1994 K1500 p/u. 5.7 motor, auto trans. Problem with smooth starting
and smooth takeoff. This problem just gradually surfaced over the
past few weeks. prior to this, the engine ran just fine.
Truck needs feathering of the gas to keep running on a cold start
(warm start okay). When taking off, engine hesitates and stumbles
until foot is almost to the floor, then it takes off fast. Once it
hits 35mph, it runs well with passing power, but not quite the power
potential that it should have. This problem happens hot, warm & cold.
Timing set a 0 degrees with timing wire under glove compartment
Recent replaced parts include.....
Fuel filter, ign coil, cap, rotor, wires, plugs, ign module, MAP
knock sensor, entire distributor, pickup coil, magnet. (no change)
Fuel pump pressure checked at 13.5lbs good.
Injectors are spraying good & evenly.
TPS checked out okay. EGR works fine.
Sprayed around TBI for air leaks... none.
Intake manifold is tight.
Took off valve covers, checked for broken springs... none.
Went through valves for tight loose ones... none.
Compression test was good and even between all cylinders.
Plugs look great and even across all cylinders, and are not cracked.
Exhaust is clean, no smoke.
Idle is normal with some slight erratic and non-rhythmic stumbles
while in gear & stopped.
When in park, and gas is stepped on, engine stumbles until it hits
2300RPM, then cleans out.
No vacuum leaks.
Since this happens cold & hot (worse while cold), I'm taking in
consideration that the problem exists outside of closed loop, which
should rule out O2 sensor. This problem is intermittent, but it acts
up more often than not. Since it "wakes up" at 35mph and above, I'm
ruling out a fuel problem. As I mentioned earlier, timing is set
My Actron is reading the ECM fine (for what an ALDL is worth). I
ECM's with a friend's truck (same year, etc)... no luck.
Now, I'm really to the point of pulling the ignition system, and
a HEI setup. I'm trying to investigate if the fuel system can work on
own with the wrong ignition system in the truck.
I don't care about the engine light.. as long as it works.
(by the way, we don't have inspections out here in the country. we
the freedom to do whatever we want to our vehicles)