Edzup Ezzer Posted September 27, 2018 Share Posted September 27, 2018 I’ve recently upgraded my 1.6K Supersport from EU2 to EU3 spec with a remapped MEMS3 ECU from K-Maps, plus new coil packs, HT leads, lambda sensor and injectors. The plugs are fairly new so I didn’t change them. Passed its MoT last Saturday without any problem. However, it has a bad misfire under load from approximately 4000 to 5000 rpm with I guess about 60% throttle, and doesn’t accelerate beyond that. (A misfire under those circumstances wouldn’t affect its ability to pass the MoT test.)Intuitively it feels like an ignition problem but that’s not based on much more than being suspicious of the bits that have been changed. Mark at K-Maps says it won’t be the ECU (and I believe him). So has anybody got any words of wisdom to impart that might help me locate the cause of the misfire? Having had the car updated (which took a lot longer than anticipated, but that's another story) I'm really keen to try it out but this misfire is so frustrating. Ezzer Link to comment Share on other sites More sharing options...
SM25T Posted September 27, 2018 Share Posted September 27, 2018 Try disconnecting the plug in the lead to the lambda sensor. If it then runs ok ... it was the sensor. Happened on my EU3 car. Link to comment Share on other sites More sharing options...
Area Representative Richard Price Posted September 27, 2018 Area Representative Share Posted September 27, 2018 Have you got access to an OBD reader?if so you should be able to check that there are sensible values coming from all sensors. Link to comment Share on other sites More sharing options...
Edzup Ezzer Posted September 27, 2018 Author Share Posted September 27, 2018 Richard,Mark Stacey (K-Maps) checked all the inputs with his laptop whilst we were trying to diagnose a significant problem (no live feed to the fuel pump) with the conversion from EU2 to EU3 (which turned out to be because I fitted an EU3 spec MFRU fitted whilst the harness was still wired for an EU2 spec MFRU). That confirmed the ECU was seeing all the inputs it needed from the sensors so they were deemed OK. I bought an OBD reader off eBay but couldn't get it to work (despite following Revilla's instructions on how to do it).So I believe the sensors are working correctly but admittedly, that was only before the car started and briefly after the ‘fault’ was corrected and ran, and not since it’s been driven on the road under load.Ezzer Link to comment Share on other sites More sharing options...
revilla Posted September 27, 2018 Share Posted September 27, 2018 I suspect in your hybrid EU2-EU3 upgraded loom the diagnostic line from the ECU may not be wired up. Link to comment Share on other sites More sharing options...
revilla Posted September 27, 2018 Share Posted September 27, 2018 You say you changed the injectors ... was that a like for like replacement? Were the injectors used in the 1.6 the same for EU2 and EU3? I know for the 1.8 VVC they were not. If you were running EU2 spec injectors with an EU3 ECU and map, the open loop fuelling could be off. The lambda sensor might then allow the ECU to trim it out to some extent at lower lower RPM and throttle openings, so the problem would show as it switched to open loop under load at higher RPM. Just a thought. Link to comment Share on other sites More sharing options...
revilla Posted September 27, 2018 Share Posted September 27, 2018 Just checked. May or not be relevant depending upon which ones you fitted but ...SpecRoverBoschFlowPressureEU2MJY1004300280-150-749218.1 cc/min2.5 bar 288.0 cc/min3.0 barEU3MJY1006400280-155-884199.7 cc/min3.0 barSource: http://users.erols.com/srweiss/tableifc.htmSo the EU2 injectors flowed 44% more at the same pressure, which is in keeping with what I found for the VVC engine - I guess the lower flow injectors run at higher duty cycles were better for emissions. Link to comment Share on other sites More sharing options...
oilyhands Posted September 27, 2018 Share Posted September 27, 2018 Andrew,I think your data for the 749 injectors is off, I’m pretty sure they deliver 218 at 3 bar, at least according to my Bosch data. When I get home I will double check.. . In any case an increase in pressure of 20% (2.5 to 3 br/) will yield an increase in flow of around 9% rather than 32% or maybe I am misunderstanding your data.Oily Link to comment Share on other sites More sharing options...
revilla Posted September 27, 2018 Share Posted September 27, 2018 Hi Dave,Err ... I'll get my coat!In that web page I quoted as my source, there are two separate lines for the 749 injectors with completely different numbers, and some of the numbers I copied into the table above don't seem to appear in either! The more I look at the numbers the less I understand. I didn't calculate the flow increase from 2.5 to 3.0 bar I took them both from the table ... or at least I thought I did ... but yes you're right they're not consistent. I make the difference going to 3.0 bar from 2.5 bar to be SQRT(3.0/2.5)=1.095, or 9.5% increase in fuel flow?If you have the definitive data from Bosch then please correct me, it looks like I was having a bad day. Do you think the correct flow rates of the two injectors are sufficiently different that my suggestion could have some merit ... or would I have been better keeping quiet and going to bed early?Andrew Link to comment Share on other sites More sharing options...
Edzup Ezzer Posted September 27, 2018 Author Share Posted September 27, 2018 Hi Andrew,Just checked my order history at Rimmer Bros and I ordered MJY100640 which I believed to be the correct ones. I didn't trust the injectors from my donor engine for obvious reasons, likewise the plugtop coils. I figured new parts would remove any doubts should I run into this sort of problem. RegardsEzzer Link to comment Share on other sites More sharing options...
revilla Posted September 27, 2018 Share Posted September 27, 2018 Yes I believe MJY100640 are correct. That's one theory ruled out at least. Link to comment Share on other sites More sharing options...
oilyhands Posted September 28, 2018 Share Posted September 28, 2018 Simple check, black slimline resin coated injector = EU3 640 (884), fawn bulky metal based injector = EU2 430 (749).I think that data is wrong Andrews, will update you when I get back,Oily Link to comment Share on other sites More sharing options...
Edzup Ezzer Posted September 28, 2018 Author Share Posted September 28, 2018 Hi Oily,I'm confident they are the right ones for several reasons, not least, because I believe there are detail differences between EU3 and EU2 injectors that make it difficult to fit the wrong ones. Nonetheless I'll check when I get home to make sure. From memory, they match your description. Ezzer Link to comment Share on other sites More sharing options...
Edzup Ezzer Posted October 2, 2018 Author Share Posted October 2, 2018 Hi Oily,The injectors are new and correct. I’m still chasing the misfire and I thought I'd found it (a loose plug lead) but no, it's still misfiring badly so I'm thinking of trying new plugs. Looking to identify the correct plug type and reading some old threads on here I came across your comment (#3) "They are resistive as the engine is wasted spark" and I am curious as to what that is about. I've not seen that mentioned in any of the other pages I've read elsewhere on the web so perhaps you could please enlighten me why wasted spark ignition and resistive plugs go together?Ezzer Link to comment Share on other sites More sharing options...
revilla Posted October 2, 2018 Share Posted October 2, 2018 I'm also intrigued by that. My understanding was that the plug leads were resistive and therefore didn't need resistive plugs. I recently had a misfire on my car (VVC so wasted spark) at idle and came to the conclusion that it was plugs, leads or coils, so swapped them and it was fixed. I did some sense checks on what I removed just to see if I could spot any differences between the two pairs that might indicate a problem (didn't find anything but who knows what was breaking down at kilovolts). One thing I checked was lead resistance and from memory both were about 6000 ohms. Link to comment Share on other sites More sharing options...
david nelson Posted October 2, 2018 Share Posted October 2, 2018 I had a misfire when I changed from eu2 to 3. Two issues. Eu2 plugs are different to eu3. Also need to have resister in them. 2nd issue was using pre owned coils that failed under load. Just a few ideas David Link to comment Share on other sites More sharing options...
revilla Posted October 2, 2018 Share Posted October 2, 2018 Ezzer, what plugs have you fitted? Link to comment Share on other sites More sharing options...
Edzup Ezzer Posted October 3, 2018 Author Share Posted October 3, 2018 David, Andrew,In my conversion from EU2 to EU3 (it wasn't religious) I fitted new plug top coil packs, HT leads, injectors and lambda sensor. I didn't change the plugs but will do so as they were fairly new and I wasn't aware that might be an issue. So for the sake of a few quid I'll get some NGK BCPR7ES plugs and try those (I am led to believe that they are the 'correct' plugs). I can't remember what the last set of plugs fitted were (my phone has 'lost' my 'oh so useful' page of notes on all things to do with my Seven. That is so annoying and frustrating, I can't tell you!! ) but I'm sure they were 'EU2' compatible plugs, and certainly worked ok. Never had a misfire before. And I'm still curious why resistive plugs should make a difference but if they work then hey, I'll be so happy!Ezzer Link to comment Share on other sites More sharing options...
revilla Posted October 3, 2018 Share Posted October 3, 2018 As far as I can understand ...Resistive plugs or leads reduce the current in the spark, which reduces the rate at which the coil dissipates the stored energy and therefore extends the length of the spark.Resistive plugs or leads damp the inductive back-emf which is coupled back into the ignition primary circuit and which can upset the drivers in the ECU.EU3 ECU uses a 731M01 ignition driver chip, can't seem to find a datasheet for it though to think what might be going on. Link to comment Share on other sites More sharing options...
oilyhands Posted October 4, 2018 Share Posted October 4, 2018 ‘Perhaps I am wring but my understanding is..In older ignition systems that use a distributor the spark is routed to the appropriate cylinder/plug by the rotor arm and the plug fires. With wasted spark systems, there are no moving parts, just two coils, one to serve cylinders 2/3 and one to serve 1/4. When a pair of cylinders is at TDC the appropriate coil is fired and the spark is sent to *both* paired cylinders at the same time, one is on the compression stroke and one is not, the one on the compression stroke is fired, the other spark is ‘wasted’ hence the nomenclature ‘wasted spark’. On the cylinder that is on the compression stroke the resistance to the spark is much higher and on the other cylinder it is lower. Without resistive spark plugs which bring up the resistance and make it equal the majority of the spark energy will discharge in the cylinder with the lowest resistance and hence will misfire on the cylinder that requires it most.Oily Link to comment Share on other sites More sharing options...
Edzup Ezzer Posted October 4, 2018 Author Share Posted October 4, 2018 Having read Oily's post (#20) I Googled resistive plugs and wasted spark and came across quite a bit of stuff (mostly on Pistonheads) which backs up that theory, amongst a lot of other stuff. Anyway, I am away for a few days now but will be ordering some NGK BCPR7ES plugs to try on my return. I can't wait. Ezzer Link to comment Share on other sites More sharing options...
Edzup Ezzer Posted October 9, 2018 Author Share Posted October 9, 2018 I'm told my new plugs have arrived and I'm very keen to try them this evening. One question I hope somebody will confirm for me. I am assuming the gap should be set to the norm, ie good old 40 thou (1 mm) but did I read somewhere (and can't find it now) that the gap should be something like 0.8mm? So what gap should I set them to please? Fingers crossed these resistive plugs are the answer to my misfire - please please please!Ezzer Link to comment Share on other sites More sharing options...
CycleSi Posted October 9, 2018 Share Posted October 9, 2018 37 thou gap is what Ratrace Motorsport and Boss Racing told me. Link to comment Share on other sites More sharing options...
revilla Posted October 9, 2018 Share Posted October 9, 2018 Every brand new OEM Rover NLP100290 I've ever checked measure pretty much exactly 0.95mm, which agrees spot on with the 37 thou figure given above. Link to comment Share on other sites More sharing options...
Andrew Hooper Posted October 9, 2018 Share Posted October 9, 2018 If you haven't done so already, try changing the plugs for platinum tipped ones. The same thing happened to me after a re-build. Andrew Link to comment Share on other sites More sharing options...
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