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Discussion Starter · #1 ·
Hi

I recently changed all 4 of my tyres from run flats to standards; and also had an alignment done, on my 2.2D auto…..

Not sure if linked or purely a coincidence, but since then the car doesn’t seem as good of a drive as it was previously, now seems a bit sluggish, gear changes are lagging a bit but were pretty smooth before; and I’m fairly sure my fuel consumption has reduced.

I’m being advised to reset the auto gearbox so it learns new driving styles, but I’m worried this may make matters worse.

Anyone had similar experiences?

Cheers
 

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Load index? The RFT feel like a 110 I guess. XL 99? and STD are 95 I think.
Did you fit STD 95s? They would feel really different I guess?
 

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Discussion Starter · #5 ·
Load index? The RFT feel like a 110 I guess. XL 99? and STD are 95 I think.
Did you fit STD 95s? They would feel really different I guess?
The run flats were the Goodyear EfficientGrip
235/45 R19 95V and I changed them to standard non run flat Goodyear Eagle F1 Asymmetric 5 235/45 R19 99H (Reinforced, Asymmetrical)
Not sure if this helps?
Thanks
 

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You describe an unusual outcome? I would gave guessed with the new tyres the ride should be more compliant over pot holes and if anything smoother and similar MPG and I would have done exactly the same thing you have and fitted XL 99H. I am a bit stumped now 🙃. Tyre circumference, rolling radius and weight and road resistance should all be pretty identical 🤔.
I would reset the gearbox, put some fuel cleaner in the tank and use a top garages standard fuel. Maybe disconnect the main battery for a couple of hours as this may reset the fuel trims to relearn them. I am clutching at straws a bit here.
The alignment along with the tyres now seems the most logical change, this will give you a different steering feel and driving characteristics which makes sense. I would monitor your fuel consumption on your normal routes over a thousand miles and draw a conclusion then?

🖐
 

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Discussion Starter · #7 ·
You describe an unusual outcome? I would gave guessed with the new tyres the ride should be more compliant over pot holes and if anything smoother and similar MPG and I would have done exactly the same thing you have and fitted XL 99H. I am a bit stumped now 🙃. Tyre circumference, rolling radius and weight and road resistance should all be pretty identical 🤔.
I would reset the gearbox, put some fuel cleaner in the tank and use a top garages standard fuel. Maybe disconnect the main battery for a couple of hours as this may reset the fuel trims to relearn them. I am clutching at straws a bit here.
The alignment along with the tyres now seems the most logical change, this will give you a different steering feel and driving characteristics which makes sense. I would monitor you fuel consumption on your normal routes over a thousand miles and draw a conclusion then?
thanks for the advice Mate I’ll try all that out and see how it goes 👍
 

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Discussion Starter · #8 ·
thanks for the advice Mate I’ll try all that out and see how it goes 👍
Just to confirm Mate, when you say reset the gearbox, is this the proper way via cable/obd through the dealer ie Nissan in UK, or you mean the steps for a throttle reset?
I believe with the gearbox reset via obd there’s software updates available too?
 

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Its probably the same as the throttle reset. It might not help at all but it will not hurt either 🖐 Its the one where the gearbox memory for the last forty shifts gets set to default and it relearns again over the next forty shifts. 🙂
 

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Discussion Starter · #10 ·
Its probably the same as the throttle reset. It might not help at all but it will not hurt either 🖐 Its the one where the gearbox memory for the last forty shifts gets set to default and it relearns again over the next forty shifts. 🙂
Thanks Mate, think I have the instructions somewhere I’ll give that a try.
One last query you may have the answer to, I read on a Mercedes forum re air filters (as it’s the same part as Q30), so I replaced mine with a Bosch one last June during a service, but some Merc owners are highlighting problems with Bosch air filter; and recommend a Mann or Filtron filter specifically for Q30.
Possibly faulty air filter as the issues I’m having recently are similar, although they only started a month ago.
Should I consider changing the filter too, just to rule that side out?
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I would change the filter out too. They are not expensive less than £20 I think on the Web. You could always keep you old one if its low mileage and see if the new one makes a difference?
Thankyou for high lighting the Bosch filter issues, that's what I am running also a Bosch filter so I need to check. I change my filters every 8k miles normally.
Our bosch filters are German bosch I think, and the Americans I guess will be bosch USA I think - so hopefully not an issue with our filters. 🤓
 

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Discussion Starter · #12 ·
I would change the filter out too. They are not expensive less than £20 I think on the Web. You could always keep you old one if its low mileage and see if the new one makes a difference?
Thankyou for high lighting the Bosch filter issues, that's what I am running also a Bosch filter so I need to check. I change my filters every 8k miles normally.
Our bosch filters are German bosch I think, and the Americans I guess will be bosch USA I think - so hopefully not an issue with our filters. 🤓
I mean it’s a small handful of people that said they had issues with Bosch, it’s a reputable company, possibly a few bad ones from a bunch who knows, but quite rightly as you’ve said there’s no harm in changing the filter, which I’ll definitely do.

Would it be easy enough to replace if I do it myself?

Thanks so much for all the advice Mate, really appreciate it 👍
 

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Dead easy, remove engine plastic Tupperware by carefully pulling off. Unscrew air filter four screws, lift back top cover toward engine, remove old filter, hoover and brush out lower housing of bugs and debris. Insert new filter, fit top cover correctly. Nip up 4x cover screws, fit engine tupperware. That's how I do it, plus write the mileage and date on the side of filter element so I know when I did it.... can you tell I'm slightly autistic? 🤓
 

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Discussion Starter · #14 ·
Dead easy, remove engine plastic Tupperware by carefully pulling off. Unscrew air filter four screws, lift back top cover toward engine, remove old filter, hoover and brush out lower housing of bugs and debris. Insert new filter, fit top cover correctly. Nip up 4x cover screws, fit engine tupperware. That's how I do it, plus write the mileage and date on the side of filter element so I know when I did it.... can you tell I'm slightly autistic? 🤓
Lol, I’d say detailed and thorough more than anything!!
Thanks mate, great advice 👍
 

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I don't want to speak out of turn but I'm fairly sure MB state not to use fuel additives due to the direct injection and piezo-type high pressure injectors?
No worries Welly 🤗 - as my opinion is purely my own and we all go through life on different paths gaining different experiences and drawing our own conclusions 🤓. Agree 👍 or disagree👎 - is all fine with me 🙏 and I respect your opinion and you are definetly not out of turn at all. 🕶
 
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Discussion Starter · #17 ·
[/QUOTE]
Dead easy, remove engine plastic Tupperware by carefully pulling off. Unscrew air filter four screws, lift back top cover toward engine, remove old filter, hoover and brush out lower housing of bugs and debris. Insert new filter, fit top cover correctly. Nip up 4x cover screws, fit engine tupperware. That's how I do it, plus write the mileage and date on the side of filter element so I know when I did it.... can you tell I'm slightly autistic? 🤓
Hello Mate

making some progress with this; and at present it could well be the battery needs replacing.

i remember some time back there was a topic where you mentioned about changing both batteries, which ones did you get for yours, I’m thinking of Yuasa or Varta for both the main and the auxiliary.

thanks
 

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Yes Roy, go premium matey so yuasa, varta or exide. Mine are holding up OK at present but as you correctly advise if you are keeping the vehicle it's best to replace them.
Any battery that has gone flat or under 11volts will be toast and isn't worth the hassle, my batteries will be four years old in November I think. The scrap prices are pretty good too so a few quid back if you cash them in when passing a good scrap metal dealer 👋.
 
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Discussion Starter · #19 ·
Yes Roy, go premium matey so yuasa, varta or exide. Mine are holding up OK at present but as you correctly advise if you are keeping the vehicle it's best to replace them.
Any battery that has gone flat or under 11volts will be toast and isn't worth the hassle, my batteries will be four years old in November I think. The scrap prices are pretty good too so a few quid back if you cash them in when passing a good scrap metal dealer 👋.
Brilliant mate thanks again!

I hooked up the CTEK smart charger for a couple of days to the existing battery which seems to have given it a nudge, but I think it’s the same battery since new (Merc Varta) which is now 6 years in, so I’ll monitor it over a few weeks then order both the Yuasa batteries 👍

I do have another yet query if you don’t mind:

as previously mentioned, since changing my tyres I’m having these issues with lagging and sluggish gear changes, the cars not performing as it did and I’m having reduced mpg/total miles per tank.
My previous tyres were the run flats Goodyear EfficientGrip 
235/45 R19 95V; and I changed them to standards Goodyear Eagle F1 Asymmetric 5 235/45 R19 99H

Now Black Circles who I purchased these tyres from, are advising I may be having the issues because I should have changed the tyres identically to 95V and not 99H, saying that my current ones are a lower speed rating which can affect the vehicle performance etc. They even said this can void my insurance as they’re not recommended tyres for this vehicle!

is this all rubbish, or do they have a valid point?

I’m going mad trying to rule out the issue here, as you can see I’ve already highlighted many things that could be the issue, but don’t want to spend hundreds replacing parts that may not need changing.

thanks mate
 

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Brilliant mate thanks again!

I hooked up the CTEK smart charger for a couple of days to the existing battery which seems to have given it a nudge, but I think it’s the same battery since new (Merc Varta) which is now 6 years in, so I’ll monitor it over a few weeks then order both the Yuasa batteries 👍

I do have another yet query if you don’t mind:

as previously mentioned, since changing my tyres I’m having these issues with lagging and sluggish gear changes, the cars not performing as it did and I’m having reduced mpg/total miles per tank.
My previous tyres were the run flats Goodyear EfficientGrip 
235/45 R19 95V; and I changed them to standards Goodyear Eagle F1 Asymmetric 5 235/45 R19 99H

Now Black Circles who I purchased these tyres from, are advising I may be having the issues because I should have changed the tyres identically to 95V and not 99H, saying that my current ones are a lower speed rating which can affect the vehicle performance etc. They even said this can void my insurance as they’re not recommended tyres for this vehicle!

is this all rubbish, or do they have a valid point?

I’m going mad trying to rule out the issue here, as you can see I’ve already highlighted many things that could be the issue, but don’t want to spend hundreds replacing parts that may not need changing.

thanks mate

Glad to know your on top of the batteries, it's a lot less painful than a dealer battery swap 🤣

Re Tyres...
IMHO 🤔 total BS from black circles😖. With respect to the load index, you cannot put less than what is specified so in our case 95 load index. No issues about running 99 load index, most fleet companies that have fully loaded vehicles will put the XL extra load tyres on as you have done. Only difference is stiffer side walls / so they are slightly thicker. Now think of RFT. Very thick and stiff side wall, so stiff you can run without any air at all, hence the Run on FlaT RFT tag... I would not be suprised if RFT being so stiff have less contact patch on the road, hence less rolling resistance, hence more MPG?
Speed ratings, V are 149mph and H 130mph.. again what's their point? I doubt if any of us here drive faster than legal limit plus 10 internationally ☺.

All the best 👋 Cornish Blue..
 
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