weird issue when idleing the engine up when cold?

[rattlebox93]

i have a 92 250 stick pod's pump maxed out 3200 spring no afc intake exhaust and when its really cold out the truck will start fine idle fine but when you slowly start to rev it up it gets to about 700rpm and then falls off to about 400-500 rpm and idles really badly and when you keep reving it up past that fall off point then it will pick back up and run good after about 1000rpm but only until the engine warms up then the issue goes away....anyone seen anthing like that? any ideas? it did it with my stock injectors so i dont believe it is the injectors thanks

[dodgetkboy78]

Sounds like a filter or lift pump.

[burnt_servo]

if you put the afc back in i'll bet the problem goes away .

my gut feeling is your dumping way too much fuel in without the afc removed and your putting " the fire out " so to speak , when the engine is cold .

slightly advancing the timing may help some what too .

[dodgetkboy78]

Wouldn't dumping more fuel cause it to rev up?

[burnt_servo]

Wouldn't dumping more fuel cause it to rev up?

if the engine was hot , yes ......

cold engine , lots of fuel can equal what rattlebox is talking about .

think of it in these terms , take a very small fire ( less than 6 inches around ) at -30c , drop a 5 gallon pail of diesel that is also at -30 on the fire .

the fire goes out ......


do the same thing at +30c and you could have a huge fire ball .

[ironeagle59]

I have intake exhaust and no AFC 3000 gov spring and bosch 190s on my truck and even when it was 8 degrees f it would rev up even when cold. Mine is advanced 14 degrees though so maybe that would help