Stall when braking, when outside temp is hot

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Topic author
Lumpy
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Stall when braking, when outside temp is hot

Post by Lumpy »

Any brainstorms on this weirdness appreciated... ](*,)

89 Astro, everything stock V-6, automatic.

Van starts fine. Runs fine highway or city. As I'm decelerating, as if coming up to
a stop sign, the engine wants to stall WHEN I start touching the
brakes and ONLY when the outside temp is maybe 90 degrees or more.
It's as if the RPMs suddenly drop so low that the engine just quits.
Once in a while it will stall in a similar manner when it's just parked
and idling, no brakes or other loads applied. But always when the
outside temp is high.

Doesn't seem to matter what the engine temp is, just started up
or running for an hour, everything above is still the same.

Does seem to happen more often when the A/C compressor is on.
A/C fan doesn't seem to make a difference. But the A/C on or off
DOESN'T seem to make a difference if the outside air temp is
in the 80s (F) or lower.

New engine 30k miles ago. New battery that always tests
fine. New plugs-wires-distrib cap-rotor
just a couple months ago. Replaced a bunch of vacuum lines
(the small lines, not the big brake booster lines). Still can't sense
any vacuum leak. OBDI codes don't show a thing. I have the hell
grounded out of this van, battery, body panels, chassis, alternator,
exhaust etc. Batt voltage is always good, 13.8 or so, sometimes
even higher. No electrical loads, including brake application, cause
the batt voltage to drop more than a couple tenths and then it
typically comes right back up as the alternator "catches up" with
the load.

I seem to recall something about the brake switch doing something
with the onboard computer, telling it to keep the rpms up(?) or
something similar.

For some reason, I still want to suspect vacuum.

Where's the magic "push this and it'll be fixed" button?... :dunce:


Lumpy

LiftedAWDAstro
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Re: Stall when braking, when outside temp is hot

Post by LiftedAWDAstro »

It kinda sounds like the EGR is slightly plugged and keeping it open just a touch. I would pull it off and just inspect it to see if you can see any chunks or pieces. Then clean it well and re-install. When it gets real plugged the van will stall all the time and it will be a bear to keep running.
Current rides:
2013 Toyota Tundra DC 4x4
2008 Dodge Nitro 4x4
2005 Nissan Sentra 1.8S Special Edition

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Vans owned:
1986 Safari 2.5L 4 speed manual - scrapped
1995 Astro 2WD conversion 4.11 posi, shift kit, DHC rock rails - sold to Skippy
1998 Astro 4x4 D44, D60, NP231, full hydraulic system with 9k# Milemarker winch and snow plow - sold to Lockdoc
2003 Astro AWD all stock - traded for a 3/4 ton truck
2005 AWD, 4.10's - sold to skippy
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Kabey's Van
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Re: Stall when braking, when outside temp is hot

Post by Kabey's Van »

Not to hijack your post but;
I have a simular problem with my van, although the ambient temperature does not seem to be a factor. When the motor is up to temperature and if I brake normaly or hard it feels as though the t/c is not unlocking and it trys to stall the engine. If I apply the brakes lightly it comes to a stop with no issues. :-k

Peter

Topic author
Lumpy
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Joined: Sun May 31, 2009 6:52 pm

Re: Stall when braking, when outside temp is hot

Post by Lumpy »

LiftedAWDAstro wrote:It kinda sounds like the EGR is slightly plugged...
Thanks Mucho!

I got in there and looked just now, based on your suggestion.
I'm not sure I can see or at least know what the EGR looks
like.

BUT

While in there, I found one of the wires supplying the TBI injectors
had worn insulation as it passed through the plate under the air
cleaner housing. That may or may not have been shorting to
ground. So I patched that with some RTV. Later today when
it gets hot I'll test it. I like to change just ONE thing at a time
when troubleshooting.

BONUS - I just learned that now that I've done a 2 inch body
lift, I can actually get the air cleaner and it's housing off the
engine from the FRONT. No more pulling the dog house just
to change the air filter. :D Even if I didn't like the look of
the lifted van, the cost and time involved in doing the lift
would be well worth the elimination of the hassle of having
to open the dog house just for that.


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Kidhauler
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Re: Stall when braking, when outside temp is hot

Post by Kidhauler »

The EGR valve is mounted behind the fuel injector and looks like a flying saucer on edge with a vacuum hose that comes off of it and goes to a small controler box mounted on the passenger side valve cover. From there there is a vacuum line that goes to the right rear side of your intake on the bottom edge of the TBI. When putting the vacuum lines back on make sure you don't push them on too far. They usually have a 90 degree bend in them where they push onto the manifold (TBI) and onto the EGR valve. If you push these too far down they will seal and the valve will not work and you will thow a engine code when the EGR fails to open.

The other thing to check is if your TAC (thermostatic air cleaner) is working correctly. This is the little cardboard tube that goes from the exhaust manifold sheild up to the intake snorkle on the air cleaner assembly. This is used to help the engine heat up faster in cold weather as it has a temp sensitive damper in the intake snorkle to shut off the cold air and help the engine pull warmer air from the outside edge of the exhaust manifold. If this is staying closed in hot weather the van will run poorly as the engine is sucking in stoopidly hot air from the exhaust manifold.

Last I would check the plugs, cap , rotor, and spark plug leads.
1999 Safari Touring edition.
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Re: Stall when braking, when outside temp is hot

Post by kings-x59 »

check the vacuum on the hose from the pcv valve to the tbi. pull the pcv end of the hose, with the engine idling put your thumb over open end of the hose, it should just about suck your thumbprint off. If that throttle body has never been rebuilt, I'd be willing to bet the whole bottom side of it is hard clogged with carbon and dirt, and I mean hard. When I rebuilt mine I had to use a small screwdriver and a lot of throttle body cleaner to scrape the crap out of it.
'89 Astro, 4.3L, TBI. Minor intake and exhaust mods. Rebuilt 700R4 trans (by me). Corvette servo, 0.5" boost valve, police grade 1-2 accumulator spring (shifts fast and solid). B&M stacked plate trans cooler. Bilstein shocks. Belltech sway bars front and back. New head unit, speakers and subwoofer. Needs paint and a new headliner.

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LaGrasta
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Re: Stall when braking, when outside temp is hot

Post by LaGrasta »

A number of you mentioned a stalling problem I'm now having. Anyone have a follow up? "Kabey's van" described exactly what I'm experiencing.
1998 Astro, 246,000 miles

K&N air filter
TruCool trans cooler
2" Overland lift & 15" BFG Terrain, 3.73 gears
JET Performance SCU-2000 (Speed Control Unit)
Gabriel Ultra shocks, rear AirLift bags & sway bar
Draw-Tite Dual Port Hitch System, hitch-mounted bike rack (4), hitch-mounted cargo tray, Thule roof-mounted cargo box
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LaGrasta
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Re: Stall when braking, when outside temp is hot

Post by LaGrasta »

UPDATE: Rebuilt the tranny and the problem has not occurred again.
1998 Astro, 246,000 miles

K&N air filter
TruCool trans cooler
2" Overland lift & 15" BFG Terrain, 3.73 gears
JET Performance SCU-2000 (Speed Control Unit)
Gabriel Ultra shocks, rear AirLift bags & sway bar
Draw-Tite Dual Port Hitch System, hitch-mounted bike rack (4), hitch-mounted cargo tray, Thule roof-mounted cargo box
User avatar

justice
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Re: Stall when braking, when outside temp is hot

Post by justice »

LaGrasta wrote:UPDATE: Rebuilt the tranny and the problem has not occurred again.
my 87 used to do the same thing when the tranny was going out
I have a ban hammer and I ain't fraid to use it!


Current - 2004 Astro Cargo


Former
95 Safari (money pit - sold)
93 Astro Cargo (totaled)
85 Astro - (Bought for parts and scrapped)
92 Astro Conversion (sold)
87 Safari Shorty (sold)
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