• Registered users are encouraged to enable MFA/2FA to add an aditional layer of security to their account. More information can be found here: https://www.ncsc.gov.uk/collection/top-tips-for-staying-secure-online/activate-2-step-verification-on-your-email

Poor MPG after oil and filter change

V

vernam616

Messages
16
Hi All

My names Dan, just bought myself a Civic Type R EP3 in Black

Bought the car with full history from a garage

Drove it home some 80 miles and around town when back, obviously just buying it i was quite prone to "Vtec'ing" it, and returned around 260 miles from the tank

Now the honeymoon period is over and the missus has been using it, driving it steady away around town, its drastically got worse, i now have 1/4 of a tank left and its only covered 166 miles, litrally seen no vtec action on this tankfull, i thought it was going to be better.

I changed the oil and filter last week along with putting a fuel additive in to try clean the injectors out could this be causing it? or should i be looking at lambda/coolant temp sens/ ICV ??

Thanks in advance for any help

Dan
 
You don't need to use fuel additives, I did use a fuel system cleaner in mine to be sure but you only really need what walkden said. I would take it out for a blast, get the car nice and warm and give it some. I bought my 1st ctr off my cousin and he used to say that when his misses drove it back and for work etc it would be as you said he used to take it out for a blast and all was good, so try that.

If that fails you could give it a really good service, flush, oil change and filter (again in your case), plugs, air filter etc.
 
Its working out at around 19mpg thats with the missus driving it

approx 170 miles from a tank, driving it steady away

anything which could cause this in particular? coolant temp sens?, plugs?
 
My god,

I was gonna post the same thing as you today.!!!!!!!

Before my recent trip to Cornwall I changed the oil (Mobil 1) and put in a redex injector cleaner filled her up with v power and headed off for the 500 mile trip, fuel economy was totally rubbish and has been since, before the mini service I was obtaining 35mpg but since I have been lucky to get 22mpg. I am very confused why this would be so I am keen to watch this thread for potential answers ;-)

Regards
Baz
 
I'm guessing you've no other issues like the engine hunting on tick over or struggling to idle? No leaks round the fuel rail/injectors?

My guess would be O2 sensor.

It won't be bad enough to throw a check engine light, but it'll be reading wrong so the car is throwing more fuel in to compensate.

Expensive replacements though so I'd exhaust all other options before rushing out and buying one.

A good way to check would be to get it on a proper AFR reader. It'll read really rich if it is.
 
It does smell rich to be honest, could a oil overfill be the problem?

when i changed the oil, the car seemed to swallow the whole 5 litres before i could get it on the max mark, which then sat perfect on max

I have a mechanic friend with snap on diagnosics kit, ill ask him to have a look with that

The engine doesnt hunt and seems to idle fine, lets hope its the lambda like you suggested

thanks for the help
 
I have had a mot since and it passed the emissions test with flying colours. So I assume my O2 sensor is working correctly.

Baz
 
I love the car and really dont mind 25-35 MPG, however the really poor 19mpg is putting me off, surely there is a problem? this cannot be correct?
 
What sort of driving is your missus doing? Lots of stop/start in town will hammer the mpg same as any car. Checked your tyre pressures?
 
That mpg is bad, the worst I've averaged in mine is around 28 mpg probably a bit lower if I really cane it but not much lower, Get it on the diagnostic see what comes up, as said could be a sensor somewhere or maybe dirty fuel filter.
 
Well this is a breakdown of the cars usage

Mon - Fri

6 miles to school, parks up all day (as she works round the corner) then 6 miles back later on, then 1 hr later she drives 2 miles to her other job 2 hours later drives 2 miles home

so all in all approx 16 miles per day, the 6 miles is a mixture of A road and town driving

Sat - Sun

This can vary depending what we are doing, anything from 10 miles to 50 miles


I reckon 19mpg is very wrong and there is a fault somewhere along the lines, the car has 105k on it with quite a decent service history, but like the original post states it was only since i carried out the oil change, have i put too much oil in and this may be causing it?
 
Although your weekly journey's are not the best, I have very similar journey's as you and mine's returning way better mpg. With this type off journey mine's returning easily 30+ mpg.
 
How is it driving? does it drive ok?

COuld be sticky brakes etc, any wheels warmer than other after a drive? Other wise as Loxy says it could be a lambda issue. That MPG isn't right
 
Actually come to think of it, i remember from today, it seems to run high on idle(choke) when first started from cold, which i think is normal, but it does fluctuate

and the car sort of runs away with itself if i let the clutch up, once warm ive noticed it can be jerky and very overly sensitive throttle, i put this down to the type of car it being, but maybe this has something to do with it?
 
Check your throttle cable or idle control valve, maybe it's letting to much air in that would possibly mean more fuel being thrown into the mix.
 
Thanks for the advice ill try ICV, im unsure of when valve clearances were done however i have got it booked in this saturday to get them done
 
You must log in or register to reply here.
Back
Top