Attaching HT leads

[BritishBlitz87]

Evening all, I've having a spot of bother this past few days, annoyingly entirely of my own making.

It's coming around to service time again, and this year I decided to do some preventative maintenance and replace the original HT leads along with the usual 20,000 mile-old spark plugs with some NGK ones, only to find my car won't start. At first I assumed I'd got the wrong leads, since the NGK ones didn't bear much resemblance to OEM, but even after spending £70 on a set from a main dealer the problem remains.

Now the engine cranks fine and almost "catches", I can see the engine rocking and firing sporadically. This varies each time I reattach the HT leads, which leads me to believe there is a connection problem.

The only thing I can think of is the HT leads are not properly fitted to the spark pl, but no matter how hard I press I can't get some of them to do the "click" sound that means they are over the terminal nut which I get attaching them to the plug outside the engine.

Prior to all this the engine was running fine, the only thing I've changed is the HT leads. I've triple checked the fring order and that isn't the problem. I haven't yet tested the ignition coils since they were fine earlier, and I suppose I could have damaged the lead connectors constantly pulling them on and off.

Does anyone have any advice?

Edited by BritishBlitz87 on Saturday 6th March 18:23

[M4cruiser]

Put the old leads back and see if it starts.

[M22s]

Did you set/check the gaps on the plugs?

[BritishBlitz87]

M4cruiser said:

Put the old leads back and see if it starts.

Forgot to mention, the old leads were perished onto the coils, I ended up snapping one of them getting it off and had to cut the rubber boots off the rest.

Otherwise I would have just done that and sacked off the whole thing

[BritishBlitz87]

M22s said:

Did you set/check the gaps on the plugs?

Apparently they come pre-gapped, you need a special tool to check because of the grooved electrode. I did the plugs earlier and they worked fine for the couple of weeks until the new leads came.

[mgtony]

Are the rubber boots too long preventing the terminal from seating properly on the plugs?

[rigga]

I know you said the firing order is correct, but did you replace the leads one at a time, old one off new one on, then move to the next, or did you take them all off first?

[paintman]

Can the rubber boots be slid along the cables so the cable sits further into the boot allowing the cable end to fit properly onto the component?

How do the new ones compare to the old ones?

What vehicle is it?
How many cylinders?
Distributor with rotor arm or coil packs?

[M22s]

BritishBlitz87 said:

M22s said:

Did you set/check the gaps on the plugs?

Apparently they come pre-gapped, you need a special tool to check because of the grooved electrode. I did the plugs earlier and they worked fine for the couple of weeks until the new leads came.

I didn’t know that - every days a learning day

[BritishBlitz87]

Hello all, thanks for your replies but I still haven't solved the problem. vehicle is a 2006 Hyundai Coupe SIII 2.0l 4cyl with ignition coils.

I can say with absolute certainty that the firing order is correct, Hyundai thoughtfully labelled both the leads and ignition coil connectors and length matched the leads, and there is literally no other way they can fit into their routing points. I did also use the one in one out method mentioned by rigga.


Upon further investigation it appears that the most likely problem, despite the fact I got it from the main dealer and being outwardly identical in every dimension, I have got the wrong HT leads again .The new ones have a bit of masking tape on in this picture.


I swapped the new OEM ones for the old ones and not only was there a distinct click that was lacking in the other two sets, but the engine was much closer to starting. Didn't work completely since I only had three of the originals left.

Closer inspection revealed the only difference between the two sets: a small black number on the connector bootthat was and possibly a very small difference in the shape of the connector, that I could only see when they are side by side.



Happens all the time with my car. Seems its a bit of a unicorn, being a 2006-registered example of the SIII which accoridng to the internet was only made 2007-2009. This means every parts broker that uses one of the registration-based parts finders ends up giving me bits for the last generation. Happened to my mechanic when he was doing my cambelt service as well.

I suppose I'll be taking the bus tomorrow. At least I'll have plenty of time to complain to the Hyundai parts desk...