Stalling

[CHEF_GOLF]

Hi all
My chim has developed a intermittent stutter when driving which then turned into the engine cutting out when driving. It started straight away but was dangerous and inconvenient to say the least. Anyone experienced this or have any pointers

[Chilliman]

CHEF_GOLF said:

Hi all
My chim has developed a intermittent stutter when driving which then turned into the engine cutting out when driving. It started straight away but was dangerous and inconvenient to say the least. Anyone experienced this or have any pointers

Could be anything, but check the morass of wiring and connectors etc around the ECU and battery for loose connections, I had this some moths back, had a play with wiring and ECU connectors and problem went away. Not a conclusive fix but maybe a place to start....

[QBee]

On a similar theme, check the under bonnet electricals that supply juice to all cylinders, so coil connections, king lead, rotor arm in the dizzy.......

[CHEF_GOLF]

Thanks. I had a sneaky suspicion that it may be around he battery. I have had custom ht leads and king lead made do I am ruling these out as they are new. Less than 100 miles. Bug thanks

[QBee]

Custom made leads, fault arises almost immediately. Err, perhaps check the king lead is fully on, or even swap the old king lead back in?

[CHEF_GOLF]

Would the king lead be the problem lead as they are all custom made to remove the resistance and are solid copper. And there is a red rotor arm on too

[blitzracing]

Never run copper leads on a modern (ish) ECU. They cause horrible spikes on the ignition primary that interfere with the surrounding electronics and the voltage spikes produced on the primary go from around 300 volts to over 600, and severely stress the ignition amp as well. The reason HT leads are resistive is to control the rate of discharge of the coil, and the spark duration. Bigger sparks at the plug dont make for more BHP, just stick to decent OEM leads like Bosch. You dont need Magnecores either what ever any one tells you.

[CHEF_GOLF]

I just went for copper leads for a cleaner spark.
Do you think that this could be the cause of stalling problem
Would changing the king lead to a resistored version make any difference due to controlling the discharge from the coil and leave the copper ht leads on
Or would I need to change them all.
Thanks

[blitzracing]

You need some restistance somewhere and I doubt just the length of a resistive king lead on its own will be enough- but you could add resistive plugs to add a bit more or you may have resistive plug shrouds already (?). Its not a very precice science at the best of times, and even when set up with resistive leads throughout, the resistance path depends on the plug lead length. I cant say for sure its the cause of the misfire, but its certainly bad practice to have near 0 ohms between the coil and plug tip- its normally 10's of K ohms . Not only does it produce nasty spikes on the coil primary, you get lots of radio interferance as well. I can tell you this from bad experiance, as I destroyed 2 rev limiters and my osciloscope when trying to track down the reason for the rev limiter failures with copper leads.

[CHEF_GOLF]

The shrouds have had the resistance taken out and the ngk plugs are resistor less. So do you think new leads and king lead. I cannot hear the stereo anyway so that doesn't bother me. Lol

[blitzracing]

Just get a set of decent carbon cored leads- they cost somewhere between £14 to £30, personally I like the Bosch ones, but any kit from the Range Rover classic should fit. Im not sure on the TVR if the king lead is longer or shorter than the Range Rover one however, so you might need to buy an extra lead if the Rangie one is too short.

[shake n bake]

It always seems to be these super leads that cause issues, time and time again they cause faults.

[blitzracing]

You only need enough spark to start the mixture to burn, and one its started it should continue by itself through the combustion chamber volume any extra spark after the initial burn point is just eroding the plug tip. The only reason to upgrade the ignition system is when the mixture is hard to ignite in the first place like LPG, very high compression or turbo'ed engines where you may need a higher initial HT to strike the arc across the plug tip in the first place. There is a lot of BS talked about ignition systems, but you wont find any improved BHP power curves before and after fitting Brand X wonder leads over a decent OEM set up....

[swallet]

shake n bake said:

It always seems to be these super leads that cause issues, time and time again they cause faults.

100% agree with this.

My car came with some snazzy blue 8mm race leads.
Looked great BUT:
Rev counter bouncing all over the shop
Radio interference was terrible

Swapped for some standard leads and voila all fixed and the tickover was smoother too with less rev hunting.

I can't think of any reason for fitting sports leads other than the nice colour. They cannot make any appreciable improvement in performance over standard.

[QBee]

swallet said:

100% agree with this.

My car came with some snazzy blue 8mm race leads.

Radio interference was terrible

Can you remember what make they were please? Mine are pale blue and Lumenition, IIRC. No problem with the rev counter, but I do have problems with radio reception.

[blitzracing]

Magnecors I suspect.

[Malcster]

Can I ask for thoughts on these leads...?

http://www.ebay.co.uk/itm/Rover-V8-Soft-Dash-8mm-B...

...are these a no-no as mentioned earlier?

[jr6yam]

Malcster said:

Can I ask for thoughts on these leads...?

http://www.ebay.co.uk/itm/Rover-V8-Soft-Dash-8mm-B...

...are these a no-no as mentioned earlier?

I had a set of leads from Powerspark, they were brilliant until half of them melted!!
Probably didn't help myself by binning the plug extenders, but my old Bosch leads are
still in one piece...

[blitzracing]

There are to ways of providing a resistance path for the spark- the cheaper leads use a carbon based core that simply provides a DC resistance. This is cheap and cheerful, and used on most leads, and works perfectly well. Any quality issues on this type of lead will be the quality of the silicon insulation, how robust the core is, and how good the crimps.

The more expensive inductive leads use a coiled wire to carry the HT, and this acts like an electromagnet, and produces a magnetic field in the core of the lead. This has an affect of producing a reverse voltage in the lead that pushes back against the incoming voltage. This produces an inductive resistance to control the coils discharge, but this is only present when the coil voltage is rising rapidly. Its quite clever as by pushing back against the coil you dont loose coil energy in the lead core, and as the coil voltage starts to fall so does the reverse voltage, so you can extract all the coils stored energy. The down side is coils discharge is still more rapid than carbon leads, so produce more primary spikes. Realistically the coil has a huge power reserve over whats needed to ignite the plug. Typically a coil can produce 35-40kv, when you need around 7-20k, so a few 10k ohms lead resistance really does not stop the spark anyway, so you dont need to worry about reducing the lead resistance down.

[stueyp34]

jr6yam said:

I had a set of leads from Powerspark, they were brilliant until half of them melted!!
Probably didn't help myself by binning the plug extenders, but my old Bosch leads are
still in one piece...

Out of interest did you use any heat protection for the leads (such as the thermal socks some people have used) or were the leads naked when they melted?