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stalling issues


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scott soroky
Novice

Nov 9, 2016, 12:54 PM

Post #1 of 16 (934 views)
stalling issues Sign In

I have a 1993 chevy G20 van with a 305 V8 that keeps stalling out. After it stalls the only way to get it to start again is if I disconnect the battery to reset the ecm. Once I do this it will fire right up again. It doesn't do it all the time and there is no rhyme or reason. Purchased a replacement ecm and used the old prom, van still stalls. Someone said the prom might be bad but that is super rare. Any thoughts??


kev2
Veteran
kev2 profile image

Nov 9, 2016, 1:01 PM

Post #2 of 16 (929 views)
Re: stalling issues Sign In

What tests have you done ?
Check codes - even if CEL is out?
When no start is there spark?
When no start is the fuel injectors spraying?
Let us know - remote starter, added alarm, modifications...


PS: Confirm TB or spider injection this is right around the switch over year


scott soroky
Novice

Nov 9, 2016, 1:27 PM

Post #3 of 16 (920 views)
Re: stalling issues Sign In

Not sure what tests have been done as i took it to an automotive garage. I do know that it is TB and it is complete stock with no added accessories. new fuel pump and ecm. according to the mechanic, who is reputable, after check multiple things he though it was the ecm until i told him it had been replaced. that's when the idea of the prom came up.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 9, 2016, 2:46 PM

Post #4 of 16 (911 views)
Re: stalling issues Sign In

Not much point in testing for codes if you are going to keep disconnecting the battery and erasing all the diagnostic info.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



kev2
Veteran
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Nov 9, 2016, 3:05 PM

Post #5 of 16 (908 views)
Re: stalling issues Sign In

Its not always easy - diagnostics work is labor intense,
OK a professional has the vehicle, when event happens plug in scanner - yeah there are OBD1 scanners BEFORE disconnecting-
The TB allows a quick visual check of fuel the basic spark and whatever codes - AGREE with colleague - just do NOT disconnect battery until conclusions are made


Discretesignals
Ultimate Carjunky / Moderator
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Nov 9, 2016, 4:48 PM

Post #6 of 16 (901 views)
Re: stalling issues Sign In

Why does your mechanic think it is the ECM or PROM causing this? What is it losing when it stalls (spark, fuel pressure, injector pulse)? Does it stall at idle, cruising, accelerating, or all the above?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Nov 9, 2016, 4:52 PM)


scott soroky
Novice

Nov 14, 2016, 12:04 PM

Post #7 of 16 (867 views)
Re: stalling issues Sign In

The mechanic said he performed some tests (did't specify) and his conclusion was the ECM. When i told him it had been replaced he then said it must be the prom. Even he agreed it was rare that they went bad though. As i was driving it this past weekend i noticed that when it stalled a couple times it was when my foot was off the gas. After it stalled on me one time i started it and feathered the gas. If i kept the rpms up it wouldn't stall at all but if i let my foot off the gas it would. Again, after it stalls it will turn over but not start until i reset the ecm. Once i do that it fires right up.


Discretesignals
Ultimate Carjunky / Moderator
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Nov 14, 2016, 1:04 PM

Post #8 of 16 (860 views)
Re: stalling issues Sign In

If it runs fine when you have foot on the gas and then only stalls when you don't have your foot on the gas, that could be an idle air control system fault.

Has your mechanic cleaned the throttle bore, throttle plate, IAC pintle, and IAC pintle bore?

Another thing that could cause stalling at idle is a stuck open EGR valve.

Most of the time an ECM that is going bad will cause stalls and all kinds of weird things at all engine speeds and/or no starts.

Resetting the ECM's memory may be a coincidence or enabling the ECM to relearn the idle control motor's position.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Nov 14, 2016, 1:09 PM)


scott soroky
Novice

Nov 14, 2016, 1:11 PM

Post #9 of 16 (856 views)
Re: stalling issues Sign In

I doubt it so i will have to have that done. any idea why i would have to reset the ecm to start again?


scott soroky
Novice

Nov 14, 2016, 1:13 PM

Post #10 of 16 (855 views)
Re: stalling issues Sign In

never mind the last question on the ecm reset, you answered it already, sorry.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 14, 2016, 1:35 PM

Post #11 of 16 (853 views)
Re: stalling issues Sign In

Just 2 cents. You were asked post #2 if the CEL (the light bulb) I take that works? If it doesn't why not? If you remove bulbs in some OBDI set ups the vehicle will either not run or run like crap.


Have a cheap code reader for these just can recall if the unit blinked or it just forced the CEL to bling. Just memory it should start with 12 and end with 12 means it's communicating. If not no codes are going to help.


All of the other suggestions still apply just saying missing or blown CEL bulbs are not without consequences. Simple, just turn key to run and it should light up as a bulb check only - does it?


T



(This post was edited by Tom Greenleaf on Nov 14, 2016, 1:41 PM)


scott soroky
Novice

Nov 14, 2016, 1:43 PM

Post #12 of 16 (850 views)
Re: stalling issues Sign In

Hi Tom. I didn't pay attention to it until it was brought up but yes the cel does work and come on.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 14, 2016, 1:53 PM

Post #13 of 16 (848 views)
Re: stalling issues Sign In

Great. I'm near sure as said it won't behave without a working one on some. Too easy to sell a car (can't say for GM trucks) and just take the bulb out or smash it so try to fool a buyer in particular. While here code 12 is, one blink and wait then 2 blinks then a longer wait and repeat means the thing is communicating.
It should at least be able to tell you it is then find out what the hell is wrong :-)


T



scott soroky
Novice

Nov 14, 2016, 1:57 PM

Post #14 of 16 (846 views)
Re: stalling issues Sign In

thanks Tom


Wrenchly
User

Nov 17, 2016, 1:32 PM

Post #15 of 16 (820 views)
Re: stalling issues Sign In

Once upon a time I had a truck that acted this way. It would run rich for a time then shut off.
The only way to start it was to pull the ecm batt fuse and put it back in.

A pile of new computers later the problem was found by driving the vehicle
with the alternator unplugged. Charging voltage was normal but the alternator
was causing the computer to wig out. New alternator fixed the truck.


scott soroky
Novice

Nov 17, 2016, 1:38 PM

Post #16 of 16 (815 views)
Re: stalling issues Sign In

Thanks for the tip, at this point i am willing to try anything.






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