[Sabo]

Hi there,

I've got an MG-F VVC from 1996. She's a pleasure to drive and is driven all year long.

Now since a few weeks I've got some issues with the car.
When I want to start the car it's about a 50/50 chance that she'll start right up.
The other half of the times there are some struggles when starting.

It sometimes takes a little longer for her to start and when she starts she runs rough for a few seconds.
Sometimes she'll start right up but still runs rough for a few seconds.
If one of the two scenarios from above appear she will rev up and stay high in revs when i even push the throttle a little bit.
Also she will misfire when i step on the gas a little too hard. (not flooring it of course)

When the car starts right up without running rough or anything, none of the above issues appear and the car will run like nothing is wrong.

I'm really lost and I hope someone on the forum is able to help me out.

Thanks in advance,

Sasha

 

[Chris T]

Welcome

I would start with checking the battery/alternator voltage and the engine earth straps, if the voltage is too low or there is a lose earth it is likely to result in poor running.

Do you know how long the ignition coils and leads are? It is possible that these are starting to fail.

Another suspect would be crankshaft sensor.

 

[Sabo]

Hmm, I'll take a look at it, might take a day or two because of work etc. But thank you!

 

[Austin2297]

Could be (in caps) the ‘cold start‘ sensor which monitors the coolant temperature and signals the ECU to fuel the correct mixture - as with a choke on a carb. They can fail and give a ‘half way house‘ resistance value which can result in too weak a starting mixture, and too rich a hot running mixture.
It’s a brass threaded unit with a 3(?) wire connector, and sits next to its sister - the temperature gauge sender which has two wires - screwed into an aluminium housing in the coolant system near the top front of the engine. If you are going to change it make sure you aren’t given the gauge sender in error.
Kind regards,
Austin.

 

[IanMc]

Are you pressing/pumping the accelerator pedal before you try to start the car by any chance? - if so, DONT. Just turn the key and let the car do its thing.

By doing this you risk flooding the engine with petrol, making the car difficult to start and run rough for a short time as it clears its throat, so to speak.

Just an idea...

 

[davidej]

Are you pressing/pumping the accelerator pedal before you try to start the car by any chance? - if so, DONT. Just turn the key and let the car do its thing.

By doing this you risk flooding the engine with petrol, making the car difficult to start and run rough for a short time as it clears its throat, so to speak.

Just an idea...

That used to the problem with cars with carburetors with an accelerator pump eg a Webber. But does it really apply to electronic fuel injection?

 

[dert]

Change the fuel filter and run some redex in the fuel. may also be a lazy fuel pump which doesn't pump the fuel fast enough on start up