Rough idle? P0171, P0174? Here's what you need to check first!!!

[lynn]

I was all worried and stressed trying to figure out what was wrong and trying all your sugestions and I just needed to go back to the basics. I had a clogged fuel filter runs great now.

 

[flagger]

Maf?

Sorry to be a klutz but what is an MAF and how do I clean it? Search function returned nothing.

 

[Lane24]

It's the Mass Air Flow sensor. It's located in the air inlet tube that comes from where your air cleaner/filter is. Just disconnect your air inlet tube ahead of the sensor, and spray some MAF cleaner through the screen at the little elements in the center of the sensor. Let it sit for 5 minutes or so...,give it another shot, let it sit for another 5 minutes, then start your engine. Some people just use electronics cleaner, but I recommend actual MAF cleaner from the auto parts store. You can also take the sensor right out and clean it that way too, but it's easiest to just spray it where it is. You can hold a rag or something behind it. Here's a pic of what you are looking for. Mine looks a little different on my engine, but it's pretty much the same idea.

 

[flagger]

Thanks for the help!

 

[dano]

mee too

Well, after reading all these posts on the PCV elbow, I'm gonna have to go out and check mine. My 05 Expy has 108K miles on it. Its got a little roughness to the idle. My wife says it doesn't sound right to her...but what does she know, anyway? (although I'm about 50% deaf in right ear and can't hear in the other), so maybe she is hearing something I can't.
Something else, if I was to buy a computer for reading codes and diagnostics, what is a good inexpensive one to buy? I see all these codes you guys have had on your expys, are these something that are there but don't show up til you put them on a diagnostic computer?
Just wondering,
dano

 

[Lane24]

I just went to the Value Auto Parts store when my CEL came on, and they read it for free.

 

[michaelinchains]

great post,wish id seen it sooner-just dropped mine off at the shop for this exact problem.

 

[ELVATO]

If you have a Harbor Freight near by, they usually have cheap OBD II scanners.

 

[BadCompanyRods]

Not to beat a dead horse.. but also check your TBs if they have a black ring around the inside of the TB that can cause rough idle and even some hesitation on extreme cases.. Get some TB cleaner and clean that up too..

 

[strokin393]

Mine starts up idles high for a second then real low then it shuts off. I can't keep it running and won't take the gas when I try to give it gas. What could this be?

 

[GAINMOB]

Don't forgetcleaning the the MAF as well. It's a5 dollar/ 25 second fix. Sometimes just cleaning it will make big changes to how you run.

has any replaced their MAF with and upgraded aftermarket? the only one i find online is for $500...uhm...yeah...not getting that one...

 

[golflover]

I have a 98 expy 5.4 L with 275k miles. My question is can I remove the entire TB with the adapter and IAC to clean it on my bench rather than in tight quarters? I wondered if the fire wall would prevent removing the 4 long bolts on the adapter. I had a panting idle, high and low and surging. I cleaned the MAF, changed the PCV, cleaned the throat of the TB while still attached. THis improved a panting low idle, now its high 1000 to 1200. I also noticed a small seam leak in the muffler. Could this be the issue?

I figure I can really inspect the vacuum lines with everything off. Any suggestions?

 

[Monicagtx]

Thank you!

The picture was a big help...im a girl so looking at the motor
I was so lost...but I was able to fix it on my own. I was literally sitting in motor reading ur instructions on my android lol....thank u again! One more thing it helps if u have small hands!!!

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[johng]

thanks

great post, found the problem in 5 min

 

[Lane24]

Great to hear.

 

[paramore11]

Thanks for the post. this helps me lot

 

[frhunter]

Vacuum tube assembly

Thanks for the heads up. I originally thought it was MAF sensor bought some cleaner and that didn't work. Checked online found your post and did some further inspection. I found that the rubber elbows were both damaged. Going to call dealer tomorrow.

 

[98Expnewowner]

Thanxs for the info one question though is there a diffence between the eddie b edition 5.4 and the sxt 5.4?

 

[awb594]

Can't find the problem

I have a '01 Expy 5.4L with a P0174 code I have been chasing for months. I have replaced the "elbow" hose all the way to the pcv valve. Got a new MAF from Ford. Cleaned the TB replaced the plugs, new fule filter. Finally I got the light to go out for about a month and now it is back on again, same code. It has always had a rough idle but today as I was coming to a stop and the engine jumped up to about 1500 rpms on its own. I am hoping someone might have a suggestion for me.

 

[Lakerfan248]

Check / Replace Air Filter

I have a '01 Expy 5.4L with a P0174 code I have been chasing for months. I have replaced the "elbow" hose all the way to the pcv valve. Got a new MAF from Ford. Cleaned the TB replaced the plugs, new fule filter. Finally I got the light to go out for about a month and now it is back on again, same code. It has always had a rough idle but today as I was coming to a stop and the engine jumped up to about 1500 rpms on its own. I am hoping someone might have a suggestion for me.

Check or maybe even replace your AIR FILTER. I have my 99 Navigator exhibiting the same problem. I did replace the hose elbow that deteriorated overtime, but only solved the problem temporarily. Not until I replace the AIR filter that colapsed inside the housing which solved the problem. It was actually choking the engine and bent the hose where the MAF is located that I found out that it was the culprit. The air filter separated and plastic cup got sucked in. After I replace it, Check Engine light was off after I disconected the battery to reset it. Good luck.