe the hose down with water to see if it bubbles anywhere. Do you think the one from the booster to the intake is the one that is giving me the problem?
Thanks

 

[steve]

What happened when you disconnected the booster vacuum line? Did you think to check the idle with it off and the manifold port sealed?

That will help you decide if the problem is a vacuum leak or electrical from the brake lights loading the alternator down.

What happens if you turn on the AC at idle?

 

[eclipsed2g]

Thanks guys for the responses. The brake light fuse is pulled and I haven't disconnected the hose yet. I will let you know soon but for right now my wife is at work and I have our 11 month old so my hands are a little full . The a/c by the way makes the idle increase 100-200 rpms but still bogs when I hit the brakes.
I bought this car a few weeks ago for $300 and I have already replaced the brake lines, did all the fluids and filters, but for some reason I went to check the brakes because the pedal had no play in it at all, and then this happened. He told me the fuse was pulled from the brake lights and that fixed it but apparently he was wrong because its still happening.
Feels like I've been to get this car to run smoothly but it was such an awesome deal its worth a few headaches. I'll try that stuff and get back to you guys in a few.
Thanks again.

Sorry I would give positive to you guys but I don't have sufficient rep yet. ASAP I will send for positive rep for you both.

 

[hydrastas]

i've had a similar issue since i bought my car a month or so ago, i've been troubleshooting the tranny and vacuum lines, egr and other numerous things but i've narrowed it down to my intake camshaft being off a shade over a tooth. when was the last time your belt was changed?

this video is already at a stop holding the brakes but if i didn't have them held the rpms would of stayed in the 700 range after getting in gear. going to a stop i have to put it in neutral at traffic lights or it'll die after i come to a complete stop . not sure if this helps or not but just throwin out about the timing thing.

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[mkgearhead]

If your brake pedal is stiff and it stalls when you apply the brakes, it sounds like the diaphram in you brake booster may be ruptured. Do what Steve said and pull the vacuum line to the booster and cap it off and see if it still stalls. If it doesn't stall, then it's time for a new booster.

 

[steve]

And if it does stall, then it's time to look at the ISC and make sure it's working correctly.

 

[anteversion]

if your brake pedal is very stiff and the vaccum line is ok. than this is the diaphragm in the brake booster that is shot

 

[eclipsed2g]

Thanks again for the responses I will try the diaphragm and line, obviously the cheaper one first . The timing was done 13,xxx miles ago so its recent. I'll try these tonight and tomorrow and will post up if either one fixes it.

 

[Defiant]

The vacuum line to the brake booster is backward. Turn it around.

 

[anteversion]

yes defiant it might be this. But strange enough since this line got the perfect shape and curve to be fitted in the right way without even think about it.

 

[crimsondragon]

Is your car auto or manual?

 

[r1991_4g63t]

The vacuum line to the brake booster is backward. Turn it around.

the line is backwards, theres a check valve in it so it can only pull vacuum and not let boost in, sounds like the valve is backwards from your symptoms

 

[eclipsed2g]

My car is a manual crimsondragon, and I was out in the garage all night and couldn't find a leak. I guess I should've checked this out before I went out and worked on it . I'll check it out tomorrow night and I'll let you guys know.

Sorry not trying to be a post whore but would anyone have a pic of this valve so I can be sure of this. Also about the firm brake pedal would the reversed line cause this or could that be from a stuck caliper piston?

 

[evileagle_95]

Pedal pressure 99.9% of the time almost always has something related back to the hydraulics of the system or the vacuum assist (booster). Start with the line, if you have any carb cleaner laying around, you can also soak the line with it and if there are any tiny cracks you're not seeing, the idle will raise. Majority of the time, a sticky or stuck caliper only creates a dragging/pulling to one side while driving, possibly a grinding noise if it's been stuck long enough!

 

[anteversion]

idle will not raise if he have a leak at the brake booster vacuum line. it is located after the mas so this
uncalculated amount of air will cause the idle to slow down, if not even cause the engine to stall

 

[eclipsed2g]

I'm thinking it's the line after some work tonight. I couldn't tell you if it drags during braking because I haven't been able to drive it further than a block yet . Is that line something I will have to order or could the local autozone etc... have it?

 

[r1991_4g63t]

idle will not raise if he have a leak at the brake booster vacuum line. it is located after the mas so this
uncalculated amount of air will cause the idle to slow down, if not even cause the engine to stall

i think he means spraying the carb clean will raise the idle if sprayed on a vacuum leak which it should do

 

[eclipsed2g]

The issue was resolved, the guy had the line from the booster to the intake on backwards and then to compensate I messed with the ISC and raised it to 800 rpm's. Thanks for everyone's help.

 

[Defiant]

Post #11. And you're not asking for my PayPal account?

 

[eclipsed2g]

Post #11. And you're not asking for my PayPal account?

yeah thanks for the advice, that was the cause. I haven't figured out the brake pedal thing yet but we will bleed them one more time. What should I have expected the guy installed the vac line wrong, thats probably why he sold me the car for $300