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vwbugman, VW Technician
Category: VW
Satisfied Customers: 821
Experience:  35 years experience on VW air cooled and water cooled repair and restoration
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Could the EGR valve cause power lose, no vacuum and engine

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Could the EGR valve cause power lose, no vacuum and engine to run hot? 1996 2.0 vw jetta. I have replaced the CAT and fuel pump. The problem is intermitent and the brake pedal gets hard as a rock when it happens and the CAT gets real hot.
Customer From your description, you have brakes that are locking up. When the brake gets hard as a rock, your master cylinder is building up pressure. Causes could be a stuck emergency brake, bad power booster, crimped line, or bad master cylinder. Check the wheels (touch the cener cap and be careful not burn yourself) when this happens. You are driving the vehicle and it is putting a load on it making it run hot. Just like driving with your foot on the brake. Does the car slow down by itself when you are coasting?
Customer: replied 8 years ago.


Don't think it has anything to do with the brakes, unless its the vacuum check valve. The brakes pedal gets hard like there is no vacuum booster. I replaced the booster about six months ago but not the check valve. If the egr valve gets stuck open couldn't that cause this to happen, by making the computer think the car is running lean and flooding the engine with fuel which would make the CAT start to heat up? It doesn't happen often and the brakes don't get un-normally hot.

It is possible but I have not seen it. Have you used a thermal gun to check the temp of the cat. Does it glow red? Does the pedal come to the top when it gets hard or do you still have slack in the master cylinder rod? I don't see how the egr valve is affecting the brakes. Does the engine smell like it is running rich when it happens? You might also try replacing the temp sensor. This sounds like it's one where I would just have to be in front of it to trace it down.
Customer: replied 8 years ago.


The pedal does come up to the top with no slack, almost like it is being pushed up. I have not checked the CAT with a temp gun. I will do more checking and get back to you but I will not be able to work on the car again until Monday.


But I can almost guarantee you that the brake are building up pressure.
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Customer: replied 8 years ago.



I have talked to some other mechanics about this issue. I have been told that the flex hoses to the front calipers are known to fail inside, creating flaps which act like a check valve. I have tried to get the car to "act up again" but it is behaving normally. I have replaced both front flex hoses and the master cylinder and hope this issue does not return. Thank you for your help in solving my problem.



It is possible but unlikely since the car is not that old. The old air cooled hoses stop up a lot but I don't think I've changed but a couple of water cooled hoses. Could you blow through the hoses with your mouth when you got them off. If you could, chances are good that that is not the problem. Anyway it doesn't hurt to change the hoses since they are not that expensive.
good luck and thanks for the accept.