2.9l acting a fool

[LtDuke]

Hey guys, I got a 1989 2.9l that I've been thru hell with. It surges at idle and drinks fuel while underperforming where it should.
New parts: fuel tank, fuel pump, injectors, spark plugs, wires, coil, cap & button, timing chain, O2 sensor, idle air sensor, map sensor, water temp sensors, O2 inlet temp sensor, upper intake manifold gaskets, timing chain, new battery to block ground, computer swapped from a 89 ranger with same set up.

No vaccum leaks found by me, the shop, or shade tree mechanic. I'm stumped.

No vaccum leaks found by me or the shop or 2 shade tree mechanics

 

[Dirtman]

Have you pulled the codes? Whats the fuel pressure? Is the timing set properly? (spout unplugged first), And "new" parts don't mean they're good especially if you didn't use motorcraft parts on the electronics. Any one of the parts you replaced could be bad, fuel pump or IAC would be most likely to be bad out of the box.

 

[LtDuke]

Shop checked continuity and said all were working as they should. Timing is set correctly. Fuel pressure is constantly 30psi

 

[RonD]

Welcome to TRS

FPR(fuel pressure regulator), has a vacuum line attached, check that vacuum line for gasoline, if found replace FPR

New stuff sucks
New used to mean "tested and working"
New now means "YOU test it and we will replace it if it doesn't work", lol

Ford still pays extra for quality control, testing of parts before they are shipped, so if its a Motorcraft part you can usually rely on it being OK, and super EXPENSIVE because its tested

3rd party, well never assume its good until YOU have tested it

IAC Valve needs to be Motorcraft or Hitachi brands only, other brands won't work well with Ford computers

Try doing a sanity check on computer, unplug a sensor and start engine, should get a CEL(check engine light) pretty quick
Read the code and clear it, plug sensor back in and try unplugging another sensor
Codes should of course match up to sensor that was unplugged

Dirty PCV valve can cause wandering idle

 

[JerryC]

Put a vacuum gauge on it, see what it tells you.