Misfiring while cruising

[rcb280z]

Connect your timing light up like you normally would but instead of putting the inductive pickup on cylinder number one spark plug wire put it on the ones in question. Watch for uneven flashing. This will tell you which cylinder(s) are misfiring.

But make sure the inductive pickup is on the plug wire tight.

Edited October 5, 2018 by rcb280z
needed to add more info

[AK260]

Connect your timing light up like you normally would but instead of putting the inductive pickup on cylinder number one spark plug wire put it on the ones in question. Watch for uneven flashing. This will tell you which cylinder(s) are misfiring.
But make sure the inductive pickup is on the plug wire tight.

Spot on! [emoji106]

Also try it on the coil to dizzy cap cable - which is where the majority of my issues lay.

It looks like your engine earth strap is next to your oil dipstick. Thick black wire goes from block to body.

Your coil has positive and negative low tension connectors. One is 12v from your ignition switch and the other is the 0v that the dizzy breaks / makes as it operates. Also you have low tension connectors at your distributor - look at those too. These connectors tend to corrode. Especially in the UK where we are constantly humid.

IMHO plug fouling at idle is a red herring here and given your photos they look OK. I had an L series that drank a lot of oil and the plugs were not just sooty but also wet and black - it never backfired or missed when cruising or on power. So your plugs for the sake of trouble shooting this issue look fine.

[AK260]

Ps your number 6 looks like it's not firing at all when compared with the others - just get some new leads - they are dirt cheap!

 

 

https://www.rockauto.com/en/catalog/nissan,1977,280z,2.8l+l6,1209248,ignition,spark+plug+wire+set,7224

 

 

[jalexquijano]

12 hours ago, AK260 said:

 

 

Spot on!

Also try it on the coil to dizzy cap cable - which is where the majority of my issues lay.

It looks like your engine earth strap is next to your oil dipstick. Thick black wire goes from block to body.

Your coil has positive and negative low tension connectors. One is 12v from your ignition switch and the other is the 0v that the dizzy breaks / makes as it operates. Also you have low tension connectors at your distributor - look at those too. These connectors tend to corrode. Especially in the UK where we are constantly humid.

IMHO plug fouling at idle is a red herring here and given your photos they look OK. I had an L series that drank a lot of oil and the plugs were not just sooty but also wet and black - it never backfired or missed when cruising or on power. So your plugs for the sake of trouble shooting this issue look fine.
 

 

My car is not backfiring. My dizzy has the pertronix 1761 ignitor module and the coil is a 1.5 ohm pertronix flamethrower connecet to a ballast resistor.

[jalexquijano]

12 hours ago, AK260 said:

Ps your number 6 looks like it's not firing at all when compared with the others - just get some new leads - they are dirt cheap!

 

 

https://www.rockauto.com/en/catalog/nissan,1977,280z,2.8l+l6,1209248,ignition,spark+plug+wire+set,7224

 

 

Which is the best Brand of leads? NGK BLUE?

[rcb280z]

2 hours ago, jalexquijano said:

My car is not backfiring

Nobody said anything about backfire. You need to read it again.

[AK260]

Of the list on rock auto I guess you can't go wrong with NGK.

 

Glad your car isn't backfiring - mine took out the baffles in the silencer and deformed the whole thing - you can see where it started blowing through the joints!!!! [emoji14]

 

 

 

 

 

[jalexquijano]

On 10/4/2018 at 4:09 PM, Mark Maras said:

@jalexquijano Normally I would say no because we haven't proven them to be defective but I'm going to say yes, dump them. They're not that expensive and I still suspect the problem is in the wires or connections.

Spark plugs 4, 3, 5 and 6 at 100 mph, 3000 rpm

[AK260]

100mph @3krpm!?!? That is a seriously long diff you have!!!

So are these pics with new leads or your old ones?

[jalexquijano]

R180 i guess with 5 speed tranny

[AK260]

I think your speedo may be a little optimistic - the longest R180 was a 3.364 which means you should get 22 (ish) mph per 1000rpm. Unless of course your gearbox has a super long top gear. [emoji14]

 

Mine is pessimistic around 30mph (i.e. Shows 25mph) then gets accurate at 80 and optimistic above 90! Ahem - All tested on a track of course, officer!

 

Don't always trust your old dials.

 

Other possibility is that your rev counter is being pessimistic and you really are doing 100 in which case your real (not indicated) revs are around 4.5K RPM! And if you think that the max speed of your car is around 120mph and max torque at c.5.5krpm, then the 22mph / 1000 rpm works.

 

Or are you running some super tall tyres!? :p

[jalexquijano]

I run the 280z 14 inch wheels