Intermittent Engine Stall After Hard Brake
 

Over the weekend I have been testing the brakes. About one out of every five or six times, the engine dies after I come to a complete stop when I slam on the brakes.

I just got done doing a complete overhaul of the braking system, of which, the vacuum booster was replaced. I figured the vacuum booster would have been the cause, but with a new vacuum booster, and the engine still dying occasionally, I think I can rule out the vacuum booster.

Before I replaced the vacuum booster, I tested the engine dying after a stop both in drive and in neutral. With that, I think I can rule out the transmission.

Sometimes I can hear the RPM of the engine drop when I apply brakes.

Could the brakes be too much of an overload for the vacuum system or a potential leak in the system?

no check engine light? could be a few things. EGR valve is bad, you can take it off and take it to autozone for free testing or the throttle position sensor or even an oxygen sensor. might even just need to turn up your idle. might just be too low. but i'm almost 100% sure it has nothing to do with your brakes!

I agree, I doubt it's with the brakes as I've changed EVERYTHING on the brake system...well, almost everything. I do think the idle may be a little low. At idle, there is an ever so gentle miss.

The RPM is sitting around 500, and if I'm not mistaken, it should be closer to 750-1000.

A low idle would explain why the engine bogs down a little bit when applying the brakes.

On the plus side, a low idle would probably increase fuel economy. :D

rpm is 600 RPM factory. Clean out your throttle body and run Chevron fuel system & injector cleaners. Also, make sure your spark plugs are in good shape. Do this and the motor should run smoother. Mine did after throttle body clean, injector cleaner, and new plugs.

Thanks. The RPM is right on at 600 RPM. I was thinking about how I wanted to attack this...fuel or air. I know it has a recent (within a year) distributor and plug wires. Plugs, MAS clean, and fuel additive doesn't take much time or money at all to do.

Thanks for the input. It helps to validate what I was thinking.

Just trying to run through my head what happens when you step on the brakes...
vacuum will change..
What engine loads are changing?
is it a really at braking or is is rapid deceleration?
Idle air control?
Throttle position sensor?
does it do it if you shift out of gear?

Actually, need something very important. What year, model, engine?

The make/model/year is a '97 C1500 Suburban 2X4, 5.7L Vortec. I thought it was in my signature line...I'll have to double check that.

When I was doing some maintenance test runs (while the brake booster was bad) I would slam on the brakes from about 30-35 MPH and the engine would die just after I came to a complete stop. I would then place it in neutral to restart with no problems during restart.

To verify it wasn't a tranmission problem, I was able to duplicate the same results while in neutral.

While doing another maintenence run/emergency stop after I replaced the booster and master cylinder, I have only had it happen once more out of five stops.

The primary fuse/relay box is loose (located near the firewall,driver's side, under the hood). The inboard side is bolted in and the outboard side plastic retention tab is broken/missing. I suspect that might be an issue. I have acquired (legally) a new/used fuse/relay box mount from a parts truck. I plan on changing that out this week.

I'm also planning on doing what Joe in NY suggested: fuel treatment, spark plugs, and cleaning the throttle body & MAS.

A little voice in the back of my head is saying to check the vaccum lines.

Couldn't find any Chevron fuel cleaner, was going to use STP fuel cleaner, but the guy at the store suggested Lucas fuel cleaner. I'm used that with a full fuel tank earlier this week. After about 100 miles, no noticeable change.

I pulled the throttle body just a little bit ago. Also got a new throttle body base gasket, but it was just fine...replaced it anyways. Cleaned out the throttle body. The idle in the butterfly was completely clogged with carbon. Cleaned it up and put everything back together. Started right up with a slightly high idle, but that seems the normal for a cold start until it gets warm. Haven't driven it yet. It does sound a little smoother. I will check the idle here in a little bit while I take her out for a short drive.

I think I still feel a little bit of roughness. If this doesn't fix it, I'll pull the spark plugs and check them, along with new plug wires (which appear to be newer).

FWIW, Techron is Chevron's name for their FI cleaner. It's the only thing I've found that works.

Gotta love those A-10s. Tremendous airplane!

+1 on the Techron... its what I have been using... is it working? IDK but its readily available at Sam's by a 4 pack case so I have been using it...
As for aircraft speak.. all I can claim is that my brother was a mechanic / crew chief for F4 Phantoms out at Bergstrom AFB here in ATX...:)

you can find the chevron stuff online and i heard really good things about bg 44k as well. also online ebay about $15 or so and also on amazon but a bit more expensive. i would change those plugs as well if they haven't been done recently

F-4s were another awesome plane. Always wanted to get a hop in one but the opportunity never presented itself. Only shortcoming was no guns. Somebody in the braintrust thought that there was no need for them in the age of missiles. :eek: IIRC, during Vietnam, they added a strap-on gun pod.

I'll have to double check the autozone or O'Reillys. Not sure if they carry it out here (N. Texas).

Yeah, I love the A-10 too. I've been crewing them for over 11 years.

The F-4 is also another great aircraft that I love. I'm glad they started to use F-16's for target drones...maybe they'll stop shooting down the F-4's

So, I've replaced the vacuum booster and the master cylinder back in November due to a bad (leaking) master cylinder. Since then, I've also done the Techron treatment and replaced the spark plugs. Still a slight miss at idle. And had the engine die again after a hard stop. I duplicated it again while in idle. It'll start right back up again like nothing happened. I'm suspecting something vacuum related as the vacuum booster is relatively new. I'm also thinking that the slight miss/low idle may related.

Still haven't figured out why I cannot connect to the OBD-II. The OBD-II shows power, but doesn't connect. I'm thinking I may need to replace the Engine Computer. Although, I would think the engine wouldn't run if the computer was bad. Fortunately, a reman computer is only about $100.

With a new computer, would I need to get the stereo security reprogrammed at a dealership?

Any input?

Stall when braking
 

Mine was EGR.. Exact symptoms as yours

Thanks for the update. I fixed the initial problem 3 years ago.... it turned out to the be the brake booster. The OBDII issue was due to a faulty ABS module. As far as the engine miss code (can't remember what it was as it was 3 years ago), I replaced the spider valve and the plenum cover gasket, but it still acted up. At the request of my wife, I sold the vehicle. I only paid $1200 for the truck, and sold it for a $1000, so it wasn't bad considering I had it for 2-3 years with 215K total on the odometer. Hopefully the new owner enjoyed (who had five kids) was able to quickly fix it and use it for needs.

2008 Chev Tahoe - Engine Stall/Rough Run when Braking
 

Stalling out
 

Here's my thoughts.i have a 96 1 door and the fuel tank is much smaller than the 4 door and isn't baffled .the problem with that is with a quarter tank or lower all the fuel runs forward and it does everytime.see if yours still stalls with a full tank .I bet not

Colorado 2.8
 

I have a 2006 Colorado 2.8 with an automatic transmission that is shutting completely off when braking, just not every time I use the brakes. It has happened several times as I am coming home. The road is rough right before I turn so I tend to hold the brakes slightly to keep the truck going slower. When I go to make the turn is when I realize the truck has turned off. I've been trying to watch the guages more as I come home and have noticed the RPMs will drop and bounce really low unless I take my foot off the brake. I ran the codes and listed them below. Any ideas?

• P0449
• P0030
• P0017

2015 Sierra
 

Twice now I've had the engine stall after a hard brake.
Once on I-35 and almost **** myself.

All the older posts seems to be about older vehicles.

Idle RPM
 

Try revving in neutral and suddenly release the accelerator. If the engine tries to die, you could try a professional injector cleaning. Cheers. Wavelength.