I've read through all the tech and posts about rough idle. My problems began a few weeks ago when I replaced the thermostat. I think the thermostat was frozen open, because the temp needle hardly ever came off the C, even in the summer. After the new thermostat, needle now comes up to just below half between C and H. But then I started having idle problems. I replaced the IAC valve with a new one, but no change. Replaced fuel filter and air filter, but still getting CEL with lean banks 1 & 2 codes. I looked at the photo of the MAF, and I don't have anything that looks like that.

Here's a shot of the housing just past the filter, and there is a hole with nothing in it just in front of the alternator.
http://i109.photobucket.com/albums/n...R/housing1.jpg

Then, another shot with the hole at the bottom of the photo, and another plug in to the housing that looks like two small wires stuck together that sit in the air flow.

http://i109.photobucket.com/albums/n...R/housing2.jpg

Then the third shot shows something connected with two Philips screws that I couldn't get loose, just ahead of the new IAC valve.

http://i109.photobucket.com/albums/n...R/housing3.jpg

I don't know what any of these "thingys" are. I was going to clean the MAF with CRC MAF cleaner, but I couldn't find anything that looked like what is being described. Sorry, I'm completely auto mechanically challenged.

'97 Ranger, 4.0, 4X2, automatic, 120,000 miles...I've had it about 18 months, and it was running pretty good until I changed the thermostat. Gas mileage seems to have gone south also. Rough idle on start, then sometimes will stall after warmed up when stopping for a light, etc.

 

You already replaced the T-stat, I would go ahead and replace the ECT, as well.

And you should also be aware of the fuel supply manifold gasket issue:

 

Old T,

I'd suggest checking to see if your MAF is clean, then disconnect your negative batterty terminal overnight. With new sensors your data tables that are accumulated in the PCM will have changed. Best to let the PCm "relearn" new data with the new/clean sensors in place.

CMOS

 

"lean" codes commonly refer to a vacuum leak, which will cause a rough idle. check the pcv system. that is where leaks are usually found, I wouldn't replace any parts unless I was absolutely sure the engines vacuum system is in perfect order.

 

The open hole in the air intake tube behind the MAF housing should have a hose in, it the goes to the valve cover where you put the oil in .If its not there then you are getting air in the intake that MAF is not reading it, its part of the pcv system .This will make the truck run bad at idle and get poor gas mileage.You probable left it off when you replaced the t-stat.Very easy to do.
Go ahead and clean you MAF while your there.

 

Is this my MAF?? Do I need to remove it when I clean the throttle body? A Phillips head fits, but they are so tight that the Phillips won't budge it. Is that because it's not a Phillips? And what is that other small filament plugged into the assembly there back toward the filter?

Also, where is my ECT located?

There was no hose in the hole of the intake assembly. Guess I need to find one, and find out where it plugs in on the other end.

Thanks for the help, all. Sorry for so many questions!

 

To clean the MAF sensor, Rockledge has a good instruction set in the tech info section (I have studied this section thoroughtly as there is valuable info in these archives). It is a delicate sensor, so take your time.
https://www.ford-trucks.com/forums/1...-cleaning.html

 

Get the hose fix first. Look where you put oil in the engine, under the cap there should be a nipple on the left outside of the tube that goes to the valve cover. That is where the other end of the hoes goes. If the hose is there just hook it to the air intake tube.Get that fixed and see how it runs then.

 

OTB, that hole that GrayRanger pointed out is not good. Like he noted, there is supposed to be a hose running from it to the top of the valve cover on the passenger side. There is a fitting on the valve cover for that purpose. In this pic of my '98 you can get a glimpse of the hose where it connects to the air intake tube :

https://www.ford-trucks.com/forums/a...ntid=516&stc=1

The sensor in your pic is the throttle position sensor (TPS). There is no need to tinker with it.

The ECT is located up near the t-stat housing, it's screwed into the upper intake. It has a 2-wire harness connector. See:

http://www.kemparts.com/TechTalk/tt13.asp

Hopefully someone who has cleaned the MAF on a '97 like yours can better describe how to access the MAF on your truck.

 

Seeing as how he said he didn't have the idle problem until he changed the thermostat & the engine is now running at the correct warm up temp, I wonder if if it's a simple as the fuel trim tables need to be reset, by disconnecting the battery, or by pulling the computers power fuse for a few minutes, to erase the old learned settings.

Then reconnecting the battery & let the computer relearn it's idle strategy & fuel trim????

Just some thoughts to ponder!!!!

 

Which fuse is the computer power fuse? I did disconnect the negative terminal yesterday for about an hour, but haven't driven it yet.

 

Disconnect NEGATIVE battery terminal overnight. That'll cover it.

CMOS

 

Well what did you find out?

 

Sorry to be so long in getting back...we are covered up at work!

Gray, you were right on, the hose was there, lying below the open hole. I was expecting it to be a much smaller hose...guess that's why I missed it. I reconnected it and left the negative cable off for about 18 hours. I bought the ECT valve, but found that I didn't have a short enough 3/4" wrench to change it out yet. When I cranked it up, the idle was still rough on cold start, but CEL was off. Got to work, about 30 miles, and it seemed to be running ok. Started it up at lunch, went about a mile and it died at the first stop. Then, on the way home that evening, CEL returned!

I still need to change out ECT valve, and I have not yet located my MAF. Will be the weekend before I can get back to it.

OT

 

The MAF is between the Air filter and the hose you replaced. The easiest way to clean it is to unplug it at the WHITE connector next to the hose you replaced, then unscrew the clamp on the side away from you air filter, then undo the air filter end and pull it lose from the big black hoes. Then spray everything on the inside, the square tub with the hole in it is where the sensor is, you do not have to take it apart any farther. Follow the direction on the can. Let it air dry and repeat if necessary. Hope this helps.
Go ahead and replace the air filter if you need too.