Yet Another Misfire

[jonnyboy]

So took our 71 '6 out for a spin yesterday all fine until around 25 miles when a misfire started.

This morning have checked and gapped the plugs (slightly wide), No.3 was really wet and very sooty, and led me to suspect that the injector for No3 might be on its way out.  Extracted injector, replaced and bled with a good pulse and spray pattern.  However misfire still very apparent so rather than freeze my buns off  in the garage thought I would turn to the collective to gather your thoughts.  Happy to replace leads, rotor arm, plugs if needs be in terms of elimination but it does fire up and run just not very well!

It has been rather tappetity - would the symptoms point potentially at a duff cam follower/cam?

Puzzled

Thanks for the advice

Jon

 

 

[Mk2 Chopper]

1 hour ago, jonnyboy said:

So took our 71 '6 out for a spin yesterday all fine until around 25 miles when a misfire started.

This morning have checked and gapped the plugs (slightly wide), No.3 was really wet and very sooty, and led me to suspect that the injector for No3 might be on its way out.  Extracted injector, replaced and bled with a good pulse and spray pattern.  However misfire still very apparent so rather than freeze my buns off  in the garage thought I would turn to the collective to gather your thoughts.  Happy to replace leads, rotor arm, plugs if needs be in terms of elimination but it does fire up and run just not very well!

It has been rather tappetity - would the symptoms point potentially at a duff cam follower/cam?

Puzzled

Thanks for the advice

Jon

 

 

Have you checked no. 3 plug is sparking, you could check that but also see if pulling a lead off at a time makes any difference to how it runs, it might just be not firing on one cylinder due to no spark.

Gareth

[RogerH]

Hi Jon,

    what make of plugs do you use.?

 

Roger

[jonnyboy]

Hi Roger 

 

Currently got NGK's in there not sure how "hot" they are though.

Gareth - appeared to be a spark with No 3 out and earthed to the block.

Jon

[RogerH]

Recent threads suggest that NGK are not what they were and they do not like getting wet (drying doesn;t help)

I had problems on my 4A. changed to Champion and all good for over a year.

 

Roger

[jonnyboy]

Thanks Roger for the tip - talking to SWMbO I have authority to purchase some new components - will advise as to outcome.

 

Jon

[Mike C]

NGK model no BUR6ET plugs fixed my misfire, but if you buy a set you will need to talk to the Finance Department.

[jonnyboy]

So update as follows.

Replaced the No.3 spark plug with used but clean plug, misfire has reduced.  Ah ha methinks

 

So ordered New Rotor Arm and Dizzy cap (Distributor Dr.) and New Magnecor Leads and full set of new NGK plugs.  Fitted Rotor Arm and Distributor cap and misfire has gone but is sounding abit "lumpy".  So this weekend will fit new leads and plugs and report back.

So am wondering if lack of use over past 18 months (diagnosed with epilepsy) has led to deterioration in the components to the extent that it caused a failure in one or more components?

Jon

[Waldi]

Jon,

sorry to hear of your epilepsy.

Old cars, like old people, don’t like long periods on non-action. If you can, take the car for a longer run, give it fresh fuel, as fuel degrades pretty quickly, and can make engines running lumpy.

To answer your question:

there could be corrosion on items like fuses, connectors, etc, but we all know the stories of cars stowed away for decades that start with just a new battery and fresh fuel.

Waldi

[jonnyboy]

Thanks Waldi

That's what my thought was around the general degradation of components - bit like me LoL

Looking forward to getting into the garage in a bit for a tinker.

Jon

[Steves_TR6]

Good luck getting the car running well Jon!

i’m just up the m3 is you want help tinkering :-)

steve

[jonnyboy]

Steve 

Really grateful for the offer (suspect it may involve beers?) however got home from weekend trip and have fitted new NGK plugs and Magnecor leads and it seems to have cured the misfire and according to the chief test pilot it now pulls and feels a lot stronger as a result.  So looks like a bit of general degredation was the prime culprit.  New leads do look good though. Pic attached!

Jon

[Waldi]

Hi Jon,

good you solved it!

The Magnecor plug leads do look very neat, with the correct length for each plug.

Where did you buy them from?

Thanks,

Waldi

 

[jonnyboy]

Evening Waldi

Sourced them from Aldon Automotive and brilliant service - did not have them in stock but contacted Magnecor directly and hey presto a few days later they appeared on the doorstep!

Price was also very competitive at less than £70 +VAT for the set (and they do look very smart)

Jon

 

[Waldi]

Thanks Jon.

Waldi

[jonnyboy]

Took the "6" out yesterday for a decent run and happy to report that misfire and overall performance has much improved with the new leads and plugs fitted.  A very happy result!

Jon

[astontr6]

On 5/3/2019 at 12:33 PM, Waldi said:

Jon,

sorry to hear of your epilepsy.

Old cars, like old people, don’t like long periods on non-action. If you can, take the car for a longer run, give it fresh fuel, as fuel degrades pretty quickly, and can make engines running lumpy.

To answer your question:

there could be corrosion on items like fuses, connectors, etc, but we all know the stories of cars stowed away for decades that start with just a new battery and fresh fuel.

Waldi

Also Waldi spark plugs leads degrade with age. A resistance check s/b done on them every so often. Spark plugs can also give very high resistance figures, especially the resistive types when they show 10K ohms and not 5K which they s/b. Distributor centre carbon brush also needs checking as I have had this brush spring disintegrate on me, more than once, with the repro Lucas caps. These are all areas that people s/b aware of.

Bruce.