So I changed out the plugs in my 2006 5.4 motor at 121K miles. Took me all day. Broke 6 of 8 and had 2 just pull the hex and threads out, leaving the rest of the plug. Listle tool is a champ! Installed Motorcraft 515 plugs. Put it all back together.

Anyways, the truck runs great now but it idles low, at around 250-500 and when coming to a stop at a light it drops the rpms so low that it dies. It starts back up fine but the idle is way lower than it should be.

I am worried that I didn't get the COPS on properly as I never heard a snap, when I put them back in, like a typical spark plug boot? Should they "snap" back on? I pushed them down as far as they would go into the plug hole but you can only do so much due to the retainer screw and catch. I did not add any dielectric grease, would that be a problem?

I disconnected the battery and removed the computer on the firewall of the passenger side for access as well during the process.

I know the problem is solely related to something during the spark plug change because it idled fine prior to the plug change.

Thoughts?

 

You should use dielectric grease. It seals off the boots. Also, clean the MAF and throttle body if they have not been cleaned.

 

Also if you applied antiseize to the new sparkplug electrode shields prior to installation make sure it was a very thin coating so as not to contaminate the electrode itself and generate a missfire. Make sure the MAF wire harness connection to the intake tube is complete and the intake tube is completely reconnected/sealed at the throttle body. It also may take a few miles to "retrain" the ECM after the battery was disconnected.

 

Ok I pulled all of the plugs and COPS again. I had put anti-seize on the threads and some of it had gotten on the shaft of the spark plug. So i just cleaned it all off and reinstalled. I added dielectric grease to the springs inside the plug boots and reinstalled the COPS.

I also cleaned the MAF sensor.

Put it all back together and let it idle in the driveway for about 3 minutes. It stalled once at the end of my street, then didn't stall on me again. She runs strong under load. Still seems to get deathly close to stalling at stop lights. The rpms seem low to me, but I honestly don't remember what they were prior to the problem while sitting at a light or coming to stop.

Trip to the store and no stalls. Thats a good sign. I'll drive her to work tomorrow and see how she does.

Does the computer need to reset and re-learn after this whole process? Could that be part of the problem?

Thanks

 

Yes the ECM is the computer and once the battery was disconnected it may take a few miles to retrain itself. However if the truck continues to idle low you may get an engine light that will indicate you have a code, then stop at an Autozone, Oriellys, Advanced Auto, whatever and they will read the code for free telling you what is causing the problem. Another thought for low idle would be the IAC valve that may need to be removed and cleaned.. make sure if you disconnected it during the plug change that the harness is reconnected at the IAC.. read this. http://www.muscularmustangs.com/iac.php

 

That looks pretty simple. I'll give that a shot tomorrow night. And check in with my commute results.

Thanks!

 

A 2006 doesn't have an IAC, it has an electronic throttle.

You WANT antiseize on the spark plug shaft - between the threads and the tip, but NOT on the tip.

You do NOT want dielectric grease on the springs, just on the inside of the boots.

 

You are right glc I skim through these posts without reading every word and that IAC gets me in trouble when it comes to the 5.4.... Keep an eye on me and yes antiseize on the electrode shield only, it is "suppose" to prevent carbon from building up in that area again.

 

The antiseize managed to get into the end portion of the plug on the porcelain, but not on the electrode. I just took it all off to be safe.

I put the dielectric grease in the boot and smeared it around by squishing the rubber around, but when you slide the spring into the boot the grease gets on the spring.

I cleaned my MAF, which looked fine. I'll try and clean my throttle body too, but it didn't look that bad to me.

These symptoms started right after changing the plugs, so I contribute it to something during this procedure. Otherwise if it was the throttle body wouldn't it have had a problem with the old plugs too?

The idle was perfect before the plug change. I only changed the plugs because of the stutter at 1200-1500 rpms when off throttle on the road.

 

You said you unplugged the battery. My guess is the TB is gummed up and when you disconnected the battery, the memory was wiped out. So know it has to relearn the crappy idle with a gummed up TB

 

Ran the truck around at lunch. No stalls. Idle still fluctuates between 250 and 500 rpm. I stopped at Pep Boys and had them check for codes and nothing came up.

She runs strong up through the gears though.

Should I unhook the battery, clean the TB and then hook the battery back up?

At least it is running and not stalling now.....

 

Yeah you might as well give it a go. When I first got my gryphon programmer a few years ago, my TB was dirty so when I would load a tune, it wiped out the adaptive learning system so it had to relearn the correct idle. Since the tb was dirty, it idled too low and would fluctuate badly when I shifted into D from R or P. It slowly went away after a few days, but that's usually a symptom of that from all my reading. Had it cleaned last winter, no issues

 

I'm gonna pull the TB this weekend and clean it. Truck seems to be running better now. No more deathly low rpms at idle, no stalling and she runs great on the freeway!! Stutter is gone.

Still on the low side for rpms at idle, but nothing horrible.

At least she is running good again.

Thank everyone!

 

What's the best way to clean the maf sensor? Using cleaner on it like ya would on a throttle body doesn't seem safe lol?

 

https://www.f150online.com/forums/ar...ml#post4193148

https://www.f150online.com/forums/ar...005-5-4-a.html

You can buy MAF sensor cleaner at auto parts stores.