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Hi all, Rick Baran from Burlington Washington here.

my 87 Bii just got it's new motor, courtesy of a HORRIBLE oil change mishap at Sears. They neglected to put an oilfilter gasket on, and I made it about 1/2 mile down the freeway...!! Anyways, the 2.9 is factory fresh, but it's surging significantly during idle when cold.

It'll surge up to say 1500, then down to maybe 800...up to 1500, down to 650...up to 1500, down to stop. Once it's warm it's just fine, and if I hold my foot on the accel keeping it at 1200 or so it's fine.

Any idears? The guys at Skagit Ford have checked all the sensors and state they're good.

Rick

I'm not to familar with the FI engines, but I'd maybe start with the TPS adjustment, then make sure the fuel pressure regulator is ok and hooked up to the correct vacuum line. Also check the condition of the idle air bypass.

Too bad sears didn't cash you out. You could have had one sweet V8 conversion for that price!

MY 2.9 used to do that

IAC Cleaning/Testing:

The IAC is usually a cylindrical unit attached to the upper intake manifold. found on drivers side of intake manifold. This unit is electrically controlled by the computer, and allows air to flow into the intake at idle, bypassing the throttle plate. The extra air is accompanied by extra fuel to bring the idle up to proper speed, and when cold, allows a high idle condition. These units may become dirty, and need cleaning. Many idle and stalling issues tend to be blamed on these units. Cleaning is achieved by removing the electrical connector, and two screws holding it on. Once off of the vehicle, clean with throttle body cleaner (or a good carburetor cleaner). Continue cleaning until unit is clean, like new; reinstall unit. This is also a good time to clean the intake, and EGR ports (if applicable).

Testing may be achieved by bringing the engine to operating temperature, noting the idle speed (should be within spec). Unplug the unit’s electrical connector, and the idle should drop to about 650 RPM. When the unit is reinstalled, it should return to normal idle speed. If the vehicle does not idle at proper RPM (too low), there are no vacuum leaks, and the TPS calibration is correct, than the unit is most likely faulty.

i would start with the IAC and see if it helps, but remember it takes unhooking the battery to reset the codes in the computer or approximatly 100 starts of a motor............ my 2.9 used to do that, and even though you have a new motor chances are they used the old throttle body and all the fuel injection system from before

if cleaning the IAC and resetting computers codes doesnt help then try the throttle positioning sensor.....BUT CLEAN THE IAC FIRST .......

to test it warm truck up turn key to on position with motor off , the center wire to ground should read 0.9 volts to ground .....if not adjust screw at lower part untill it does...... if adjusted with idle correct, but this is unlikely your surging problem it is usually accustome to the IAC bieng dirty.....

if the only thing that slows you down on being able to do this cleaning on the IAC is a gasket, go inside get your home phone book and use the back page and cut one out formit, its no more than a paper gasket used on it, thats what i used on mine and it worked wonderfully ........

The IAC was replaced, courtesy of Skagit Ford. I still have the problem. I'm going to treat the intake with SeaFoam today and I'll let everyone know if this improves performance. I also checked the IAC voltage and idle-checked the engine with the IAC unplugged...normal. So I'm going to move onto the MAF sensor next.
Although the guys at Skagit did reuse the intake manifold, they cleaned it very thoroughly. I'll keep looking for vacuum leaks also.

How would I check for the correct vacuum connection on the Fuel Pressure Regulator?

Rick

I might be wrong but i t sounds like the ecu trying to adjust idle speed. I have seen many cars do this sometimes for almost an hour. being its a new motor that would be my first guess. cars also do this if you dissconnect the battery too long. my suggetion would be to drive it around a few days see if it goes away.

There is and adjustable IAB plate that Ford makes to correct idle problems. I gave one to Nobody the other day, maybe he can post up the #. Also the vacuum lines on the intake box can do weird things if not correct. I would take it back to the stealership and make them fix it since it's new.

ok then my next step would be check the TPS, with key on and motor off the center wire should be reading about 0.9 - 1.0 volts when a meter is attached between it and ground, disconnecting it should affect the motor causing it to die....

and i know it might sound stupid but change the PCV valve as this too can affect idling conditions on the 2.9 v6...........

also a partially stopped up fuel filter can affect a motor at idle....... causing irratic idling conditions, and a decrease in fuel milage.