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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: jaden1997 on January 30, 2014, 03:16:12 pm
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My 87 S10 Blazer stalls when i drive and come to a stop. I've checked just about all the obvious things, but I'm now leaning toward something with the distributor. I was wondering if anyone knew about anything that could be causing it to stall out. Btw it starts right back up each time.
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you check the idle??....could be the idle set to low.
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I adjusted the idle screw a few times, but there was no change in the truck stalling out.
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My 87 S10 Blazer stalls when i drive and come to a stop. I've checked just about all the obvious things, but I'm now leaning toward something with the distributor. I was wondering if anyone knew about anything that could be causing it to stall out. Btw it starts right back up each time.
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Automatic trans or standard ? Which engine do you have ? Does it start to run rough as soon as you slow down or only when you come to a stop ? If automatic, does it downshift ok through the gears as you are slowing down ?
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Automatic transmission, 2.8L V6, it runs rough when i slow down, like you can hear it trying to shut off. Then when i get to a stop it usually does shut off. Yeah it downshifts fine as i'm slowing down.
I don't think it's a transmission problem at all since it will idle oddly in park.
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vacuum leak, the tbi base gasket can be sucked in and cause a problem then once you hit the brakes you will draw more vacuum and stall. this is one theory.
another thing is fuel pressure problems, the tbi uses in tank fuel pump the rubber hose between the pump and fuel pump assembly can crack and cause bad pressure or the pump can cause bad pressure or the sock can cause bad pressure. but fuel problems are usually if it runs crappy other times then just stopping.
egr can also cause a stalling problem.
does you cel light up when you first start the truck? does it stay on? any codes stored?
one more thing, does it stall if you take it out of gear and come to a stop or slow down? tcc in the trans
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I checked for vacuum leaks already and there weren't any. I just rebuilt the throttle body too. I don't think there's anything wrong with fuel because i did a test and i'm getting 13 psi of fuel, which is the right amount. I cleaned out the egr just to see what would happen before. The light isn't on. If i put the truck in neutral then slow down or stop, the truck still stalls out. But i didn't think it was anything in the transmission because the truck will idle weird even when it's in park.
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what vacuum numbers are you pulling?
when its acting up does it still read 13 psi?
does it act up 100% of the time idle and coasting?
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Yeah it reads 13 psi all the way until it shuts off. The. It goes to 0 of course. When I first start up the truck it idles fine. If I let it sit for about 10 minutes, it will start to idle bad.... Or if i start it up and drive for a few minutes then it will idle bad and most likely shut off.
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Vacuum numbers?
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yes numbers. idle vacuum and cruising vacuum. how easy does it start after the stall any smoke?
do you have to wait for it to cool down before the idle or stalling clears up?
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egr test
http://www.gmsquarebody.com/forum/showthread.php?t=6902
the thing im thinking about is when its cold it runs fine but once it OT it starts to screw up. maybe the coolant temp sensor? unplug it and see how it runs (should make it rich) it has to be sensor related since its seams fine in open loop (cold)but once it closes it runs like crap. i wana say the o2 sensors on those engines are ignored till OT then the will start doing their job. i know im all over here but stay with me. also the iac kind of sticks out a little
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Right I see where you're coming from. I'll have to get back on the vacuum numbers.
But it starts just fine after each stall. I don't have to wait or anything. I'm thinking that it's sensor related also. As far as the iac, i cleaned the one that was on there and even tried a different one, but there wasn't a change.
I'm not so sure about the egr valve. I took it off and cleaned it, but it wasn't getting stuck at all. I can certainly read about it in the website and see if there's anything I missed.
When I was looking around the engine once, I think I found 2 coolant temp sensors. I can take a picture of it if you need me to. I just unplug them and see if it runs differently?
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I adjusted the idle screw a few times, but there was no change in the truck stalling out.
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The IAC valve controls the idle speed
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One sensor cts tells the ecm the coolant temp its in the intake near the thermostat housing. The other is the coolant switch its in the head and goes to the dash gauge. My 94 was running like crap while taking off if you didn't floor it it would stumble and try to stall. I got to thinking and unplugged the egr solenoid and she ran good. Plugged it back in and 10 feet down the road she started bucking unplugged it again and she cleared right up. Now our truck are acting different but unplug it and see what it does
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Hmm alright i'll unplug the solenoid and see what happens. I'll have to look at the temp. sensor too
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the temp sensor will only give you too much gas (a cold engine) just do one sensor at a time and see what she will do
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I've also been looking around my distributor too. I took a look at my pickup coil and this is what it looks like. I feel like I need to replace it and see if it fixes my problem. (http://img.tapatalk.com/d/14/02/05/guzava7u.jpg)
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i only had one pick-up coil go bad on me, on my 86 she just stopped after ridding about 20 minutes. first thing i could think of was the coil just cause the way it stopped. waited for it to cool down still no fire, replaced it with a known good one. still no fire, then came the replacement of the distributor (we always have a known good distributor laying around, i usually have one in my tool box) fired right up. replaced the coil and sat her on the shelf for next breakdown.
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I'm honestly down to that coil, a sensor, or maybe the computer itself being bad. I'm running out of things to check and test lol
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did you unplug the egr solenoid ?
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No I didn't yet. I meant to ask.. Unplugging the vacuum lines or the pigtail at the bottom? I'm guessing pigtail
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yes, pigtail
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Ok i'll have to try that today. I'll let you know what happens
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Unplugging the egr solenoid pigtail didn't change anything. It just made the check engine light come on when i got to cruising speed lol
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well im kind of out for suggestions. the only thing i can think of is a vacuum leak and i think you eliminated most of the possibilitys
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may not help you out too much... but i had a similar situation. my 90 model would idle funny once it warmed up, every now and then it would stall at a stop sign or red light, but it would also try to stall when i would take off... sometimes it was random sometimes it was like clock work after checking a million things i got mad one night and pulled the dist out threw it across the yard and threw another one in that i had in my parts chest... has ran like a top ever since.
question(s).. i know you said you have checked the obvious things but that can be different stuff for some people. have you checked the timing (make sure you used the right procedure. tbi engines are different from carb engines you have to unplug the fancy wire)
have you checked compression?
you said it idles funny if you put it in drive and hold the brake while you pus the gas does it start to miss more?
anyone else think the o2 sensor could have something to do with it? i worked on an explorer one time that had a bad o2 reading bad rich and the car actually leaned itself out trying to "correct" the fuel supply just trying to brain storm :)
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well, this probably has nothing to do with it, but maybe the TCC switcjh is sticking on. I know Cavs, Corsicas, Berettas had an issue with this in the auto trans. its a completely different trans but this was the same complaint. just throwing something out there.
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would the tcc still mess with it if he switch to neutral? the oxygen sensor doesn't do anything till the engine coolant sensor reaches operating temp. then the "cold start" kicks off and the oxygen sensor starts working regulating how much fuel. so.... it could be a problem. why did you rebuild the throttle body?
this might help
10. The engine is revving up and down when I come
down to an idle. There is a large “sucking” sound
coming from the throttle body when it is warmed up.
My engine stalls or almost stalls when I come down
to an idle.
This is usually an indication of a vacuum leak; again make sure that you have no vacuum leaks.
This could also be an indication of the wrong base ignition timing. Verify that you have set your
ignition timing correctly (see #4).
Your engine may also require more air going through the throttle plates at idle than it is currently
set for. Here is a procedure to check this setting.
a. Make sure your engine temperature is at full operating temperature.
b. Jumper Pins A & B of the ALDL connector (I use a paper clip) with the key on but the
engine off. This is the same thing you do when checking for engine codes and your
check engine light will flash off and on.
c. Wait about 45 seconds or until any trouble codes present have flashed through; code
12 is normal (see #14) After this then unplug your IAC valve which is on the throttle
body but do not turn off the key.
d. Remove the jumper from the ALDL, turn the key off, wait 15 seconds and start the
engine. It may start hard and you may have to depress the throttle pedal a little bit to
start the engine.
e. If you have a fast idle this did not work or you have a vacuum leak that is not
repaired, or the throttle plates are already too far open. You may have to tape over the
fresh air hole that the IAC receives its air from.
f. If you do not have a fast idle then it is OK and you can proceed to adjust the throttle
plates. Let the engine idle for a little bit and then check you idle speed. The speed
should be about 575 – 600 at idle in drive or about 50 rpm less than you requested for
your chip. If it is lower than this you can raise the idle up or if it is above this determine
if you should bring the speed down. More than likely it will always be lower.
g. There is a little cap on the side of the throttle body by your throttle lever that has an
adjustment screw under it (if not already removed).
h. Remove this cap and use the screw under there to adjust your base idle speed
without the IAC operational. Base idle is to be set in drive for an automatic transmission.
i. If you have done all of this and you still have an issue we may not have received all of
the proper information to build your chip and you will need to call tech support.
If you have gone through all of the above procedures and the engine is still
idling too high you will need to call tech support. When you call tech support
you will need to have the following information available.
Voltage measured between the black wire and brown wire on the TPS with the key on engine not
running__________________
Engine RPM at start up idle on a cold start___________________________
Engine RPM at idle with stabilized temperature_______________________
Engine RPM at idle with IAC fully seated or blocked off.___________________
IAC counts at stabilized idle in drive if using a scan tool____________________
Engine operational temperature_______________________
Initial ignition timing_____________________
Any information that you feel is important for diagnosing the issue at hand
The above is from HERE (http://www.73-87chevytrucks.com/techinfo/TroubleshootingTBISystems.pdf) the only problem i have is who the heck is tech suport
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^^ Power hitter :D
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would the tcc still mess with it if he switch to neutral? the oxygen sensor doesn't do anything till the engine coolant sensor reaches operating temp. then the "cold start" kicks off and the oxygen sensor starts working regulating how much fuel. so.... it could be a problem. why did you rebuild the throttle body?
this might help
yeah, agree with that. I was just trying to think of posibilities and things I've seen. thanks for the clarification on that. plus the diag sheet. wonderful schtuff.
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I forgot to check this lol. I went to the junkyard and pulled the distributor and computer out of another Blazer. I'm going to swap each out this weekend and see what happens. I'm really thinking that it's the distributor now. I will look at the thing about the IAC valve as well
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