'03 Explorer XLT dies when braking

[fishbonz91]

Hi ya'll,

My V8 recently started having a pretty serious issue. I was coming home from work monday of last week and hopped off the highway and slowed down to turn under the overpass and my car just shut off. I lost power steering but my stereo stayed on which means its not an alternator/battery type issue. When i crawled underneath my vehicle I started noticing all kinds of things(its been a while since i last looked). I automatically assumed it was in either my fuel system or my intake/exhaust.

My first guess was fuel filter since i hadn't changed that yet so I swapped that out. No fix. While I was down there i noticed that my down stream passenger side o2 sensor had become disconnected and had to be replaced so I swapped that out with an OEM one from Bosch. $50

I then disconnected my muffler to see if maybe I blew out a catalytic converter again but that wasn't it either. It simply ran louder like it should.

I checked my air filter that I replaced six months ago. Cleaner than my dishes.

I pulled off my IAC valve and it was obviously broken(the retaining rod was missing?? maybe shot through the rubber boot?). I replaced that for about $100. It helped smooth out my idle but my car still died.

So then i started chasing vacuum leaks around and found none. I checked my brake booster valve as well and it had plenty of suction.

Found an oil leak around my oil filter adapter gasket. Changed that.(not an easy task given its location). Changed oil and coolant at this point as well.

My explorer now runs better than it ever has but it still wants to die on me!! No CEL. Rpms in idle are normally around 750 or so but like to drop and surge whenever i hit the brakes. I'm at a loss. Next thing I guess would be to check the EGR valve?? I'm assuming the MAF would throw a code. Im really hoping it's not the torque converter because those get pretty pricy. I really thought it would be the brake booster. Any ideas would be much appreciated! Sorry for the long post but I wanted to provide all the info!

 

[swshawaii]

PCV elbow checked? Does NOT always throw a CEL or trouble codes, at least with the 4.0 SOHC. Good luck.

May only apply to late 2002 and after build dates (4.6L). See posts #11 and #12
https://www.explorerforum.com/forums/showthread.php?t=217062

 

[fishbonz91]

I pulled the pcv hose and had suction on both ends. The elbow looked fine. Thanks for the quick reply!

 

[TechGuru]

Is your brake booster leaking when you apply the brakes?

Try disconnecting your brake pedal switch to rule out any electrical issue, if it still does it your brake booster has to be leaking really bad when you apply the brakes allowing a massive amount of air into the intake.

You could also try disconnecting your brake booster line and plugging the intake side and see if it does it. Be careful if you drive it that way, you will experience what it was like before power assisted brakes were invented. Required a very strong leg.

 

[fishbonz91]

How do i tell if it's leaking? Would the pedal travel to the floor?

 

[dla]

Hi ya'll,

My V8 recently started having a pretty serious issue. I was coming home from work monday of last week and hopped off the highway and slowed down to turn under the overpass and my car just shut off. I lost power steering but my stereo stayed on which means its not an alternator/battery type issue. When i crawled underneath my vehicle I started noticing all kinds of things(its been a while since i last looked). I automatically assumed it was in either my fuel system or my intake/exhaust.

My first guess was fuel filter since i hadn't changed that yet so I swapped that out. No fix. While I was down there i noticed that my down stream passenger side o2 sensor had become disconnected and had to be replaced so I swapped that out with an OEM one from Bosch. $50

I then disconnected my muffler to see if maybe I blew out a catalytic converter again but that wasn't it either. It simply ran louder like it should.

I checked my air filter that I replaced six months ago. Cleaner than my dishes.

I pulled off my IAC valve and it was obviously broken(the retaining rod was missing?? maybe shot through the rubber boot?). I replaced that for about $100. It helped smooth out my idle but my car still died.

So then i started chasing vacuum leaks around and found none. I checked my brake booster valve as well and it had plenty of suction.

Found an oil leak around my oil filter adapter gasket. Changed that.(not an easy task given its location). Changed oil and coolant at this point as well.

My explorer now runs better than it ever has but it still wants to die on me!! No CEL. Rpms in idle are normally around 750 or so but like to drop and surge whenever i hit the brakes. I'm at a loss. Next thing I guess would be to check the EGR valve?? I'm assuming the MAF would throw a code. Im really hoping it's not the torque converter because those get pretty pricy. I really thought it would be the brake booster. Any ideas would be much appreciated! Sorry for the long post but I wanted to provide all the info!

If it dies when coming up to a stop light - suspect the TCC.
If it dies any time you step on the brakes when stopped and in park - suspect the brake booster.

 

[fishbonz91]

By tcc you mean torque converter clutch? How could i check that?