Solved some K04 issues, but need help with another.

[RacerFreddy]

Simply put, I got the MAF issues sorted out a bit, fuel trims still sit a bit high +9-10%, and I still have high RPM stutters. APR's tune *cough* *cough*. In the future I will be looking into a hybrid intake combining my two cold air intakes and the stock MAF housing. That's for another day.

The problem now, is ever since I fixed my bum S3 injector and put on my Twintercooler, I've had horrible idle issues and cold start misfires. I have done the following to correct as much with fuel trims and air leaks as possible. Alongside general fixes to help my chances.
- As mentioned above the car now runs in spec under load, +1% at idle at the moment, due to replacing a MAF sensor to a very OE spec one.
- Checked for and repaired various air leaks, both in the intercooler piping and the vacuum system. PCV is deleted, and the lines for rerouting are free of leaks as well.
- Refreshed a load of sensors (aside from the MAF)including the ones on the HPFP, the MAP sensor, the IAT sensor, and the front O2.
- Coils and plugs are the newest version of the Red R8 coils (full rubber sleeve) and NGK PFR7S8EG (OE plugs)
- When replacing the injector I got a new top seal, but left the teflon one alone, and the valves looked pretty good, had cleaned them previously.
- Cam follower is regularly checked, and since switching to Rotella oil and upgrading to K04, the wear is really slow now, not much of a concern at the moment.

So here's the rub, my idle fuel trim is at +1% at the moment, but the lambda is reporting a pretty constant subtractive trim in the lambda control, meaning it is pulling fuel. Makes sense right, the S3 injectors are bigger, and maybe they don't need to stay open as long at idle. APR's tune also runs richer all the time I hear.
However... this is still causing the misfire/sputtering at idle, almost like a cylinder is being flooded. It's popping and almost backfiring somewhat aggressively only parked at idle. It's only cylinder one that gets hit very hard by this, which is the location of the injector I had changed to the OEM S3 injector, so it matches the other three.

Using VCDS I went into basic settings today and ran the lambda control shut off adaptation, which at full operating temp where the car pops the most, it shut down the front 02 and lo and behold it stopped the live adjustments to fuel trim, and stopped the popping and misfiring.

TLDR... Why when the O2 is turned off in the adaptation and live trim adjustments stop trying to pull fuel from a obviously rich idle does this stop the misfires? Is it possible something is throwing off the front 02, usually that would be an exhaust leak, but that would have it reporting lean, not rich. A really hard question I know, but that's the only thing in all my testing and logging that has thrown up a red flag.

My thoughts are either 1. it's all tune related and I need to switch, looking at Untironic because of Uniconnect and the flexibility of dialing in parameters for different parts in use and flashing to stock as needed. Or 2. That one injector is either still bad, the spray pattern is whack, or the seal is bad, and I need to go in with a whole new set of S3 injectors and just hit them all while I'm in there, and maybe check for carbon buildup again.

Either way I see it I'll be out 500-1000 buckaroos, but I really want this thing to run right, I haven't been able to fully enjoy K04 for a full year now, and just am over the constant small issues.

Thanks for reading my wall of text guys, let me know what you think.

 

[RacerFreddy]

*Update*

Fixed the idle issue, was the updated set of coil packs it turns out. Even though they were the newest red top Bosch units, something wasn't playing well, likely the resistance. My spark was getting blown out no doubt. Went back to the previous revision red tops, I don't even know what brand, no VW stamp, so who knows. They are working much better at idle.

Fuel trim partial still sits at +10.9% (Idle -2%), but I started work on my hybrid intake, using my old K&N as a base, I have the OE MAF housing hacked up ready for a coupler, we'll see how I can get the trims to behave after that goes on. Have to wait until next weekend.

High RPM (within 18-22 PSI) misfire is still there, but is not based on cylinder 1 which has been the guilty party at idle. It spread evenly, hitting 3 and 4 the most, which is only ever the case in that RPM. I hope I'm correct in assuming that going to the OE MAF with APR's tune will help even or eliminate that high RPM hiccup. I know my MAF readings are off at that RPM, I never see the g/s that other K04 users usually see. Likely the fueling gets a little wacky.

Wish me luck.

 

[ROH ECHT]

The R8 and other Red Top's are a higher resistance of about 5.x ohm...OEM are 3.3 ohm. Your plugs need to be a smaller gap of 0.026" or less with 5.x ohm coils.

Glad you addressed the coils, because my first thoughts reading through the first post was to address the coils and the plug gap.

You mention the additive trims of +1%...but is that what you see when you clear error codes before looking at the MB? You know it makes an adjustment so to land on about 1% right? It's true value, block 1-additive only, is immediately seen after a clearing of codes. Post what value you see after doing this please. Your HPFP is upgraded, right? I just want to verify...I am sure it is, but....

You should check the MAF to intake seal. My multiplicative was at 17% and I smoked tested mine and smoke came from the opening for the MAF in the p-flo intake. I helped it seal better and the multiplicative went down to 7%. Usually an additive in the multiplicative is from unmeasured air going into the combustion. Any small leak post MAF will do this.

Lastly, you mention you replaced "the" injector. Did you replace one? Or all? Which injector are you using with the APR tune?

 

[BurgerGuy]

I have similar issues on Unitronic Stage 2+ (K04) w/ RFD. Have been chasing a lean LTFT of ~+18. It usually varies between +14 - +19. My guess is a bad/tired O2 sensor, exhaust leak, or something else. No unmetered air entering the system before the turbo. Gonna take it to the shop this week.

As for cold start misfires, I've found that if I unplug the MAF, then cold start the car there are zero misfires and the car idles great. Replaced the MAF, but still getting cold start misfires. Once the engine is warmed, it'll start up without any fuss.

 

[RacerFreddy]

Firstly idle misfired came back, it starts better than before, and doesn't throw codes as often for cylinder 1 and random misfire, but when warm it still pops and backfires, with the occasional miss from cylinder 1. I really am befuddled why only cylinder 1 has so many issues at idle now, it never misfires when driving.

Either way, Ron to answer your questions, I'm running OE# S3 injectors, they came with my CTS K04 kit. One was a bum from factory and couldn't handle any real load, and replaced just that single one, cylinder 1, with a used S3 injector, handles load just fine, just idles like crap.

Yes it has APRs hpfp, a brand new unit not rebuilt.

In regards to how the trims run, post code clearing, idle will act as normal. Although a fresh clear on a cold start is tragic, misfires on cylinder 1 up to 80 times until the high idle settles down to 750 rpm.

While driving the short term will add, correcting for a lean condition, I have made certain I have no leaks, short of professional smoke testing. Long term will climb to a hair under +11%, which as of recently has the car feeling peppier and has mileage has increased. No doubt because timing is not being pulled as severly. This is compared to the 17% I had regularly and one night 24% which caused a limp mode. Replaced the MAF with an OE Hitachi unit. Once it stabilizes it runs as normal, this is in partial trims mind you.

At idle trim, after long term has settled, it seems the ECU is heavily leaning towards pulling fuel, -10 to -15% at idle, correcting for a rich condition. This makes it backfire and misfire slightly, because if I deactivate lambda control via basic settings, those idle hesitations cease. I'm lost as to why it is pulling so much fuel, as to why it isn't affecting the long term, and to what would be causing a new 02 to read so rich, unless S3 injectors could, but I only heard RS4 injectors could overichen the mixture.

MY last ditch effort for what I have on hand is I just completed my custom intake. I have the stock MAF housing connected to my old K&N tube, and will see how that effects LTFT and idle tomorrow. May have an update then. I will also bring my plug gaps back down, they are sitting at .028 or thereabouts, but since the car likes my older red tops, I will play will plugs some more as well.

 

[ROH ECHT]

The most recent topic I have found relating to rich at idle and lean off idle ended up being the throttle body going out...not completely yet but out of spec. He noticed the fuel trim condition in the data and it eventually began to run rough with rough starts and misfires in #1 and #3. This guy had gone through all of the same...searching leaks, compression testing, new injectors & coils & plugs, Lambda O2 sensor, MAF, and more. Many visits to the dealer and another shop determined it was the TB and replaced it. He reported a few months later all is still good. I believe your in the same boat, not that it may indeed be the TB...but something uncommon.

 

[RacerFreddy]

That would be wild, although I've always checked the basic setting of it, it reports correctly from what I've seen, but something I will look into. That would be the first time of a throttle body being an issue that I've seen, across lots of VW models.
Could it be related to the flapper motor as an alternative, since it seems so prevalent on cold starts, I don't know exactly how much of a roll that plays otherwise in the powerband for example.

It is worth noting that my throttle is kinda an on off switch when it comes to boost onset with the K04. I kinda blamed APR's tune for that one, it doesn't ramp up linearly, it's like 3/4 throttle is capped to 8-10 psi, then I really have to romp it to get it to spike up to 22 pounds and have it taper off like normal. Again, looking through vagcom it responds normal enough, although I'd also say it reads 100% open really early on the pedal too, it's not at just before the kickdown "click." Unfortunately I don't really know what is normal, and what has been changed via the tunes. I'd like to have Unitronic with Uniconnect so I could go stock and see what happens in some areas, but it is what it is.

 

[RacerFreddy]

Update time with no good news.

Used my custom intake, saw fuel trims go up from where they were at +9.8% LT on my CTS intake to +12.1% with the stock MAF housing intake. Saw a positive response on g/s readings, and high load/RPM misfires have also gone down.

Swapped the plugs to my colder set of BKR8EIX and gapped down to .025. This is what really seemed to help the high load misfires, because after doing the intake they were still present. Idle misfire is also still present but seemed to die down as the fuel trims adjusted in the short term. I'm going to run it this way for a while, and check my fuel trims over the next week.

I'm stumped and pissed, the cylinder 1 plug still looks leaner than the others, so I'm still expecting to have to change another injector, at the least. Worse case is a valve is not sealing right or something, or the tune is messing with everything, and I need to switch.

 

[ROH ECHT]

Misfiring may be the throttle body like the other person...who knows.

The fuel trim; have you checked the maf's mounting seal? These aftermarket intakes are sometimes off dimensionally regarding the depth for the MAF and if too deep, the MAF cannot seal completely when attached. If you want; remove the intake, plug both ends but apply pressure inside through one capped end. See if it leaks around the MAF. If it does and you can correct the MAF seal...that will drop the fuel additive adjustment.

 

[BurgerGuy]

Update time with no good news.

Used my custom intake, saw fuel trims go up from where they were at +9.8% LT on my CTS intake to +12.1% with the stock MAF housing intake. Saw a positive response on g/s readings, and high load/RPM misfires have also gone down.

Swapped the plugs to my colder set of BKR8EIX and gapped down to .025. This is what really seemed to help the high load misfires, because after doing the intake they were still present. Idle misfire is also still present but seemed to die down as the fuel trims adjusted in the short term. I'm going to run it this way for a while, and check my fuel trims over the next week.

I'm stumped and pissed, the cylinder 1 plug still looks leaner than the others, so I'm still expecting to have to change another injector, at the least. Worse case is a valve is not sealing right or something, or the tune is messing with everything, and I need to switch.

What spark plug and gap does APR recommend for the tune you're running? I was using BKR8EIX on my Unitronic Stage 2+ K04, but 8 is two ranges colder than stock (6). You want to use BKR7EIX which is just one heat range colder than stock or whatever make/model/gap APR recommends to use with their tune. Unitronic Stage 2+ uses BKR7EIX.

 

[ROH ECHT]

I see APR still recommends NGK BKR8EIX spark plugs gapped to 0.024" ±0.002" for the 2.0t FSI K04.

 

[RacerFreddy]

I will check the MAF mounting seal, but considering that it is a new MAF with a new seal, and right now I'm using the stock MAF housing, I could see no possible way for there to be a leak there causing the increase in trims. I find it extremely disappointing that I saw a worsening in trims going to the stock housing, when everyone else with APR tune woes had theirs fixed by it. Like I said I'll drive around this week on the hybrid intake and see what happens, but if nothing really improves I'm going back to my CTS intake, I don't like how quiet the stock housing is either.

I ordered a brand new OE S3 injector, not used with a crappy old teflon seal, I have a new throttle body and intake manifold gasket lying around, next chance I get I will be ripping down to that injector again, and redo gaskets, and do a cam follower, it's about time for a change either way. Hopefully to eliminate fuel cutting if any, and vacuum leaks due to old gaskets.

Seems I'm good with recommended plugs, gapped at .024-.025 on my BKR8EIX. I know my ignition is better up to standard seeing as my high RPM misfires have decreased, when there is the most air/fuel mix to blow out the spark.

 

[BurgerGuy]

I see APR still recommends NGK BKR8EIX spark plugs gapped to 0.024" ±0.002" for the 2.0t FSI K04.

Where do you see this on their site? I ask because while troubleshooting my own misfires up until this past February I found part of the problem (aside from eBay injectors) was the fact the plugs were too cool. Heck, even you told me to try using PFR7B's overe here: https://forums.vwvortex.com/showthread.php?9358463-07-K04-GTI-Misfires

My understanding is for every 100hp more the engine makes you should go a heat range cooler, but if APR recommends BKR8EIX for their FSI K04 tune then more power to ya.

 

[RacerFreddy]

I've used every kind of OE plug with varying gaps to no success, there really has to be little to do with ignition issues. I've tried PFR7B, BKR 7 and 8 EIX, and PFR7S8EG , gapping them all between .024 and .030 and nothing has solved misfires. Whether it be the idle misfire on just cylinder 1, or the high load high rpm ones that spread across all cylinders.

At this point, I think my first injector, carbon build up, or a vacuum leak isolated near cylinder 1 is to blame at idle. As far as my high end ones, I'm out of ideas, I thought fixing fuel trims would help. Tonight I got into it and the same shit happens in 4th and 5th gear, at full boost, 5-6k rpm. I'm starting to believe it's fuel cutting, whether that is the HPFP or the LPFP is anybody's guess. I need to run some more logs when I get the misfires to see what may be fluctuating out of spec.

When I check my fuel trims, I swear to christ if they haven't settled back down and the stock MAF housing has made them worse I'm going to flip.

 

[BurgerGuy]

It was injectors that fixed high RPM misfires for me after trying a ton of other stuff. It was so bad the motor couldn't even reach redline. Eventually, I got misfires down to just cylinder 1, but replacing all four injectors to ensure none of the others were goofed plus switching to BKR7EIX gapped to .028 got things under control. Now, I'm just trying to figure out why my LTFT keeps bouncing around between +14% - +18.75%. Anyways, back on topic

A couple questions. Sorry if you already answered any above...I did read, but didn't see any info.

• Are your intake manifold runner flaps deleted? This will cause misfires/stuttering on cold starts.
• Have you verified you're running the latest rail pressure sensor on the fuel rail? Part number is 06J906051, but whether you need C or D will be dependent upon your VIN. My '07 uses the red one (D). Split is in the '07 model year.

If/when you do replace the injector(s) make sure you get seal kits. They're pricey, but better to have peace of mind knowing nothing will leak.