engine runs like crap when cold

[mr heavy-chevy]

hello

this is starting to really annoy me. its worse some times than others.
recently it was pathetic. like, if the truck was not a stick shift, so i could rev the **** out of it and ride the clutch, it would probably have died if it was an automatic.

it starts great, it idles great, it runs great, but give it any load when cold, and it faceplants.

so im at a loss.

let me know if you have had this problem and what fixed it.
thanks for any help

 

[Georgeb]

Please provide more details. TBI or carb? Any aftermarket parts? Recent work done?

 

[rich weyand]

Let me guess. Someone took the thermac off and it's running an open-element air cleaner.

 

[mr heavy-chevy]

1987 TBI
totally stock
recent full tune up including ICM

i removed the smog pump. plugged the vacuum line. plugged the exhaust air ports. and removed the electronic vacuum plug.



i electronically unplugged the EGR valve and it seems to be better..... but time will tell.
its an intermittent problem.
im letting it cool off again as we speak. but the problem is at its worst when its early morning dead-cold.

 

[Georgeb]

I would check your fuel pressure.

 

[mr heavy-chevy]

i removed the closed loop wire for the smog pump wiring harness and unplugged the harness... i think i fixed it.

 

[mr heavy-chevy]

SAME PROBLEM STILL EXISTS.
it boggs really bad cold... when its hot, it launches... no idea why...

 

[89Suburban]

SAME PROBLEM STILL EXISTS.
it boggs really bad cold... when its hot, it launches... no idea why...

Just a long shot but try disconnecting the EGR valve. Are you getting any engine light at all? There is a TBI troubleshooting thread in here.

 

[mr heavy-chevy]

Just a long shot but try disconnecting the EGR valve. Are you getting any engine light at all? There is a TBI troubleshooting thread in here.

if i disconnect the EGR i get a code after the motor has warmed up and is cruising down the highway.
it does not affect the cold stumble situation at all

 

[CRM]

i removed the smog pump. plugged the vacuum line. plugged the exhaust air ports. and removed the electronic vacuum plug.

Have you tried reinstalling everything to see if it clears up?

 

[Georgeb]

Have you checked the fuel pressure yet? Needs to be between 9-13 psi.

 

[mr heavy-chevy]

i know that the fuel pressure TO** the TBI is fine. because its starting and running great...
and looking at the cones spray, it looks like its leaving the TBI fine....

im just guessing at this point

 

[Georgeb]

i know that the fuel pressure TO** the TBI is fine. because its starting and running great...
and looking at the cones spray, it looks like its leaving the TBI fine....

im just guessing at this point

Yeah but my 87 started and idled fine and fell on it's face when you tried to move it cold. The culprit was a clogged fuel filter. Warm it was fine. That's why I asked.

 

[mr heavy-chevy]

Yeah but my 87 started and idled fine and fell on it's face when you tried to move it cold. The culprit was a clogged fuel filter. Warm it was fine. That's why I asked.

oh wow weird. well if it does it today i will put a new one in. the one on there now looks pretty new tho.
i did swap out the water temp sensor in the intake though

 

[Georgeb]

oh wow weird. well if it does it today i will put a new one in. the one on there now looks pretty new tho.
i did swap out the water temp sensor in the intake though

Mine was also new. It got plugged in about three months. I had crap in the tank.