Thought I'd post a current issue I'm having with my TJ Magna. It is 2003 model coming up to 200,000k and was going to try and nurse it though to about 250,000k when the following issue occurred.
I filled up the car at the local Shell and within a few minutes it started to run rough. I left it for a day and it did not improve so thought it may have been the fuel. I rung the servo but they said had received no other complaints. The symptoms are that it runs rough at idle and wants to sit below 400 to 500 rpm. It stalls when cold. When it warms up it is better but still sits at about 400 rpm when idling and is on the cusp of stalling. First thing was I drained the tank (what an issue this was - i ended up damaging the o-ring in the push on plastic elbow onto the fuel filter - there must be a better way!!!) Anyhow got that sorted but still runs rough, but now even worse. When I increase the throttle it seems to peak at about 3000 rpm and won't go any higher and seems to be gasping for air/fuel. I'm not sure if I did some damage to the fuel line like it is sucking in air or something. The way I drained the tank was unconventional - I could not find the drain plug so removed the inlet end of the fule hose from the fuel filter and tried to get fuel to come out but it wouldn't. Ended up using a compressor to bolw air into the tank form the fill pipe to force the fuel out - I know this sounds wierd but only thing I could thing of at the time.

If you have any thoughts or can put me onto someone who could advise that would be great.

And was that fuel contaminated?

MAF unplugged?
Air inlet tube loose, massive air leak.
Almost dead ignition coil.
Fuel pump.
Jumped cam belt. (please tell me it isn't the original belt)
Crapped out cam or crank angle sensor.

Know someone who is an eggspurt on Magnas?

Thanks for your post MadMax. To answer your questions;

Fuel looked ok, but a little bit of stuff dropped out of it after settling - not a huge amount though.
MAF is pulgged in. I too air filter arrangement off and let air enter directly into throttle and made no chnage to symptoms
Fuel pump - possibly. I am going to change fule filter and see if it makes a difference
Possible jumped cam belt (sorry to say still origional - would you belive that I've been really busy lately and just haven't got round to it??)
Crapped out cam or crank angle sensor - possible

Any thoughts on diagnostic tips?

Thanks

Vito

Ok. I seem to have made some headway if someone can provide me advice.

I changed the fuel filter and this made no difference. I then had a look at the timing belt, and it was quite loose - I could easily move it up and down with my fingers 6 to 7 mm. I then started and started the car a few times, checking the belt tension each time. I noticed that sometimes the belt was quite tight, and other times I could easily move it 6 to 7mm. If MadMax is right, then a belt change would be in order. I was wondering if there was a way to see if the gears on the cams were in the correct positions or if they had jumped a tooth. I notice there is a notch in the cam and one at the top of the timing cover - are these meant to align???

Thanks in advance.

Vito

I was wondering if there was a way to see if the gears on the cams were in the correct positions or if they had jumped a tooth. I notice there is a notch in the cam and one at the top of the timing cover - are these meant to align???

Thanks in advance.

Vito

Wow no timing belt change in 13 years / 200,000KMs? She could go at any moment! Definitely get that replaced if you intend on keeping the car.

Here's photos of the gear alignments with their respective notches:
http://i.imgur.com/VyeMFjJ.jpg

http://i.imgur.com/C6jQPU8.jpg

http://i.imgur.com/JdwTTei.jpg

Hope that's helpful :)

Edit: apologies for the large images

Hey AaronoTG - really appreciate the photos - I'll let you know how I go. I'm thinking the problem is that the belt is so old and loose that as I increase the rpm and more load come on the belt, the belt stretches and thus puts the timing out. Not sure if I'm talking sense but works for me!! Thoughts?