Vacuum booster/ master issues.

[BADASSOMAR]

So I recently did the conversion from the power master to vacuum and now having issues. The day it was completed I drove the car home from shop and while on the freeway doing about 75ish car was running fine, but when speed dropped to about 40 mph or so and I started to accelerate car felt like it was misfiring or bogging if that makes any sense?? After I got home I parked the car for about 3 days and when I went on a drive my pedals went to the floor and had no brakes again. Swapped master for a new one, did a bench bleed, did the brakes also and car felt fine stopping. Drove it a couple more days and then my pedal hit the floor again. could my booster be bad??? Anyone had this issues before??? Also , car is still doing the misfire when doing about 45 mph after speed comes down. Also not sure why someone drilled and tapped the plenum when can had a vacuum block already?? Any tips or help is appreciated. Thanks

Omar

 

[hensleyt]

first where did you get the conversion kit ? Im not sure how a booster can cause the pedal to go to the floor, you must have a fluid leak. Look at all the connections for leaks ,all the wheel cylinder and calipers too. Try bleeding the breaks again this time you should not have to bench bleed. start with the right rear then left then right front and left front last. I have not done my kit, hope someone can correct me but I think the lines have to be switch on the new master cylinder.
Not sure about the miss is it at sustained speed of 45 it misses our just a miss at 45 coming to a stop?
If some one drilled my plenum I hope he removed it. This is why Im the only person that touches my car. There are exceptions but if I can't stand in the shop to watch I go some were else. They may look like a Monte Carlo but their NOT.

 

[1986 Buick GX1]

I have not done my kit, hope someone can correct me but I think the lines have to be switch on the new master cylinder.

You are correct. The lines do need to be switched, however, they are different sizes and are idiot proof. Hey, I did it. Lol

 

[BADASSOMAR]

the pedal came from a local guy that has made a few. Booster and master cylinder came from a local parts store.

first where did you get the conversion kit ? Im not sure how a booster can cause the pedal to go to the floor, you must have a fluid leak. Look at all the connections for leaks ,all the wheel cylinder and calipers too. Try bleeding the breaks again this time you should not have to bench bleed. start with the right rear then left then right front and left front last. I have not done my kit, hope someone can correct me but I think the lines have to be switch on the new master cylinder.
Not sure about the miss is it at sustained speed of 45 it misses our just a miss at 45 coming to a stop?
If some one drilled my plenum I hope he removed it. This is why Im the only person that touches my car. There are exceptions but if I can't stand in the shop to watch I go some were else. They may look like a Monte Carlo but their NOT.

The pedal came from a local buddy that has made a few for other guys and has worked great, booster and master came from a local auto parts store with lifetime warranty, I am going to double check all my connections for leaks before I pull it back out and replace it. The misfire happens when accelerating and speed gets up to 35-45 mph and once it gets to higher speed it’s normal.

 

[BADASSOMAR]

 

[KC87]

Wouldn't be the first time a booster was bad, especially if it was a rebuilt one.
I would never buy the master and booster together as one unit, if one is bad most places are going to want
both back to replace on warranty.

 

[mikes86ttop]

Do you have a check valve installed?... Mike

 

[hensleyt]

I don't think the miss is related to the new vacuum brake instal. Vacuum leaks usually bring BLM out of control high idle, stalling things like this.
Yes the check valve is a must have.
I believe you are working with two different problems. During the booster install you will be in close proximity of plug wires and plugs to the ignition module. I would check my plug wires and all caps for damage. and the injectors harness too its right there also.
Back to the breaks. Is the red brake light on?

 

[SCOOBY DOO]

Can you give us SM numbers with the engine warmed up in Park.

 

[BADASSOMAR]

Do you have a check valve installed?... Mike

I don't think the miss is related to the new vacuum brake instal. Vacuum leaks usually bring BLM out of control high idle, stalling things like this.
Yes the check valve is a must have.
I believe you are working with two different problems. During the booster install you will be in close proximity of plug wires and plugs to the ignition module. I would check my plug wires and all caps for damage. and the injectors harness too its right there also.
Back to the breaks. Is the red brake light on?

No check valve , just the I e on the booster, adding one this weekend, also going through and replacing all vacuum lines that are dry and old. I will look over all my connections and plugs also see if I find anything there. Some one mentioned to me that the TC lockup solenoid coins also be the cause of this???? I’m also going to check that out this weekend. can does not have a Scanmaster and also going to install one. Thanks