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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22750
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Rover 75 connoisseur auto 1999 when in traffic idling go to

Customer Question

rover 75 connoisseur auto 1999 when in traffic idling go to pull away and it jumps forward in morning starts up no problem as soon as engine gets warm it starts to jump forward when i am in traffic at standstill
Submitted: 1 year ago.
Category: Car
Customer: replied 1 year ago.
i have not had an answer to my question yet wich i asked yesterday i am sorry for the slowness of any replys from me as i am 75 years old and have just been out of hospital from bowel cancer thats when my car started to play up also the engine never stalls or cuts out thanks george.
Expert:  Matt replied 1 year ago.


This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.

if the engine condition is the same then chances are the meter or the connection to it is faulty

It’s also worth cleaning the MAF sensor wires, as they can get coated with dirt over time which then offsets the reading

Use some contact cleaner or brake cleaner to spray onto the wires to remove the dirt – on no account touch the wires with anything as they are very fragile

Customer: replied 1 year ago.
matt thanks for your expertise as i stated in my letter i am 75 and am still recovering from my cancer operation .tomorrow i will take my car to a garage i use with a copy of your letter for them to sort out. i will do your rating tomorrow thanks again george
Expert:  Matt replied 1 year ago.

understood George

please do get back to me on this post if I can help further, no need to open a 2nd question

Customer: replied 1 year ago.
i had a mechanic come to inspect the car he took it for a drive and came back to tell me it has nothing to do with your anwser he stated it was most defitney a fault to do with gearbox and clutch. george
Expert:  Matt replied 1 year ago.

Hello George

in that case if the car jumps forward when the clutch pedal is fully down then the 1st thing to try is bleeding the clutch to replace the fluid with fresh

if the fluid is very black thats bled out then this shows the clutch seals are breaking up and the slave and possibly the master cylinder may have to be replaced