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Help with hesitation at high RPMs - fuel starve?


KnifeySpoony

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Originals look fine.  The recent switch in also look fine except for 4 which is a little carbon fouled.  That would indicate a rich mixture or weak spark not getting optimium combustion.  Seems to line up with the issue of not getting consistent or a weak spark.  

 

I would not worry about the dielectric grease.  Its fine for now.  

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  • 4 weeks later...

Yea i tested continuity with a meter - def intermittent on that one plug - on BOTH wires. Crimp on the pins looks good; i think the wire broke right near where it enters the connector. It didn't seem to have a lot of stress there; will have to be careful routing wires next time...

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  • 1 month later...

Catching up on this based on our chat yesterday.  The problem you described (and showed me) seemed like a potential issue for *all* duratec cars, mine included.  Could you describe the fix and maybe a shot of the wiring under the coil cover?  You drive harder than I probably ever will, but the fix seems easy enough that I'm gonna just do it proactively.

 

I've also read that tucking the coil wires might help keep that cover off my bonnet, so I mean to get in this weekend and see if I can clean it up, and prevent this "broken #4 plug wire" issue.

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2 hours ago, Austin David said:

Catching up on this based on our chat yesterday.  The problem you described (and showed me) seemed like a potential issue for *all* duratec cars, mine included.  Could you describe the fix and maybe a shot of the wiring under the coil cover?  You drive harder than I probably ever will, but the fix seems easy enough that I'm gonna just do it proactively.

 

I've also read that tucking the coil wires might help keep that cover off my bonnet, so I mean to get in this weekend and see if I can clean it up, and prevent this "broken #4 plug wire" issue.

 

The wires failed right where they enter the connector that plugs into the coil for #4. I'm pretty sure that the aft edge of the plug dust cover (or whatever it's called) was rubbing on the wire there and caused the failure. Interestingly, there is a hole there that was filled with a grommet. The grommet was in contact with the wire there. My belief is that the cam cover rubbing on the wire was a known failure point and Caterham decided to "solve" the problem by drilling the hole, then filling it with a grommet to "punch out" the space there a little bit to clear the wire. However, the solution didn't work well. I decided to just leave the grommet out, which gives the wire ample clearance it seems. Another option is to just ditch the cover entirely. Unless driving in flooding rain (which I never intend to do), I don't see its purpose. 

20220712_185734.jpg

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As a further indication that it is tight quarters under that cover ….

I noticed last week that the two bolts had vibrated loose from the cover. I removed the cover and noticed a gray dust like substance on the second coil form the top (in picture). It easily rubbed off and did not appear on any of the other coils. I texted Josh Robbins, he quickly looked at his own new car and established the gray material was from the label on the inside of the cover. In the second picture of my cover you can even see the impression from the screw. Not much clearance there.

Dust on coil.png

Dust on coil cover.png

Edited by kayentaskier
crossed out stupid part of statement
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It looks like the dust cover could be shimmed with 1/4" thick washer epoxied to the bottom of the cover or the stand offs modified. Shimming should also improve the clearance at the coil on the end.

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I'm guessing the bonnet contact is only from engine movement (left mount lift) under load. You could check the actual clearance at rest with modeling clay.

If that is the case, a loop/strap over the left engine mount could be added. A 3/8 bolt could be fitted to a 1/8x1x6 (as long as needed) strip. The head would be between the mount bolt head and the strap with a jamb nut to set the height and engine movement. It doesn't need to be especially strong/heavy.

Otherwise, I'd remove the cover.

Edited by MV8
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For what's it's  worth ,I have seen this a lot , the engines runs well in low RPMs and at higher RPMS  but if a pump runs dry it can have damage that can't be measured unless you know the flow rate .I,have seen pumps go dry then the owner refills turns the key , and the 1 second charge up to fill the lines and injectors kicks in , BUT !!! How can you tell if it had full flow rate at WOT , you can't I have never seen this info published . The car owner will hardly ever notice anything wrong , unless he hits WOT and then never gives it a second thought .

      After having this problem in my shop ,I always ask , did you run it dry ,, if they say yes I'll tell them it's time to get a replacement .

Ford in tank pumps are notorious about this , some will run slow and you will never know it , they also get very hot IN SIDE THE TANK 

 What I have done is remove the OEM pump assembly ,remove the garbage pump and install a out side the tank pump . Safer , easier to replace later . The original pump sender housing is still in use . Works every time . remember the auto manufacturers buy the cheapest parts they can find , use as little as possible people to building and charge the most they can .

 

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