I want to buy a brand new ignition coil as I think it may cure my rough idle. I have bought a 2nd hand one and it improved the idle but I want to try a new one as I think it will make it a lot better. Before anyone asks, yes I have cleaned the throttle body.

Are there any good brands to get. Ebay seem to list a few different ones with the only brand mentioned being Fuelmiser.

I want to buy a brand new ignition coil as I think it may cure my rough idle. I have bought a 2nd hand one and it improved the idle but I want to try a new one as I think it will make it a lot better. Before anyone asks, yes I have cleaned the throttle body.

Are there any good brands to get. Ebay seem to list a few different ones with the only brand mentioned being Fuelmiser.

can't help with the what or where but my TW has never had a dead smooth idle, always been a characteristic. not sure if a new coil would do much as I'd expect if it was suspect you'd know driving it under load and higher RPM than at idle.

I've been in 3rd gens that had a completely smooth idle, so these cars are capable of it.
I don't know what it is that causes so many of these to idle rough. I've been in a few that exhibit the same rough idle symptoms so it must be a single common factor

I have nw ones here on the shelf for $75.00 if that helps

Jimbo,
What characteristic of the coil do you think is causing your rough idle, given that the car presumably runs OK under driving conditions. Is your fuel consumption normal?

There are some many factors that can lead to a rough idle. But if you've already replaced the ignition coil I doubt a new one will solve the problem. Have you tried checking spark plugs, leads, vacuum leaks etc first?

Jimbo,
What characteristic of the coil do you think is causing your rough idle, given that the car presumably runs OK under driving conditions. Is your fuel consumption normal?

It seems to only do it when the engine is fully warmed up, on the short 10 to 15 min drive to work in the morning it idles really well by the time I get there, but go for a longer drive on the way home and it idles rough. I think when hot the insulation in the coil is less effective allowing the spark to short. Seems to be a bit better with the air-con running as this would turn on the fans and bring the under bonnet temps down. Any how I have already replaced the rest of the ignition system (leads, plugs, cap & rotor) so may as well change the coil. I tested this as I came home with a very rough idle, then changed the distributor over which already had another coil in it, upon restarting the idle was a lot smoother.

I have nw ones here on the shelf for $75.00 if that helps

What brand are they and how much through ebay with postage?

Seems to be a bit better with the air-con running as this would turn on the fans and bring the under bonnet temps down.

Turning the air-con on causes the ISC to increase the idle speed to compensate for the additional load from the AC compressor, this is more likely to be the reason for the improved idle with AC on than reduced engine bay temperature. If you disconnected the battery before swapping out the dizzy the apparent improvement will be due to the ECU using default idle settings, and the problem will most likely come back in time. My guess would be a maladjusted TPS, blockage or leak in the TB air channels, incorrectly set up TB set screws etc., however if replacing the coil fixes the problem I'll have learned something new which is always a good thing! If you do drop the $75 on a new coil let us know how it goes.

I've been in a lot of 3rd gens that exhibit a very similar rough idle. There must be a common fault in all of them that a lot of these cars have.
I feel maybe the EGR may be malfunctioning somehow?

I've been in a lot of 3rd gens that exhibit a very similar rough idle. There must be a common fault in all of them that a lot of these cars have.
I feel maybe the EGR may be malfunctioning somehow?

I have a rough idle now which went away for about 5000kms after a change of spark plugs but now has returned with vengeance. Its only when the engine is hot and I feel it relates to the purge valve which was previously faulty and not purging, but may be purging too much now (hence running lean and causing misfires). Will test out this theory on the weekend.

Good luck getting the V6 to idle nicely.
You could do the usual things, like TB clean, injector clean (proper), testing the EGR, purge, PCV systems, replace plugs, leads etc and not get too much of an improvement.
My TJ can get rough when hot, I just up the rpm by 100-200 rpm with the right foot and it smooths out nicely.

I have found that the CJ Lancer with fly-by-wire throttle and variable valve timing idles smoothly at 600 rpm on the tacho under all conditions, so I'm assuming valve timing on the V6 at idle has something to do with it. Plus those big 600 cc combustion volumes, low air flow speed at idle, varying spray patterns from aging injectors, and you are pretty much stuck with a rough idle.

If someone notices just say "Yeah, I've got hot cams. Don't really start to come on song until 4,000 rpm." lol

EDIT: I have a spare ignition coil I bought off eBay, don't know how good it is, but that's not the problem anyway.

Turning the air-con on causes the ISC to increase the idle speed to compensate for the additional load from the AC compressor, this is more likely to be the reason for the improved idle with AC on than reduced engine bay temperature. If you disconnected the battery before swapping out the dizzy the apparent improvement will be due to the ECU using default idle settings, and the problem will most likely come back in time.

Even once the air-con was turned off the idle was still good. When I changed the dizzy I didn't bother disconnecting the battery, just changed it over and restarted the engine within 10 minutes. The throttle body is clean as well as the egr valve. I have some money to spend on ebay so may as well try a new coil.

Doesn't hurt to have a spare I guess.

I have a rough idle now which went away for about 5000kms after a change of spark plugs but now has returned with vengeance. Its only when the engine is hot and I feel it relates to the purge valve which was previously faulty and not purging, but may be purging too much now (hence running lean and causing misfires). Will test out this theory on the weekend.


Good luck getting the V6 to idle nicely.
You could do the usual things, like TB clean, injector clean (proper), testing the EGR, purge, PCV systems, replace plugs, leads etc and not get too much of an improvement.
My TJ can get rough when hot, I just up the rpm by 100-200 rpm with the right foot and it smooths out nicely.
....

I've changed my EGR and purge valve and the idle became a lot better, but not completely smooth. It is almost acceptable but not really, whereas before at times the idle was so bad that the passenger seat was vibrating.
How would the purge valve affect idle?
As I temporarily blocked the EGR on the intake manifold and it did not make idle better so I assume the EGR might be ok?

Incidentally, I change spark plugs, leads, distributor cap, button, ultrasonically cleaned injectors and cleaned out the throttle body really well, however this made zero difference to idle


Very rarely my car idles really smooth. Smooth enough that it almost seems like the engine is off, so these engines are capable of it but there is something that seems to be preventing it from entering this smooth idle.
My car essentially feels like 1 cylinder is not firing properly most of the time at idle

I have a rough idle now which went away for about 5000kms after a change of spark plugs but now has returned with vengeance. Its only when the engine is hot and I feel it relates to the purge valve which was previously faulty and not purging, but may be purging too much now (hence running lean and causing misfires). Will test out this theory on the weekend.


Good luck getting the V6 to idle nicely.
You could do the usual things, like TB clean, injector clean (proper), testing the EGR, purge, PCV systems, replace plugs, leads etc and not get too much of an improvement.
My TJ can get rough when hot, I just up the rpm by 100-200 rpm with the right foot and it smooths out nicely.
....

I've changed my EGR and purge valve and the idle became a lot better, but not completely smooth. It is almost acceptable but not really, whereas before at times the idle was so bad that the passenger seat was vibrating.
How would the purge valve affect idle?
As I temporarily blocked the EGR on the intake manifold and it did not make idle better so I assume the EGR might be ok?

Incidentally, I change spark plugs, leads, distributor cap, button, ultrasonically cleaned injectors and cleaned out the throttle body really well, however this made zero difference to idle


Very rarely my car idles really smooth. Smooth enough that it almost seems like the engine is off, so these engines are capable of it but there is something that seems to be preventing it from entering this smooth idle.
My car essentially feels like 1 cylinder is not firing properly most of the time at idle

What brand are they and how much through ebay with postage?

Not interested in listing on ebay sorry, not worth my time to pay all the fees etc. Postage is $15

They are Jaylec, we used a lot of Jaylec stuff

I've changed my EGR and purge valve and the idle became a lot better, but not completely smooth. It is almost acceptable but not really, whereas before at times the idle was so bad that the passenger seat was vibrating.
How would the purge valve affect idle?
As I temporarily blocked the EGR on the intake manifold and it did not make idle better so I assume the EGR might be ok?

Incidentally, I change spark plugs, leads, distributor cap, button, ultrasonically cleaned injectors and cleaned out the throttle body really well, however this made zero difference to idle


Very rarely my car idles really smooth. Smooth enough that it almost seems like the engine is off, so these engines are capable of it but there is something that seems to be preventing it from entering this smooth idle.
My car essentially feels like 1 cylinder is not firing properly most of the time at idle

Purge valve takes air/fuel from the charcoal canister when the engine is warm and above a certain rpm (ie. adds more air to the mix). It 'purges' your charcoal canister of fumes. If its faulty and stuck open, it introduces extra air to the mix when it shouldn't (ie. at idle) causing a lean misfire.

Anyway, I disabled my purge system and my idle is still rough, so it didn't fix my car.

Keema cars had a sale on the weekend offering minimum $5k trade in on used cars. Was tempted to throw in the towel and trade the magna for any car as I'm sick of trying to fix the rough idle.

How did you disable the purge system?

And how bad is your idle? Does it ever have moments where it idles smooth?

How did you disable the purge system?

And how bad is your idle? Does it ever have moments where it idles smooth?

I disabled the purge system by blocking off the vacuum line on the charcoal canister.

There are moments when it idles smooth, but it seems to be getting worse. It feels like a misfire under 1500rpm and now it does it whilst accelerating too up to that rpm. Could be ignition coil or any number of things on the ignition side or the fuel side.

Keema cars had a sale on the weekend offering minimum $5k trade in on used cars. Was tempted to throw in the towel and trade the magna for any car as I'm sick of trying to fix the rough idle.

Just in case you or anyone else is unaware, these "minimum $5k (or minimum any other value) trade in" offers means the dealer is over-inflating the price of the vehicle offered for sale by $5k(at least).

Stay away.

Just in case you or anyone else is unaware, these "minimum $5k (or minimum any other value) trade in" offers means the dealer is over-inflating the price of the vehicle offered for sale by $5k(at least).

Stay away.

Yep , refered to in the industry as over allowance.

People fall for it all the time and get caught up in the trade in valuation. The only real figure that matters is the changeover $$$$.

Aust Fleet Sales here in NSW are notorious for it. Over priced in over allowance high rollers.

I'll assume when you cleaned the TB you got the ISC as well. I had a similar problem with my Magna a while back. I had a pinhole in the rubber fuel line leading into the rails. So you could try checking that as well. I didn't eeally notice a fuel smell or anything even in the bonnet as the hole was very small, but my fuel consumption had increased slightly. My idle wasn't as rough as yours sounds either, but it sounds like you've checked everything else.

Kotetsu, where was the hole?
Was there staining from the fuel at all?

It was right near one of the clips, a small discolouration on the hose, but not really noticeable until I looked closely. I didnt notice any staining on anything else. I assume the fuel was evapourating off the hose, so not really staining anything.

Well about a month ago I got a new Tridon coil from Supercheap as I had some gift cards to use up. The idle is definitely better, but still a bit rough at times so there must be something else causing it to idle rough intermittently. Seems to have a bit more grunt now.