2.0L Duratec ~9600 miles, Misfire when warm

[JakeC]

Hey All,
I'm hoping someone here might be able to shed some light on an issue I am having or have some suggestions on troubleshooting next steps.

 

I have a 2021 420R SV (metric) which has the 2.0L Duratec and about 9600 miles.  The car is used mostly for autocross with some track days sprinkled in, and I drive the car to and from the envents.

After the last event (a couple of months ago now) I started getting some misfires when going up hills on the way home. At first I thought I was just running low on gas, which was true, and when I coasted down hill the misfires went away, or so I thought.

The next time I had the car out (just a normal drive) the misfires came back and the longer I drove the worse it got, meaning the lower in the rpm range it would misfire under load.
Any time I have tried to drive the since the troubles started, it would be fine, and I could do a pull in second through the rev range and not have any troubles at first, but as the engine came up to temp, the misfire would come back.

I've had similar feeling issues in the past with other cars, and it was always a bad coil.  So the troubleshooting started.
I purchased a single new coil and swapped it into each cylinder, and nothing changed.

So I thought maybe it could be multiple bad coils, so I swapped in 4 new ones and did 4 new spark plugs at the same time.
That made no difference.

Next I did the Cam Position sensor, since it was an easy change and relatively cheap.
No change.

 

Next I did the Crank Position Sensor, and I have read those have a tendency to go bad.
That made no difference.

So I thought well, if timing and spark are ok, then maybe its a fuel issue.
I put on a fuel pressure gauge at the rail, at idle at temp, its between 45 and 50psi, at wide open throttle when not misfiring its between 40 and 45 psi, and at wide open throttle when misfiring its about the same between 45 and 50psi. (I have video if needed)
I don't know what the proper pressure is supposed to be, but I figure since its the same when working properly and not, then its probably in the ballpark.

So next, I got a cheap injector tester/cleaner thing and pulled the injectors.
When testing they all flowed about the same but the weren't "hot" either.
So as a final last ditch effort I bought 4 new injectors, and installed them today. (on the tester they also flowed nearly the same, but not as well matched as the stock ones)
And the problem persists.

So now I am all out of ideas  I truly don't know where to go next.
I do have a easimap dongle and the software on a laptop, but I'm not super familiar with it, and the ECU is the stock locked one.

I would be truly grateful for any ideas on what to do next.
At this point I'm not above taking it to someone to look at, if anyone knows a reputable place to take it near Austin Texas.

If there is more information needed I would be happy to provide, and at this point I am willing to try nearly anything.

 

Thank you!

[JohnCh]

The harness for the coils is a known issue, and it behaves like you're describing when a wire develops a fracture. I'd start there. You might be able to find the offending wire(s) with a multimeter and some luck recreating the conditions or simply treat it like a wear item and replace it. Rocky Mountain or Beachman Racing might have one in stock. 

[Croc]

Hmmmm….you have followed the basic diagnosis approach I would take.  John’s suggestion is the next one I would try.  
 

If that does not work then a Hail Mary is check your electrical cutoff switch and rollover cutoff safety button.  Your symptoms are vaguely like a problem I had on a 620 recently.  I ended up replacing the cutoff switch and removing the rollover cutoff button.  
 

If you need a good Caterham mechanic, it’s not Austin but it is reasonably close in Dallas, then Jeff Sloan is a former Caterham dealer at Brit Auto. Great guy and knows his stuff.  
https://britauto.com

 

 

[JakeC]

Thank you @JohnCh and @Croc!

 

I'll try a new loom first and report back.  Thanks again!

[KnifeySpoony]

Yet another vote for coil loom - mine went bad and symptoms were identical

[JakeC]

9 hours ago, KnifeySpoony said:

Yet another vote for coil loom - mine went bad and symptoms were identical

Nice, thanks much. Fingers crossed that is all it is. Trying not to get my hopes up too high lol

[Ian7]

Is 40-45psi fuel pressure correct for this engine? While our nearly-stock 2 litre race motor is a Zetec, not a Duratec, we run 60psi.

[JakeC]

1 hour ago, Ian7 said:

Is 40-45psi fuel pressure correct for this engine? While our nearly-stock 2 litre race motor is a Zetec, not a Duratec, we run 60psi.

Honestly I don't know for sure. The sbdmotorsport pdf here mentionsed 3Bar / 44.1 psi:
https://www.sbdmotorsport.co.uk/wp/wp/pdf/2L_Duratec_TP-DURA-2-0L-K3_Taper_Throttle_Kit_Instructions.pdf#:~:text=You will first,Bar (44.1 psi)
But I don't know how to find out for sure.

[jeffs]

Shot in the dark, but have you checked the water temp sensor?  I've had two go bad on me.  Put a data logger on the car and the ECU was getting 0C while it should have been closer to 80C.  My car has two sensors, one feeds the ECU and one feeds the dash...  Dash would show good temps, the ECU was getting garbage data.  Car would run fine until it warmed up, then it would run stupid rich and misfire like crazy.  

[JakeC]

38 minutes ago, jeffs said:

Shot in the dark, but have you checked the water temp sensor?  I've had two go bad on me.  Put a data logger on the car and the ECU was getting 0C while it should have been closer to 80C.  My car has two sensors, one feeds the ECU and one feeds the dash...  Dash would show good temps, the ECU was getting garbage data.  Car would run fine until it warmed up, then it would run stupid rich and misfire like crazy.  

Oh shoot, no, I didn't try that, I will see what Easimap says tonight, thanks for the tip!

In the mean time I have a loom on order as well.

[JakeC]

@jeffs I just checked and the temp seems good. Ecu matches the gauge. Thanks for the idea though!