Load Related Idle Surge

Sean Owner/Technician California Posted   Latest  
2013 Ford Fusion SE 1.6L (R) 6-spd (6F35)
Rolling Idle Under Load
In Gear
Operating Temp

49k original miles

Repair history: head gasket had slow failure causing coolant consumption, replaced and engine ran well. Idle speed under longer engine run times would hunt and be more dramatic under load like ac etc. New OE throttle body. Found an Identifix post about these transmissions having bad torque convertors (among other things) causing engine load in gear and sure enough, this unit failed the psi test chart and fluid was black and full of fine debris. Now with reman Ford unit, and solenoid/shift strategy updated with IDS, idle still bad. Can't find any info about Idle Relearn Procedure. KAM reset, and so was misfire profile correction, or whatever Ford calls it. Letting it idle and correct itself has been pointless thus far

Idle speed will be normal from cold start, and engine runs fantastic with no codes or concerns. At idle, especially in gear and with any accessories running, the idle will rise and fall like an older Honda with vacuum leak. Has even caused a rare stall for customer before the transmission repair.

Fuel trim always within 2% total, both intake and exhaust cams showing < 1 degree difference (usually like 0.0 to 0.4 degrees to be exact). I took images of scan data, and I feel like the turbo wastegate pid is a silver bullet that I don't know how to use. It jumps from 0% to 85% and what I can find says this is PCM duty cycle control. But, the Ford chart also says that this command should never be above 19.75% at idle, and mine goes to the full 85%. Is this pid stating command? I feel like if I could just tell it to stop engaging the wastegate we'd be fine….

2 scan data images show the fluctuation in park, 2 show it in drive. 

I have images of running compression wave forms. idle, and snap throttle.

I am not well versed in the delicate changes expected in the waveform of variable valve timing engines. I am using a basic snap on compression gauge hose to take my sample and a Fluke pv350 on cylinder 1, with coil #1 on channel 2. sorry for the secondary causing the compression waveform having a dirty signal, but my coil was less than 3 inches away from the fluke during testing. 

Thomas Owner/Technician

If you feel the wastegate is the issue, just disable it. Remove the hose or disconnect the solenoid. This may help give direction.

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Justin Mechanic


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Caleb Diagnostician

Were the correct timing tools used for the head gasket job??

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Tyler Technician

Like Caleb asked, were the timing tools used? I'd reinspect if possible, as it's very easy to get these engines out of time even when the tools are used. The most common issue I've seen is getting the crankshaft out of time, but having the crank balancer in time. You end up with idle issues (since the engine isn't breathing correctly) and no cam/crank codes. As you saw, your in-cylinder…

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Karl Diagnostician

Do you have IDS file to share? Is the Waist gate stuck? I agree 85% is acting like it's trying to actuate but not successful and the same time idle swings with it. The in cylinder captures are not much help other than you can see ignition timing looks correct or atleast close by the spikes in the psi waveform. At least one of the captures anyway?? Very hard to tell

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Jeffrey Mobile Technician

Totally agree. So the first thing I noticed is that it looks like the scaling is for a snap on pressure transducer yet you have a pv350? Second is that you didn‘t start “Zoomed” in enough to properly see the spark. Sync on channel 2 with a time base of less than 50ms. Then you can zoom out to get a 720 degree pic. There also should be a way to get vacuum from the pv350 I think!

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Paul Mechanic

Given your compression shots, exhaust back pressure building due to waste gate over command? Or is there a back pressure issue causing waste gate to be commanded in an attempt to reduce it? The first pattern looks like exhaust valve opened very early and the others like it was stuck then popped open. Maybe a transducer issue?

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Richard Technician
New York

I agree with Tyler and Caleb, double check those timing marks. You could also try looking at the ignition parameter on the scan tool to see if it is adjusting alot at idle.

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