Ignition Parts for 1999/2000 450

[RumbleTumble]

Hi All

I want to replace the ignition components on my 4.5 Chimaera, to try and eliminate a misfire which occurs at around 1500-2000rpm. I'm hoping that its an electrical ignition related problem so want to start by replacing distributor cap, rotor arm, HT leads and possibly the coil. Plugs are new from recent service but I'll check them at the same time.

If that doesn't fix it then I'll have to take it to a garage as its probably beyond my technical capability...

Does anyone have a link to a reference of Rover Parts that I can obtain from Halfords / local motor factor? Or do I need to go to TVR Parts?

Thanks in advance for your help.

[igiveup]

Start cheap, remove the spark plug extenders and put ht leads straight onto plugs. Cable tie the leads up so they do not foul on the exhaust headers.

Go for a drive and see if this cures it. Simple cheap fix if it works. Then get some boots to protect the ht leads, £10.99 on ebay. Or get the more expensive ceramic leads at £90+.

[N7GTX]

this ^^^^^^^^

Many many misfires are due to the plug extenders. Best remove and replace as said above.

This list may help you in the future: http://www.chimaerapages.com/parts-list.html

[QBee]

After 6 faulty plug extenders, I would agree with the last two posters, but I would also advise against replacing several things at once. You then don't know which one worked and hence which replaced parts are useful spares, and more importantly, you will have introduced new but quite possibly faulty parts into the system, which will give you endless grief until you work out that it's the new part that is still faulty. Stepper motors are the most common part that are faulty new, but there are others.

I wouldn't cable tie the HT leads together, personally, as you can get shorts between them. I would just use the clip things that are there to keep them neat, the ones that look like little plastic Christmas cracker antlers that are attached to the rocker covers.

[RumbleTumble]

Great - thanks for the advice above. Yes I'll try without the extenders first and if that fixes it then great. I'll also take a look at the cap and rotor for obvious wear.
I'll look at the link to see if it helps sourcing parts - if needed.

[QBee]

Do you know how to work out which cylinder is misfiring?

[RumbleTumble]

QBee said:

Do you know how to work out which cylinder is misfiring?

Not without trial and error. Any pointers?

[igiveup]

Cable tie again, put a cable tie against the exhaust manifold, when they get hot the cable tie will melt on the ones working.

[ClassiChimi]

The misfiring pot will be throwing out unburnt fuel into the exhaust manifold, Hence that area being cooler. If it's only happening at a curtain rev range maybe harder to detect, try running from cold and keeping the engine in the misfire range, that should highlight the cooler area of the manifold,
It's easy with a heat detection tool, just point it at each point where the exhaust manifold meets the heads and if it's a serious misfire the temp will be lower at that pot.
If you do narrow it down then plugs do fail, start with changing that for a known good one or new.

[QBee]

The thermometer is 5055521136115 on Ebay. About £11. It's laser infrared and works very quickly. Useful for all sorts of things including trackday tyre temps and amusing cats and grandchildren.

[RumbleTumble]

Thanks for all the pointers folks - much appreciated.

[ClassiChimi]

Amusing cats and grandchildren

I really should get one of those detectors, instant knowledge of where's getting very warm,
It's an eye on the engines performance and could alert you to a problem looming,
My only issue is it gets so hot in the engine bay that heat soak would cause some confused readings but then it's still better than just looking at the blooming engine!

That did make me laugh Anthony, I had an old mate who used to send his Dog bonkers with one, hilarious and we spent hours doing it

[QBee]

Yes, the engine bay does suffer heatsoak pretty quickly, which makes the readings confusing.

To clarify, to test for a misfire with an infra red thermometer, you need to start with a cold engine, fire it up and let it idle, and test the temperatures of each manifold about one inch from the gasket over the course of the next 60 seconds as it heats up.
That way you clearly see which plug is not firing before the heat of the neighbouring ports radiates across the manifold.

I gave that Ebay reference for a reason - there are loads on there, but you need one that goes up to more than 500 degrees C, and not all of them do.