Fiesta 2013 1.0 Ecoboost misfire and or hesitation under light throttle

[MechEng]

Hi all, my 1.0 ecoboost has recently started to misfire or hesitate under light throttles. This is a repeat of a problem I had about 2 years ago which was never diagnosed but cleared itself which is always a bit unsatisfactory Initially the symptoms were very noticeable and made the car difficult to drive, then progressively improved during the 10 mile journey home and are now just annoying. Codes P0089, P0087 and P2626 were showing but no engine check light. The upstream O2 sensor, HP fuel pump and fuel rail pressure sensor have been changed. I also attempted to clear the keep alive memory by disconnecting the battery for an hour, don't know if this worked but it did zero all the average fuel economy data. Any no improvement. Now the symptoms are less noticeable there are no codes. So the car in now at a local garage and they are struggling as well. After a bit of discussion we realised that my scan tool and the garage scan tool both indicated that the low range fuel pressure sensor was showing 5 volts which sounds more like open circuit than an an accurate reading. We have both independently looked for a low pressure fuel sensor but can't find one, other fords have low pressure sensors near the inlet to the HP fuel pump but this car only has a fuel pressure damper. Anyone know what the low range fuel pressure sensor reading 5 volts is telling us? The garage thinks its running lean at light throttles as the fuel trim values are going high, hence the misfire or hesitation. Always starts and idles perfectly, even passed its MOT. Small bore plastic vacuum lines around the back of the engine have been removed and inspected, all look fine. Any ideas out there?

[DaveT70]

1: You need Forscan to reset KAM

2: What fuel are you using? Try better fuel, see if it goes away.

3: Clean MAF, ensure air cleaner is clean and not damp

4: Turbo bypass valve is weak and can leak, fit a turbosmart replacement (cheaper and more durable than OEM)

5: Have the plugs been changed? Did you fit standard OEM? If not, change them

6: If all that fails then it could be a clogged injector or a coil is going down

 

[unofix]

FORScan: https://forscan.org/download.html

New style 'vLinker FS' lead for use with the latest version of FORScan: https://www.bmdiag.co.uk/forscan-diagnostic-cable-for-ford-vgate-vlinker-fs

 

[MechEng]

Dave thanks for your reply and suggestions. At the moment I can only comment on two of your points. The fuel idea has crossed my mind, the car is usually filled with regular supermarket fuel, however, on this occasion I had just filled up with fuel from one of the major UK fuel and oil brands, still regular unleaded E10. Within about 5 minutes of leaving the pump the engine was struggling. The plugs were changed at 40k as I was aware of a slight hesitation back then, no improvement, the car is at just under 50k now. New plugs are NGK Spark Plug SILZNAR8C7H (93593) same NGK part number as the originals. 

[Tizer]

It does sound like it is running lean, it's strange that there are not codes all the time.

I don't know what Scan Tool you are using but FORScan is your best bet for Live Data on any Ford car. You may or may not be able to monitor High and Low side Fuel Pressure readings, actual and desired. I have a different engine to your one but for comparison my Low side pressure is normally around 400-450 Kpa.

I think the Fuel Pump Module is at the Fuel Tank, I'm not sure where it measures the pressure though.

The wideband front O2 sensor should show a Current of 0 most of the time under constant or no Throttle openings. if everything is working correctly.

If your Scan Tool can give you access to Mode 6 Data then there may be some clues there. FORScan can access Mode 6 but I don't know what TID's are available for your car.

 

[MechEng]

John, thanks for your reply. The garage needs some thinking time so they haven't physically worked on it in the last few days, I need to chase for updates. We both feel that the the low range fuel pressure sensor reading a constant 5 volts is worth investigating, but as we can actually find a low pressure sensor (under the bonnet) we are none the wiser. Is it in the fuel tank as part of the pump module? Or are there two circuits in the fuel rail pressure sensor? If I need to take the car back as is I will invest in the FORScan system suggested above.

My thinking is at low absolute loads the target fuel pressure is relatively low so the PCM is looking at the low range sensor, however this is at a constant 5 volts (no pressure conversion on my scan tool) which sounds like top scale, so the PCM thinks it needs to shorten the injector pulse width. With a false high fuel pressure this leads to lean running and the fuel trim controls ramp up to compensate. Just a theory....

My scan tool is Foxwell NT530 Full Systems Scanner for Ford, which is a small stand alone hand held unit with access to all vehicle modules. Its my first scan tool which has been useful but is limited by my knowledge and the small screen.

[MechEng]

Update, car is back from the garage without a diagnosis. The engine hesitation misfire symptoms are very mild at the moment and only occur while the engine is warming from a cold start, say 1 to 3 miles after start at about 50mph and on light cruising throttles. Monitoring live data, fuel trims and control status shows the system in closed loop control, then when the hesitation misfire occurs the short term trim goes very high, 20+. This happens fairly quickly, say 5 seconds per event and maybe 5 events during a warm up cycle. Once at normal operating temperature the car drives perfectly with both fuel trims very close to zero, although there is a power dip flat spot at full throttle 5500rpm which is odd, e.g. when overtaking. No PCM codes so I'm using the car to see if anything changes or codes appear. So far I filled the the tank with premium fuel and added an injector cleaner, no change after 100 miles. Changed the coil packs, no improvement. MAF and air filter look to be clean and dry. I do see code B10EA from the positive temperature coefficient heater sometimes but have assumed that cant be related. I haven't done anything with the turbo bypass valve so far assuming that at these very light throttle loads the turbo can't be contributing much if anything. Now invested in FORScan and cable suggested above so will dig a bit further over the next few days, any suggestions on which variables to monitor? 

[MechEng]

OK ForScan up an running and after much testing I can see the fuel rail pressure sensor raw voltage signal intermittently dropping to zero volts for a few mili-seconds then recovering. The dip is so fast the computed pressure in kPa doesn't mirror the raw voltage, but both their trends look noisy. The problem is variable and intermittent but looks to be the same using both the original and a spare fuel rail pressure sensor. Any thoughts, is the fiesta 1.0 ecoboost prone to wiring loom faults, ecu faults, multiplug pin corrosion, water getting places it shouldn't?

[unofix]

First check all ground connections are clean and tight. Check battery terminals are properly clamped and that the earth lead between the engine and chassis is good.

[MechEng]

Checked all the ground connections I could find, they all looked good. The car has now been back an forward to a Ford main dealer over the last two weeks and they are stumped. On Friday they proposed and fitted a new in tank fuel pump but still in improvement. Their proposal is now a wiring loom or PCM, the first cost a lot in labour and the second a lot in parts and no guarantees. Anyone changed a PCM for a second hand unit, can ForScan do the setup and or reprograming?

[DaveT70]

Just now, MechEng said:

Checked all the ground connections I could find, they all looked good. The car has now been back an forward to a Ford main dealer over the last two weeks and they are stumped. On Friday they proposed and fitted a new in tank fuel pump but still in improvement. Their proposal is now a wiring loom or PCM, the first cost a lot in labour and the second a lot in parts and no guarantees. Anyone changed a PCM for a second hand unit, can ForScan do the setup and or reprograming?

Du du duddle du dot com 😘

[unofix]

Parts cannon loaded and ready -- Customers paying -- Fire at will !!

 

Seriously you need to find a different garage.

[MechEng]

Update, still not fixed, Ford Main dealer have discussed with Ford UK and both are unable to offer a diagnosis with any confidence. So, as its intermittent and clears after 5 or 6 miles I'm continuing to drive it hoping some new clues will appear, its done about 2k miles since the last trip to the garage.

[p38fln]

 I bet that your actual problem is the spark plugs.  I had an F150 and an Escape both do exactly these same things.  For the F150 I asked a Ford dealer in Minnesota to diagnose it.  Those idiots told me I needed a new charge air cleaner, intercooler, possibly new turbochargers and whatever it was would be like $3000.  
 

I took it back home since I didn’t have $3000 at the time and on a gamble went down to the auto parts store and bought the tools and spark plugs to swap the plugs out.  About two hours later, I burned rubber all the way down the on ramp to US-61.  Kinda forgot the power the 3.5 eco boost had when it was running right…at least no cops were nearby lol. 
 

pretty much the same story with the Escape (Kuga 2 US version with 2.0 TT eco boost) except I went straight to the plugs without paying a dealer $100 to diagnose it.  
 

I wouldn’t have thought a UK dealer would make the same mistake but I’m almost sure they did.  They diagnose all the pretty computer BS and forget that under all the plastic and computers and pretty engine covers there’s still a spark-ignited engine. 
 

in both cases, the engines were significantly under the mileage recommendation to replace the spark plugs.  

[MechEng]

Yes I agree. Like you I thought spark plugs and changed them early on but sadly no improvement. Later when I handed it over to the main dealer they changed the plugs again but no improvement.

Clues so far is that it doesn't like colder temperatures e.g. less than 5-10 Deg C. The PCM was changed by the main dealer back in May, I suspect a couple of minor miss fire moments since but the jury is still out, particularly given the warm summer weather. Changed the crank sensor the other day as a precaution as the last two cars I have owned have needed crank sensors in mid to later life. Time and the winter will tell.

[twostroketom]

Hi folks,

This video may help. He shows location of low side pressure sensor (and goes through other common faults).

https://www.youtube.com/watch?v=0J83RZi3eCE

 

[MechEng]

Hi thanks for your reply. I have looked at the video and that's exactly as I would expect to find it. Although the engine appears the same on my car there is no sensor on the low-pressure side fitted. The low side fuel line appears to be plastic and has a small, sealed device, possibly a damper, no connections or wiring for a sensor, must be a model or year variant

The car has run perfectly all summer but in the last couple of weeks the fault is back. I've pulled the injectors and sent them for cleaning and testing, will report back results.

[MechEng]

In addition to removing the injectors other items including air ducts, air box, filter MAF, battery, PCM and battery box were removed to help further inspect the wiring loom. Starting at the PCM, centimetre by centimetre the loom was inspected for clues. Were the loom turns behind the engine there is a metal bracket which supports the connectors to the two oxygen sensors. The loom runs below this bracket and in my case there was a rusty stain on the loom. With closer inspection it was clear that there was contact between the loom and the square edge of the bracket. The bracket was removed, and loom insulation damage was visible.  Each of the wires on the HP fuel rail sensor were back probed in turn and with the multi meter set to ohms the loom damage area was probed with the other lead. This revealed a short circuit to earth for one of the HP fuel rail sensor wires. As fuel poor pressure measurement and control was one of the key symptoms this was almost certainly the smoking gun. Insulation and wiring loom made good, bracket modified to keep clear, injectors refitted and all other parts. The engine started fine and has been driving perfectly for over a week now. So, there you have it all the computers and over a £1k at the main dealer couldn't fix it, but patience, a good eye and some heat shrink and tape and it's fixed for free. Speechless....