1998 Ford 4.2L V6 idle issue

Start at any mechanic or auto parts store to read the codes. Write them down and research solutions (Adjustment? Replacement?) once you know where the problem lies.

Well, first step is to do a basic tuneup, do a check for vacuum leaks, clear the codes, drive around and see what codes get set. With a '98 you get computer control but without so much ability to look inside the computer control.

But... if you don't know what the plugs are like and you don't know if there are vacuum leaks and the fuel filter might be the original one that came with the car, you should at least get the car up to good driving condition before attempting any diagnosis.

Maybe a plastic Jesus might help too. Do actual diagnosis.

--scott

I guess I will need a ODB code reader? Will any one do or only the older ones?

Maybe. 1998 was a transition year... california cars all had OBD-II, some trucks had OBD-II, but some cars and trucks still had OBD-I. Check the manual if you don't see an obvious OBD-II port. You may be having to count light flashes.

--scott

Since he mostly needs to know why it's not running well, he should probably just use the (usually free) code reading services rather than buying a reader at this point.

He might not even need that.

--scott

Thanks, I got a code reader for 21 bucks at Wallymart.

It fit on the plug under the dash, and with the eng running it indicated: P1537, P1538 Found this post online with some things to look into.

I noticed a slight clicking coming from near the alternator area on the pass side after the new belt was on and eng running. As the eng warmed up, the clicking seemed to diminish, almost sounded like a bearing in the really early stages of EOL.

Previously I had noticed an RPM drop when idling at a light one time, seemed like it was gonna stall but fully recovered quickly.

Last week the truck sat unstarted for 3 days, and it started up ok but this RPM drop happened after only 15 seconds, then as before, it recovered fine and I moved the truck into the workbay and did the serpentine belt job.

Didnt see the RPM drop with the new belt, but it only sat 2 days not 3.

Wondering if it could be the alternator bearing, or the idler or tension pulley once in a while binding, slowing down to nearly a stall?

The dealer did say he replaced the tension pulley not long ago, and the old belt had signs of fraying on the outer edges....?

Ok did a little more research and youtube viewing.

Apparently the codes point to (2) IMRC valves and if they are bad you can see idling and fuel economy issues...so that may explain my drop in idle I noticed, and it does seem at times I get poor gas mileage on occasion.

The RT IMRC is Part No. F65Z-9S514-CC, F65Z-9S514-CB Cannot find the PN for the LT side, but an ebay seller told me the OEM Ford valves will almost always have dry rotted diaphrams and are junk and ought not be purchased...and to go with aftermarket.

In one of the youtube videos, they claim you will hear a clicking sort of sound near the intake manifold if these are bad, so that may explain the noise I made not of in the other post.

Another video claimed replacing the Vacuum Solenoid Purge Valve , PN: F65Z-9H465-CA / F65E-9H465-CA solved the 2 error codes so I am thinking about buying this one on ebay:

I guess also a good idea to look at the vacuum lines behind the battery like the other webpost mentioned in the event its a leaky line.

The Truck was at this used car dealer 12 yrs, mostly sitting waiting to be sold, he ran it every now and then for short trips to Home Depot to pick up large items as its got the 8 foot bed, so maybe those diaphrams did dry rot or crack in there?

Ignore the second code. The first code tells you that the computer thinks the intake manifold runner isn't moving.

Some engines will use engine vacuum to move these, some will use a servo. if yours uses engine vacuum, the first step is to check for vacuum leaks which you should have done already anyway..

The next step is to make sure they do move freely by hand, and THEN to check out the position switches that let the computer know that they are open or closed.

Did you replace the tensioner at the same time as the belt? If you squirt a little Super-Lube into the tensioner bearing, does the noise stop?

Have you looked for vacuum leaks yet? You should check plugs too (which won't be causing any of your problems but is a good idea on a vehicle with no maintenance history).

No, that has nothing to do with your stalling problem. That is a different issue. Find out why the computer thinks the runner isn't moving.

--scott

Wound up buying 2 new Dorman replacement IMRC's was gonna try this myself, but theres a lot of stuff to remove to get at them.

Dropped it off at a service station, he says there are (12) 8mm bolts that hold the plenium to the intake and they are corroded pretty bad, cant get any of them to turn without the socket stripping the head of the bolts.

Not much room to work a drill in there for an EZ-out he says, so hes putting it back together and I will I guess try and hunt down another shop or maybe try it myself.

I did buy this purge valve and had a mechanic put it in while he tried to replace the IMRC's. He says the 8mm plenum bolts are stripping as he went to remove them, so he gave up claiming he would do more harm then good but after he changed the purge valve, theres clearly an improvement. Apparently that supplies the vacuum to the IMRC's and the idle is better and the sluggishness at 3000 RPM happens a lot less often.

I thought about trying to remove the plenum myself and use one of these

Also , after the mechanic replaced the purge valve, the check eng lite is on. Will reset with OBD, but returns later with the 2 error codes plus a new one referencing the EGR system.