high idle and others

[fc2young]

so i have this issue. my truck starts fine but then the idle goes to 1100 if i touch the gas and stays there till i turn it off. also my dash gauges are acting wierd. the oil pressure and eng temp gauges completley bottomed out the other day. heater was blowing hot and plenty of oil. ive got no codes at all from the computer except the one that says everything is ok. could these be related or should i assume they are different issues and troublshoot seperatly?

1990 bronco 5.8 e4od

 

[bobstrat]

if you don't touch the gas at all it idles normally? the intake manifold gaskets are a pretty common failure. mine would idle at around 1500 rpm when the gasket between the upper plenum and intake manifold was bad.

 

[fc2young]

if you don't touch the gas at all it idles normally? the intake manifold gaskets are a pretty common failure. mine would idle at around 1500 rpm when the gasket between the upper plenum and intake manifold was bad.

yeah i had thought of that, but my gaskets are only about 4 months old. had to replace a blown head gasket. im beginning to think i have a ecm/harness issue. I've noticed that when i turn the heat on with fan to full speed my tach jumps up anther 500 rpm but the motor doesn't sound like its speeding up at all.

pulled my throttle body to check the tps and iac both are good but i discovered the linkage was bent and it wasnt going passed 1/3 open. fixed that and now when i mash the go pedal its almost like when the truck was new.

cheking for bad wires but there are a lot.

 

[Seabronc]

From your description, it sounds more like a connection or grounding problem. Check the harness connection by disconnecting, checking for corrosion and reconnecting it. Check the instrument panel grounding connection under the dash, (on my truck it is just to the right of the gas pedal), a black wire connected to the fire wall. There should also be a ground from the back of the engine to the fire wall which could be bad.

Good luck,

>-

 

[fc2young]

think ive got the fast idle down. my vacuum line to the acv (emission thing) was missing. looks like its been gone for some time too. most of the tubes are dried and extremely brittle. also found my egr solenoid is busted. going to get it all back together this weekend and go from there. gonna multimeter it too, check wiring and what not.

 

[BroncoJoe19]

How to Check a ground

Turn the power to the circuit on, and using a digital volt meter, put one lead to the grounded wire, and the other to a good ground. If there is voltage, clean your ground.

Turn power to the circuit off, and use a self powered test light, or an ohm meter, and test the grounded wire to a good ground. IF the light goes on, or there is continuity on the ohm meter, then the ground is probably good. (There may still be ressistance in the connection, if significant one will see it in the ohm meter, or the light may not shine brightly.) Using a DVM is a better method!

good ground.

The best ground is the battery neg terminal. There may be some resistance in the battery connector, and wire(s) that then connect to the engine block, body frame, and interframe connections. To locate a good ground, one should use a DVM digital volt meter, and put one probe to the bat neg terminal, and the other to a ground. Ideally there will be no voltage recorded (unless there is an open) a few millivolts are acceptable. If one finds voltage, one must locate any poor connections between that ground and the neg terminal of the bat, and clean it.