Ok here's one ...

[swisstoni]

I've got a 95 4.0HC. Been running fine lately. Had it since new.

Started up in the station carpark tonight, no problems.
Idled nicely for about 10 seconds and then almost died. I just managed to catch it with the throttle.

By letting my foot up slowly and watching the revs I could tell it was going to die without some throttle.
Not wanting to be stranded (for 10 mins at least), I limped home in this fashion, fretting slightly at every halt in traffic.

Just before home (3 mile journey from Station) it started to run really rough and was still doing so when I reached home.

I placed my ruck-sack on the accelerator to keep it running and opened the bonnet hoping to see some helpful sparks in the darkness denoting a nice easy electrical fault - nothing. All leads nice and firm.

Returned to seat, not running quite so rough now and even idled on its own. Tried restarting and it restarted ok - still a bit rough though.

Looking back I have noticed a couple little initial nasty 'moments' after starting from cold recently, but it has always sorted itself out.

Obvously somethings on it's last legs - would an aging coil cause this sort of thing (the leads and extenders are only months old).

[YIW1393]

All together now



Stepper Motor

[pies]

Pic of said motor


Cleaning instructions here

[swisstoni]

cheers but does that explain the part when it really got rough - I was revving it hard and it was rough all the way up the range like I had lost a lead

I thought the stepper made small compensations, not great big ones ???

[heliox]

It does sound like a lack of fuel.

Dodgy fuel pump maybe

h

[drum4it2]

I had a misfire problem... not exactly like yours and the one thing that made the most improvement was the ignition pack - and then the coil... just a thought - I'm no expert though

[Steve_T]

Stepper motor is there to control the idle, it sometimes but not always accounts for funny tickover behaviour. Rough running throughout the rev range is a different matter. It may be something simple like one of the leads has fallen off, it may be complicated - I've no idea. If you're an expert I'll shut up and leave you to fix it. If not, I'd recommend consulting an expert if you see nothing obvious when you have a look around the engine bay.

Steve.

[Bomber]

Steper motor is easy to isolate as problem...unplug it. Car will run fine without this connected.

[swisstoni]

I'm certainly no expert so I appreciate the suggestions.
This morning it started fine fast-idled nicely and then about a mile down the road (by which time I thought it had gone away) tried to die again from a steady 2000rpm. Limped to Station misfiring.

My hunch is coil - its the original so I suppose it should be dying by now anyway after 9 years!

Anyway I'll report back in case it helps any fellow sufferer ..

[Incorrigible]

Idling sounds like stepper, misfiring at high revs sounds like HT circuit

When were the leads last replaced ?

Coils is an easy change and a new one certainly wouldn't go amiss after 9 years, do the cap and arm at the same time

[verysideways]

Agree, i'd be hunting the dizzy cap and rotor arm. Newish leads and it only starts to giev trouble when it's warmed up a bit, steadily getting worse, misfire all the way through the rev range?

What's a new cap and arm? 20 quid? 30 maybe?

Just be careful when you swap the leads over from old cap to new. One at a time (or draw yourself a picture).

HTH

VS

[M@H]

Just had a shock.. I thought I'd see how much a Distributopr cap was and stumbled across TMS's website, a new distributor (they don't list the cap alone) is £428.58 GBP + vat

HOW MUCH !!

[trefor]

You can buy caps from them - I have before. And Rotor arms. Get HT leads from Act or Magnecor for around 80 quid. I also recommend new plug extenders for around 3 quid each from Act (Vauxhall part - 8 quid from them).

Also, get a Bosch coil - do a search on here for coils and you'll find a topic about this a few months ago.

[swisstoni]

just to narrow things down a bit, the leads and extenders are less than a year old and the dizzy bits were examined about 3 months ago and pronounced sound (not to say that things haven't gone west since of course).

[verysideways]

plugs?

[yiw1393]

Do you know any other V8 Rovers in your area? Tivs or Landy/Range Rovers?

You could narrow down the dizzy/rotor arm,etc by swapping bits one at a time.

Is it a regular miss? or does increase and decrease?

[Bomber]

Sorry to be such an irritation, maybe you have some strange desire to spend money, but have you undertaken the exercise of unplugging the steper ...as suggested earlier.

Easy option, no cost, before spending fortunes to eradicate problems. I suggest that distributors, leads etc, would not have raised their head as this problem wsuggested.

Apologies if the 30 seconds it takes to unplug is considered a waste of time.

[swisstoni]

I will indeed disconnect the stepper as you suggested mate - but I've not done it before and I don't want risk knackering anything during the week. I'll try it at the w/e in daylight.

[Bomber]

Hope it works, and don't worry, it just unplugs, and if no change, replug.

[bigblockmark]

Had a similar problem on my 4litre a few years ago.I turned out to be the airflow meter.Just another suggestion,good luck . Mark