7 days and still a weak spark - inspiration required please
Discussion
Been chasing this down for so long would you believe its getting a bit tiresome?
We have a spark that only a spark tester can show, with the garage lights off. Nothing at the business end of the plug. Plug is on a HT lead direct off the coil held to the engine with a pair of mole grips - to remove dizzy from the equation.
The story so far (very abridged). The car is an 290 S2.
Changed ignition module, and then dizzy plus ignition module thanks to a loan from Phillpot.
Changed coil for a brand new one off the "alternative parts list". VALEO 245025. Old one was duff for sure.
- Haynes manual for Granada 2.9 says primary should be 0.72 to 0.86 ohm, this is 1.5 ohm, and the secondary should be 4.5 to 7 kohms, and this is 6.8 kohms. Is this likely to be a problem? Anyone else got this coil on a 2.9?
Bridged coil positive direct to battery - to eliminate any resistance fault supplying power to the coil.
Removed "yellow" connector. And fixed a bunch of other wiring bodges - including a bit of thin co-ax used to extend the solenoid feed!!! - no wonder the solenoid has been a bit iffy.
Checked -ve coil with led/resistor tester, shows flashing while cranking.
Now becoming stumped. Tomorrow need to check the earth side, but don't know where to find the earth of pins 40/60 of the ECU. Does anyone know where it is? I assume the -ve of the coil is pulsed to earth via the ignition module, then the ground connection back the the ECU, then to the ECU ground on pins 40/60. Any resistance in this path would mean less voltage across the coil primary and therefor less spark from the secondary. As the coil is only an ohm or so, then even 1 ohm of resistance in the earth would be a problem.
Any further ideas appreciated.
Thanks in advance,
Cheers
Dave
We have a spark that only a spark tester can show, with the garage lights off. Nothing at the business end of the plug. Plug is on a HT lead direct off the coil held to the engine with a pair of mole grips - to remove dizzy from the equation.
The story so far (very abridged). The car is an 290 S2.
Changed ignition module, and then dizzy plus ignition module thanks to a loan from Phillpot.
Changed coil for a brand new one off the "alternative parts list". VALEO 245025. Old one was duff for sure.
- Haynes manual for Granada 2.9 says primary should be 0.72 to 0.86 ohm, this is 1.5 ohm, and the secondary should be 4.5 to 7 kohms, and this is 6.8 kohms. Is this likely to be a problem? Anyone else got this coil on a 2.9?
Bridged coil positive direct to battery - to eliminate any resistance fault supplying power to the coil.
Removed "yellow" connector. And fixed a bunch of other wiring bodges - including a bit of thin co-ax used to extend the solenoid feed!!! - no wonder the solenoid has been a bit iffy.
Checked -ve coil with led/resistor tester, shows flashing while cranking.
Now becoming stumped. Tomorrow need to check the earth side, but don't know where to find the earth of pins 40/60 of the ECU. Does anyone know where it is? I assume the -ve of the coil is pulsed to earth via the ignition module, then the ground connection back the the ECU, then to the ECU ground on pins 40/60. Any resistance in this path would mean less voltage across the coil primary and therefor less spark from the secondary. As the coil is only an ohm or so, then even 1 ohm of resistance in the earth would be a problem.
Any further ideas appreciated.
Thanks in advance,
Cheers
Dave
Measured earth wire from ignition module to ecu as .2 ohm, and from ecu to ground also as .2 ohm. However measuring from ignition module via ecu to ground was high res. Turned on ignition. Dropped but only to 195 ohms. I am guessing that this earth path is used to ground the coil so suspect the ecu. Does that make sense? This would mean a replacement ecu needed.
I believe most coils have the secondary earthed through the case. The one pictured may have achieved an earth through the case because the back of the fiberglass where its bolted is covered with a metal mesh which is itself earthed.
We have done an tap to earth on block from the coil secondary, and this does make a spark.
We have done an tap to earth on block from the coil secondary, and this does make a spark.
Which nicely brings me back to the question. I would really appreciate someone doing a comparative test. This will only work on a 2.9.
I think my ignition earth path from the coil is poor, but I am "poking and hoping" a bit so need a comparison. I think the path for the ignition earth is from the ignition module, to the ecu, then out of the ECU to ground. This would make sense, as there is paste between the ignition module and the dizzy.
If a kind volunteer would
1) pull off the plug on the ignition module which is mounted on the side of the dizzy.
2) Put a small pin (I used a tiny watchmakers screwdriver) into the bottom (Blue/Black) hole of the plug
3) measure the resistance to the battery negative. This reads something over 2000 ohms.
4) Then switch the ignition to the run position. Mine drops to about 190 ohms.
I "believe" this should be close to zero and is my problem. However, the wire to the ECU, and the earths from the ECU are all good. Suspect is now the ECU, but need a comparison to be sure.
Next steps irrespective are to get an ECU, and then if that does not work, shell out for an auto electrician. Have had the lid off the ECU, and no obvious water ingress.
Many thanks in advance.
I think my ignition earth path from the coil is poor, but I am "poking and hoping" a bit so need a comparison. I think the path for the ignition earth is from the ignition module, to the ecu, then out of the ECU to ground. This would make sense, as there is paste between the ignition module and the dizzy.
If a kind volunteer would
1) pull off the plug on the ignition module which is mounted on the side of the dizzy.
2) Put a small pin (I used a tiny watchmakers screwdriver) into the bottom (Blue/Black) hole of the plug
3) measure the resistance to the battery negative. This reads something over 2000 ohms.
4) Then switch the ignition to the run position. Mine drops to about 190 ohms.
I "believe" this should be close to zero and is my problem. However, the wire to the ECU, and the earths from the ECU are all good. Suspect is now the ECU, but need a comparison to be sure.
Next steps irrespective are to get an ECU, and then if that does not work, shell out for an auto electrician. Have had the lid off the ECU, and no obvious water ingress.
Many thanks in advance.
Le TVR said:
Sounds like a failing condenser or condenser earth? But IIRC the condenser is integral to the ingition amp and you've already swapped that out.
I think the ignition amp earth is from the dizzy? Might be worth checking that or even running a new wire direct.
The earth is on the Black/Blue towards the ECU from the ignition amp. Need someone to test this resistance to earth with ignition off and on so I can compare (Please :-) )I think the ignition amp earth is from the dizzy? Might be worth checking that or even running a new wire direct.
Cheers
Dave
Hi All
Thanks for having the interest and taking the time to support this re-commissioning.
I ma delighted to tell you that its a runner!
Just to remind you, the symptom was originally no spark. Quickly found coil was a gonner. Then it was an extremely weak spark, so weak that it did not spark at all and could only be detected with a spark tester.
Going downstream, changed ignition module, then whole dizzy (thanks Phillpot), then ECU (is anyone interested in having one for a spare?). No change.
Yesterday, started working upstream, had obviously checked for 12V before, but this time checked resistance to battery with ignition on (but earth disconnected). Read about 80 ohm. Bad. So traced it back and found a twisted joint on the white wire into the taco, fixed that and it dropped to 26 ohm. Then realised the connections in the taco leads did not connect to the correct colours in the loom??? Something up. Took apart the connectors, put the black one to the measured earth in the loom, the red one to the measured battery, and the white on to the other. Really confident now..... No joy!
Pissed around for another 20 mins then FINALLY figured out that the taco and speedo connectors were reversed. My coil was being fed by the speedo!!! (FYI I only got the car 10 days ago). Swapped these over - spark to light up Blackpool.
Put the whole thing back together, crossed fingers and turned the key. It must have turned over about half a turn and burst into life - wow, its been standing for over 3 years that I know of, so I am pretty pleased in the end.
Total cost
Postage for START tester and Loan Dizzy - £12
Coil £50
Ignition module £24
ECU £40 (wasted)
So in total £126, of which only £50 was definitely required. However, a ton of wiring bodges removed and the yellow connector gone.
Phillpot, I am away with work now for a couple of weeks so cannot set the timing up until I get back - let me know if its a problem to hold onto the tester.
Thanks again to all
Regards
Dave
Thanks for having the interest and taking the time to support this re-commissioning.
I ma delighted to tell you that its a runner!
Just to remind you, the symptom was originally no spark. Quickly found coil was a gonner. Then it was an extremely weak spark, so weak that it did not spark at all and could only be detected with a spark tester.
Going downstream, changed ignition module, then whole dizzy (thanks Phillpot), then ECU (is anyone interested in having one for a spare?). No change.
Yesterday, started working upstream, had obviously checked for 12V before, but this time checked resistance to battery with ignition on (but earth disconnected). Read about 80 ohm. Bad. So traced it back and found a twisted joint on the white wire into the taco, fixed that and it dropped to 26 ohm. Then realised the connections in the taco leads did not connect to the correct colours in the loom??? Something up. Took apart the connectors, put the black one to the measured earth in the loom, the red one to the measured battery, and the white on to the other. Really confident now..... No joy!
Pissed around for another 20 mins then FINALLY figured out that the taco and speedo connectors were reversed. My coil was being fed by the speedo!!! (FYI I only got the car 10 days ago). Swapped these over - spark to light up Blackpool.
Put the whole thing back together, crossed fingers and turned the key. It must have turned over about half a turn and burst into life - wow, its been standing for over 3 years that I know of, so I am pretty pleased in the end.
Total cost
Postage for START tester and Loan Dizzy - £12
Coil £50
Ignition module £24
ECU £40 (wasted)
So in total £126, of which only £50 was definitely required. However, a ton of wiring bodges removed and the yellow connector gone.
Phillpot, I am away with work now for a couple of weeks so cannot set the timing up until I get back - let me know if its a problem to hold onto the tester.
Thanks again to all
Regards
Dave
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