Join Date: Jun 2018
Location: Wilmington NC
doug42190 is offline
1993 4.3 TBI emissions questions
Best I can tell my IAC is not functioning properly. I put in a new OEM unit last November. It ran OK but not great -- sometimes it was great.
Things I have done over the past 6 months since I had no history on the truck and it was no crank no start when I got it.
2) IAC valve
4) Plugs, wire, rotor, dist cap. module under dist. cap, coil under dist cap, and battery
5) Engine coil
6) EGR valve
7) Knock sensor
8) Water temp sensor (both)
9) Water pump, thermostat, radiator hoses, belt
10) Changed oil, filter, trans fluid and filter, diff fluid
11) Fuel tank and pump, filter and rubber fuel lines (weren't alcohol friendly)
12) Rebuilt TBI
13) New harmonic balancer
14) MAP sensor
15) Heater core
16) New air filter and PCV valve
That's all I remember at the moment.
I have tried to set the base idle several times but I cannot get past the "give it 30 seconds,(KOEO) with A and B terminal shorted together on the OBD connector" for the pintle to withdraw. I set my pintle at 1" -- installed it, turned the key on then Key off -- jumped the connector, key on for 90 seconds, unplug the IAC valve, pull out the jumper and started the car. I don't have a tach but my guess is it idled between 1600 and 2,000 rpm.
Did this three times. Each time I removed the IAC and measured the pintle and each time it was 1 and 3/32 inches.
Is the IAC valve bad? Is there some way I can check the 4 wire plug for voltage or ohms or ??? When I plug the IAC in the truck idles normally -- I guess about 800 rpm's or so. At times it will "surge" or buck enough to be irritating. Sometimes at low speeds, sometimes highway speeds.
I would appreciate any insight or ideas.