babymerc Posted March 10, 2023 Share Posted March 10, 2023 hi all, having real trouble with my 270s. Took for mot which it failed miserably on emissions, over 9 on co2. Very reluctant to star recently. Changed battery today because the old one was getting tired. Now it won't start, turns over fine, removed spark plug and it was wet. Turned over with plug still removed and there was no spark. Really at my wits end now don't know what else to do. The car is standard self built by me in 2015/16. Any help, suggestions would be greatly appreciated. John Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted March 10, 2023 Member Share Posted March 10, 2023 What's the voltage across the battery at rest, and the minimum when cranking?Check all of the relevant cables and connections: battery, starter, engine earths.Try jump starting it from another vehicle, engine at 3,000 rpm, fat cables.Jonathan Link to comment Share on other sites More sharing options...
babymerc Posted March 10, 2023 Author Share Posted March 10, 2023 Hi Jonathan, battery is brand new, turns over fine Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted March 10, 2023 Share Posted March 10, 2023 Hi John, I would look to see if the ECU ground is tight and gives close to zero ohms resistance to the engine block, if not go through all the major earthing points to see they are clean and tight. Next would be to check that the ECU is getting close to battery voltage in it's supply. The common grounds and 12V supplies to the coils should also be checked for integrity. Link to comment Share on other sites More sharing options...
babymerc Posted March 10, 2023 Author Share Posted March 10, 2023 Hi James, silly question but where would I find the ecu ground cable Link to comment Share on other sites More sharing options...
babymerc Posted March 10, 2023 Author Share Posted March 10, 2023 Hi James, silly question but where would I find the ecu ground cable Link to comment Share on other sites More sharing options...
babymerc Posted March 10, 2023 Author Share Posted March 10, 2023 James found the ground. Reading 0.4 ohm to engine block Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted March 10, 2023 Share Posted March 10, 2023 Hi John, I'm not sure which ECU that you have, but if it is an MBE ECU, the wiring diagram I'm looking at from a 2012 Sigma engined car has the ground lead 320mm from the ECU connector. It should be a black lead with a yellow stripe with a 6mm ring terminal on the end that is under an M6 nut on a stud attached to the body. Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted March 10, 2023 Share Posted March 10, 2023 Hi John, I would say 0.4 ohm is reasonable, as long as it doesn't vary if the wires are flexed. If you have the MBE ECU, the ECU power should be on pin 10 and 13 (switched from ignition). The common ground on the coils is likely the white wire with yellow stripe that is chained between the coils, which could potentially have a break in it at a connector.Also assuming that when you did the spark test, the plug threads were resting against the bare metal part of the block or cylinder head with the coil attached and non of the plugs showed a spark? Link to comment Share on other sites More sharing options...
babymerc Posted March 10, 2023 Author Share Posted March 10, 2023 James, had the plug resting on the manifold. Where will I find 10 and 13? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted March 10, 2023 Member Share Posted March 10, 2023 Please let me know if you'd like the wiring diagrams.Jonathan Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted March 10, 2023 Share Posted March 10, 2023 John, if it is the MBE ECU, it should have the following connector, the casing can be taken apart carefully, but it is easy to damage it. The red locking tab can be slid out to remove the connector clamp, allowing the connector to be probed: Link to comment Share on other sites More sharing options...
babymerc Posted March 10, 2023 Author Share Posted March 10, 2023 I'm wondering if the initial cause for the off the scale emissions has finally given up Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted March 10, 2023 Share Posted March 10, 2023 Difficult to say, but ensuring there is a strong spark while cranking would be the first thing I would trace and rectify.Here is some more ECU connector info:https://sbdmotorsport.co.uk/wp-content/uploads/pdf/MBE9A4-PinoutIssue_F.pdfhttps://sbdmotorsport.co.uk/wp-content/uploads/pdf/Open_wiring_harness-ecu_connector.pdf Link to comment Share on other sites More sharing options...
babymerc Posted March 10, 2023 Author Share Posted March 10, 2023 Thanks for that James and Jonathan, but I'm quickly getting into the realms of "I'm not sure what I'm doing ". Might have to find a way of getting it to someone Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted March 10, 2023 Share Posted March 10, 2023 If you feel comfortable in removing the ECU connector, you can probe the continuity and resistance to the coils and individual grounds the ECU uses and measure the supply voltage to the ECU.I would also ignore the pin location specifics I put in post #12 if your car isn't wasted spark ignition and is coil-on-plug, as I took it from a 2012 diagram, Jonathan should have a more updated version. If you do have a wasted spark system with a single or dual coil instead of coil-on-plug, I would suspect the wiring to the coil or a coil pack failure itself.Other issues could be a crank or cam sensor failure or wiring to those sensors that is bad, so the ECU is not able to trigger the spark. Link to comment Share on other sites More sharing options...
Tom_Arundel Posted March 10, 2023 Share Posted March 10, 2023 Where are you? Link to comment Share on other sites More sharing options...
babymerc Posted March 10, 2023 Author Share Posted March 10, 2023 Hi, I'm in n.wales near moldJohn Link to comment Share on other sites More sharing options...
colindavies56 Posted March 11, 2023 Share Posted March 11, 2023 Down the road from me then, Link to comment Share on other sites More sharing options...
John Vine Posted March 11, 2023 Share Posted March 11, 2023 Back to basics for a mo...Can you post the full MOT emissions results?JV Link to comment Share on other sites More sharing options...
babymerc Posted March 11, 2023 Author Share Posted March 11, 2023 Sorry John, the chap stopped and cancelled the test as soon as it failed emissions, so he didn't charge me. I should have been clearer on my first post Link to comment Share on other sites More sharing options...
ChrisC Posted March 11, 2023 Share Posted March 11, 2023 It's a same your not closer because it sounds an interesting problem.Your MOT emissions I suspect are caused by a all to common lambda sensor failure. It's happened before and will happen again, but I don't suspect it's the reason for the no start. Can you check the fuses, unrelated shorts on seemingly unrelated circuits have caused no starts in the past. Example, speed sensor failure (also common) and indicator earth problems (that one is even on video).What is interesting is you say the plugs are wet. Normally fuel and spark are not triggered by the ECU if it's not happy to run. I work on a Sigma that died on track, months after the last mechanic trapped the crank position sensor wire between the starter and the block. This car didn't spark or fire the injectors because it couldn't see the crank position sensor feed.So with wet plugs I am assuming the ECU is happy, which makes me think about checking the wiring to the coil pack. The coil pack is less likely because it will normally fail for just two cylinders. Ultimately I think your going to need the assistance of someone with the Easymap lead to learn what's going on. But check your fuses first ;-) Link to comment Share on other sites More sharing options...
babymerc Posted March 11, 2023 Author Share Posted March 11, 2023 Thanks for that Chris. Checking the fuses will be my last throw of the dice. Will do this morning. As for easymap interrogating the car would be ideal. John Link to comment Share on other sites More sharing options...
babymerc Posted March 11, 2023 Author Share Posted March 11, 2023 All fuses check out OK, changed o2 sensor for 2nd hand one I had. No luck Link to comment Share on other sites More sharing options...
John Vine Posted March 11, 2023 Share Posted March 11, 2023 #21: Ah, ok. The reason I asked is that I'm assuming the tester meant high CO (carbon monoxide) rather than CO2. Also, a value of "over 9" is impossibly high for CO. Perhaps he meant 0.9? And even that is 3x the limit, and points to an over-rich mixture.I'd agree that a dodgy lambda sensor is prime suspect for the emissions fail.. I'd also agree that Easimap is the best way to get to the bottom of your problem -- or rather, two problems, possibly unrelated: poor emissions and failure to start.By the way, in #10 you said that you tested the plug for sparks by resting it on the "manifold". This may be a dumb question (in which case, my apologies), but did you mean one of the exhaust primaries (that is, something metal connected to the engine/chassis)? JV Link to comment Share on other sites More sharing options...
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