Car cutting out, tach all over the shop

[soldave]

Had to come at some point, and so I had my first scare in Lotus ownership today.  Sorry for the long story here but I like to try and give as much detail as I can.

 

So I was driving along the motorway at 60mph and driving for about 30 minutes with no problem.  I start to feel a slight hesitation in the engine and glance down at the tach to see it wavering just a tiny bit.  Thought it was nothing so pressed on.

 

About 20 seconds later the car is losing power before spluttering back, tach now dropping to 0 for a split second, then up to 6,000rpm, then back to 1,000 then 0 etc.  Car is losing power and speed so I shift down into 4th.  As I took my foot off the accelerator the revs drop off completely and the car dies.  Dropped the clutch into 4th gear and it fires back up into life with a backfire, but is still losing power.  I come off at the next junction and pull over (each time I shift down or have to bring the car back to life by dumping the clutch it backfires).  Barely got into a layby in 1st gear (the only one giving me power by then) and stopped.  Car then proceeds to idle fine as if there was no problem.  I gave it some revs and it's clean as a whistle.

 

Turned off the engine and first thing I checked (although in hindsight not so related) were spark plugs.  Checked they were all in nice and snug and they were, and I checked the leads into the distributor cap as best I could with the air box still there.  Left it 10 minutes and started the engine again.  Seemed fine so slowly pulled out of the layby and onto the street.  Drove down the street for half a mile and back and it's fine so I pull back onto the motorway.

 

Halfway down the sliproad it starts going crazy again.  Pulled into the hard shoulder and kept the engine running wondering what the hell to do.  Left it running for 5 minutes and decided to give it one more try.  Proceeded to drive to my friends (15 miles away) and then a couple of hours later drove the 35 miles home very steadily (50mph).

 

But what could have caused that?  I'm guessing something to do with the ignition (distributor, coil etc) but am not so familiar with these systems and not sure where to start.  What parts should I be looking at and what could have gone wrong but then fixed itself and allowed me to drive on?

 

A little worried to drive far right now in case this happens again so would appreciate any thoughts.

Edited November 1, 2014 by soldave

[Dunc]

you've lost ignition whilst the engine was running.

 

If there is no ignition, the engine continues to draw fuel unless its at idle when the ignition stops. when you then start it, it backfires.

 

I had the same thing last week with a carpet that got caught under the accelerator pedal. I killed the ignition as I thought the throttle had failed. When I pulled over and checked the timing belt was still there, then started the car, it gave a huge backfire as it ignited all the ingested fuel.

 

I'd check you connections to the LT of the coil and from your ignition switch.

 

I'd also have a look in the 'strib for a frayed wire that might be shorting. Shorting the ignition feed will put your rev counter to zero.

[soldave]

Yeah, I kind of thought that's what might be causing the backfire when it came back to life again.

 

Thanks for the thoughts on what to check.  Hopefully I'll find something that's a bit loose.  I'd hate it to be a problem I can't source.

[jonwat]

Next time check the coil, if it's too hot to touch it needs replacing :-)

[soldave]

Next time check the coil, if it's too hot to touch it needs replacing :-)

Thanks.  I'll do that.  What would that mean if it's too hot to the touch, as in what would be causing it to be too hot?

[soldave]

Oh, might be related or might be unrelated, but should the vacuum pipe be open on the distributor or should it be connected to something?  On mine it's just open and the service manual says things like, "Reconnect the vacuum pipe, (if fitted)"

[black eclat]

I am thinking its a fuel issue. Idling fine but losing power under load.

Fuel pump or fuel lock solenoid me thinks.

Edited November 1, 2014 by black eclat

[soldave]

I am thinking its a fuel issue. Idling fine but losing power under load.

Fuel pump or fuel lock solenoid me thinks.

Would a fuel issue cause the tach to just start swinging around wildly?  Even going above what I the speed should have my rpm at?

[black eclat]

Would a fuel issue cause the tach to just start swinging around wildly?  Even going above what I the speed should have my rpm at?

 

I remember from a previous experience I had with my Eclat where I was making some good progress and all of a sudden started to loose power and pick up again, my tacho was bouncing about but so to were the engine revs.

When I applied throttle, rough running, remove throttle and it would stabalise.

My problem was that the flowlock solenoid gets it earth connection from being bolted to the chassis. Mine had come loose.

 

Your description made me rememeber my issue. I suppose the key question here is were the engine revs matching the oscillations of the tacho? If not then its more likely electrical as already mentioned above.

[soldave]

I remember from a previous experience I had with my Eclat where I was making some good progress and all of a sudden started to loose power and pick up again, my tacho was bouncing about but so to were the engine revs.

When I applied throttle, rough running, remove throttle and it would stabalise.

My problem was that the flowlock solenoid gets it earth connection from being bolted to the chassis. Mine had come loose.

Your description made me rememeber my issue. I suppose the key question here is were the engine revs matching the oscillations of the tacho? If not then its more likely electrical as already mentioned above.

Ok I'll add it to the things to check. Thanks for explaining it a little. Whereabouts is the flowback solenoid?

[black eclat]

Ok I'll add it to the things to check. Thanks for explaining it a little. Whereabouts is the flowback solenoid?

 

Bolted on to the chassis rail right beside the clutch release arm. Usually rusted and covered in crud.

[johnpwalsh]

Strange one but I kind of tend to agree with Dunc, If she is running have a feel of the coil and see if it's hot as it could have started to fail, going from memory that one would be about two and half years old but in saying that I had two brand new ones straight out of the box on my S3 which were both faulty. If you have her running for say 15/20 mins and the coil is ok I would do, again as Dunc has suggested and check for a broken/frayed wire from the distributor. For sure it's electrical, if it were fuel and she was dying on you while driving the tacho would drop with the revs but wouldn't bounce about as erratically as you have mentioned unless the revs suddenly picked up and she was screaming. As for the fuel flowlock as mentioned by a couple of the other guys I have never had an issue with that one so wouldn't like to comment but worth a try. 

[910Esprit]

Does your car have a Lucas electric rev limiter?  (black box with 3 wires)  If so try running it with that disconnected.  

[Dunc]

the tacometer swinging and the backfire would definatley suggest that it is on the ignition side.

 

If it was fuel startvation that stopped the engine, it wouldn't have ingested surplus fuel so wouldn't be going bang.

 

The bad news is that it is intermitent, which makes it hard to trade.

 

Things to consider:

 

Run an auxiliary wire with an inline switch from the permanant live to the feed of the ballast resistor. You will need the switch under the bonnet to turn off the engine, but if it cures your issue, you don't have to worry about taking the distributor out (which is a R-PITA on our cars....).

 

Whilst putting this wire in place, use some sandpaper on the terminals of the coil until they are nice and shiny and crimp the spade clips in a bit to ensure they are tight and making a good contact. If the problem disappears with the aux wire in place and switched on, its an issue with the feed to the coil.

 

If its still there, I'd be looking at the wiring in the distributor:

 

step 1: Put engine to TDC using a 19mm socket and a power bar on the crankshaft pulley bolt (do not be tempted to crank it ont he cams - always the crank pulley.) Put the notch in the pulley to the timing tooth mark ont he right, and look to see that the little indentations on the sides of the cam pulleys are pointing at each other. If they are not, crank it until the pulley notch comes round again and look again. There is a similar mark on the distrubutor drive pulley (the wheel next to alternator). This mark should be pointing due south.

 

There is a little clamp bolt on the distributor drive which you take off and you can withdraw th distribitor, Leave the HT wires on the cap if you can to avoid getting them muddled.

 

Once the distributor is out, check that the little wires near the base plate are not close to being munched/freyed, and check them with the continuity tester on your multimeter. Give them a wiggle to make sure they are not shorting through their insulation on something.

 

NB If you dont yet have a multimeter - get one as it will be the most used tool on your for old Lotus. Dont use an old voltmeter - that beep continuity tester is the single best function for working on this car. Maplin are selling their "precision gold" multimeter at 20 quid at the moment, - Its ace - had mine for 15 years.

 

(The above assumes you have a balast resistor and a 10V coil.  If your not using a ballast coil - just put the switched Aux wire onto the +ve of the coil.)

 

Let us know.

Dunc

[soldave]

the tacometer swinging and the backfire would definatley suggest that it is on the ignition side.

 

If it was fuel startvation that stopped the engine, it wouldn't have ingested surplus fuel so wouldn't be going bang.

 

The bad news is that it is intermitent, which makes it hard to trade.

 

Things to consider:

 

Run an auxiliary wire with an inline switch from the permanant live to the feed of the ballast resistor. You will need the switch under the bonnet to turn off the engine, but if it cures your issue, you don't have to worry about taking the distributor out (which is a R-PITA on our cars....).

 

Whilst putting this wire in place, use some sandpaper on the terminals of the coil until they are nice and shiny and crimp the spade clips in a bit to ensure they are tight and making a good contact. If the problem disappears with the aux wire in place and switched on, its an issue with the feed to the coil.

 

If its still there, I'd be looking at the wiring in the distributor:

 

step 1: Put engine to TDC using a 19mm socket and a power bar on the crankshaft pulley bolt (do not be tempted to crank it ont he cams - always the crank pulley.) Put the notch in the pulley to the timing tooth mark ont he right, and look to see that the little indentations on the sides of the cam pulleys are pointing at each other. If they are not, crank it until the pulley notch comes round again and look again. There is a similar mark on the distrubutor drive pulley (the wheel next to alternator). This mark should be pointing due south.

 

There is a little clamp bolt on the distributor drive which you take off and you can withdraw th distribitor, Leave the HT wires on the cap if you can to avoid getting them muddled.

 

Once the distributor is out, check that the little wires near the base plate are not close to being munched/freyed, and check them with the continuity tester on your multimeter. Give them a wiggle to make sure they are not shorting through their insulation on something.

 

NB If you dont yet have a multimeter - get one as it will be the most used tool on your for old Lotus. Dont use an old voltmeter - that beep continuity tester is the single best function for working on this car. Maplin are selling their "precision gold" multimeter at 20 quid at the moment, - Its ace - had mine for 15 years.

 

(The above assumes you have a balast resistor and a 10V coil.  If your not using a ballast coil - just put the switched Aux wire onto the +ve of the coil.)

 

Let us know.

Dunc

Thanks for that really detailed write-up.  Possibly a dumb question but I'll need to reset ignition timing if the distributor comes out, won't I?  If that's the case I'll need to wait until I can get access to a timing light.

[soldave]

Well the first stage of trying to find the problem has got me absolutely nowhere.  Got the airbox off to give me a little room to see things.  First, I can't get the coil off right now to inspect it (or replace if needs be).  It looks like the captive nuts that the coil bolts clamp into are rusted and now spinning (you can see the photos below).  There's hardly any room to move so I'm not sure what I'm going to do with that.  Possibly get a set of very thin vice grips and see if I can grab onto something so I can back the bolts out.

 

Looked down to the starter solenoid and checked the connectors to that.  Surprisingly, one of them just came away in my hand (as you can see below).  It's the connector on the solenoid side that's broken off from the solenoid, and which goes to the coil according to the wiring diagram.  Not sure when it has broken off and can't see it affecting this, unless it's been grounding itself somewhere and causing a problem.  Not sure what to do about this though - can I tap into another wire going into the solenoid to get this connection secure, or if not what could I do other than having to get a new solenoid?

 

Looking down in the engine bay, I did notice this ground cable could do with replacing but that's probably not related.

 

Last of all I looked at the distributor cap.  While the spark plug leads were all secure, the coil lead does seem to have some movement in it.  Have a look at the video below:

 

 

And so there I've left it for now.  Need to find out how to fix this solenoid connector, and then how to remove the coil before I go any further

[soldave]

Looking at that coil again, I think the only way that clamp is coming off is if I get a dremel and cut the head off the bolts.  Alternative would be to get a 1/4" socket set with a universal joint and see if I can get a socket into the actual clamping nut and do it that way.

[andy b]

I am with 910

the rev limiter just unplug it it is next to the lucas constant energy black box drivers side engine bay towards the head light sometimes has a tie wrap around it you can just unplug it and the car will run ok without it.

andy b

[soldave]

I am with 910

the rev limiter just unplug it it is next to the lucas constant energy black box drivers side engine bay towards the head light sometimes has a tie wrap around it you can just unplug it and the car will run ok without it.

andy b

Interesting.  Why would the rev limiter cause the tach to report higher readings than I'm doing?  Not saying it's not that, but just wanting to learn the why's as well.

[Dunc]

This era of Lotus (late 70's eclat) doesn't use the AB14 Lucas constant energy and electronic rev limiter. They were only introduced on the 1983 excel. The older series 1 elites and eclats used points with Lumenition fitted to the later series ones. Where a rev limiter was specced, it was a mechanically sprung rotor arm. The series 2 (and perhaps late series 1's) used lumenition electronic ignition.

 

I'd remove the starter and solder that connector back on. Not that big a job to remove it, especially if your airbox is off.

[soldave]

I should have a bit more confidence in myself!  I was thinking to get a soldering iron and solder the connection back on.  Might even be able to do it in situ.

 

Cleaned up the distributor cap just now.  A couple of the points were really dull, as was the rotor, so have cleaned them up a bit.  Still nothing that would jump out to me as causing the problem I had though. 

[cbclotus]

Hi Dave I am useless with spanners .Good luck finding the fault.Mike

[soldave]

Hi Dave I am useless with spanners .Good luck finding the fault.Mike

Thanks Mike.  Spanners I'm not too bad with (once I have a full toolkit).  Electrics... I despise!

[Denis247]

Have you checked the condenser?, sounds like it could be breaking down with heat. Would also cause tacho problems. Cheap and easy 1st thing to check (by substitution),

[soldave]

Have you checked the condenser?, sounds like it could be breaking down with heat. Would also cause tacho problems. Cheap and easy 1st thing to check (by substitution),

I haven't and I've actually got a brand new condenser that I could swap out (as well as points).  Now assume I'm a dumb person who doesn't know much at all about distributors (it's not hard to imagine!).  If I set the engine to top dead centre and then remove the distributor to see what I'm doing, would I have to reset the ignition timing when I put it back in?

 

If so then I might have to try and replace the condenser with the distributor in place.