85 22RE replaced head & timing chain. Timing was out 20 degrees when started. Found broken wire in harness to tps & was able to time to 5 BTDC with pins shorted. Truck had miss but ran OK at 20 BTDC. At correct timing truck won't start & stay running cold unless I press accelerator & rev to 1300 for 30 seconds. It then runs rough & puffs grey smoke at idle. Once truck warms up its starts ok but still smokes. Valves are adjusted correct and timing is in correct position with idle @ 750. Has anyone heard of this? Motor has 110,000. Any help would be appreciated.

 

The auxiliary air valve increases the idle at lower temperatures. What usually happens most of the time is the orifice in the throttle body that leads to the air valve gets clogged.

Remove air intake hose from the throttle body, feel around the left corner of the TB and you should feel a couple of orifices there. Remove the fat hose that goes from the bottom of the throttle body to the air valve and liberally spray throttle body cleaner through all of the orifices. It's important to remove the hose from the throttle body to the air valve since the throttle body cleaner will short out the heating element in the air valve.

 

Well it starts better than it ever did. Runs great untill it warms up (3 minutes after starting) then it starts puffing smoke and has a miss at idle and remains missing when accelerating. The miss is pretty steady or rhythmic. Checked timing and valves all are to spec. No engine codes (except 1 flash indicating ECU is operating correctly). Checked for vacuum leaks and have found none (used o2 safe carb cleaner). Any Ideas?

 

Might check the EGR valve, it could be plumbed incorrectly and opening at the wrong time. It does have a temp. sensitive valve (BVSV) under the throttle body that allows vacuum to reach the EGR modulator when the engine warms up, But if set up right, it should be closed at idle and only come on above certain RPMs and at certain throttle positiions. For a quick test, try disconnecting/plugging the vacuum line to the EGR and see if anything changes.