Pokey Posted July 21, 2022 Share Posted July 21, 2022 I've got a weirdo for you all. One cylinder isn't firing due to a lack of spark. To be specific, the ignition circuit B (second to fire) is non-functional in my 420 (2.0L Duratec). It came on suddenly at the end of a long-ish drive. The coil is fine (swapped around to be sure) and I have the expected 12V on one of the two wires at the coil connector but no control signal on the other wire. Whereas the other three coils receive signal from the ECU, this one does not. I've tested and re-tested to be sure I have continuity from the coil to the ECU on that signal wire, and that resistance along that run doesn't differ from the control wires to the other coils. I've visually inspected the crank sensor and cam sensors but haven't gone further down that path as I wouldn't expect a problem with a single cylinder if either of those sensors are bad. Perhaps I shouldn't be making that assumption, but Easimap isn't throwing any faults and the crank counter increases as expected. So... short of the ECU itself not working properly (which would be strange, in general, and even stranger for it to fail in this way), what else might account for the ECU not recognizing that it needs to signal the coil to fire? Link to comment Share on other sites More sharing options...
sf4018 Posted July 21, 2022 Share Posted July 21, 2022 No idea but if you do suspect it to be the ECU I have a spare Caterham 420 ECU (30L279A BOM Code 1.0) sitting on my shelf I can send to you. Link to comment Share on other sites More sharing options...
MV8 Posted July 21, 2022 Share Posted July 21, 2022 I guess this is all the time and not engine temp or tps dependent. Try moving the plugs around too or simply replacing (check new plug gap). Are you using the rpm drop test of disconnecting each coil while idling? Jiggling the wires where they meet the coil connector since they can get loose? Just fyi: There is an extender for plugs buried in the head in order to use an inline glass tester. Link to comment Share on other sites More sharing options...
sf4018 Posted July 21, 2022 Share Posted July 21, 2022 Related question - online it says the standard plug gap for the Duratec 2.0 is 1.3mm but for race applications some people say reduce it to 1mm. For a CoP setup like this does it even matter as long as it works? Link to comment Share on other sites More sharing options...
Pokey Posted July 21, 2022 Author Share Posted July 21, 2022 15 hours ago, sf4018 said: No idea but if you do suspect it to be the ECU I have a spare Caterham 420 ECU (30L279A BOM Code 1.0) sitting on my shelf I can send to you. Super kind offer. I may wind up PM'ing you at some point. Thanks! Link to comment Share on other sites More sharing options...
Pokey Posted July 21, 2022 Author Share Posted July 21, 2022 1 hour ago, MV8 said: I guess this is all the time and not engine temp or tps dependent. Try moving the plugs around too or simply replacing (check new plug gap). Are you using the rpm drop test of disconnecting each coil while idling? Jiggling the wires where they meet the coil connector since they can get loose? Just fyi: There is an extender for plugs buried in the head in order to use an inline glass tester. Unfortunately, the issue is upstream of the spark plug and the coil. And, yes, you can unplug the coil on cylinder #2 and it makes no difference to idle. I can say with a good degree of confidence that the issue is a lack of pulse from the ECU reaching the coil. The question I'm trying to answer is why - did the ECU suddenly and unexplainably fail in such a limited fashion, or (in my mind more likely) is there something happening that should not or not happening that should that triggers the ECU to send the pulse. The latter seems more likely, but short of the crank and cam sensors I can't think of what else that might be. If I had a spare ECU, crank sensor and cam sensor then I would go ahead and swap because why not, but I suspect that there is something else amiss. Link to comment Share on other sites More sharing options...
Pokey Posted July 21, 2022 Author Share Posted July 21, 2022 Related question, does anyone know if the MBE ECU even uses the cam sensor signal? The wiring harness/ECU pinout indicates it is connected, but it isn't clear to me whether the ECU uses anything more than the crank sensor. Link to comment Share on other sites More sharing options...
sf4018 Posted July 21, 2022 Share Posted July 21, 2022 (edited) I have an unlocked ECU from SBD motorsports, it's essentially identical to OEM except for the mapping which was tuned for the replacement fuel system I put in. You can dig around the setup by downloading this... 420R ECU Unlocked.ecc ...and reading into Easymap 6 software on your PC. According to this setup it looks like the rising and falling edge of the cam sensor is used. Edited July 21, 2022 by sf4018 Link to comment Share on other sites More sharing options...
sf4018 Posted July 21, 2022 Share Posted July 21, 2022 Link to comment Share on other sites More sharing options...
MV8 Posted July 21, 2022 Share Posted July 21, 2022 1 hour ago, sf4018 said: Related question - online it says the standard plug gap for the Duratec 2.0 is 1.3mm but for race applications some people say reduce it to 1mm. For a CoP setup like this does it even matter as long as it works? A larger gap is better if the coil is up to the task. Under boost, gaps may be reduced to have as reliable a spark as NA with the same ignition system. Link to comment Share on other sites More sharing options...
JohnCh Posted July 21, 2022 Share Posted July 21, 2022 @Pokey I have new crank and cam sensors you can borrow. They are currently installed on the 2.4L on the engine stand in my garage. -John Link to comment Share on other sites More sharing options...
MV8 Posted July 21, 2022 Share Posted July 21, 2022 Allow me to clarify. I'd try moving the wiring around at the connector with it idling and listen if it tries to pickup (intermittent at the pin). Generally, ECU failures isolated to one cylinder are not unheard of. Link to comment Share on other sites More sharing options...
Pokey Posted July 21, 2022 Author Share Posted July 21, 2022 1 hour ago, sf4018 said: I have an unlocked ECU from SBD motorsports, it's essentially identical to OEM except for the mapping which was tuned for the replacement fuel system I put in. You can dig around the setup by downloading this... 420R ECU Unlocked.ecc 128 kB · 0 downloads ...and reading into Easymap 6 software on your PC. According to this setup it looks like the rising and falling edge of the cam sensor is used. That would suggest that the locked ECU uses the sensor then. I'm not where I can use Easimap today so can't open the file, but I'll try to find the panel for the cam sensor tomorrow. Link to comment Share on other sites More sharing options...
Pokey Posted July 22, 2022 Author Share Posted July 22, 2022 I can't find an Easimap "panel" for the cam sensor, but I did unplug the sensor while the engine was idling with no effect, good or bad. Could be the ECU doesn't use the sensor at idle or at all, or it could mean the sensor is bad. No idea but I can't help but thinking that I'm missing something. @sf4018, I loaded the ecc file into Easimap but can't figure out how to see the settings. I suspect that one has to flash the ECU with the file and then read the values off real time, obviously something I can't do with a locked ECU, unless you know better? Link to comment Share on other sites More sharing options...
sf4018 Posted July 22, 2022 Share Posted July 22, 2022 (edited) Go to System / Maps and Settings, then you'll see a bunch of folders with the settings in them. There's one folder called "Cam Sensor Setup". Open a setting in that then it will ask you to select a device to view, double click on "Other ChipFile" then find the .ecc file on your PC. That’s just to view the ECC file. Dunno if you can read the settings from the locked ECU or not (I’m assuming you have the OBD2 to USB cable), but if not what’s on the ECC file should be what’s in the locked ECU. Edited July 22, 2022 by sf4018 Link to comment Share on other sites More sharing options...
Pokey Posted July 22, 2022 Author Share Posted July 22, 2022 Well... maybe this is an answer as to whether the cam sensor is used, there is no cam sensor folder: Link to comment Share on other sites More sharing options...
MV8 Posted July 22, 2022 Share Posted July 22, 2022 I reread your posts in case I missed something. My understanding is: You've tested the coil in a different position to fire a different plug. You've tested the wire between the ecu and the coil connector and found no issue. But: You have not actually tested the ecu output, plug, or coil connection. If this is the case, before replacing the ECU or changing programming, I suggest: Using a test probe with an led or incandescent handle, put the grounding clip on the battery positive and back probe the ecu control grounding signal at the coil connector while running. Do not test the ecu output without the coil connected. You may need a paper clip to reach the wire side of the connector. If it flashes, continue. Wiggle the wire back and forth. Does it continue to flash regularly? Continue. Replace or swap the plug with another position to see if the problem follows. Link to comment Share on other sites More sharing options...
Pokey Posted July 22, 2022 Author Share Posted July 22, 2022 @MV8, thank for the response. I had done what you described but using a logic probe and with the coil disconnected. The pins in the connector are weather sealed, but I was able to get in the back of the connector using some very small gauge wire and just re-ran the test on #2 and #4. As before, #2 has no pulse from the ECU while #4 does. I'm as confident as I can be that there is no ECU signal to #2. Link to comment Share on other sites More sharing options...
Pokey Posted July 22, 2022 Author Share Posted July 22, 2022 @JohnCh pointed out that if the issue were the ECU not receiving a trigger (i.e. the crank and/or cam sensor) to send the pulse, then the pulse would not be sent to the injector too. I just tested the injectors on #2 and #4, and both are getting the pulse. So it appears to not be sensors. For grins I tested the resistance across the coils on #2 and #4 (same) and swapped the coils and re-ran to check for pulse yet again (no difference). I'm running out of things to test and am now checking with Bruce B. to see if he has an old MBE lying around that I can plug in and crank the engine over to test. It doesn't need to start, just crank would be enough to check for the pulse at the #2 coil. Link to comment Share on other sites More sharing options...
Pokey Posted July 22, 2022 Author Share Posted July 22, 2022 Hold on, got one more thing I can test. @MV8's point about going through the back of the connector to test is something I might be able to do at the ECU. If so this would be the definitive test of the wire run between the ECU and coil. That run has checked out so far, not just continuity but it also has the same resistance as the other three coils, but if there is no pulse at the ECU then I'd know the wire didn't matter. Link to comment Share on other sites More sharing options...
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