R75 V8 Misfire / Running like a pig when hot

[clynch26]

Hi All

New member so please be gentle...

I have just purchased my 5th Rover 75, the latest being my 2nd v8, I guess that makes me an enthusiast. However, my 04 75 v8 that I have just purchased runs fine while cold and under normal conditions but following a trip through London yesterday it started to run like a pig in heavy traffic (to the point I nearly fumbled around for my breakdown cover card). The temp gauge did not register abnormal temp and I could hear the fan cutting in and out but undoubtably once I got going again everything seemed better albeit not perfect until I started again this morning from cold. It ticks over warm at around 500 but this varies a lot but from cold it's what I would expect a constant 1k or there abouts.

Not sure what the cause can be, I did think coils but I am no mechanic, it's only done 28k.

Thanks for reading and Help!

Chris

[spartacus]

We've all had a bit of that - get's a little warm under the bonnet sir. Once you get going again it tends to disappear. Become a full member and you will learn many things young Skywalker.

[Tim]

Fuel evaporation, coils, plugs perhaps,

[AndyG]

WELCOME

My immediate thought is overheating under the bonnet,

Remove the sound deadening heat retaining carpet under the lid.

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[colintf]

Hi All

New member so please be gentle...

I have just purchased my 5th Rover 75, the latest being my 2nd v8, I guess that makes me an enthusiast. However, my 04 75 v8 that I have just purchased runs fine while cold and under normal conditions but following a trip through London yesterday it started to run like a pig in heavy traffic (to the point I nearly fumbled around for my breakdown cover card). The temp gauge did not register abnormal temp and I could hear the fan cutting in and out but undoubtably once I got going again everything seemed better albeit not perfect until I started again this morning from cold. It ticks over warm at around 500 but this varies a lot but from cold it's what I would expect a constant 1k or there abouts.

Not sure what the cause can be, I did think coils but I am no mechanic, it's only done 28k.

Thanks for reading and Help!

Chris

Hi and welcome Chris

[2V8s]

when you were stuck in the traffic - did you switch off at all and restart? because pretty much all cars will then run a little rough due to heat soak evapourating the fuel.

Otherwise - yes it could be a coil pack breaking down but unless you're unlucky that would normally tend to be one cylinder at a time rather than general misfiring and poor running.

Idle at 1000rpm is too high though - even from cold or soon after, it'll settle below that and eventually sit at around 600-650 rpm at idle (or should do).

I think keep using the car in general driving and see if its a repeat general problem or only happens when car fully warmed up and then stuck for a while in stop start traffic situations.

As mentioned, removing the under bonnet insulation does help a little with heat dissipation.

[clynch26]

Thanks for all of the posts so far on this,

Looks like I will remove the insulation from under the bonnet and see how i go. I didnt stop the car and restart while in traffic for fear of not getting it going again, i knocked it in and out of drive as i stopped and started for fear of it stalling while stationary. Incidentally the exterior temp displayed was much higher the real temp outside and i suspect this was due to the tropical conditions under the bonnet.

I would describe the car when hot and on tick over as 'hunting', with the engine going from barely running to around 500 rpm and back again.

[Coasting]

Ive had this problem, when I was stuck on the M27, car was very lumpy whilst edging along in the traffic but once going it cleared up and I was treated to a massive wave of heat emminating from the dash board

Does removing the insulation make the car much noisier?

[clynch26]

Yep that's it, i had to put the air con on cold, i did think its was rather odd in mid Nov!

I wondered about the noise also, i guess i will find out soon enough