Off Idle Hesitation Stumble

[Torinate]

I’m dealing with vct issues myself, at the moment. If you have vcmscanner you can log vct mode, commanded angle, actual cam angle, and solenoid duty cycle for all cams.

Thanks Mike.

I don’t believe I have VCM scanner. Is that in Forscan or on an nGauge? If not, haven’t got it.

Of course, I’m not abreast of the values so would rely on others to tell me what’s going on.

What problems are you having with yours?

Watching live data stream with Forscan there’s zero misfires while warming up and in a higher idle. Once RPMs drop to normal level after car is through cold start, the misfires occur. Grr!!

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[engineermike]

What problems are you having with yours?

My bank 1 exhaust cam is drifting retarded at wot/high rpm even though the solenoid is going to 0% (full advance). It’s not bad enough to set a code but it’s definitely affecting power and messing up the tuning strategy.

 

[Torinate]

Yuck! So is your fix to replace the VCT solenoid?

 

[engineermike]

Yuck! So is your fix to replace the VCT solenoid?

Yep that’s the first step. Got one coming tomorrow.

 

[Torinate]

Just by chance have you took it to a Ford dealership just to have them do a engine scan with there high dollar machine? Your issues are ignition no doubt about it. Just trying to pin point it is the issue. Definitely don't want you dropping parts on it for no reason. The crankshaft sensor on the rear of engine block, VCT, coils, and cam sensors on the rear of cylinder heads have to looked at. I believe you can ohm the vct or give a power jolt to hear if it clicks. Me personally I think it's the coils. Your symptoms was exactly how mine was. My car would not pop soon as I started it up, but once it warmer up it start popping at idle. Soon as I traced my engine code to #1 cylinder I had removed the weapon x coil that I purchased off ebay which I would never do again. I put my stock coils back in and the car didn't pop at all and no hesitation. What I will do since I have some free time. I will video the bad coil and show my symptoms I had and then I will put the stock back in.

Sounds good. I’m leaving towards it NOT being the coils. I took the #1 coil (most misfires) and moved it to #2 (least misfires). Ran another mode 6 and the misfires didn’t change - #1 was still the worst and #2 was again the least. Scoped the #1 cylinder again and everything looked completely normal. Compression test was excellent throughout. So misfires didn’t move with the suspect coil moving. Leads me to think that is not the issue. Only way to know for sure is to switch out all the coils for a guess but that’s a $600 dollar guess with no real data pointing to it being the issue. I wish it were that simple. I changed plugs - never a bad idea - no changes though. So that was a $100 guess.

I guess I would have expected some difference when switching the coils around but there’s wasn’t anything. Done that twice now. Numerous crank relearns and KAM resets did nothing. Injectors cleaned and fuel system cleaned. Nothing. Running out of ideas...

 

[MKL_DS]

O2 sensor issues will lead to misfires in many cases. Are both front O2's functioning properly?

 

[Torinate]

O2 sensor issues will lead to misfires in many cases. Are both front O2's functioning properly?

As far as I can tell, yes, no issues. Nothing has thrown a cel so no indication of where to look specifically.

 

[MKL_DS]

As far as I can tell, yes, no issues. Nothing has thrown a cel so no indication of where to look specifically.

scan them to be sure and confirm the harnesses are not melted, etc.

 

[downtoearth1986]

As far as I can tell, yes, no issues. Nothing has thrown a cel so no indication of where to look specifically.

Any updates on the ride. Was you able to get it fixed?

 

[Torinate]

Nope. No updates and still there.

I’m at a loss as to what to do next...

 

[downtoearth1986]

Nope. No updates and still there.

I’m at a loss as to what to do next...

Did you ever replace the coils yet?

 

[Torinate]

No. Nothing changes when they’re moved around. I’ve done that 4 times with the same results.

 

[engineermike]

I’m a bit unclear as to what exactly the symptom is. I reread the first post and it’s not clear if it’s during tip-in, wot, or at part throttle. Also a log was posted but it was long and I don’t know exactly where in the log the problem occurred. I think detailed log analysis might help but I don’t have anything to go off of. Maybe it’s here but if so I missed it.

 

[Torinate]

There’s 2 issues I believe. Unsure if they’re related.

The first is off idle. I guess tip in. Press the gas and there’s a stumble or hesitation before the car goes. It’s almost as if the car drops rpm before it takes off. Noticeable pulling away from stop lights or stop signs.

The second is random misfires at idle. Mode 6 data shows numerous cylinders doing it. Sporadic cylinders but #1 has been the worst. They move around though. It doesn’t matter the coil I exchange it with. Still hasn’t thrown a cel though. So I see the car has misfires, but it doesn’t. On one of the logs it shows a misfire under load with subsequent afr going lean. .74 lambda to 1 (it’s posted - can’t remember exactly).

I notice the exhaust pop at idle and an occasional pop (but only once) on decel. When monitoring live stream through Forscan I know the idle pops are misfires as when I hear one I see the misfire count go up. Can’t say that I’ve seen one during cruise though. Idle and decel with idle being the majority.

 

[engineermike]

On the stumble, you need to get a high speed log of the issue that includes pedal position, throttle position, all 4 cam positions, both lambdas, and spark timing ONLY, and log on the fastest data rate. One of those things isn’t doing as it should. Once you narrow it down to one of the above, you can diagnose from there.

On the misfire, did you swap around injectors too? Misfire can only be caused by spark, fuel, or compression and you appear to have ruled out spark and compression.

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