ChrisT
Club Retro Rides Member
Posts: 1,670
Club RR Member Number: 225
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Can you not open the case of the ECU up and look over the PCB with a magnifying glass, sometimes it can be as simple as a dry joint or component failure, which is normally obvious as resistors normally burn out and capacitors can pop or leak, if you do be careful of personal static electricity as you don't want to make things worse! Did have a quick look over it a while back, not with a magnifying glass though, nothing obviously wrong. Maybe time to cut your losses and go for an Emerald or something? Have been looking at the cost of a Nodiz system instead, just in case the ecu is repairable or expensive to fix but the thing is I don't know if it is the problem yet, don't wan to replace it all and find the misfire still there.... |
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ChrisT
Club Retro Rides Member
Posts: 1,670
Club RR Member Number: 225
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Dec 21, 2018 17:19:08 GMT
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Thanks, they didn't come up on a google search for 'ecu repair', will have a look... Meanwhile, localish guy got back to me, he can't test the ecu off the car and recommends a session on his rolling road, which I know will probably get to the bottom of it but can't easily get the car to him. He did say however that the Weber Alpha ecu's were reliable and unlikely to be the problem..... Even though I'm sure it's not the HT leads I ordered a set of new ones from www.mrreretroleads.co.uk ebay store just to rule them out of the equation, as I thought fitting them made no difference whatsoever... Really don't know where to look next, may have to get it to a rolling road and see what that shows up. Did wonder if, as suggested a long time ago, it might be head gasket so redid compression test, not even results across the cylinders, which I initially put down to engine not being fully run in yet. Numbers 1 and 4 are showing higher readings, suggesting 2 and 3 maybe at fault, yet after running the engine the infrared thermometer is showing 1 and 4 as noticeably cooler, ie not firing...  |
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So are 1 and 4 showing wet plugs or is it just no 1?
To be honest it’s very rare that the problem is with the ECU. They are pretty bloody reliable things.
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ChrisT
Club Retro Rides Member
Posts: 1,670
Club RR Member Number: 225
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Dec 24, 2018 13:31:08 GMT
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So are 1 and 4 showing wet plugs or is it just no 1? To be honest it’s very rare that the problem is with the ECU. They are pretty bloody reliable things. Yeah, 1 & 4 are wet. |
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to test the Webcon Alpha ECU injector outputs you can use some LEDs instead of the injectors, then crank the engine over and check they all light up. Might be worth removing the spark plugs for extra cranking speed. (output is 12v, so you may need a resistor inline with the LED)
The injectors are batch fired 1+4 and 2+3, you may have a blown output op-amp. Quite easy to fix if you are good with a soldering iron.
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Last Edit: Dec 25, 2018 9:02:40 GMT by Deleted
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Dec 25, 2018 10:56:12 GMT
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Have been looking at the cost of a Nodiz system instead, just in case the ecu is repairable or expensive to fix but the thing is I don't know if it is the problem yet, don't wan to replace it all and find the misfire still there.... I got a nodiz with plug and play loom for the xe that's going in my capri, i thought the price was very good |
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ChrisT
Club Retro Rides Member
Posts: 1,670
Club RR Member Number: 225
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Dec 25, 2018 12:17:46 GMT
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Have been looking at the cost of a Nodiz system instead, just in case the ecu is repairable or expensive to fix but the thing is I don't know if it is the problem yet, don't wan to replace it all and find the misfire still there.... I got a nodiz with plug and play loom for the xe that's going in my capri, i thought the price was very good Yes, will be watching to see how it all goes/works..... Problem with going with new ecu is that it'll need mapping as well. |
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ChrisT
Club Retro Rides Member
Posts: 1,670
Club RR Member Number: 225
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Dec 25, 2018 12:21:06 GMT
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to test the Webcon Alpha ECU injector outputs you can use some LEDs instead of the injectors, then crank the engine over and check they all light up. Might be worth removing the spark plugs for extra cranking speed. (output is 12v, so you may need a resistor inline with the LED) The injectors are batch fired 1+4 and 2+3, you may have a blown output op-amp. Quite easy to fix if you are good with a soldering iron. Sounds simple in theory, but if it was wouldn't the ecu tester be able to do something like that rather than returning untested. Also, it's only controlling spark as I'm running carbs. |
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Dec 25, 2018 16:44:00 GMT
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I got a nodiz with plug and play loom for the xe that's going in my capri, i thought the price was very good Yes, will be watching to see how it all goes/works..... Problem with going with new ecu is that it'll need mapping as well. From what I gather there are most engine spec map out there |
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ChrisT
Club Retro Rides Member
Posts: 1,670
Club RR Member Number: 225
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Dec 25, 2018 17:20:39 GMT
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That's good to know  |
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Dec 26, 2018 10:24:12 GMT
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its not going to be spark unless the dizzy cap is warped in some way, given the coil is triggered by the ecu via crank signal.
you have compression on all 4 so all i can think it being is carb related.
whatever map you use it will need checking on a rolling road, any aftermarket ecu even these days are a long way short of the computing power of a self correcting oem ecu.
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ChrisT
Club Retro Rides Member
Posts: 1,670
Club RR Member Number: 225
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Dec 26, 2018 10:58:24 GMT
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its not going to be spark unless the dizzy cap is warped in some way, given the coil is triggered by the ecu via crank signal. you have compression on all 4 so all i can think it being is carb related. Did initially suspect the carbs but couldn't think what would cause over fuelling on 1 and 4, seems strange something wrong with both carbs. If it were float level I'd expect 2 and 4 with the engine sloping back slightly... |
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Dec 26, 2018 11:49:28 GMT
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its not going to be spark unless the dizzy cap is warped in some way, given the coil is triggered by the ecu via crank signal. you have compression on all 4 so all i can think it being is carb related. Did initially suspect the carbs but couldn't think what would cause over fuelling on 1 and 4, seems strange something wrong with both carbs. If it were float level I'd expect 2 and 4 with the engine sloping back slightly... Could it be air leaks around carb and inlet manifold?... seems weird over both carbs though beetle engines suffer due to the manifold arrangement, which is why I mention it as ours had weird running wandering over cylinders before we changed some parts |
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Dec 26, 2018 12:29:34 GMT
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Could always try spraying brake cleaner into the trumpets to see if that helps it run. Gives you an idea whether it’s fuel or spark.
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ChrisT
Club Retro Rides Member
Posts: 1,670
Club RR Member Number: 225
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Dec 26, 2018 13:31:12 GMT
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Could it be air leaks around carb and inlet manifold?... seems weird over both carbs though beetle engines suffer due to the manifold arrangement, which is why I mention it as ours had weird running wandering over cylinders before we changed some parts Recently replaced inlet manifold gasket and rubber seals between carbs and manifold, shouldn't be them, the afr gauge is showing rich, thinking air leak would be lean.. |
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Last Edit: Dec 26, 2018 13:31:49 GMT by ChrisT
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ChrisT
Club Retro Rides Member
Posts: 1,670
Club RR Member Number: 225
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Dec 28, 2018 21:07:37 GMT
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Today's random stabs in the dark at the workshop yielded nothing  Thought that maybe, if 1 and 4 are over-fueling, leaning them off with the mixture screws might at least get it running right at idle but no, couldn't even get it to start with them in one turn, or any other position. Plan B - try starting with a direct 12v to the coil rather than using the ecu to trigger it, unlikely to work without being able to rotate the dizzy so the timing is anywhere near right, but worth a try just on the off chance it starts and runs on all four cylinders. It didn't work but then I couldn't get it running with the ecu reconnected either. Too cold to do any more investigation |
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Dec 29, 2018 11:21:20 GMT
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I still suggest squirting brake cleaner into the inlets to see if it fires.
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ChrisT
Club Retro Rides Member
Posts: 1,670
Club RR Member Number: 225
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Dec 30, 2018 11:05:48 GMT
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Forgot to try that idea...
Yesterday began by cleaning the plugs before starting it, still missing but not as bad, had to keep reving it to keep it going as it wouldn't idle though.
Thermometer shows all four cylinders firing, not even temps across the exhaust manifold but a lot closer than before.
Tweaked the throttle stop a bit to get the idle higher but that caused the revs to 'float' about, like the carbs were out of balance or mixture not even - checked idle screws were back in the right position after previous tinkering.
Not sure where this is leading me, different symptoms every day....
Didn't get any further as battery was about flat.
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Dec 30, 2018 11:30:59 GMT
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With the results you are getting Chris if it were my car I would:
1. Back off the throttle stops until all closed and then wind in half a turn.
2. Wind in all the idle/mixture screws closed then open each buy one and a half turns.
3. Set it to TDC No:1 and check the static timing and adjust if needed.
4. Try to start/run the engine if it runs great if not on all stops and mixture screws adjust by only half a turn each until it runs.
5. Wright down all adjustments needed to get it to run.
That way you will start from a level point and you will have a record of how everything is set.
If you have got an exhaust gas analyzer (Gunson Do a great one) great set the mixture using that and a Gunson Colour tune.
Just my view on the problem from what you have said.
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