Generally, i dont like to be one of those people to open up another topic that has been exhausted time and time again, but after extensive research, i really am struggling to find a forum response that matches fully with my issue.

I brought my 1.2 tsi 2016 CJZD Rapid earlier this year. As soon as I picked up the car, i noticed the issue, but the garage i purchased it from had wiped their hands clean. Since then, i have been trying to research and diagnose the issue without throwing the parts cannon at it.

I am experiencing misfires and hesitations at 1500 and 1800 rpm which generally can be replicated on the driveway as well as on the road when your at 30mph and your not under load. When driving, the hesitation and mini kangaroo hops occur when going from gliding to applying a little load. Similar to if you were slowing up to a roundabout and then reach for a few revs to pull away gently. The severity of the hesitation and hops can vary sporadically or with temperature of the car and even the temp outside.

No codes on diag tool other than random mis fires on all cylinders.

Unsure of when they were last done, first things first, changed the plugs with oil and air filter change too.

Oil flush and injector cleaner used too.

Technicians at work said coils all day long despite me testing them and the wiring. But i changed them, but it did not cure the issue.

From there, checked live data whilst driving and it was running rich at low revs but not high. I checked all hoses and pipes and changed out some seals before smoke testing the system.

I had a theory that if the coolant temp sensor was reading incorrectly and the ecu thought it should still be in cold mode, that would cause the timing to be pulled and could cause similar symptoms. So when the diag tool said 70 degrees when the dash said 90, i swapped out the sensor. Cold starts are better but the misfires remain.

Performed a leak down and even though there was leakage, it was not terrible and was consistent across the board.

Any ideas guys?

Direct injection maybe needs carbon clean get them intakes etc checked. It does happen.

Thanks, forgot to say how I have had the intake off with a camera down to the valves. Thanks for the response though.

Have you tried running it with a full tank of UL+ - maybe even Esso, to see if this improves things while you are using it or even if this "goes" away after using a tank of UL+?

I'm sure that my wife's 2015 Polo 6MT with that engine code ended up at round about 50,000miles, with a slight hint of that - that really worried me, but I loaded up with a full tank of UL+ Esso and it disappeared, car now at just over 59,000miles and excluding that tank full of UL+, is now back to fuelled with Costco UL.

My wife's previous car - a 2002 Polo 1.4 75PS 5MT did have a bit of that, but after replacing the EGR valve - no change, MAP sensor - no change, oil separator - it ended up not being very good at trapping oil, it seemed to run better especially if I used UL+ in the tank.

Horrible feeling when you have that!

Edit:- what is the mileage?

Edited Thursday at 18:151 day by rum4mo

21 hours ago, Deereman44 said:

So when the diag tool said 70 degrees when the dash said 90

If you are refering to the engine "water" (coolant) temperature dial with needle guage take little notice of that as it's 90 biased, for fully warmed engine you want 90+c on the oil temperature readout.

Given all the rest that you have done running through a couple of tankfuls of higher octane petrol, for the higher cleaning additive packages rather than octane they have, would be an inexpensive test, possible cure, combined with a few sensible sustained Itialain tune-ups runs (higher revs, lower gears) at around national speed limits for say 20-30 minutes at a time to get bigger volumes of air and fuel through the engine and out of the exhaust and warm things. So probably dual or motorway roads unless you have good clear a and b roads to use where second and third gears can be held. All after engine is fully warmed up (90+c on the oil temperature).

Some other quick thoughts -

Was the running rich fuel trim short term or long term or both?

Have you checked there are no outstanding updates for the car?

Checked the lambda sensor readings?

Did you check/clean clean the MAF sensor?

Checked/cleaned the throttle body?

Check/clean inside the air filter box and all tubing and trunking?

Does the car have DSG?

That's me out of simple, or any, ideas. Good luck.

@nta16 MAP please, not MAF and there are a couple of them.

True about the better cleaning properties of the UL+, but even increasing the Octane rating of the fuel might quickly reveal a change which might help sort this "fluffing" activity.

When I had that very slightly with my wife's 2015 same engine Polo, maybe because I had had that with the previous 2002 Polo 1.4, I was extremely quick in spotting it - but maybe after a single tankful of UL+ it went away and so far stayed away - why/how I don't know, but it does not do that now at all - and I will quickly feel it when/if it returns - a really horrible feeling especially when these 1.2TSI engines, well at least the 110PS version, are brilliant in terms of drivability and fuel economy.

Hi all. Thanks for the replies and suggestions. Much appreciated and its good to hear of other peoples stories and issues.

I have not tried premium fuel yet and even though, im doubtful, i will give it a go. I didnt find the injector cleaner nor fuel conditioner help.

With regards to o2 sensors. Yes i forget to mention i did test these. Voltages / graph of them bouncing from top to bottom on bank 1 looked good and operational. Bank 2 / downstream was steady.

Air box, maf, map, throttle body, piping all been stripped, inspected and cleaned. New seals on throt bod inc seals on air pipe to turbo.

Car is manual so no dsg

Fuel trims.. from memory and i cannot find a screenshot were bouncing from -20 to +20 depandant on drive but would level out to near 0 when crusing or idling. Long term would sort it self out and be +/- 5-10

I will try some prem fuel and and an italian tune as i have a big A road very near me with some hills.. bye bye good mpg 😅

4 hours ago, rum4mo said:

@nta16 MAP please, not MAF and there are a couple of them.

i sit corrected, as you know I mix things up or reverse things and also have plenty opf brain-farts, I think I'd have been alright on the VW computer programing in-house and external teams. 😁

1 hour ago, Deereman44 said:

I have not tried premium fuel yet and even though, im doubtful, i will give it a go. I didnt find the injector cleaner nor fuel conditioner help.

. . .

Fuel trims.. from memory and i cannot find a screenshot were bouncing from -20 to +20 depandant on drive but would level out to near 0 when crusing or idling. Long term would sort it self out and be +/- 5-10

I will try some prem fuel and and an italian tune as i have a big A road very near me with some hills.. bye bye good mpg 😅

See what the fuel trim readings are after going through a full tankfull of higher octane (less ethanol, greater cleaning additive package) fuel and a few good Itailian-tune-up runs as the higher air and fuel volume with cleaners may at least help if not fully resolve your issue(s).

petrol.pdf

As for those that worry too much about mpg (and I'm not sure it's anyone that's here really) a small extra used now could save lots more in the future running of the car.

For the purposes of checking, after a run looking at short term fuel at idle might only tell you if things have improved the live running data of the =/- swings along with looking at other live running data pionts might tell you more. For this a another person viwing this whilst the driver concentrates on driving is best. It may be better if youi get someone else to drive and you give instructions on what variations in driving you want or need for the loive data (wherte road conditions allow of course and not so easy when it's the verbal-handbrake operating the pedals).

Good luck, let us know how you get on.

Edited 22 hours ago22 hr by nta16
adsd out of date petrol pdf