KnifeySpoony Posted September 7, 2023 Share Posted September 7, 2023 (edited) Not to doubt you, but how do you know for sure there is no spark on #1? Edited September 7, 2023 by KnifeySpoony Link to comment Share on other sites More sharing options...
ralph Posted September 7, 2023 Author Share Posted September 7, 2023 Here's my evidence: wet/clean plug (put a new one in, there's no evidence of combustion at all) used ignition coil tester pen to confirm spark on other three cylinders, thought this a bit janky so... pulled the plug and grounded it on the block while turning the engine over - no spark ...identical symptoms with your loaner loom (thanks, btw), and, to be thorough, I remeasured resistance from the ECU connector to each COP lead, and they're all nominal (around 0.6ohm), both with your loom and the original. Per the Rocky Mountain crew, while those coil loom faults are not uncommon, having one develop in 1700mi on a car that isn't doing track laps is pretty weird. Link to comment Share on other sites More sharing options...
KnifeySpoony Posted September 8, 2023 Share Posted September 8, 2023 Gotcha. Fwiw my loom failed at less than 2k mi. But clearly not your issue. Try a new ecu? Link to comment Share on other sites More sharing options...
ralph Posted September 8, 2023 Author Share Posted September 8, 2023 Warranty repair of ECU now underway. Repair, not swap, because MBE doesn't sell this ECU anymore (n.b. MBE9A4 "currently being re-designed"). This could take a while, which is a bit frustrating, given that the weather will turn soon. I would love to get my hands on a stock (plenum, not RBTB) 420R ECU if any owners/dealers out there have one, but so far the only 'spares' I've found have the wrong mapping... Link to comment Share on other sites More sharing options...
KnifeySpoony Posted September 8, 2023 Share Posted September 8, 2023 We could hook up my ECU with incorrect tune. I assume it won't run but we can do a quick crankover to see if it will spark... Link to comment Share on other sites More sharing options...
ralph Posted September 8, 2023 Author Share Posted September 8, 2023 Appreciate the offer. I don't want to do anything that might (be construed as something that could) do any damage or otherwise complicate a clean warranty repair process. I suppose I could kill fuel supply and just dry-crank, so nothing untoward happens to the motor. I see your angle though -- what if, after however many weeks, the newly repaired ECU arrives and presents the same symptoms because I missed something else. Worth considering -- not worth you going out of your way though. Related, I just saw your post re:loaner mbe9a4, so I'm not going to bother with a similar post. I reckon there are just none to be had; sounds like we have a bit of a wait for the 9m4...starting to think that getting an unlocked ECU mapped might be worth a stab... Link to comment Share on other sites More sharing options...
CBuff Posted September 9, 2023 Share Posted September 9, 2023 I was following the ecu sagas. Asked Caterham (thru the importer) if my almost under construction 420 would have the 9a4 or 9m4. Seems like it will still be the 9a4, unfortunately. for what it’s worth. Link to comment Share on other sites More sharing options...
ralph Posted September 9, 2023 Author Share Posted September 9, 2023 Interesting. So, CC still has a pile of these to burn down, my guess. Well, let's hope that supply isn't exhausted before the 9m4 is available... Anyone out there have 420R-duratec/plenum map files for an unlocked ECU? Link to comment Share on other sites More sharing options...
ralph Posted September 14, 2023 Author Share Posted September 14, 2023 (edited) MBE kindly waived the "warranty void if this cover is removed" stipulation and let me take a peak at the ECU board: ...I don't really know what I'm looking at here, but I'm guessing those four chips are the coil drivers, and guessing the fried one is for cyl #1. Waiting for MBE to give me the go/no-go verdict on shipping this (i.e. if it's too fried, they'll just send a replacement; if they deem it fixable, I'll ship it back to them for repair). The only other question that remains is what mapping to get. If I'm going to be waiting a while anyway, I could just throw RBTBs on... Edited September 14, 2023 by ralph 1 Link to comment Share on other sites More sharing options...
KnifeySpoony Posted September 14, 2023 Share Posted September 14, 2023 Glad you found the issue. Although pic not working for me. And RBTB... Hell yes... Link to comment Share on other sites More sharing options...
MV8 Posted September 14, 2023 Share Posted September 14, 2023 (edited) Requires logging into google to view (I don't) but good to hear you've nailed it down. May want to check out the entire ecu harness integrity (i.e. intermittent shorts) before plugging in the new. I'd probably go standalone ignition and carbs or ms if there is a repeat. Edited September 14, 2023 by MV8 Link to comment Share on other sites More sharing options...
ralph Posted September 14, 2023 Author Share Posted September 14, 2023 Fixed the pic - sry, rookie maneuver there. 1 Link to comment Share on other sites More sharing options...
ralph Posted October 31, 2023 Author Share Posted October 31, 2023 For anyone else in ECU limbo, the way my situation resolved may be informative: MBE took a look at my ECU and said "nope"...not worth trying to fix. Guessing they are out of 9A4s, because the ECU I'm getting is a 9M4 (likely part of the delay since those were still being qualified until very recently -- like days, not weeks ago, I think), and, since I left it an open question before, I did indeed opt for the RBTB mapping, and yes, RBTBs just shipped with the ECU. Still poking around for a map to the RBTB upgrade minefield...I see lots of chatter about TPS tweaks... P.S. @KnifeySpoony I haven't forgotten that I still have your coil subloom. Will ping next time I'm driving through the East Bay... Link to comment Share on other sites More sharing options...
KnifeySpoony Posted October 31, 2023 Share Posted October 31, 2023 No rush. Enjoy the roller barrels! If you need a sheet metal cutter I have a pneumatic nipper that worked great on my bonnet. You're welcome to grab it. Re: roller barrel map, it seems the consensus is the CC map is quite good. People say it's better than the plenum map. I certainly don't have any issues with it nor long for improvement. Link to comment Share on other sites More sharing options...
ralph Posted November 15, 2023 Author Share Posted November 15, 2023 The weirdest thing happened: I got the ECU/RBTB package from Caterham, but there were misfit/missing parts and no useful instructions!!?!!....<rimshot!>...thank you, thank you,...I'll be here every Wednesday night this week...please tip your waitress... But seriously folks...couple relevant points for anyone considering the RBTB upgrade, and a couple questions for anyone who's done it before: Useful instructions: Cosworth build manual appears to be a reasonable source of truth on RBTB assembly: https://dubaipetrolheads.com/biggles/download/CSR260 _Build_Manual.pdf (pgs 28-31)...if there's a better one, I'm all ears... Misfit parts: Easy: mounting nuts were wrong thread pitch (tapped them out to M8/1.25) Impossible: carbon fiber backplate was supposedly redesigned (per CC) to no longer require a belt tensioner mount mod to fit; the one I got does not fit, so that would mean grinding down the tensioner mount, which seems...ghetto...but doable... Missing parts: dzus type quarter-turn connectors for the air filter came with only the male side; maybe this is a blessing in disguise, since dzus type fasteners aren't the greatest for fastening points subject to lots of vibration in otherwise rigid parts...might just throw bolts in there and suffer the extra effort when I have to clean the filter. Assembly snags: Early throttle stop -- I roll the barrels to wide open and keep them there with a pair of screwdriver handles, mate the two spring-loaded sides together, mount the assembly to the studs, put the throttle cable in place, etc., pull the screwdrivers out, tweak the adjustment screws to get them set to idle position with a ~6mm gap, at which point they only open about half-way when attempting to open the throttle, and I can't seem to figure out where the contention is. Anyone had this problem?...or have ideas what might be stopping the rotation (nothing I can see from the outside, and there's really nothing inside that would do it, AFAICT...) No template for slicing the hole in the bonnet...anyone got one?...I can just trace around the air filter and measure where that probably lands with the bonnet in place, but this feels like a measure twice / cut 4-5 times scenario, and I have to believe there's a better way. Also curious to hear from folks who have cut on the small side vs. large side...I'm leaning toward the former (trying to right-size for a tighter fit), but if there's no real advantage to it, maybe it's not worth the extra precision...thoughts? In other news, I have the 9M4 installed (not much to report on that until the new snoot gets sorted out), and I did manage to pick up the more robust coil sub-loom, which from the looks of it, should probably be standard equipment -- it's way beefier -- if anyone was waiting for (either of) these, there is apparently some stock now. 2 Link to comment Share on other sites More sharing options...
Croc Posted November 15, 2023 Share Posted November 15, 2023 56 minutes ago, ralph said: Useful instructions: Cosworth build manual appears to be a reasonable source of truth on RBTB assembly: Just a suggestion for the future. No need to go to a Dubai website as USA7s has all of this plus more in the download section https://usa7s.net/ips/files/category/29-engines/ More categories here https://usa7s.net/ips/files/ And I agree with you as to the absolute lack of any guidance and missing bits from an upgrade kit from Caterham. Unacceptable given the money we pay. @JohnCh will be along shortly to tell you how to cut a hole in a bonnet - he did it recently. 1 Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 15, 2023 Share Posted November 15, 2023 1 hour ago, ralph said: The weirdest thing happened: I got the ECU/RBTB package from Caterham, but there were misfit/missing parts and no useful instructions!!?!!....<rimshot!>...thank you, thank you,...I'll be here every Wednesday night this week...please tip your waitress... But seriously folks...couple relevant points for anyone considering the RBTB upgrade, and a couple questions for anyone who's done it before: Useful instructions: Cosworth build manual appears to be a reasonable source of truth on RBTB assembly: https://dubaipetrolheads.com/biggles/download/CSR260 _Build_Manual.pdf (pgs 28-31)...if there's a better one, I'm all ears... Misfit parts: Easy: mounting nuts were wrong thread pitch (tapped them out to M8/1.25) Impossible: carbon fiber backplate was supposedly redesigned (per CC) to no longer require a belt tensioner mount mod to fit; the one I got does not fit, so that would mean grinding down the tensioner mount, which seems...ghetto...but doable... Missing parts: dzus type quarter-turn connectors for the air filter came with only the male side; maybe this is a blessing in disguise, since dzus type fasteners aren't the greatest for fastening points subject to lots of vibration in otherwise rigid parts...might just throw bolts in there and suffer the extra effort when I have to clean the filter. Assembly snags: Early throttle stop -- I roll the barrels to wide open and keep them there with a pair of screwdriver handles, mate the two spring-loaded sides together, mount the assembly to the studs, put the throttle cable in place, etc., pull the screwdrivers out, tweak the adjustment screws to get them set to idle position with a ~6mm gap, at which point they only open about half-way when attempting to open the throttle, and I can't seem to figure out where the contention is. Anyone had this problem?...or have ideas what might be stopping the rotation (nothing I can see from the outside, and there's really nothing inside that would do it, AFAICT...) No template for slicing the hole in the bonnet...anyone got one?...I can just trace around the air filter and measure where that probably lands with the bonnet in place, but this feels like a measure twice / cut 4-5 times scenario, and I have to believe there's a better way. Also curious to hear from folks who have cut on the small side vs. large side...I'm leaning toward the former (trying to right-size for a tighter fit), but if there's no real advantage to it, maybe it's not worth the extra precision...thoughts? In other news, I have the 9M4 installed (not much to report on that until the new snoot gets sorted out), and I did manage to pick up the more robust coil sub-loom, which from the looks of it, should probably be standard equipment -- it's way beefier -- if anyone was waiting for (either of) these, there is apparently some stock now. Something definitely not right re: inability to open barrels all the way. Can you take a pic of it as it sits? I have seen pics of people routing the throttle cable incorrectly. re: bonnet cutout - I have the CC template, but it leaves a big gap posteriorly to allow for the factory carbon airbox. If you want it to be just big enough for the filter, you'll need to do a custom job. Link to comment Share on other sites More sharing options...
JohnCh Posted November 15, 2023 Share Posted November 15, 2023 1 hour ago, Croc said: @JohnCh will be along shortly to tell you how to cut a hole in a bonnet - he did it recently. See this post: Link to comment Share on other sites More sharing options...
ralph Posted November 15, 2023 Author Share Posted November 15, 2023 @KnifeySpoony Here's a look at the assembly installed, and, again, I can't see any parts that are actually colliding at the premature stop, but it does look like the spring on the left is pretty tight already for this position (a tad past idle). When the barrels stop, it's less of a sudden percussive stop like two metal parts colliding (which, again I can't see happening anyway), and slightly progressive, more like a spring running out of available slack, which (modulo confirmation bias) seems consistent with the observation of the tight spring on the left....but all that said, I need to take this apart and make sure I understand the spring rotation and just the basics of how these parts come together. At initial mounting, the barrels stay open (??!!), and then after a tap or two on the accelerator, something slips and they drop to idle...maybe something's slipping into the wrong place, maybe a spring is too short...or is on backwards?...maybe, just maybe, I just have no clue what I'm looking at here... Will take it apart again and maybe snap some pics at the various stages... Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 16, 2023 Share Posted November 16, 2023 Hard to tell from the pics. I can't really see where the cable is routed. It is possible to have the barrels rotated the wrong way around and still route throttle cable. I'd pull them off and make sure you have then indexed in the right position when mounting to the head. Link to comment Share on other sites More sharing options...
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