Hi, new to forum, but I've had my Navigator a while and outside of a battery haven't had any major issues.
I had noticed for a couple of days it was starting "hard" in the mornings, up to about 1800 rpm,not something it had done in the past. then Yesterday went to pick up the mother-in-law for Thanksgiving and it suddenly wanted to die every time it came to a stop or started to coast (which was often in yesterdays holiday traffic).
Did a bit of reading online and came up with a plan to change the TPS and IAC as my plan to fix it. Did that this morning and cleaned out the TB blades etc etc....and now when it starts and it revs past 2500 and it idles high in gear (1100rpm).
Any ideas as to what could be causing this?????


thanks
Nick

 

Vacuum leak?
Is the CEL lamp on?

 

The service engine light came on last night driving. I reset it (disconnected the battery) after I changed the IAS and TPS bits but it came back on when driving it around (my code reader could not get anything from the port, apparently FORD used CAN/OBDII, and my Accutron reader can't read that ). I found 2 vacuum elbows (coming out of the PCV valve) that where rotted out and changed those.
It starts, goes to 2800...slowly comes down to about 1000...then bounces to 1400...then back to 1000.


Nick

 

Continue to look for vacuum leaks. When an engine won't come down to idle as normal, it's usually due to a lean condition.
Maybe a miss due to a bad cop or plug?

 

What engine is in that vehicle? The 32-valver?


What kinda shape is the PCV in?
PCV is usually a three stage affair.
Pinch of the PCV hose with a vise-grip and see if the idle still goes high on start up.


At idle, unplug the IAC to see if it makes any difference.

 

Thanks for the feedback guys.
It is the 32v motor.
I found 2 elbows on the PCV line basically rotted. I took some hose and made some temporary ones. But it still revs way up on start up, but actually seems to drive fine (doesn't stall anymore).
Pulling the hose from the IAS drops the idle and it wants to stall.
I'll have to wait until Friday to find a reader that will work with the Ford OBDI port (I'm guessing it's going to say PCV issues)
Do you have to do some type of calibration of the new TPS??

Thanks
Nick

 

It's not OBD I, it's OBD II, you need to get a scantool supporting that.

 

It is also not CANBUS, that came a few years later.

If your scan tool cannot connect, check the fuse for the cigar lighter. See owner's manual.

There is no calibration of a TPS, it probably wasn't bad in the first place as it is very unlikely to cause your symptoms.

Your symptoms are of either a huge vacuum leak, a sludged-up Idle Air Control valve, or a combination of those two factors. Fix all the vacuum leaks paying particular attention to the PCV hose elbow all the way around back where it hooks into the intake. That's the most common and least accessible of the elbows and tubing.

 

Did you plug the electrical connector back into the IAC valve?

 

Thanks again for the input gents.
Yes I know it's OBDI II, my accutron reader does not power on when it's plugged into the port. I'll check the fuses for the power outlets.
The IAC is plugged in properly.
Wouldn't a vacuum leak make it difficult to start and idle poorly?
It starts fine just revs up wildly (2000 rpm+) then slowly settles back to about 1000rpm, however it does take a while to return to idle after you blip the throttle.
Thanks
Nick

 

Those are both common symptoms of a substantial vacuum leak or an inoperative IAC valve.

Keep in mind that the IAC valve is, in essence a controlled vacuum leak.

 

Then perhaps cleaning the IAC wasn't good enough, you might have to replace it.

 

The PCV valve can be a huge vacuum leak if it is sticking in the wide open position. Pinch off the PCV line and see if that brings the idle down.


I believe there is a code for that - P1506.
Get the codes read (and write them down).

 

Ok so I fixed the OBDI port (fuse had blown).... And I had two codes..1506 and 0174. I found 2 of the PCV elbows rotted and have been replaced. I disconnected the battery, grounded the positive side and will run it a bit tomorrow so it can relearn what "idle" is.
Thanks
Nick

 

That should solve the problem.