[jonnybobs]

Hi All,

We have a rover 25 1.4 iS. W-2000 Reg.

I have the most strange issue with the car!

Intermittanly the car will rough idle, like its hunting, revvs up and down (not by much). If you try and drive the car in this state, the car wont go. Then only cure for this is to really stamp on the gas. Then it clears if like magic and runs fine.

I have changed the following parts for new ones and nothing has helped.

1) HT Leads
2) Coil Packs
3) Spark plugs
4) Engine coolant temp sensor

When the car runs ok, I even disconceted the Lambda sensor and there was no change, I had hoped that when I did that the car would then run rough, but it was fine.

AGgghhhhh..... What can it be? Everything else is fine. I am getting really aggravated by this and am scared to allow my wife to use her own car.!!!

Any help please


John & Louise

[Fatdave]

same thing happened to my coupe last winter, not quite as bad as you describe though. i cleaned my throttle body with carb cleaner and a year later its still runs fine.

[jonnybobs]

Irronic really, we've decided to wash and valet the car and I just so happened to have some brake cleaner to hand,,,,....


Guess what just go shot in to the Throttle body...? *laughs*... I decided to spray it and let it sit...

Spray again and turn the car on, that was interesting, it did have trouble starting and idleing for a sec or two. I could re-create the symptom.

So, maybe this has worked..... Ill spray more in later.

Rememberin g that this is an intermittant fdault!

[jonnybobs]

Well,

that diddn't work.............. :(

I'm out of ideas..........! It does feel like its holding back slightly too....

[E_T_V]

When was the fuel filter last changed?

Also check the lambda sensor heater relay is working.

I presume you changed the ECU temp sensor rather than the gauge sensor.

[jonnybobs]

Fule filter is about the newest part on the car.... *laughs*....

I'm about to remove the Air Intake Control Valve and clean it. Seems a simple enough job that won't do any harm if it does not cure the issue.

I am fast running out of ideas. Louise (wife) tells me that the issue is more pronounced when the car is cold... (Or has not been run in an hour or two!!!)

This could be indicitive of a sticky IACV???

Any further thoughts?

[E_T_V]

Certainly worth cleaning it out.

When you replace it then remember to do a reset on it.

Turn igntion on
Depress throttle pedal fully 5 times in quick sucession
Wait for the clicking noise to stop
Start car and wait for idle speed to stabilise

The air valve only really affects the throttle on/off transistion as well as idle so if it still does it when the throttle is open then it isn't likely to be this, but a clean out won't hurt.

Does the rpm gauge bob about when the car misfires? If so then I'd be looking at the crank sensor (although these usually break down when hot not cold).
If the crank sensor isn't working correctly then the igntion doesn't know when to fire and so it'll misfire.