Rough Idle and Noise from Intake(?)

[mkd8919]

Hi Everyone. I’ve got a 1993 Explorer XLT that has developed a strange noise under the hood and a rough idle. In the last week I’ve noticed that it seems harder to start, and idle seems to be quite rough. A couple of times it has died while idling. As of today it is stumbling so much at idle that I shift into neutral while stopped and hold it at 1k RPM, where it seems to run fine. The noise I am hearing is hard for me to place. It sounds like either metal grinding, much like you would hear if your brake pads are worn through and rubbing on the rotor (but much higher pitch) or an air leak from a metal tank. I can hear it while driving and it’s quite loud with the hood open. The noise is present when idling and in park, and also when driving. It becomes very quiet when not accelerating. From what I can tell it’s coming from the driver’s side, in the area around the intake manifold or the head. From what I can tell the noise did not slowly develop. One day everything seemed fine, the next morning I was having issues. The check engine light has not come on at any point. My explorer has around 126,000 miles. Any ideas?

EDIT: I forgot to mention, I checked the oil and it seems fine. The noise does not change when turning so I don't think it is related to the power steering. The MAF was failing so I replaced it with a junkyard replacement. The MAF was replaced along with new plugs and wires @109,000 in 2014. Serpentine belt and Air filter were changed at 114,00 in 2015.

EDIT 2: So I posted this before any real searching, as I want to get this fixed ASAP and wanted people to see the post as soon as possible. After a bit of searching, most of my findings seem to point at the IAC valve for both the noise and rough idle. Does that sound right to anyone else? I should be able to clean that tonight and see if it makes a difference, otherwise it looks like a new one is $50.

 

[mkd8919]

Update, I tried cleaning the IAC valve, no improvement. So I replaced the IAC, but I'm still seeing the same symptoms. After driving it around the block it may be slightly better, but that may also be me being optimistic. Any ideas on what to check next?

 

[Explodr94]

You have to reset computer when cleaning/replacing IAC. It will run rough for no apparent reason if you don't. Hope that fixes problem.

 

[mkd8919]

You have to reset computer when cleaning/replacing IAC. It will run rough for no apparent reason if you don't. Hope that fixes problem.

By resetting the computer, do you mean unhooking the battery for 5 minutes or so?

 

[Explodr94]

Yes, disconnecting battery would reset computer.

 

[Centaurious]

You can use a Mechanics Stethoscope to listen for and track down noises, just take care around moving parts.

 

[mkd8919]

Short update, between work and the weather, I haven't had a chance to unhook the battery yet. It does seem that things have changed, but it's more of a sideways step. Since replacing the IAC, I believe the noise is mostly gone. However I am noticing now that it takes longer to start, and once started is idling very high, around 2k. Once it warms up, it then starts to act like it was before, where it is almost dying at stop lights. Still no CEL.

Could the MAF sensor be the issue? I was thinking I would unhook the battery tonight, and then clean the MAF and see if that helps. I had to replace the MAF back in 2014, but I replaced it with one from a U-Pull-it lot, so I thought it may be going out.

 

[Cheddar Dan]

How is your snorkel seal from MAF to Throttle body? If it is as iffy as mine there may be leak????
Good luck!

 

[Rhaegal94]

I experienced similar idle problems in the fall but didn't hear metal grinding like you mentioned. After checking hoses, I ended up replacing the IAC valve, the MAF sensor and doing the steps below. Once I did the idle reset the problem was fixed. The steps below were posted by goalieman59 in another thread. I don't know if it's necessary but I do it whenever I reconnect my battery.


NOTE 1: The Ford owner's manual directs that the idle program be relearned following any service when the battery has been disconnected. To do this, it states that the engine should be started and allowed to idle for the (approximately) 70 seconds without touching the gas pedal. Adding the accessory loads ensures that the EEC and IAC valve can accommodate the additional air flow requirements and still maintain the programmed idle speed.

NOTE 2: It is preferable that the car be driven immediately after setting the idle programming. While driving, allow the coolant temperature to rise to the normal range and run the car through its entire performance range.

Idle Speed Program Reset Procedure
-----------------------------------------
1) Disconnect the negative battery terminal.
....Optionally, disconnect the keep alive memory (KAM) connector in the small
....wire also landed to the negative battery terminal.
2) Wait at least 30 seconds.
4) Reconnect the KAM connector or negative battery terminal.
5) Start engine normally (never press the gas pedal).
6) Allow the idle speed to settle for at least 30 seconds.
7) Within 70 seconds of starting the engine, concurrently apply all accessory loads.
....a) Climate control to MAX A/C.
....b) Headlight switch ON, brights ON.
....c) Turn steering wheel slowly ~1/4 turn side to side.
....d) Press brake pedal.
....e) Automatics only: shifter to DRIVE.
8) Do not turn off engine for at least 5 minutes.