Another Rough Idle - set screw moved?

1994 - 3.0L 2WD

Just replaced rotors, Calipers, and pads. Bleed brakes - all is well there, then moved on to the Valve Cover Gaskets and the upper Intake Gasket.

That went well with minimal surprises, the one surprise was that there were 2 gaskets on the upper intake. My purchased replacement only had 1, so that is all she got back. This is only suppose to have a single gasket yes?

Valve covers went fine as well, my first time doing an intake and valve covers so I went slow, and methodically, taking several pictures of vacuum lines prior to ripping them apart and moving things. Came in handy when reassembling, that is for sure.

While I had it apart and had easy enough access, I swapped the plugs too. I failed to research here, so I did not use the motocraft SP-500's, instead going with NGK from autozone.

After reassembly, I had a really rough idle, sounded like it was about to stall and engine was bouncing around. She ran smooth prior to my "fixing", so that was a bit troubling. Initially I thought I missed a vacuum line or had one not seated properly. I looked over them again, verified with my photo's and then sprayed BrakeKleen (was out of carb cleaner) at all the connections...... idle remained unchanged so no vacuum leaks.

Had it sit there a few, then unplugged the IAS, and she died rather quickly. PLugged it back it, cranked her up, and turned the idle screw up until she no longer was jumping around and sounding like hell, then unplugged the IAS again, idle fell lower, and started bouncing around all rough again, plugged the IAS back in and idle raised and smoothed out.

I did NOT touch the idle screw upon my work dismantling the intake, is it common for that to get "shifted" during that process? My truck does NOT have a tach so I am unsure of the RPM's. Need to get one installed so I can check that idle speed out.

Thanks for any input on idle screw setting getting moved during intake removal.

To check for which cylinder is not acting right unplug the wires one at a time. I use a set of plug wire pliers with a ground wire on it so you don't get shocked. Possible vacuum leak around the intake. If you have injectors, check the lock tabs, if one is broken off. Take a zip tie and secure it. Last thing to check is for plug tip damage or porcilin being cracked. The plug will have a lone on the insulator if it is cracked. This would allow the spark to go to ground.

pulled a couple codes on her today after buying a reader.

172 - HEGO O2 sensor fault/lean
and
332 insufficient EGR flow detected.

The bottom end of the hardline to the EGR valve is loose on the exhaust header, so I assume that is it. Although there are a couple vacuum lines from that hardline too, but they seem ok, might replace them anyway.

On the O2 sensor. I see one easy enough, is their one on both sides or just the single one for the 3.0L ????

NOTE:

These are the plugs that I removed. They are ordered as I pulled them if you are sitting at the front of the truck. FOULED unit (top right) would be closest to the driver.

Are your plug wires on in the right order?

yeppers the wires are in correct order. I replaced 1 plug at a time and reconnected wire to make sure the wires went back on correct plugs.

Well the set screw isn't likely. It mostly affect idle speed.

Is there any chance you disturbed or damaged an injector connector? You would have been right in that area.

Or the distributor? You would have been doing a lot of work in that area as well.

MrDonivan said:

Had it sit there a few, then unplugged the IAS, and she died rather quickly. PLugged it back it, cranked her up, and turned the idle screw up until she no longer was jumping around and sounding like hell, then unplugged the IAS again, idle fell lower, and started bouncing around all rough again, plugged the IAS back in and idle raised and smoothed out.

Click to expand...

The throttle plate is supposed to be closed when off the accel pedal and the IAC takes over idle control. By turning the idle screw you are allowing by-pass air through the throttle plate and the IAC.

I would reset the throttle screw to factory then check/adjust the TPS to spec. See if that helps. The TPS tells the computer when the throttle plate is closed and the IAC takes over.

Rearanger said:

The throttle plate is supposed to be closed when off the accel pedal and the IAC takes over idle control. By turning the idle screw you are allowing by-pass air through the throttle plate and the IAC.

I would reset the throttle screw to factory then check/adjust the TPS to spec. See if that helps. The TPS tells the computer when the throttle plate is closed and the IAC takes over.

Click to expand...

Once i get that damn lower shock bolt situation resolved, I will for sure give this a go. I have a tach purchased, just need to get it installed so i can be sure of the idle screw RPM settings. Thank you.

MrDonivan said:

pulled a couple codes on her today after buying a reader.

172 - HEGO O2 sensor fault/lean
and
332 insufficient EGR flow detected.

The bottom end of the hardline to the EGR valve is loose on the exhaust header, so I assume that is it. Although there are a couple vacuum lines from that hardline too, but they seem ok, might replace them anyway.

On the O2 sensor. I see one easy enough, is their one on both sides or just the single one for the 3.0L ????

Click to expand...

Tightened up the HardLine on the EGR Valve, then end that attaches to the Exhaust. Took it for a run and the CE light came on again. Got her home and pulled the codes:

172 went away, but not the 332. Funny how changing the EGR system can fix a O2 sensor. But it confuses me on the 332 code. I rechecked the other vacuum lines for the EGR, and the EGR was replaced last summer.

I reseated all the injector electricals to make sure they were on, and I gave all the spark plug wires a good tug to double check those too.

Turned the idle down, she is better than she was, but still random and rumbly. Started pulling the dash apart to install the Tach, but having a hard time locating that Tan w/yellow stripe wire, watched a few video's and it seems like it should be right next to the fuse box but I must be freaking blind or something. And what freaking wire do we splice in on the dimmer? shit. I can re-wire all kinds of shit on my superbike, but this damn truck is confusing for some reason.

If your EGR is leaking it will affect idle.

Installing a Tach, I have the 2 sets of Power/Ground hooked up, I just need to connect the "green wire" to the Tech Lead.

Looking in the TECH ARTICLES, I see my year/engine states hook it up to the wire that is Tan w/yellow stripe.

Is this what I am looking at here? I didnt think it would be part of a larger connector.
1994 2wd 3.0L

Used that Tan/Yellow wire to hook up the Tach.

Cold, the idle is fine , immediately starts up and runs approx 1200-1300 rpm, then drops to around 500-700, stumbles, grumbles, then boosts back up to 1200 and runs fine, then after a bit droops back down to 500-700 all grumbles and stumbles.

rinse repeat... sometimes she stalls. Once she is warm, then she idles fine.

I am still throwing an EGR code, 332.
sigh.

Going to try a new EGR gasket. I replaced the within the past year sooo.......

MrDonivan said:

Once she is warm, then she idles fine.

Click to expand...

Test the ECT (engine coolant temp) sensor when hot and compare OHM reading to spec.

Meter set to 200k Ohms

Cold reading before starting: 26k
Operating temp reading is : 2.5k

Took it for a short drive until the CHECK ENGINE light came on, throws the following codes:

118 (ECT high voltage)
172 (O2 sesor)
332 (EGR Valve)

I had seen the O2 sensor previously but it went away for awhile. Is there just the 1, or does both exhaust headers have one?