dangerous flat spot on roundabouts

[grandy]

hi guys, been meaning to ask this but keep forgetting to do so,can anyone please advise me why i get this flat spot on trying to get away a bit sharpish,best first tell you me car is 75 v6 petrol auto,asually catches me out on roundabouts.got new set of plugs in it,took out the old air filter replaced it with K&N but yes much better but still got the flat spot

[Canonite]

Originally Posted by grandy

hi guys, been meaning to ask this but keep forgetting to do so,can anyone please advise me why i get this flat spot on trying to get away a bit sharpish,best first tell you me car is 75 v6 petrol auto,asually catches me out on roundabouts.got new set of plugs in it,took out the old air filter replaced it with K&N but yes much better but still got the flat spot

Poor acceleration at low revs?

[James.uk]

Check for slack in the cable, and oil up all the throttle controls including that actual foot pedal..
...

[MrDoodles]

Sounds like the MAF starting to break down to me!

[James.uk]

Does the V6 engine have a MAF?
...

[Mike Noc]

Well it has an IAT/MAP sensor which does the same job. If you know the inlet air temperature and pressure then the ECU can work out the mass of air entering the engine.

Mike

[MrDoodles]

Originally Posted by Mike Noc

Well it has an IAT/MAP sensor which does the same job. If you know the inlet air temperature and pressure then the ECU can work out the mass of air entering the engine.

Mike

Sorry was on my phone when I posted that and couldn't see which engine he had!

[David3807]

Originally Posted by grandy

hi guys, been meaning to ask this but keep forgetting to do so,can anyone please advise me why i get this flat spot on trying to get away a bit sharpish,best first tell you me car is 75 v6 petrol auto,asually catches me out on roundabouts.got new set of plugs in it,took out the old air filter replaced it with K&N but yes much better but still got the flat spot

You sure its a flat spot and not the auto box being relectant to change down a cog or two??

My first 75 was a 75 2L V6 auto (X plate) and it was a bit reluctant to change down especially at roundabouts which gave the impression of a flat spot. If you buried the pedal in the carpet it would eventually change down two gears and off it went like a scalded cat. I got into the habit of using the manual selector for the gears at roundabouts which got round the problem.

You could also try sport mode on the autobox to see if that helps.

I also understand that MGR issued revisions/upgrades for the engine management and autobox computer software from time to time so it might help to get the car on a T4 (dealer computer) to see if your car has been updated.

Lastly (and I dont want to change this thread to a discussion on fuels and placebo effect) I tried half a tank of BP Ultimate which on my car improved the autobox changes for the better including this roundabout issue.

HTH

[grandy]

thank you all for your help , and thank you David for yours have done as you say used sports mode ect ,pull away manually it's no big deal my 75 runs well it's just that getting going from standing start, i will however give the change my fuel to BP ultimate a go,thank you David for that one all the best GARY.

[SD1too]

Gary,

Also check your VIS actuators. If the balance valve is open (or partially open) when it shouldn't be, it can have quite an effect on engine performance.

Simon.