86C4

Casual User
May 29, 2014
21
2
VetteCoins
626
Car
1986 C4 Z51 coupe
Province
AB
Ok, so it starts when its cold, let it warm up and cycle through a couple, three fan on/off cylces. Then she will just quit. The attached picture shows the the temp when it shut down. On the attempt to fire up (without stepping on the accelerator) it will want to go (meaning fire), rpms go up a bit and then she dies. (I am pretty sure I could coax it to stay started by feathering the accelerator)
No present codes.
When running fuel pressure is 38lbs.
Fuel tank is 3/4 full.
All injectors ohm out around 14.7 cold and 17.8 hot (replaced last summer)
Did FPR test pulled vac hose off went to 45 ish then back to 38ish when reapplied.
Pulled out the IAC cleaned and put back.
Rewired the TPS connector ( because I hurt it doing a back probe last year and I recived a tps voltage to high code and realized the top male probe wasnt seating in the TPS, since rerwire no code).
Hei Coil and ignition module changed out about 3500 km ago, plugs last summer.

So this is what I have possibly narrowed it down to possibly,
MAF
Bad coolant temp sensor
Some type of heat soak issue in the ignition parts.

But like alot of people right now I dont have the cash to just through a bunch of parts at it and hope it works....lol

So the family is tired of me swearing and trying to figure this out without asking for help.......

Can you help a guy out????

Thanks.
 

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Last edited:
definitely sounds like a heat soak issue. Most likely something electronic.

Pull the trouble codes and see if there's and history codes hiding in there. May point you in a direction. Just don't start replaceing parts the ECm tells you has a fault. Sometimes, the part showing a fault code is not actually what's wrong, but another component is causing it to not work right and throw a code.

Pulling OBD I codes is easy, you just short pins A and B in the ALDL and count the flashes on the "check engine" light:

gm-aldl-connector.gif



Edit: whoops, I missed that you already pulled codes with nothing in there....
 
Yeah, I did do that and I will again just to make sure that nothing came up after it died. I tried to post a video up so people can listen to it and maybe catch something I am not hearing but the forum wont let me.....Thank you for the reply though!
 
Yeah, I did do that and I will again just to make sure that nothing came up after it died. I tried to post a video up so people can listen to it and maybe catch something I am not hearing but the forum wont let me.....Thank you for the reply though!

throw it up on youtube and link it here...
 
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Reactions: Rruuff Day
I AM SOOOOOOOOOO DUMB............:Banghead::doh:
Had a vacuum line screw up ( I was certian they were right), so after I corrected that it fired up multiple times with ease. I am chasing a couple of other gremlins but I won't entertain you all with my stupidity.

:Cheers2:
 
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Reactions: dannyboy
Ok, so it starts when its cold, let it warm up and cycle through a couple, three fan on/off cylces. Then she will just quit. The attached picture shows the the temp when it shut down. On the attempt to fire up (without stepping on the accelerator) it will want to go (meaning fire), rpms go up a bit and then she dies. (I am pretty sure I could coax it to stay started by feathering the accelerator)
No present codes.
When running fuel pressure is 38lbs.
Fuel tank is 3/4 full.
All injectors ohm out around 14.7 cold and 17.8 hot (replaced last summer)
Did FPR test pulled vac hose off went to 45 ish then back to 38ish when reapplied.
Pulled out the IAC cleaned and put back.
Rewired the TPS connector ( because I hurt it doing a back probe last year and I recived a tps voltage to high code and realized the top male probe wasnt seating in the TPS, since rerwire no code).
Hei Coil and ignition module changed out about 3500 km ago, plugs last summer.

So this is what I have possibly narrowed it down to possibly,
MAF
Bad coolant temp sensor
Some type of heat soak issue in the ignition parts.

But like alot of people right now I dont have the cash to just through a bunch of parts at it and hope it works....lol

So the family is tired of me swearing and trying to figure this out without asking for help.......

Can you help a guy out????

Thanks.
 
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