Lotus Elan

ignition coil

PostPost by: street » Sun Apr 19, 2020 7:39 am

I am struggling to get my +2 to start, i had this before and replace the battery +6 years and started straight away. Reading many posts there are lots of reasons, so i have checked the following

1 Battery test, shows it was just under amp load, however always wants a charge after attempting to start
2 Visual spark plug test, definitely glowing orange
3 Coil test .3 ohms across terminals / 8.0 Positive to HT lead output
4 Voltage to coil ( with ignition on) 10.48 volts

I have order a new set of spark plugs, as the cheapest bit.

Do the above readings suggest on starting im not getting enough amp load. I recall before i changed the battery last time around, with the addition of jumper pack it started straight away.

Ignition coil, is it on its way out, about 7 years old and has stood still for 5 years, not sure of make but i suspect relatively cheap ebay product.

I read that a coil pack that is on its way out, will make starting harder, run lumpy, misfire and stall, which is every symptom i have.

All help appreciated.

Thanks
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PostPost by: vincereynard » Sun Apr 19, 2020 7:48 am

A new set of plugs is a good move. Mine simply refused to start having checked every thing a number of times. New plugs - fired on the button. Plugs ain't what they used to be!
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PostPost by: HCA » Sun Apr 19, 2020 8:03 am

street wrote:4 Voltage to coil ( with ignition on) 10.48 volts
Thanks


Is this a reading with just the ignition key on position 1, or cranking (engine spinning on starter) voltage?

If it is cranking then just about ok, but if this is voltage from the battery and no cranking, then imo, low.
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PostPost by: wotsisname » Sun Apr 19, 2020 8:44 am

what age of +2 ? Think the later ones have a ballasted coil. if earlier, I agree it should be more than 12v static.
I am also struggling to start my +2 and suspect the coil, Thinking that cranking without the plugs in the engine may have led to coil failure?
I measured resistance of primary and secondary windings and get readings out of the suggested (google) range.
I looked to see if I could get a spark (main lead from coil with screw in, held close to an earth) by grounding the -ve side of the coil intermittently.. is this a valid test? (I get no sign of spark).
1968 Elan plus 2 - project
2007 Elise S2 [modified with a Hethel 70th sticker (yellow)]
2000 Elise S1 - Sold
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PostPost by: JonB » Sun Apr 19, 2020 8:48 am

Check the main ground in the boot. There’s a pair of bolts securing the body to the chassis through bobbins. On my car, the bolt heads, chassis and washers were rusty and it was like the battery was dying every time I tried to start. I pulled the bolts, ground the chassis rust off and put new bolts in. Fitted a cooper strap between the bolt ends in the boot (for extra connectivity to the chassis) an connected the ground. Now it turns over like a new car.

Regarding ballast resistors. My car doesn’t have one, but it’s fitted with what looks to be a Lucas Sport coil. I think these don’t need ballast, is that correct?

Check the HT leads with an ohm meter. I had a misfire caused by a failed lead. Had very high resistance.
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PostPost by: 512BB » Sun Apr 19, 2020 9:12 am

[quote="wotsisname"] I am also struggling to start my +2 and suspect the coil, Thinking that cranking without the plugs in the engine may have led to coil failure?

Highly unlikely Adrian. Remove the spark plugs, fit one HT lead to a single spark plud laid across the cam cover and spin the engine over. It should spark intermittently if all items in the chain are working correctly.

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PostPost by: gjz30075 » Sun Apr 19, 2020 9:33 am

Jon, the Lucas Sport coil DLB105 does NOT need an external ballast. The DLB110 requires an external
ballast. The coil i.d. might be stamped on the bottom, if there is no decal.
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PostPost by: JonB » Sun Apr 19, 2020 10:05 am

I think it's a 105. Anyway, the car goes like all hell.

The coil is gold coloured (looks like an anodised aluminum can) and the strap securing it is not the matching one. The pictures I've seen of it have a Lucas sticker on the strap, not the coil. So I think some lazy OP swapped the Lucas coil into the original holder (it's actually a bit loose but I've lined it with foam). There's no markings on the coil itself that I could see.
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PostPost by: miked » Sun Apr 19, 2020 11:17 am

Generally:
Due to the long route from the battery going through its travels around these cars, it is possible to see voltages less than 12. If you think about the route through the ignition
switch etc and the wire size. Plus some less than clean conections, it does not take much to get below 11 volts. Ignition switches can have some intermittent resistance.
I have worked on a few were the meter danced everywhere.
As the engine starts and the charging system kicks in it will obvoiusly increase.
The load taken by the starter pulls the voltage down quite dramatically under cranking.
Those things mentioned like the boot earth. I have always done two bolts and a busbar on all cars in that position. I have even added a large negative lead to the front. Plus two front engine flexible straps. You can't get too much copper in circuit when it comes to getting a good voltage and fast starter spin.
As I recall torque is proportiional to voltage squared, so you loose a lot of turning force with depressed voltage, which leads to even more current trying to be drawn.
I favour a ballast coil system for better starting as you are letting a lower voltage rated coil have whatever is available while cranking.
For argument sake. A 12 volt rated coil under cranking maybe struggling to see 8 volts.
Then, for say, a ballast coil which could be rated at 6 to maybe 9 volts getting the maybe 8. I know which one I would pick.
I cured my starting problem on the last Plus 2 I owned like this.

My advice is not specific but as stated above general guide from what i have done when chasing my tail. Some will say it is overkill.
My recent posting for the Zetec with a Nodiz on an Elan showed up problems. The Nodiz would only spark with the plugs out on a freshly charged battery. With them in, the loading supressed the voltage. I banged in a second positive and negatvive plus I fed the module with 4mm from the battety direct with an ignition supplied relay. No more low volts for me. :D

Cheers Mike
Last edited by miked on Sun Apr 19, 2020 5:02 pm, edited 1 time in total.
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PostPost by: vincereynard » Sun Apr 19, 2020 11:37 am

Lots of good stuff above.

A favourite of mine is to give it a squirt of EasiStart. No response on that you definitely have an ignition problem. In fact if the car has been left over a week I always use EasiStart so as to give the starter / ring gear and easy time!
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PostPost by: HCA » Sun Apr 19, 2020 4:19 pm

HCA wrote:
street wrote:4 Voltage to coil ( with ignition on) 10.48 volts
Thanks


Is this a reading with just the ignition key on position 1, or cranking (engine spinning on starter) voltage?

If it is cranking then just about ok, but if this is voltage from the battery and no cranking, then imo, low.


Without any mention of a resistor in your original post, I assumed your coil does not use one.

Do you have a ballast resistor fitted? If you do, then a static 10.48V, albeit slightly high, could be possible. Maybe you will confirm?
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PostPost by: wotsisname » Sun Apr 19, 2020 7:46 pm

Thanks for your replies (Street - I hope you don't mind that I jumped in with a similar tale of woe).

I had already looked for a spark, leaving all four plugs on the camcover, without joy... I have an aldon electronic ignition inside the distributor so am hoping it is still working..
I checked the coil had 12v+ at the + terminal (meter connected to earth and +), which was ok.
following advice from here...
I measured the resistance of the leads (4.3 to 5kohm for the 4 plug leads). The coil to cap lead is ca. 8k ohm... seems a different type ( marked 15kohm, hotwires, silicone high performance 0879D). I am assuming these to be ok.
Coil removed to bench. I get 5.7kohm from +to the output and same reading from -ve to output. + to - gives a reading of 3.7ohm... multimeter leads contribute 1.0 ohm.
firstly.. am I doing the right measurements? my assumption here is that the coil is duff... its barely used, but quite old... car was last started about 12 months ago ... have been trying to get it all finished ready for a drive this year (fingers crossed).
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PostPost by: mbell » Sun Apr 19, 2020 8:07 pm

It might be in the Aldon... There is a minimum voltage needed for to them to work, i'd guess somewhere around 10v.

I have similar problems with my car after being parked for a while, even on trickle charger. Turns over ok on starter but won't fire, if i hook my jump pack up at the solenoid it fires straight a way. Then will then restart fine unless it's parked up for an extended period.

I suspect a combination of factory meaning the ignition module isn't getting quite enough voltage to work, hence no spark. I've been going through my car trying to improve grounds and connections but still hitting this issue.

If you have a spare battery you could try powering the module from that rather than the car and see if that address it or not ..
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: HCA » Sun Apr 19, 2020 8:39 pm

This morning you had 10.48V at the coil and tonight you have 12V. mmm.

Again I assume a non-ballast (ie a 12V coil) and your readings are static and not cranking. In which case your battery was poor this morning and better - but not perfect - tonight. I would want to see a 12.6V reading. So before anything, I’d get a new battery ( you did say that when you had this before, a new battery solved it)

You have no spark and assume the coil, why? Tonight you tantalise us with new info that you have an Aldon ignitor! I suggest you search some of the MG and TR sites where the phrase of ‘fit an Aldon or Pertronix and carry a condenser and points in the glove box’ abounds!

You say you have voltage at coil so I assume all connections are good.

Check the HT lead is clean and perfectly seated in the coil.

Take the HT lead off the distributer and hold it close to the engine whilst cranking. Still no spark? Then check/ replace the Ignitor.

With these done, then look at coil...
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PostPost by: street » Sun Apr 19, 2020 9:44 pm

HCA, thanks for replying, you are however mixing in response from wotitsname
I have 10.48v static on key position 1, yes this was the same issue all those years ago, new battery and issue went away. the issue with living in NZ is the cost of things, batteries are $300+ here for the same one that is 50-100 pounds in uk.

I have an orange spark, even with plugs wet with fast start wont ignite.

I did change the old Petronix system (1990) version over 6 years ago, i will look and see what make mine is.
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