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  Aug. 19, 2008 3:49 p.m. Brust New Reader

  I'm having an issue with the 4age 20v in my MG Midget. I just got it back on the road after extensive suspension work and it drove great for about a week. Here's the issue: I drive about 6 miles each way to work. One day my tach started jumping wildly and the car jerked every now and again (as if power was cut off to injectors/ignition/ecu). I drove it for a few days like this- tach reading nothing like accurate RPM's, car jerking off and on, but otherwise running fine. Sometimes I'd get bad pinking on second gear acceleration.

  I checked the ecu for codes: only code is the O2 sensor, which I've had since the installation in '03 with no problems. The work I did on the engine prior to installation was a water line re-route, oil pump, and new set of plug wires. I've checked all grounds, and they are as before. The coil checks fine per the manual. I replaced the ignitor a year ago with another used one. It seems to get really hot after several start attempts. Now the car is very difficult to start, when it starts at all. I have a spare ECU, which seemed to fix it at first, but now acts the same as the original.
  

  I'm thinking ignitor, but wonder if anyone else has any experience/insight/advice. I've done all the troubleshooting I can from the manual.

  I'm not quite ready to go megasquirt yet, as I want to drive it more, but this is taking me one step closer.

  Thanks Brust

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  Aug. 19, 2008 4:05 p.m. Dr. Hess SuperDork

  It sounds igniter-ish to me. The tach should come off the coil negative, which gets igniter output. If the tach is freaking, it is possible that either the igniter is giving junk or that the +12v to the coil or a ground is flakey.
  

  Of course, how much of the wiring is still Lucas?

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  Aug. 19, 2008 10:50 p.m. Brust New Reader

  Zero Lucas. Not that a Brust Roethler wiring harness is going to be any better, but it's mine at least, and so far, it's been bulletproof. God I hope its igniter-ish. It's an easy replacement.
  

  I managed to start it this afternoon. Ran it for about 10 minutes with same indications. Touched the igniter shortly after shutdown and it was HOT. Burnt my finger almost. I'm hoping that's the culprit, but losing faith that it's the only problem because I've already replaced one igniter a year ago. I'm buying two from Ebay- do you know if one is better than any other? My current igniter says #201 on the top, but ebay has #123 in spades for $10 (think 91 3sgte). I think the connector is the same and I'm about to pull the trigger and buy two of them from the same dude.

  Thanks for the help.

  Brust

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  Aug. 20, 2008 8:13 a.m. Dr. Hess SuperDork

  I dunno if one or the other igniter will work better. On my 20v with the OEM ECU, I used the wrong igniter (MK1 MR2) and had to go to a MSD6a to get it to work. This was before people had worked out what igniter to use on a 20v. Another thing that might be causing you problems is the coil. If that coil is shorted internally, that might overheat the igniter. The coil can be about any standard ignition coil. I ran an Accel from O'Reilley's.

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  Aug. 20, 2008 11:07 a.m. Brust New Reader

  Okay, well I'll give the igniter the first shot. Hopefully these "plug n play" igniters from the 90's will work fine. The coil tested fine with the resistance check, but I know if they get hot, things can happen.

  Thanks again.

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  Aug. 29, 2008 6:46 p.m. Brust New Reader

  Well, I received the 123 igniters and they aren't "plug n play". Luckily the guy sent a pigtail and connector with them, so wired it up anyway with same results. I'm running low on ideas here-

  Symptoms: -doesn't start at all most of the time -tach very erratic- doesn't correspond to engine speed -once started, it runs beautifully, although the igniter is VERY hot after a few minutes running. When tach begins to go erratic, the engine surges maybe another 500-1000 rpm, but always below about 2k. -tried to time it, but showing well after tdc on my timing light. Well outside the range of the disty adjustment. I replaced the timing belt a couple weeks ago, but it ran fine for a week prior to having these problems- no hard starting etc. I'm quite confident I aligned it with the correct tooth on the timing belt.

  Anything? I'll get it somehow, but sure could use some ideas.

  Brust

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  Aug. 29, 2008 11:14 p.m. Brust New Reader

  update if anyone's out there: Replaced the ignition switch and now seems to start every time or close enough. Still have wavering tach, still have hot igniter.

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  Aug. 30, 2008 8:31 a.m. dan_efi New Reader

  Could it be that your coil/iginiter combo is supposed to have a ballast resistor? Or possibly a length of resistor wire such as in a Ford Duraspark system? Without that, they usually seem to run fine for a while but eventually start fizzling parts.

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  Aug. 30, 2008 7:35 p.m. Brust New Reader

  It never had a ballast resistor before. I've had the swap installed for 5 years with no problems until now. I have replaced the igniter once, but other than that, no problems.

  I'll check further into that possibility though.

  Thanks

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