Low load stumble, intermittent, no codes.

[OCDFist]

I've had an intermittent engine stumbling issue for a couple of weeks now. A few times now, after fully warmed up, under a low load, the car will stumble, pop, but will idle. I try to play with the throttle a few times, it won't go WOT, and no codes are shown. As soon as I think about pulling over, the car goes back to normal. Happened once on the highway, twice on a 40 mph side road. This started before installing an Airtec fmic. I changed the spark plugs, .028" gap, but it happened again after changing plugs. Checked electrical connections on top of the engine, all look good. It's at the 10,000 mile fuel pump window, but it hasn't left me stranded and runs normal outside of the few seconds that it's wonky. I don't know what exactly to watch on the Cobb when it's happening, and with no codes, there's no smoking gun. Not going to the dealer yet. Mods to the car are in my sig.

 

[OCDFist]

Anyone changed the in-tank fuel pump on their own yet? Is there an official recall? Would it be intermittent or just die a quick death? I haven't let this thing go below 1/8th of a tank yet.

 

[CanadianGuy]

yes there is a Fiesta fuel pump recall
https://media.ford.com/content/ford...ues-four-safety-recalls-in-north-america.html
http://www.fiestastforum.com/forum/threads/4762-Fiesta-on-Recall-List
http://www.fiestastforum.com/forum/threads/5022-A-new-recall-possibly-coming-on-the-FiST

You can enter your VIN here and find out if your car is affected.

https://owner.ford.com/tools/account...e/recalls.html

and there is a thread where [MENTION=1447]Chris G[/MENTION] had the recall issue.
http://www.fiestastforum.com/forum/threads/5041-FiST-Died-Randomly-amp-amp-Won-t-Start

 

[Chris G]

Anyone changed the in-tank fuel pump on their own yet? Is there an official recall? Would it be intermittent or just die a quick death? I haven't let this thing go below 1/8th of a tank yet.

My pump went. It was fine one second and completely dead the next. It was the strangest thing. When it was replaced, the dealership didn't say anything about the recall as it was pretty new at the time.

 

[OCDFist]

Of course it didn't act up yesterday or today, while driving in situations where it did earlier in the week.

I ran a whole can of spray Sea Foam through the port after the throttle body today, killing all the bugs around my driveway. I'm watching Desired & Actual High Pressure Fuel, Low Side Fuel Pressure, STFT, and Fuel Pump Monitor on the Cobb hoping I can see what's up the next time there's a hiccup.

 

[OCDFist]

The problem showed up today during stop & go drive through town and I noticed something on the AP. Normally FRP Desired and FRP Actual are between 650 psi & 2200+ psi. FRP Desired & Actual dropped to 54 psi when it was having the problem, but it would go back to normal and back to 54 psi during driving. If it was just Actual I'd suspect the high pressure pump, etc, but the Desired is low. That means either the computer is wonky or a sensor is telling it to be wonky, correct?

I uninstalled the Cobb AP for now and I'll see how it goes for a couple of days. Can't watch the FRP now, but obviously I'll know if the FRP goes to 54 psi long enough to cause the stumble.

 

[me32]

Maybe a fuel pump issue

 

[Chris G]

Just curious... what is your build date?

 

[OCDFist]

Just curious... what is your build date?

05/13

 

[Chris G]

Mine was built a whole year after yours at 5/14. I think the recall is for vehicles that are early April to mid-June 14.

 

[OCDFist]

Update :

The FRP Desired and stumble happened more frequently this past week than ever before, always when warm and a couple of times right at start-up. I read on a forum about regular Fiesta grounding issues, so I removed the main ground wire connection at the left shock tower area & sanded off the paint. That was Friday night. I drove it about 100 miles all weekend without a hiccup, in all kinds of driving.

If it ends up being a permanent solution, the only explanation I can think of at this point is that all of the rain we're getting every other day made a satisfactory ground connection into a spotty one. Seems to have more pep right off idle where before it would be a little laggy. Time will tell.

 

[OCDFist]

This issue is popping up again, the ground connection only seemed to help, or maybe just a coincidence. Still trying to figure out why FRP Desired will go basically off (54 psi) for a second and then back to normal. Happens hot or cool, rain or shine, usually on deceleration, low cruise, or idle. Google HPFP failures usually end in death, this one comes and goes with randomness. I guess FRP Desired is not just a value commanded by the computer? If it was, why is it commanding it to be off for a split second?

 

[CanadianGuy]

Did you recheck the ground? Maybe it built up rust/corrosion blocking electrical connection. Or you may have a bad cable?!? I'm guess based on your previous results only but I know when I had electrical problems on our 89 tempo it was a rusted connection that I had to sand down and add conductive grease to keep it clean.

 

[OCDFist]

Did you recheck the ground? Maybe it built up rust/corrosion blocking electrical connection. Or you may have a bad cable?!? I'm guess based on your previous results only but I know when I had electrical problems on our 89 tempo it was a rusted connection that I had to sand down and add conductive grease to keep it clean.

I used dielectric grease on it, so that's good. I also found grounds on the left shock tower and the right shock tower, sanded & greased them. The battery cable looks stout, but not above getting a new one.

 

[mouse]

I've been having the same issue as well but only when it rains. I'm gonna start monitoring the FRP Desired. There are three things constant in my problems... The rain, 2J Intake, and the gas station. I'm waiting for it to rain again to see if I can eliminate that as a reason for the issue. So far, other people that have the 2J Intake don't have this issue and I've been getting gas somewhere else where I know I'm not getting crap gas.

 

[mouse]

I just checked the VIN for the recall and my car doesn't fall into any recalls.

 

[mouse]

I'm happy to to report that crappy gas was the reason why my car had the same issue. It's been raining here for a couple of days and I'm free of issues.

 

[me32]

Did anyone take the car in to the dealer an show a tech?

 

[OCDFist]

The issue was occurring daily, rain or sun, so I replaced the FRP sensor with a new Ford part on July 17th, after reading the Internet and taking a stab in the dark. No problems since then, rain or shine. $70.00, No patience for dealers.

 

[OCDFist]

Well, the new FRP sensor seemed to keep the "54" Desired FRP away for a while. However while doing about 35 logs for a DHM tune, the issue returned at 5000 rpm and up, every time I was wide open, sometimes even part throttle at high rpm. Not a cool thing at wide open. Nothing was hurt as far as I know, but the car would act like I closed the throttle. Since I haven't read any other posts anywhere about a similar problem, I took another stab.

Today I replaced the HPFP (only about $230 from Ford Parts.com) and it everything is fine again. I actually see 2400+ FRP max and before I swear I never saw more than 2200-ish max. Power is great and I'm going to compare logs with the old high pressure fuel pump. Anyway, I'm super excited, because now I can move on to E30.