I have a 1989 b350 ran wagon. I am having troubles with it. When you crank it, it idles up and down. When you rev it up around 2000 rpms it still revs up and down. Eventually at idle it will die. I have rebuilt the throttle body (gaskets), replaced the MAP sensor, replaced the Egr valve. I have double and triple checked all the vaccum lines. I replaced the fuel filter. I replaced the fuel pressure regulator. The injectors appear to be good. The flow cone looks good. I don't see any defects in it. The stream is constant and well formed. I don't see any errant streams or weak spots in the flow. I am at my wits end. I don't have any specialized tools like for checking the fuel pressure or vacuum. Anybody here have any type of suggestions for me ? I really need it running again.

 

Is the idle speed actuator motor 's pintle extending and retracting causing the idle to fluctuate?

Do you get any codes when you do the "key dance"?


Grounds are always suspect and should be eliminated as culprits. The engine computer is grounded on the intake manifold under the coil mount.

Battery to engine and battery to firewall need to be removed polished and retightened. Cables with green or white corrosion need to be replaced, and adding a 4awg ground cable between the frame and the engine block somewhere is good preventative medicine.

Disconnect the battery and inspect the connections at the engine computer. Look for corrosion or broken wires that were probed by a mechanic that did not care.

After returning the computer connectors and battery cable, see if wiggling the connectors at the computer causes any idle fluctuations.

If the brakes are funky/weak, replace the check valve on the brake booster

 

at idle the actuator is causing the revving but at higher speed it does not.
There are no codes other than the battery has been disconnected
grounds are good.
The brakes are fine no reving or stumbling when I pump them

 

is this a 318?

 

It is a 360