Missing when cold

[PoloGIT]

I am not sure if the problem I had with my 2015 Polo GTi is the same as yours. About a year after my Polo GTi was delivered, I had a cold start problem. When I initially drove up the road and gave it a slight squeeze on the throttle, I would get a huge hesitation. I took it to my dealer who found nothing wrong. I asked them to keep the car overnight and try it again. I went back the next day and again they told me they found no problem. I took the car home. Next day I started the car and drove off. It seemed to have been cured. The only thing the dealer told me was as part of the service they tightened all the pipes around the turbo. I wasn't sure whether to believe that was the cure - however, it may be worth a check. The problem did come back, but not as severe, but I decided to drive the car much more gently and wait at least a hundred meters before trying to accelerate much (still only a slight squeeze on the throttle - I live in a 40 kph area!). I have not experienced anymore problems since adopting this regime of cold start driving.

Thanks, that's certainly something to consider.

[PoloGIT]

If you can go to engine/measuring blocks/look at block 031 and 032. There will be a field called STFT/short term fuel trim/or additive STFT. It varies in different versions what its actually called. When the car us well up to temp and has been running around for a while, idle it, look at that block and the % should be less than +-3%. Much more than that and you have a vacuum leak.
If you delete the SAI you'll have to plug off the airbox hole. Follow the vacuum pipe from the combi diaphragm which will lead to the SAI solenoid. You can turf the SAI vacuum pipes and the bigger pipes but you'll need to either leave the solenoid plugged in or resister out that part of the loom. Despite the SAI being ticked off in the tune, that just means the second cat sensor isn't looking for a lean condition. However at the solenoid, the ECU still needs to see a complete circuit there. If not, for some reason your closed loop fuel trim adaptations wont work. It'll never go into closed loop. So easiest is in the meantime to leave the sai solenoid plugged in while you rationalise all its pipework, and then attack it with a resister later.

Pretty sure VCDS Lite only gives us the first 20 or 25 measuring blocks, doesn't it?

I used to have a hacked full version with the last Polo but not sure that still works, or the cable died or something. Guess i better stop being so tight and fork out for it.

[PoloGIT]

Hey guys, so finally got around to checking 31 and 32 measuring blocks...they say "Lambda xxx" with figures at 0.something. Have I got the right ones here?

It's still often running like balls when cold, and sometimes bad when not entirely cold too. For what it's worth, I've got a bottle of injector cleaner in the tank ATM...probably about 2 thirds through that tank now and not seen any improvement thus far.

[sambb]

first things first, is the air filter clean? I'm not being a **** in saying that. Mine was cold starting horribly recently. I've recently moved my pod to draw directly off the cold air feed that takes air from over the radiator. Because its right at the front of the car the filter gets really dirty really quickly. I hadn't anticipated that the intervals would change that much. I'd swapped in another set of coils, looked at mixtures, checked the o2 sensor bung was tight and looked for air leaks etc . Found that the filter was filthy, blew it out and problem never came back!

[PoloGIT]

first things first, is the air filter clean? I'm not being a **** in saying that. Mine was cold starting horribly recently. I've recently moved my pod to draw directly off the cold air feed that takes air from over the radiator. Because its right at the front of the car the filter gets really dirty really quickly. I hadn't anticipated that the intervals would change that much. I'd swapped in another set of coils, looked at mixtures, checked the o2 sensor bung was tight and looked for air leaks etc . Found that the filter was filthy, blew it out and problem never came back!

Interesting... Yes, I'll check that out. I guess it's about a year/10k+ ago that I swapped in a new filter, and also installed the PD160 and de-flapped the intake, so you might well be into something Will report back, cheers.

[PoloGIT]

Ok, checked the air filter, it looks pretty good. Was replaced Jan last year, so guess it would be a good idea to replace it, but I don't think that's the issue atm.

Re measuring blocks, is this what you are expecting to see?



Thanks

[sambb]

I do a lot of kays and generally do my filter before any track events. I couldnt have been longer than 2 months interval and it started basically kicking over into cold start and after the initial burst where it fired to life it would splutter for a second or two like it had a miss, and then come good again until the cold start routine was finished and the idle settled. Filter had every kind of insect/dust etc, blew it out and problem gone. bizarre. It could be that they are running them very specifically at cold start for emissions reasons that the slightest unexpected flow through the maf or whatever and it chucks a wobbly. Maybe the dirty filter has it run richer than it wants for that first fire up so it quickly tries to pull fuel out resulting in misses? - not sure but thats all it was with my car. I'm up to about 30 miss free cold starts when previously every second or sometimes all the cold starts being bad. You could just make sure the airbox is clean and do a test start with the filter removed to test the theory.

[sambb]

oh and RE the vcds stuff, block 031 should be updating constantly even at cold start. Block 032 though will only start showing STFT trim changes when the cold start/warm start routine finishes I think. Its long term fuel trim LTFT usually needs the coolant temp to be greater than 75 degrees + some other conditions before you'll see it appear and getting it to update can take sometimes a long drive in cruise mode ie closed loop. If your block 032 trims dont eventually appear/update, let yus know cos there's a couple of simple things that can cause that other than say a dud 02 sensor.
You could also monito block 091 I think it is - it'll say 0.00 or 20.0 degrees cf. That shows inlet cam advance. It advances to 20cf = 20 crank degrees only at cold start up. If its not doing that then you might have a weird cold start because the cam is all over the place due to a dud chain tensioner or the cam advance solenoid isnt moving the cam.

[PoloGIT]

oh and RE the vcds stuff, block 031 should be updating constantly even at cold start. Block 032 though will only start showing STFT trim changes when the cold start/warm start routine finishes I think. Its long term fuel trim LTFT usually needs the coolant temp to be greater than 75 degrees + some other conditions before you'll see it appear and getting it to update can take sometimes a long drive in cruise mode ie closed loop. If your block 032 trims dont eventually appear/update, let yus know cos there's a couple of simple things that can cause that other than say a dud 02 sensor.
You could also monito block 091 I think it is - it'll say 0.00 or 20.0 degrees cf. That shows inlet cam advance. It advances to 20cf = 20 crank degrees only at cold start up. If its not doing that then you might have a weird cold start because the cam is all over the place due to a dud chain tensioner or the cam advance solenoid isnt moving the cam.

Sam, sorry for the delayed response. Finally had a chance to to it for a decent drive with VCDS. Regarding block 091, I had taken the car for a drive about 2 hours earlier and it's a 25 degree day here, so although the temp gauge was at the bottom, it may not have been completely cold. The CF reading I had then was -2.0. During my 40km drive that moved up to +1.0. Doesn't really line up with what you say above but maybe it wasn't cold enough?

[PoloGIT]

Regarding the other blocks, if you are implying I should be seeing those empty fields with data in, well this is what it looks like after 40km of driving...

[sambb]

no those bin bits field dont matter. But maybe a bit of concern re the block 032 lambda (multi) value. -20.3% means its pulling a lot of fuel. Have you made any mods that would be over fuelling it recently?

[h100vw]

Dunc, what's the performance like. Any chance that you have a boost leak? Most of the time I see fuell removed at idle and LTFT.
Try logging 003 115 and 118 from 1500 revs to say 6k. Then message me the log

[PoloGIT]

no those bin bits field dont matter. But maybe a bit of concern re the block 032 lambda (multi) value. -20.3% means its pulling a lot of fuel. Have you made any mods that would be over fuelling it recently?

Nothing I can think of. SAI delete was the most recent engine related mod, but I was having this issue prior to that. Bear in mind I'm running a catless DP with Gav's stage 2 tune...would that impact those figures? It's not going to be unhappy on the 98 RON E10 fuel I feed it? Thanks for your help.

[sambb]

Oh ok yeah it could be the tune. My tuned cars have always been out of the expected multi % ranges. 98 RON E10? Our E10 is only 94RON here. Our 98 RON is pure pure petrol 98.

[PoloGIT]

Oh ok yeah it could be the tune. My tuned cars have always been out of the expected multi % ranges. 98 RON E10? Our E10 is only 94RON here. Our 98 RON is pure pure petrol 98.

Yep 98 E10. Force 10 >> Gull NZ
We can get 98 RON pure petrol too (probably comes from your side) but its a bit more expensive and I figure some E is good for our boosted cars... They do E85 in some select locations...I've not tried it.

Any more thoughts on why my car is running so poorly? Cheers