Curious Duratec issue

[papak]

I was running the engine the other day (2.3l Duratec) in preparation for an oil change and decided to check the header temps with a laser pyrometer. To my surprise, the temps at the top of the header pipes , 1-4 were 390, 370, 170, 162. I was so surprised that I replaced the battery in the pyrometer. No change. 
 

I checked the plugs and they showed a predictable pattern, #1 whitish grey, #2 tan/grey, #3 sooty black, #4 wet and black. I replaced the plugs as well as the coils. Still a relatively smooth idle with the same temps. 
 

I’ll pull the cam cover tomorrow to check the valve springs and I have a query in to Specialist Components to determine how the coil signals are paired in the ecu (Typhoon 2). The engine has 7500 miles on a full rebuild. The injectors were cleaned and rebuilt at the time of the rebuild as well as new rings, valve guides and seals. The induction is 48 mm Jenvey ITBs.

 

Any other suggestion as to what to look in to would be appreciated. This temp discrepancy was not evident a few months ago when the headers were ceramic coated and reinstalled. We’re it not for the pyrometer readings, I wouldn’t know anything was amiss.

[MV8]

"This temp discrepancy was not evident a few months ago when the headers were ceramic coated and reinstalled." Was the temp checked or it just wasn't obvious as it is now without checking the temps? I'd do a compression test and check the injectors for spray pattern, leakage, and flow rate. I would not assume it is waste spark since there are individual coils. Oem is waste spark only during cranking.

You could try switching the coil wires if they will reach or jumper (spare connector pigtails).

[JohnCh]

As MV8 suggests, definitely do a compression check.  Easy way to rule out an injector issue is to swap # 3 or #4 with #1 or #2 and see if the low temp follows the injector.  Do you have coil-on-plugs or the earlier coil pack?  If the latter, I've had a couple of those act up over the years so that is a possibility.  If you have the CoP, check the wiring at the connector to make sure things are seated properly.  Probably a good idea to look over all the wiring for the injectors and ignition to make sure there is no visible damage. 

 

-John

[Pokey]

Assuming COP, a logic probe tester at the coil is the easiest way to rule out everything electrical upstream.

[MV8]

This is another problem with grossly overpowered cars. They can be running like crap and it's hard to tell from driving.

[KnifeySpoony]

You said it idles well, but how does it pull under load?

[papak]

Once it's warmed up, it pulls just fine. I replied the coils with a spare set. I'll be running  compression check today as well as checking the injectors. When the newly coated exhaust was reinstalled, I checked the temps and they reflected the past experience where the center cylinders ran about 20F lower than 1 & 4.  COP with stock pistons (9.5).

Edited July 21, 2023 by papak

[ashyers]

papak,

Is it possible you have an issue with the throttle sync leading to wacky temps at idle but OK running under load?

 

Andy

[papak]

Turns out it is a leaking head gasket between 3 and  4. Since there is no evidence of fluid transfer between oil and coolant, it hasn't been a huge issue. I'm in the process of removing the drivetrain over the next few days. Parts are on the way. I'm taking opportunity to  be upgrade the cams to Crower Stage 2,  ¾ race along with the valve springs. Crower said 2-3 weeks for the cams to arrive. I'm having hand surgery at the end of August so I'll be hustling to get the car back together before then. In the interim, it will be all out disassembley, cleaning and prepping.