Good Day people I've got 94 Aerostar 3.0 L with a very poor idle condition it goes up and down constantly almost to the stall point!(occasionally does stall)It runs fine during driving range and does not miss or idle bad once it is in gear (stopped In gear)but once it is put in park back comes the poor idle.Any Ideas would be very helpful NOTE: Ive recently had tune up & I changed the maf sensor.Thanx In Advance

 

Bubba:

After having been here for awhile, Most Idle problems seems to be one or more bad spark plug wires. After that the Spark Plugs,
If they don't fix it any one or combo of sensors or Connections.

 

Did you keep the electronics that were with your old meter to use on the new one? Ford would sometimes change the calibrations from year to year, sometimes multiple times in a year. If you changed the electronics on the meter as well I would look at that first. Also clean the IAB valve on the side of the TB.

 

VacuuumVacuumVacuum!

I had a similar problem in my 3.0L, the rear vacuum tree was almost naked with all of the lines had popped off. Pull off the rear engine cover, reattach, enjoy idle.

 

JTHill24:

Plugs & wires were changed with the tune up also would'nt I expect some missing or crossfiring during driving range (especially stopped in gear) if the plugs or wires were foul? scott9050: I'm not sure I follow you do you mean did I keep the old MAF sensor ? And if so how do you re-calibrate the new one? A little history may be in order all I did is change the old MAF sensor with one my buddy had on the same kind of van (Parts van that was running fine but he got a new one because tranny burned)I just changed air box, Maf, pipe and all up to the throttle body.Also you mention the IAB valve Is that different then the IAT sensor?agelder:Have checked all vacuum lines and connections everything seems to be in order.Thank you very much for your replies and anymore ideas I would be very thankfull for Thanx In Advance.

 

Still think agelder is on the right track. It sounds like a vacuum problem.

If you are sure it is not, do a search on this forum for Idle Air Control valve (IAC) for information about how to clean/replace this component. Also look at the PCV valve if this has not been changed in a while. Use needle nose pliers to crimp the hose from the PVC going to the intake and see if this stops the up/down idle condition.

 

Still odd that, while in park it will crap out, but in gear, waiting at a light or something, it's ok. Idle Air Control is the only other thing I could think of if all of the vacuum lines in the back are attached. Sure there is not a leak elsewhere in the vacuum system? Symptoms just seem so similar to what I had.

 

Hi Fordguy:

Three things I would check first before going on to more expensive stuff.

1) Pull the MAF sensor again and check to see if the wires are still intact. They are very fragile and could have broken off when you pulled them from the other vehicle. Also, it's easy to forget to plug the connector back in after you replaced the MAF sensor. Check that again.

2) Check the vacuum octopus at the rear of the engine again. Just because the hose was connected doesn't mean that it's not leaking. On my car, the transmission modulator went bad and transmission fluid got sucked into the engine via the octopus, and that ruins all the vacuum hoses there. I had to replace all of them before my car runs again. Also, there are some ports on the octopus that are capped off with rubber caps. Those could have gone bad also if you have transmission fluid going up that way.

3) This is a long shot, but there is a big rubber hose connected to the side of the thingy that connects the air box and the throttle body. Could you check and see if it's connected.

Good luck and let us know what happened so we could learn from your experience.

Regards

 

Thank you guys for your replies I took out the IAC sensor on the throttle body and gave it a good clean and that seem to take care of the up & down idle conditiion at least temperarily I'm assuming it was that (fingers crossed)The condition did return couple days later Im thinking I'll change that and maybe the plugs as it was running pretty rich for a while I suppose they're probably BLACK by now.Cant see anything else obvious to me all vacuum lines appear connected and in fair condition so Im hoping a new IAC sensor will do it .If you guys think of anything else please drop me a thread......... Thanx again.