The 'E' Type Forum

Chaps I have just pulled the plugs on my 3.8 after the second time it started to misfire after I fitted the 123 Tune. They are all quite a bit sooty and were not so with the standard distributor previously. I was supplied a gold lucas look coil by SNG to go with the 123 tune, but it does make me wonder what others have found is the best coil to go with this set up. I fitted Rob Beere plug leads at the same time and just feel something is possibly not compatible. Was running perfectly with the original dizzy and non fancy bits!! I am sure its a simple fix, but interested in coil specs for those running the same set up. thx

https://www.123ignitionshop.com/gb/57-coils

thanks Andrew. I will take a look at that, the problem seems to be that the gold Sports coils that are being sold as Lucas appear very often to be substandard . I guess its going to be trial and error perhaps.

The plot thickens. Apparently VW busses use the blue coil..

https://www.ratwell.com/technical/BlueCoil.html

I had a problem of a misfire with a 123.I did everything plugs coil carbs fuel supply dizzy cap leads it turned out to be a faulty regulator allowing overcharging this caused micro spikes in the electrics causing the misfire.I found the info on there web site also cap should be replaced every 30000 kmh .Replacing regulator solved the problem.

Adam

Dear Andrew,

The 123 website specifically recommends the Bosch blue coil and says don't use the gold coil, as echoed by Andrew in Australia, so SNGB haven't supplied what the manufacturer recommends. Conveniently, no one introduces or reminds you that you are now dealing with electronics in a hot and potentially electrically noisy environment, so a poor earth at the alternator, regulator and/or distributor or semi-perished wiring on other inductive or switching loads will all have to be considered as contributors to the failure mode.

kind regards
Marek

Here is the coil information from the 123 website
Which coil to use with the 123ignition unit?
This depends on your engine:

- For 6 cylinder engines we advise to change your coil to a high performance coil because of the short load time in the higher rpm range. Make sure you use coils with a primary resistance of at least 1.0 Ohm. ( 1,0 Ohm or more ) For standard street engines we advise a "Bosch Blue" or "Beru ZS106" coil. For high rpm engines a "Bosch red (0 221 119 030)" or "Beru ZS109" is much better.
- For 8 cylinder engines we advise to chance yor coil to a high performance coil because of the very short load time in the higher rpm range. Make sure you use coils with a primary resistance of at least 0.6 Ohm. ( 0,6 Ohm or more ) For low rpm engines a "Bosch red (0 221 119 030)" or "Beru ZS109" will be a good choice, for higher rpm engines we advise a special coil for V8.

Note: We hear a lot of complains from our customers about the fake "Lucas Sport" or "Lucas gold" coils, better don't use these coils.

Maybe worth considering using resistor spark plugs - BPR5's. I had a problem with misfire on the EDIS/Megajolt and it was traced back to using non-resistor plugs even though the HT leads were resistor. What I found, and this might sound crazy but reproducible, was on my test route I got misfires in exactly the same locations. I realised I was probably driving over 3 phase cables buried in the road and the RF noise from those and the ignition noise overwhelmed the electronics. Hence BPR5's are now compulsory for EDIS/Megajolt and given the £12 or so cost certainly worth fitting to see if they make a difference.

Thanks guys. All good intel here. I had read the coil information on the 123 website already but was keen to see what others had found out. I will be going to the car this afternoon. Once gardening duties have been dealt with. I cannot recall which plugs are currently fitted. I am A think they are NGK BPR6 Will report back. There is
No running misfire as such but they soot up on choke when starting. I really suspect a weak spark and weak coil. There are no markings on the coil! It could be anything for all I know. I shall do a resistance test on that to see what I have to start with

For what it’s worth, I run a Lucas gold coil with the 123 and it’s been problem free. I forget now where I bought it from.

andrewh wrote: ↑

Sat Jul 20, 2019 11:38 am

I cannot recall which plugs are currently fitted. I am A think they are NGK BPR6 Will report back.

They should be OK - 6 is the heat rating:


Bosch 'Blue' is an excellent coil and would be my choice. I assume a PO has not fitted a ballast resistor somewhere in the circuit?

So its got BP6ES not Resistors plugs. This is my full nut and bolt rebuild which I have not fitted a ballast to. The car was fine with the original spec distributor and coil. Really, there is not much to worry about, it runs fine but the plugs are getting sooty if not given a really good run. My guess is either coil or plugs or both. I shall swop out the coil and maybe change the plugs for resistor ones.

thanks David. Maybe the slightly hotter plug will help. I shall have a fiddle around and see whether I can get it burning better. Being the 123 Tune, I have altered the timing curve and so I need to really clarify whether it is timed correctly. I do have a suspicion it may be too advanced . The instructions for timing it up are highly ambiguous to say the least ( 123 instructions ) . I need to get it on the ramp and put a timing light on it and see where it is currently, and then compare that with the information on the app. Hey ho. Wasn't planning anything else this afternoon!

David, the NGK site says BPR6's for the 3.8/4.2, and BPR5 for the V12. So I run 6's. Is this not right?

Jaguar specified Champion UN.12Y plugs for the 3.8 and N.5 for the 4.2. The Champion heat range runs from 1 to 25 for automotive applications, with 1 being the coldest. NGK heat range runs from 2 to 11 with 11 being the coldest. The UN12Y cross references to the NGK BPR5; the N5 cross references to the NGK BPR6. However if the plugs are fouling then moving up the heat range is recommended hence my suggestion of BPR5 for Andrew.

Hi David.....thats thrown in a googly.....I thought the BPR5 was for the 4.2.. they have beed mentioned on the forum many times.....its actually in the knowledge base section under upgrades(but dosent mention 4.2)
Edit...The 4.2 service handbook spec is Champion N.11Y ..A corss reference i looked up is NGKBP5 https://www.sparkplug-crossreference.co ... MP_PN/N11Y

ok, well an earth lead was pretty average so I improved that and cleaned the plugs. No misfire after that, however, I am struggling with the set up of the 123 Tune. Here are some snaps of the app at various RPMs. The advance curve was supplied to me by a company that has some considerable experience with power tuning XK engines, however, one needs to get the right starting point. I am concerned that its not possible for the 123 to know where it is other than in relation to where it was when you installed it. By which I mean, that you put the vehicle at the timing mark , according to 123. Now the issue is whether they mean 9 degree before TDC or TDC itself. Consequently one can be 9 degree further advanced . I do wish these companies would make things clear. These are my readouts. It felt not very smooth until I retarded it whilst on the move until it became much better.

Hi Andrew...a friend was setting one up recently....and haveing similar problems...he noticed that his actual rev counter and the one on the app were showing a difference of 500rpm (app 500 too high)...so he adjusted his map by 500rpm so that the correct advance is happening at the true rpm reading and not what the app is showing.. Steve...PS.. he also physically set it to 8btdc then adjusted with timing light