Very slight 'hesitation' on re applying power

Chat about your 9n Polo (inc GT and Fun)
bvs
Silver Member
Posts: 271
Joined: Sat Feb 13, 2016 7:56 am
Drives: 02 1.4s 16v
Location: perth

Very slight 'hesitation' on re applying power

Post by bvs »

Car has just walked through another MOT : )
Lovely little car (1.4 16v) but she does have one minor fault (always since we had it).
During gear changing and/or when re applying power after having had the throttle fully closed - the engine sometimes has a very brief 'hesitation' before power comes back on,sometimes it gives the car a bit of a lurch/transmission thump as it is quite a sharp change of power.
I just wondered if anybody has any ideas ?
Not a serious problem but a little annoying sometimes.
RUM4MO
Bling Bling Diamond Member
Posts: 5859
Joined: Sat Dec 30, 2006 9:12 pm
Drives: B8 S4 & 6R/6C1 1.2TSI 110
Location: Mid Lothian

Re: Very slight 'hesitation' on re applying power

Post by RUM4MO »

Good news on the MOT front!

The other issue, I've forgotten what you have done in the past to/with that car, but maybe the Throttle Body needs cleaned out, paying special attention to the EGR valve pipe junction/port area at or near the Throttle Body, then perform Basic Settings using something like VCDS. Perform Basic Settings on the EGR valve as well for good measure. That just leaves removing and carefully washing the MAP sensor and checking all air/vac piping under the bonnet for security and damage.

Edit:- is this happening all year round or just during colder weather?

Another Edit:- I could have included check spark plugs or coils, but I'd hope that any misfiring would bring the fault light on - though maybe that has a counter with reset so that engine might not be missing enough to switch the fault light on. Or, engine coolant sensor? The list, potentially, goes on!
bvs
Silver Member
Posts: 271
Joined: Sat Feb 13, 2016 7:56 am
Drives: 02 1.4s 16v
Location: perth

Re: Very slight 'hesitation' on re applying power

Post by bvs »

Hi Rum
EGR was cleaned out in the summer,I did wonder if perhaps there was a basic setting that needs tweaked for throttle control where the throttle is going from overrun (fuel shut off) to accelerate.
It has seemed slightly worse during the winter but not sure if it is temp related or just worsening slightly.
danjsimmo23
New
Posts: 6
Joined: Mon Mar 06, 2017 3:03 pm
Drives: polo 6n1 1.4 8v, polo 6n2 gti
Location: GB croydon

Re: RE: Very slight 'hesitation' on re applying power

Post by danjsimmo23 »

bvs wrote:Car has just walked through another MOT : )
Lovely little car (1.4 16v) but she does have one minor fault (always since we had it).
During gear changing and/or when re applying power after having had the throttle fully closed - the engine sometimes has a very brief 'hesitation' before power comes back on,sometimes it gives the car a bit of a lurch/transmission thump as it is quite a sharp change of power.
I just wondered if anybody has any ideas ?
Not a serious problem but a little annoying sometimes.
i had this before i knows exactly what you mean. after about 2000rpm it kicks in again.... mine conked out after a while i think it may be piston rings wearing out or possibly valve seats need seeing to but not too sure. get it to a garage asap ide say.

Sent from my SM-J500FN using Tapatalk
bvs
Silver Member
Posts: 271
Joined: Sat Feb 13, 2016 7:56 am
Drives: 02 1.4s 16v
Location: perth

Re: Very slight 'hesitation' on re applying power

Post by bvs »

It is not that serious Dan,the car runs fine,there is just a slight 'flat spot' or hesitation when moving the throttle from closed to slightly open especially after being on the overrun,so the flat spot is only transient between idle and a whisker above it.
I am assuming that on this engine when you throttle right back to slow down - the ECU shuts off the fuel completely and I think the flat spot is that the ecu may be a little slow opening up the fuel supply when we depress the throttle,it is sometimes ok but sometimes there is a transient 'jerk' as the engine catches again.

cheers baz
RUM4MO
Bling Bling Diamond Member
Posts: 5859
Joined: Sat Dec 30, 2006 9:12 pm
Drives: B8 S4 & 6R/6C1 1.2TSI 110
Location: Mid Lothian

Re: Very slight 'hesitation' on re applying power

Post by RUM4MO »

I think that what that previous poster wrote is true, but only for the earlier variants of these engines, ie the 8V and the A** engine coded ones. I had that what I'd describe as almost feeling like "transmission shunt" when you were off the throttle and went back on, I think that that showed up only after I had cleaned the throttle body etc, with time it "sorted itself out" - so maybe your car will also do this by gradually changing the long term trim values in the engine's ECU. One thing that you could try is to remove the battery lead for 30 minutes, that time is to allow any stored voltage to drop to zero, ie inside the ECU as that will cause the ECU to lose its stored "learned values", then lead back on and after you have driven it for a while it will learn new values - I think.

The reason I asked about if it was happening in warmer weather prior to this winter was, just in case the thero flap valve on the air cleaner was stuck and feeding in cold air in cold weather and so causing a slight freezing/chilling/condensing of the injector sprays in the inlet area of the head when the engine was running on its leaned off normal warmed up "mixture".

Edit:- cleaning up the MAP sensor would be easy and make sure that the ECU was getting its best chance of being fed the correct signal/pressure.
bvs
Silver Member
Posts: 271
Joined: Sat Feb 13, 2016 7:56 am
Drives: 02 1.4s 16v
Location: perth

Re: Very slight 'hesitation' on re applying power

Post by bvs »

Thanks Rum - I will be doing a spring service whenever it warms up LOL and will look at it then : )
bvs
Silver Member
Posts: 271
Joined: Sat Feb 13, 2016 7:56 am
Drives: 02 1.4s 16v
Location: perth

Re: Very slight 'hesitation' on re applying power

Post by bvs »

After making the mistake of putting some cheap tesco petrol in the Polo recently,this really got the engine 'rattling' (detonation/pinking) when accelerating during gear changing /going uphill - so last week we took a trip round to the nearest shell station (not that close LOL) and put some v power 99 octane in the tank,stopped the pinking almost straight away and when we took the polo for a wee drive yesterday I thought it was hesitating much less,the boss drove back and she agreed.Not sure if it has fixed the problem entirely but we will monitor the cars driveability :)
RUM4MO
Bling Bling Diamond Member
Posts: 5859
Joined: Sat Dec 30, 2006 9:12 pm
Drives: B8 S4 & 6R/6C1 1.2TSI 110
Location: Mid Lothian

Re: Very slight 'hesitation' on re applying power

Post by RUM4MO »

Hum, pinking under load maybe around 1800>2000 rpm, maybe you have read that I had that issue, Shell + stuff stopped that in its tracks, and made quite a bit of improvement to the general driveability of that 2002 1.4 BBY Polo, that much that if I had changed back to normal fuel, my wife would have got quite annoyed!

So, what did I think that my original problem was, well as that car was consuming too much oil, I ran out of ideas and put my money where my mouth was and replaced the oil separator, it cost a bit - maybe roughly £100, but it stopped the oil usage in its tracks and if I had been allowed to go back to using normal petrol, I might have been able to see if that car was back to being able to run without pinking.

So, what is the oil usage of that car, it seems like if you start drawing oil in with the air, the resulting fuel/air mix is too low in "antiknock" so you get pinking.

My wife's old Polo would pink even when cold in winter, if it was under load at about 1800>2000 RPM.
bvs
Silver Member
Posts: 271
Joined: Sat Feb 13, 2016 7:56 am
Drives: 02 1.4s 16v
Location: perth

Re: Very slight 'hesitation' on re applying power

Post by bvs »

Funnily enough I was thinking of replacing the oil separator at some stage - depends if we keep the car long term I guess :)
If we use branded fuel the car does not pink normally,I should have filled up with Tesco 99 fuel instead of the normal cr@p - we had vouchers to burn LOL.
If the separator is clogged - would that explain a bit of oil in the air intake/filter ?Not too much oil but there is some !
She does use a bit of oil but nothing really bad,I have never felt it necessary to work out the oil consumption,but always keep a supply of 'top up' oil in the car (bought when on offer).
RUM4MO
Bling Bling Diamond Member
Posts: 5859
Joined: Sat Dec 30, 2006 9:12 pm
Drives: B8 S4 & 6R/6C1 1.2TSI 110
Location: Mid Lothian

Re: Very slight 'hesitation' on re applying power

Post by RUM4MO »

I'd need to look back over the service/repair records I have some where for that 9N Polo, but I seem to remember it used maybe a litre of oil every 1500>2000 miles prior to me replacing the oil separator, and after that basically no oil used. I'll try to locate these records and get back.

I've just checked my records for that 9N Polo and found that it was using oil at the rate of a litre every 1200 miles, then after replacing oil separator it dropped to the rate of a litre every 3000 miles.

So, really it does not take too much oil usage to bring on pinking/knocking.
coopern
New
Posts: 40
Joined: Tue Oct 06, 2015 10:11 am
Drives: Polo 1.4 BUD 9N3 petrol manual
Location: West Midlands

Re: Very slight 'hesitation' on re applying power

Post by coopern »

I asked in the 9N3 section about a similar 'hesitation' problem on my 1.4 BUD petrol engine, it was present at 5k miles and is the same now at 31k. I think my engine is just a slightly improved version of the older 1.4 engine on the 9N. The hesitation on my engine is particularly bad with the air con switched on, maybe one and a half seconds before the engine responds to the pedal, but i've been told its the ecu and nothing can be done and nothing to worry about. Very annoying though.
bvs
Silver Member
Posts: 271
Joined: Sat Feb 13, 2016 7:56 am
Drives: 02 1.4s 16v
Location: perth

Re: Very slight 'hesitation' on re applying power

Post by bvs »

What fuel do you normally fill up with Coopern ?
Since changing to 98 ron fuel - our 1.4 16v throttle response has been much better.
Previously the engine had seemed to cope with 95 ron fuel ok but we had only ever used 'branded' fuel, filling up at tesco with tesco 95 ron fuel was obviously a big mistake and would seem to prove the theory that supermarket petrol does not have as good additives as branded petrol - I am saying that because previous to the tesco fill up I had never heard the polo 'pinking' at all.
coopern
New
Posts: 40
Joined: Tue Oct 06, 2015 10:11 am
Drives: Polo 1.4 BUD 9N3 petrol manual
Location: West Midlands

Re: Very slight 'hesitation' on re applying power

Post by coopern »

Thanks, I will try a higher octane fuel.
I always use branded standard unleaded petrol (95?) and the hesitation is always present regardless of the weather or the time of year. If a higher octane rating helps I would have expected the vw service guys to know about it and to have told me when I expressed concern about the engine delay/hesitation, shortly after buying the car.
bvs
Silver Member
Posts: 271
Joined: Sat Feb 13, 2016 7:56 am
Drives: 02 1.4s 16v
Location: perth

Re: Very slight 'hesitation' on re applying power

Post by bvs »

I know for my car model 1.4 16v 9n then 98ron is probably reqd to prevent piston damage due to pinking,although I cannot remember what it says on the fuel filler flap (I will have to remember to check :))
Post Reply