Stalling at low speed/idle

[Chris Watkinson]

Ok folks, I believe issue has been fixed by the shop. Sure enough, they replaced the fuel pump control module, and they had a misfire on #4 so swapped out the plug and coil there. Seems to be running pretty good now, and efficiency immediately went back up from about 9mpg to 12 or so.

For those not familiar with the fpcm, it's on top of a rear subframe support and they're notorious for corrosion. You can see it from outside looking in the driver rear wheel well. I took off the spare tire, stuck my head up in there, and look toward the side of the vehicle, just under where the gas cap would be. It's easy to access, and I prob could have taken it off myself and replaced it, but I just didn't have time/money to throw parts at the problem and I wasn't getting ANY fuel supply codes at all. Couldn't even verify if fuel pressure was abnormal.

Anyway I appreciate all the tips. I cleaned the MAF sensor just in case. I looked at Chilton/Haynes manual, but will look for a repair CD instead! And I don't know if I've EVER changed the fuel filter So I'll put that on the list for preventative fixes. I'm assuming my catalytic is still in need of replacing, but good to know its not the culprit this time.

Thanks again. Here's a pic of the FPCM still attached, from the inside view, indicating part number:

 

[Plati]

Thank You. Very important and useful when people follow up with resolution.

 

[Procrastinator]

Hello everyone I’m new here and just became owner of my first Eddie Bauer a couple of months ago. It’s has 230k on the engine and runs good except for when it idles. Sometimes it’ll be fine, most times it’ll idle so bad it’ll go dead... but she’ll crank right back up. When I first got it, the only code it threw was the fuel filter. I haven’t changed it yet. But if it runs great on acceleration (no missing, cutting out, bogging down etc..), would the fuel filter have that kind of effect at idle speed? I had suspected a vacuum leak and I look under the hood and DID find a short vacuum line that looks like it connects somewhere but I have yet to find where it goes. It looks like the previous owner taped the end off. I’ll try to take a photo of it tomorrow. I didn’t know whether to post in this thread or not since the symptoms are sort of similar. However ANY help is GREATLY appreciated! Thanks in advance!

 

[Cooper]

Yes a clogs fuel filter could cause a rough idle. I bet that vacuum hose is the one that run in back of the battery and under the PCM. ust discovered mine had popped loose a few days ago.

 

[1955moose]

You might want to start your own new thread but anyway, first off what year and engine size? Most likely the bigger 5.4 liter. Your describing a vacuum or as it's called an intake leak. The easiest way to find out what's leaking is to smoke out your intake system through the large hose going to the brake vacuum booster. You can buy a low cost smoker for $40.00 on up. If your the Mcgyver type, you can build your own. Or just pay a low cost repair shop to do it for you, then repair yourself, or if easy, let them finish. It's possible you have other things contributing to your stumble, but the fact that it runs fine during acceleration and all other times, that's where to start. You can swap out the fuel filter, easy enough to do, but the fact your not stumbling accelerated I'd tend to doubt it's clogged. If you also do a fuel pressure test, that would let you know if fuel is making it solidly up to injectors. Running pressure is 28-42, key on engine off is 35-45. If your anywhere close to these numbers your pump, and fuel filter are fine. It's a large filter, and takes quite a bit to clog up.

Sent from my N9131 using Tapatalk

 

[Procrastinator]

I apologize for the waaaay late reply and update. Thanks for your feedback. I just swapped the filter out and you’re right, no change. I notice that idle drops to around 6000 and lopes pretty bad. As far as that vacuum line I was talking about, it’s on the drivers side..I didn’t have my phone with me earlier but I’ll take a pic and upload—I have no clue where it could go and wonder if it’s not the culprit.

 

[Procrastinator]

Ok...something new just happened and maybe this calls for a new thread I dunno...I went to town and all seemed to be doing fine even while sitting still. Until that moment I went to slow down to stop at a stop sign and I got a surge of power (like it wanted to go through the stop) then it just shut off. I cranked it right back up. It just boggles my mind.

 

[Procrastinator]

Here’s the photo of the mystery vacuum line. Any ideas?