94 k1500 5.7 stalling at idle. About to lose my mind.

[sbradc]

Hello, so I have been chasing this problem in my truck for about 2 weeks now. It started with the injectors not firing one morning. So I changed out the ignition control module along with the pickup coil, rotor, and rotor cap. So put everything back together and it fired up great but now its dies at idle. Basically as soon as it idles down to 700 rpms it shuts off. It seems to drive down the road okay after taking it around the block but it just will not idle with any load on the engine. So far I have tried the following

• different new ignition control module.
• fuel pressure tested at right around 11 psi.
• changed the pickup coil to the old one from before i started having the problem.
• tried the old cap & rotor.
• new iac valve.
• new ac delco plugs.
• new egr and cleaned
• tested the map sensor and it seems good.
• new coil.
• set timing to 0 with est wire disconnected.
• replaced the base gasket on the throttle body because it seemed to have a slight vacuum leak and cleaned up around the iac port.
• test voltage on tps and was right around .7 volts but swapped with a spare i had that showed around .5

It will idle all day long with the est wire unplugged and will even let the idle drop down to around 500 rpm without stalling. The last thing I have tried is once again resetting the iac valve but this time I unhooked the iac connector after pulling the jumper and started the engine. I expected it to have low idle but instead it idles at right around 1200 rpm. Im not sure if this means I need to adjust the idle down but havent got a chance to do that yet. If anybody has any help or advise to offer that would be awesome because I have hit a wall.

 

[magimerlin]

Is your check engine light on? If so take a piece of wire and connect terminal "A" and "B".. turn ignition to on position. The light will blink the codes. It will do a 12 no matter what(tells you it's working).. blink once then pause then blink twice... Will do each code 3 times then move to the next.. plenty of right ups on how to read tjem if need more in-depth directions. And the obd1 codes are on this site as a sticky thread somewheres....

And since I didnt see mention of it... have you changed your fuel filter yet?

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[sbradc]

Is your check engine light on? If so take a piece of wire and connect terminal "A" and "B".. turn ignition to on position. The light will blink the codes. It will do a 12 no matter what(tells you it's working).. blink once then pause then blink twice... Will do each code 3 times then move to the next.. plenty of right ups on how to read tjem if need more in-depth directions. And the obd1 codes are on this site as a sticky thread somewheres....

And since I didnt see mention of it... have you changed your fuel filter yet?

Sent from my SAMSUNG-SM-G891A using Tapatalk

No unfortunately no check engine light. Jumping the terminals will flash 12 and thats it. Fuel filter was changed probably less than a month ago. Ive tried to research as much as I can and even bought a obd scanner so I can datalog the ecm and get a better ideal of whats going on but still have a lot to learn about that. Should the engine idle down with the iac unplugged or is it normal for it to have a high idle after doing the reset steps? Thanks for the help!

 

[sbradc]

So, for anybody that runs across this issue in the future I finally figured out the problem after 2 weeks of beating my head against the wall. It turned out to be the distributor. Found a cheap gm used one on ebay, threw it in now it idles and runs great. Here is a video of the issue before I changed out the distributor. Hopefully this helps someone out and much thanks to everyone that posts all the helpful info on this site.

xc_hide_links_from_guests_guests_error_hide_media

 

[A_Medina]

Just this happened yesterday while I was taking a turn, but my distributor has been making a “whining” noise for a month, I think I will go first with that, not that long ago replace the fuel filter, the IAC valve isn’t that old and new spark plugs just about 2 weeks ago. Thanks for sharing it.