Ford Bronco II

CHANDLER

MEMBER
FORD BRONCO

Hello, I have a 1986 Ford Bronco II 4x4 XLT fuel infected with and automatic transmission and a 2.9 liter V6. My problem is that it's running really rich smoking black puffs of smoke out of the exhaust I hooked it to a scanner and it says insufficiant EGR flow and thats it. But it doesnt smoke when im accelarating or if I have my foot off the gas only when im trying to maintain speed it blow out puffs of smoke. I have no idea what to check I heard it could be many things. If you could please help me I would really appreciate it. Thanks

1 Reply

RUDPRO

MECHANIC
224 POSTS

First, with the engine cold, start it, wait 1-2 minutes and feel the EGR valve. It should not be hot. If it is, the valve is stuck open, replace it. To test further, follow this procedure:

Install a tachometer on the engine.

Detach the engine wiring harness connector from the Idle Air Control (IAC) solenoid, it's on the side of the throttle body.

Disconnect and plug the vacuum supply hose from the EGR valve.

Start the engine, then apply the parking brake, block the rear wheels and position the transmission in Neutral.

Observe and note the idle speed.

If the engine will not idle with the IAC solenoid disconnected, provide an air bypass to the engine by slightly opening the throttle plate. Do not allow the idle speed to exceed typical idle rpm.

Attach a hand operated vacuum pump to the EGR valve vacuum port. Slowly apply 5-10 in. Hg (17-34 kPa) of vacuum to the EGR valve. You should see movement of the EGR valve stem.

If the idle speed drops more than 100 rpm with the vacuum applied and returns to normal after the vacuum is removed, the EGR valve is OK.

If the idle speed does not drop more than 100 rpm with the vacuum applied and return to normal after the vacuum is removed, inspect the EGR valve for a blockage; clean it if a blockage is found. Replace the EGR valve if no blockage is found, or if cleaning the valve does not remedy the malfunction.