CannyColin Posted December 30, 2022 Share Posted December 30, 2022 Hi, I have a 1993 Manual N/A which has been running fine for the past few years. However, it has just started playing up. When you first start up, it is OK, starts straight away, tickover nice and smooth, around 1200 rpm. But after about a minute it starts spluttering. You can just about keep it from stalling by pumping the accelerator pedal, but the Rev Counter dives instantly to lower revs (ie more quickly than the revs die). That makes me think it's an ignitiom problem? I have cleaned the connectors on the HT Coil and the Ignition module . . . also the connector on the MAP Sensor. Made no difference. There are also NO Fault Codes being stored . . . so I am at a loss ! Any suggestions would be welcomed. Quote Link to comment Share on other sites More sharing options...
CannyColin Posted December 30, 2022 Author Share Posted December 30, 2022 Just been giving this more thought . . . Obviously doing resistance checks on the HT Coil would look fine, as the car runs perfectly from cold startup . . . But I'm wondering if it might start breaking down after a minute or so (which would obviously cause the very intermittent running I am getting). Has anyone ever had a problem with their HT Coil? (I see you can get a brand new one for only £25). Quote Link to comment Share on other sites More sharing options...
CannyColin Posted January 1, 2023 Author Share Posted January 1, 2023 Well I figure it must be either the HT Coil breaking down . . . or more likely the Igniter (electronic ignition module) . . . I have managed to find a brand new Coil for only £12 ! So ordered one of those . . . if that doesn't sort it, I will get a new Igniter . . . amazed that I found a brand new one for just £52. I will post the results, as this may be useful to someone else in the future. Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted January 1, 2023 Share Posted January 1, 2023 Try another NA Engine ECU from a friend if you can. When capacitors on the board fry themselves they can make the engine do weird things, had symptomes similar to the above before. If you can rule out ECU as not being an issue then continue diagnosing the rest of the systems. If ECU is the culprit then you will go down a long rabbit hole try to diagnose it starting from the outside working in otherwise. Quote Link to comment Share on other sites More sharing options...
CannyColin Posted January 2, 2023 Author Share Posted January 2, 2023 Hi Mike. Well I did think that it MIGHT be the ECU causing the problem . . . but that was going to be my 3rd choice. I just figured that something is breaking down after a couple of minutes, and thought the ECU was less likely than the Igniter or HT Coil. A new HT coil is very cheap . . . even the Igniter module isn't bad . . . (the company that sells the Igniters said they fail quite often) . . . plus I don't know anyone who might lend me their ECU. Obviously if the Coil or Igniter ISN'T the problem, I will have to find a new ECU. Quote Link to comment Share on other sites More sharing options...
CannyColin Posted January 2, 2023 Author Share Posted January 2, 2023 Also, if it is the ECU itself causing the problem, wouldn't it throw up a Fault Code? Quote Link to comment Share on other sites More sharing options...
Scooter Posted January 3, 2023 Share Posted January 3, 2023 is it worth checking the coolant sensor too? Quote Link to comment Share on other sites More sharing options...
CannyColin Posted January 4, 2023 Author Share Posted January 4, 2023 Well the engine is still pretty cold when it starts cutting out, so don't think it would be that. In case it turns out to be the ECU, I emailed a company that sells ECUs on eBay to ask if they had a 89661-14610, and they didn't. But they said people often send them theirs for repair. However, I'm actually an Electronics Engineer, so I could probably sort it myself. (I have heard before that it's the decoupling capacitors that sometimes fail, and I don't imagine it wouldn't be hard to replace them) Quote Link to comment Share on other sites More sharing options...
Style Posted January 5, 2023 Share Posted January 5, 2023 20 hours ago, CannyColin said: Well the engine is still pretty cold when it starts cutting out, so don't think it would be that. In case it turns out to be the ECU, I emailed a company that sells ECUs on eBay to ask if they had a 89661-14610, and they didn't. But they said people often send them theirs for repair. However, I'm actually an Electronics Engineer, so I could probably sort it myself. (I have heard before that it's the decoupling capacitors that sometimes fail, and I don't imagine it wouldn't be hard to replace them) I'd heard it was more the capacitors leaking out onto the board and causing surrounding damage, but I may be wrong. If you succeed in your repair and feel comfortable doing it, you may become a lot of peoples best friend on here It's becoming a pretty common occurence these days so it would be good to have a member who can repair and return Quote Link to comment Share on other sites More sharing options...
Hamilton Posted January 5, 2023 Share Posted January 5, 2023 Helpful video here if you do end up opening the ECU. Doesn’t look too difficult if you have some experience. Please keep us posted! Quote Link to comment Share on other sites More sharing options...
CannyColin Posted January 5, 2023 Author Share Posted January 5, 2023 Yes, electrolytic capacitors often do that, so thanks for the suggestion. In the past I have bought faulty TVs where the capacitors on the Power Supply Board have done exactly that. It's a fairly easy (and cheap) fix. However . . . in my case I don't think this will be the cause . . . if it was a problem in the ECU I think it would be there all the time. My fault only begins a couple of minutes after starting the engine, which I think is more like something breaking down (which I think is the HT Coil or in the Igniter module). Hoping the Coil will arrive tomorrow . . . I will keep you all updated ! 1 Quote Link to comment Share on other sites More sharing options...
CannyColin Posted January 7, 2023 Author Share Posted January 7, 2023 Well the new HT Coil arrived today . . . However, despite saying it was compatible, it DIDN'T have the retaining lugs either side of the HT Lead takeoff, so it won't stay in place as there is a spring. Anyway, to suss if this was the cause of the fault, I held it in place with a cable tie, and didn't get any mis-fires. Although I haven't been for a proper drive to really confirm all is OK, which I will do when I get the correct coil. So I am sending it back and ordering a coil that I can see is correct. More to follow ! Quote Link to comment Share on other sites More sharing options...
CannyColin Posted January 11, 2023 Author Share Posted January 11, 2023 Sent the wrong coil back (they even paid for return postage, which was good) After a different eBay search, managed to find the correct HT Coil (with the lugs) for just £15, so ordered that one - it arrived the next day ! Just fitted it and been for a test drive . . . car runs perfectly again ! So obviously the coil was breaking down internally once it got warm. Many thanks for all the advice - and if I ever get any bad running issues I will certainly look inside the ECU, and replace any bad electrolytic capacitors. 1 Quote Link to comment Share on other sites More sharing options...
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