When I use the brakes on my 1989 Wrangler 4.2L 5-speed the engine stalls. It
doesn't happen during idle and the brakes are used, just when coming to a stop
while driving. When I am driving and I put the clutch in, the engine idles
fine. It's only when the brakes are used. At idle, if I twist the steering
wheel side to side, it loses a few RPM, but nothing like how the engine just
dies when the brakes are used. I've tried moving the idle up to 20,000 RPM,
but it doesn't help, the brakes just pull the RPMs down low enough to stall the
engine. The carb is running a little rich but not bad. Brake fluid looks
good. The engine has over 165,000 miles on it. Oil pressure is up towards 80
during idle and driving, but sinks quick when brakes are applied while driving.


I'm going crazy over this.

Any ideas why this is happening.

Thanks!
-Mark

 

That implies a sticky EGR valve to me.

The EGR opens at speed and if it closes to slow, it dies when braking.

You can disconnect and plug the vacuum line to it to see if that makes a
difference. If so a good soak in carb cleaner can free them up after
you remove it.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Mark12211 wrote:
>
> When I use the brakes on my 1989 Wrangler 4.2L 5-speed the engine stalls. It
> doesn't happen during idle and the brakes are used, just when coming to a stop
> while driving. When I am driving and I put the clutch in, the engine idles
> fine. It's only when the brakes are used. At idle, if I twist the steering
> wheel side to side, it loses a few RPM, but nothing like how the engine just
> dies when the brakes are used. I've tried moving the idle up to 20,000 RPM,
> but it doesn't help, the brakes just pull the RPMs down low enough to stall the
> engine. The carb is running a little rich but not bad. Brake fluid looks
> good. The engine has over 165,000 miles on it. Oil pressure is up towards 80
> during idle and driving, but sinks quick when brakes are applied while driving.
>
>
> I'm going crazy over this.
>
> Any ideas why this is happening.
>
> Thanks!
> -Mark

 

That implies a sticky EGR valve to me.

The EGR opens at speed and if it closes to slow, it dies when braking.

You can disconnect and plug the vacuum line to it to see if that makes a
difference. If so a good soak in carb cleaner can free them up after
you remove it.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Mark12211 wrote:
>
> When I use the brakes on my 1989 Wrangler 4.2L 5-speed the engine stalls. It
> doesn't happen during idle and the brakes are used, just when coming to a stop
> while driving. When I am driving and I put the clutch in, the engine idles
> fine. It's only when the brakes are used. At idle, if I twist the steering
> wheel side to side, it loses a few RPM, but nothing like how the engine just
> dies when the brakes are used. I've tried moving the idle up to 20,000 RPM,
> but it doesn't help, the brakes just pull the RPMs down low enough to stall the
> engine. The carb is running a little rich but not bad. Brake fluid looks
> good. The engine has over 165,000 miles on it. Oil pressure is up towards 80
> during idle and driving, but sinks quick when brakes are applied while driving.
>
>
> I'm going crazy over this.
>
> Any ideas why this is happening.
>
> Thanks!
> -Mark

 

That implies a sticky EGR valve to me.

The EGR opens at speed and if it closes to slow, it dies when braking.

You can disconnect and plug the vacuum line to it to see if that makes a
difference. If so a good soak in carb cleaner can free them up after
you remove it.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Mark12211 wrote:
>
> When I use the brakes on my 1989 Wrangler 4.2L 5-speed the engine stalls. It
> doesn't happen during idle and the brakes are used, just when coming to a stop
> while driving. When I am driving and I put the clutch in, the engine idles
> fine. It's only when the brakes are used. At idle, if I twist the steering
> wheel side to side, it loses a few RPM, but nothing like how the engine just
> dies when the brakes are used. I've tried moving the idle up to 20,000 RPM,
> but it doesn't help, the brakes just pull the RPMs down low enough to stall the
> engine. The carb is running a little rich but not bad. Brake fluid looks
> good. The engine has over 165,000 miles on it. Oil pressure is up towards 80
> during idle and driving, but sinks quick when brakes are applied while driving.
>
>
> I'm going crazy over this.
>
> Any ideas why this is happening.
>
> Thanks!
> -Mark

 

That implies a sticky EGR valve to me.

The EGR opens at speed and if it closes to slow, it dies when braking.

You can disconnect and plug the vacuum line to it to see if that makes a
difference. If so a good soak in carb cleaner can free them up after
you remove it.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Mark12211 wrote:
>
> When I use the brakes on my 1989 Wrangler 4.2L 5-speed the engine stalls. It
> doesn't happen during idle and the brakes are used, just when coming to a stop
> while driving. When I am driving and I put the clutch in, the engine idles
> fine. It's only when the brakes are used. At idle, if I twist the steering
> wheel side to side, it loses a few RPM, but nothing like how the engine just
> dies when the brakes are used. I've tried moving the idle up to 20,000 RPM,
> but it doesn't help, the brakes just pull the RPMs down low enough to stall the
> engine. The carb is running a little rich but not bad. Brake fluid looks
> good. The engine has over 165,000 miles on it. Oil pressure is up towards 80
> during idle and driving, but sinks quick when brakes are applied while driving.
>
>
> I'm going crazy over this.
>
> Any ideas why this is happening.
>
> Thanks!
> -Mark

 

Hi Mark,
Could have a leak in the power brake assist diaphragm, usually you
can hear it from under the dash, at the push rod.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Mark12211 wrote:
>
> When I use the brakes on my 1989 Wrangler 4.2L 5-speed the engine stalls. It
> doesn't happen during idle and the brakes are used, just when coming to a stop
> while driving. When I am driving and I put the clutch in, the engine idles
> fine. It's only when the brakes are used. At idle, if I twist the steering
> wheel side to side, it loses a few RPM, but nothing like how the engine just
> dies when the brakes are used. I've tried moving the idle up to 20,000 RPM,
> but it doesn't help, the brakes just pull the RPMs down low enough to stall the
> engine. The carb is running a little rich but not bad. Brake fluid looks
> good. The engine has over 165,000 miles on it. Oil pressure is up towards 80
> during idle and driving, but sinks quick when brakes are applied while driving.
>
>
> I'm going crazy over this.
>
> Any ideas why this is happening.
>
> Thanks!
> -Mark

 

Hi Mark,
Could have a leak in the power brake assist diaphragm, usually you
can hear it from under the dash, at the push rod.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Mark12211 wrote:
>
> When I use the brakes on my 1989 Wrangler 4.2L 5-speed the engine stalls. It
> doesn't happen during idle and the brakes are used, just when coming to a stop
> while driving. When I am driving and I put the clutch in, the engine idles
> fine. It's only when the brakes are used. At idle, if I twist the steering
> wheel side to side, it loses a few RPM, but nothing like how the engine just
> dies when the brakes are used. I've tried moving the idle up to 20,000 RPM,
> but it doesn't help, the brakes just pull the RPMs down low enough to stall the
> engine. The carb is running a little rich but not bad. Brake fluid looks
> good. The engine has over 165,000 miles on it. Oil pressure is up towards 80
> during idle and driving, but sinks quick when brakes are applied while driving.
>
>
> I'm going crazy over this.
>
> Any ideas why this is happening.
>
> Thanks!
> -Mark

 

Hi Mark,
Could have a leak in the power brake assist diaphragm, usually you
can hear it from under the dash, at the push rod.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Mark12211 wrote:
>
> When I use the brakes on my 1989 Wrangler 4.2L 5-speed the engine stalls. It
> doesn't happen during idle and the brakes are used, just when coming to a stop
> while driving. When I am driving and I put the clutch in, the engine idles
> fine. It's only when the brakes are used. At idle, if I twist the steering
> wheel side to side, it loses a few RPM, but nothing like how the engine just
> dies when the brakes are used. I've tried moving the idle up to 20,000 RPM,
> but it doesn't help, the brakes just pull the RPMs down low enough to stall the
> engine. The carb is running a little rich but not bad. Brake fluid looks
> good. The engine has over 165,000 miles on it. Oil pressure is up towards 80
> during idle and driving, but sinks quick when brakes are applied while driving.
>
>
> I'm going crazy over this.
>
> Any ideas why this is happening.
>
> Thanks!
> -Mark

 

Hi Mark,
Could have a leak in the power brake assist diaphragm, usually you
can hear it from under the dash, at the push rod.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Mark12211 wrote:
>
> When I use the brakes on my 1989 Wrangler 4.2L 5-speed the engine stalls. It
> doesn't happen during idle and the brakes are used, just when coming to a stop
> while driving. When I am driving and I put the clutch in, the engine idles
> fine. It's only when the brakes are used. At idle, if I twist the steering
> wheel side to side, it loses a few RPM, but nothing like how the engine just
> dies when the brakes are used. I've tried moving the idle up to 20,000 RPM,
> but it doesn't help, the brakes just pull the RPMs down low enough to stall the
> engine. The carb is running a little rich but not bad. Brake fluid looks
> good. The engine has over 165,000 miles on it. Oil pressure is up towards 80
> during idle and driving, but sinks quick when brakes are applied while driving.
>
>
> I'm going crazy over this.
>
> Any ideas why this is happening.
>
> Thanks!
> -Mark

 

Not familiar with that model, but would it by any chance use vacuum
assist for the brakes?

If so, the vacuum boost probably has a pretty good leak when
the pedal is depressed, causing extreme leaning out.

An even more obscure cause could be something in the brake light
sensor shorting out enough to drop the ignition?

Mike Romain proclaimed:

> That implies a sticky EGR valve to me.
>
> The EGR opens at speed and if it closes to slow, it dies when braking.
>
> You can disconnect and plug the vacuum line to it to see if that makes a
> difference. If so a good soak in carb cleaner can free them up after
> you remove it.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Mark12211 wrote:
>
>>When I use the brakes on my 1989 Wrangler 4.2L 5-speed the engine stalls. It
>>doesn't happen during idle and the brakes are used, just when coming to a stop
>>while driving. When I am driving and I put the clutch in, the engine idles
>>fine. It's only when the brakes are used. At idle, if I twist the steering
>>wheel side to side, it loses a few RPM, but nothing like how the engine just
>>dies when the brakes are used. I've tried moving the idle up to 20,000 RPM,
>>but it doesn't help, the brakes just pull the RPMs down low enough to stall the
>>engine. The carb is running a little rich but not bad. Brake fluid looks
>>good. The engine has over 165,000 miles on it. Oil pressure is up towards 80
>>during idle and driving, but sinks quick when brakes are applied while driving.
>>
>>
>>I'm going crazy over this.
>>
>>Any ideas why this is happening.
>>
>>Thanks!
>>-Mark