1993 Chevrolet C1500 Silverado 5.7 from North America
Summary:
Best truck in its class!!
Faults:
I have replaced the wiper motor, one wiper arm and brake lines.
Other than that, just general maintenance things.
General Comments:
I love this truck. It is extremely dependable, we use it to haul everything imaginable, we take long trips in it, and it has never let us down. The motor is still incredibly strong for its age.
My husband says it's time for a new one, and it will for sure be another Silverado.
Would you buy another car from this manufacturer? Yes
Review Date: 4th March, 2012
3rd Jul 2012, 16:01
Hi.
Yeah that cam is likely your problem. If all other aspects of driveability are OK, you can likely fix this easily. Check to see if your TPS is set at 0.5V for starters, and if not, set it there. We are assuming that the "minimum air" setting was at least close before the overhaul. Leave the idle screw alone for now. Put the engine in diagnostic mode with the key on, engine off (this will close the IAC). Unplug the IAC and leave unplugged, start the engine (I assume it will not idle). Remove the throttle body and drill 1 small hole in each butterfly on the lower half in the same place on each butterfly, starting with 1/32". After you drill it enough to idle, take note of the RPM increases after each drilling. When you get close to 500RPM, try not to go too far over/or under. You can use the "idle" screw to tweak it after the drill gets as close as possible, then re-set the TPS voltage. Make sure you remove the throttle body every time and clear out all the metal shavings to protect your engine. Remove the diagnostic adapter from the ALDL, plug in the IAC, and you should be up and idling.
IF you have a scan tool, this is much easier. Check the IAC position; it will likely be all the way open. If so, do the throttle body drilling like before. When the IAC gets close to "centering" itself stepwise, you can use the "idle" screw to tweak it to the centered position. Then reset the TPS and you are good to go.
Key: Set the TPS first. Everything is based on this, as after you modify the butterflies, the engine only needs to idle correctly, and see the idle starting point at the correct TPS voltage.
Hopefully it has not been tampered with. If so, or if you suspect it, you will need to put the throttle body on a completely stock engine of same make, year and displacement to get it right. Then put it on your vehicle and do the above.
It's hard to un-drill those holes once you drill them, unless you have a spare throttle body. Only other option is to replace the camshaft.