[Klippie]

As a new GT owner I've used only one tank so far which worked out at 27mpg, my daily run to work is only five miles its a good fast road so that's not too bad I suppose but a lead foot doesn't help.

Once I get used to driving it correctly the MPG should improve I'am still revving it like a N/A engine I need to learn to use the torque more.

I'am using Momentum 99 octane fuel.

 

[Handsolo]

Can anyone give me an idea of the average mpg they are getting from their GT. Ive had this car about two weeks now and im averaging 20/21 around town and 26/27 on motorways. This is just normal driving putting my foot down now and again but on the whole steadyish driving. Im also getting a slight judder on idle that gets even worse when heater is on no4. Just wanted a bit of a comparison to see if this is normal before contacting the dealer hope you guys can help.

Did you ever get an answer to the judder and below avg mpg?

 

[gdh300]

Hi Handsolo (a bit naughty!), welcome to the forum!

I think Klippie (the last poster) has either sold or is still in the process of selling his GT and I'm not sure if gallimore1986is till about. Do I guess you have similar problems?

 

[Handsolo]

Hi Handsolo (a bit naughty!), welcome to the forum!

I think Klippie (the last poster) has either sold or is still in the process of selling his GT and I'm not sure if gallimore1986is till about. Do I guess you have similar problems?

🤣 the names an old one from way back when, maturity hasn't changed much!

I do, im not too concerned with the mpg, as mine is steady at 28mpg driving as I like and 36mpg when nan's in the car. The rough idle is though, even when cruising at 40 or 50 you can feel the engine labour slightly, feeling like it does at idle(this is intermittent). Mines got 70k on it, just done a service but am yet to change the plugs, which I'll do soon... and I understand the valves may be covered in coke by now (cleaning them is last on the list) I've been looking around for clues to what is a common cause for the idle issue, but not really found the answer

 

[gdh300]

The occasional to persistent lumpy idle of the G4FJ has been posted about a lot on here. Seems to be no rhyme-nor-reason to it; ambient temperature, engine temperature, fuel, age, mileage, etc. If you have a bit of time, you could troll through this post, which identifies a one-time culprit.

My GT is on about 63k now (new plugs within in last 18 months) and the tickover is never particularly smooth but doesn't get as bad as some on here described. I've only recently switched back to 95RON, running it on V-Power previously and I do treat it occasionally to some snakeoils, so doing my bit to keep it reasonably clean. But yes, these direct injection only engines are supposed to get coked-up around our mileages. Can't say though that I've noticed nay loss of performance or increase in mpg. Are you thinking of getting one of these hydrogen (?) clean jobs done on it?

 

[Handsolo]

The occasional to persistent lumpy idle of the G4FJ has been posted about a lot on here. Seems to be no rhyme-nor-reason to it; ambient temperature, engine temperature, fuel, age, mileage, etc. If you have a bit of time, you could troll through this post, which identifies a one-time culprit.

My GT is on about 63k now (new plugs within in last 18 months) and the tickover is never particularly smooth but doesn't get as bad as some on here described. I've only recently switched back to 95RON, running it on V-Power previously and I do treat it occasionally to some snakeoils, so doing my bit to keep it reasonably clean. But yes, these direct injection only engines are supposed to get coked-up around our mileages. Can't say though that I've noticed nay loss of performance or increase in mpg. Are you thinking of getting one of these hydrogen (?) clean jobs done on it?

Not heard of a hydrogen cleaning!?
I was considering getting the valves cleaned and then installing a catch can after, I have seen that it can be done through the intake manifold with media blaster (Hazelnut shell) and a hoover, its something I want to do myself but may have to get someone to do it for me as I don't have or want to buy a media blaster set up! So that's why that's last.
I'll be looking to do most job myself on this car and I'm one of those that would work to get the engine back to as new as possible (within reason) Thanks for the link, I'll have a read while my Vans in for a service 😀

 

[ArthurCollins2]

Coming back to the lumpy idle, mine has started to suffer recently. So far it's more of an annoyance, it doesn't struggle pulling away or under load.

I was playing around today and on mine at least, it seems related to fan speed. At the highest fan setting, the idle problem is quite bad, although it never felt like it would stall. Reduce the fan speed and the idles goes back to normal. I don't know if that points to a fan issue or the problem is a bit deeper. I'll mention it at the next service and see what they say.

 

[Handsolo]

Coming back to the lumpy idle, mine has started to suffer recently. So far it's more of an annoyance, it doesn't struggle pulling away or under load.

I was playing around today and on mine at least, it seems related to fan speed. At the highest fan setting, the idle problem is quite bad, although it never felt like it would stall. Reduce the fan speed and the idles goes back to normal. I don't know if that points to a fan issue or the problem is a bit deeper. I'll mention it at the next service and see what they say.

I have changed the spark plugs and filters (not fuel) and it made no difference to me. I never have the fan on more than 2 if I can help it and mostly use the auto so that's not the same for me. What has made a vast improvement is using 99 Octane from Tescos! Big improvement, so it's better....but I don't think these cars should only run smooth on the most expensive fuels, something has to be holding it back in the Chambers. If I do get the valves and pistons cleaned (still on the "to do list") I'll update results here