Intermittent Timing Pull Issues

[IcedGingerBread]

Looking for advise on how to use my VCDS to find out why my car (2008 A4 2.0T manual transmission with APR stage 1) is pulling timing under 50% throttle to WOT. It is accelerating well to roughly 3k rpms then timing is pulled until 3.5k. Starts accelerating properly again then looses all power again for a few hundred rpms. It goes intermittently until red line. Its drives perfectly normal as long as I don't put my foot down, which I have avoided unless I am testing a new part or logging.

Before getting the VCDS I unfortunately replaced way too many other items starting with a new K03 turbo from FCP Euro (I started getting low boost codes and my waste gate was flapping). After replacing the turbo is when I started noticing these surges in power. I assumed that my fueling system couldn't keep up with the fresh turbo so I then replaced my low pressure fuel pump, fuel filter, and high pressure fuel pump / cam follower. Problem still persisted so I bought another another rev D diverter valve because maybe the one that came with the turbo was bad? That didn't work. Got a new PCV with ECS rubber hoses and multiple sets of coils and plugs throughout these item replacements just incase.

This is when I decided to purchase a VCDS with Ross-tech. My requested boost and fueling pressures all looked okay to me, but I did notice that the car was pulling excessive timing in random spots throughout the rpm range. Read somewhere that this could be fuel injectors so I bought a new set of injectors and walnut blasted the intake valves while I was in there. Surging problem still there but I'm getting up to 34 mpg now (before new turbo it was 23ish).

I've also replaced my oil filter housing, engine mounts, and snub mount because I had them laying around. Did a cold compression test and all cylinders were at ~165 psi. Almost all parts have been purchased from FCP and a couple from ECS.

Car is going to the shop that put the tune on it next week, but I've got some time this weekend and wouldn't mind trying to figure out screwed I am lol. What should I test / log?

Thank you

[Jayz691]

Did you log timing pull and knock feedback? Confirmed your are getting timing pull and not another issue? If so, how much pull, and what is the requested timing adv where the issue occurs? Screenshots of a log may help.
Do you have any e85 available by you, to use for testing?

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[IcedGingerBread]

I did not log knock feedback and all my logs are before I put the new injectors in. That's something I can do later this evening. Sounds like I should log knock feedback, requested timing adv, injection timing on all cylinders, and engine speed?

Pretty sure a Shell nearby sells e85. My tune is for 93 and that's all I ever put in it.

edit: Forgot to add that the timing pull before the new injectors was quite extreme, basically up to 12.

[IcedGingerBread]

I've got a new log but I have spent a solid 30 mins trying to upload a photo or attachment to this website in the gallery. Tried on mobile too without any success. I assume something is wrong with the website right now? Or am I just slower than I thought?

https://docs.google.com/spreadsheets...D5A/edit#gid=0

Hopefully I'm allowed to share google docs and others are allowed to open it

[Jayz691]

Can't access it, not sure why.
I just asked about e85 cuz if its a fuel issue, if your put a gallon or 2 of e85 in, drive it a little too let your trims adjust, and log it. If it goes away its a full quality issue.
Don't need inj timing, just timing pull, and knock voltage is good to look at too.
And im constantly having issues with AZ too..

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[IcedGingerBread]

Sorry updated the document I had it on a private mode. As for the E85 I'm willing to try it but I've pretty much gone to same gas station my entire life so I would assume that's not my issue. I've had the car a solid 6 years now. I'll have to get another log with voltages tomorrow.

[Jayz691]

Looks like a little pull on 3 of 4 cylinders, but ~2? isnt much. Its requesting up to like -18? near redline, so pulling 2? isnt much. Not something you would really feel..
For shits and giggles, throw a gallon or so of e85 in and see of that little bit of pull disappears.
I got a few ? on my k04 tuned cars, and tuner said its normal. If I add a little e85(1-2gal), it gets rid of it and can feel a difference. So maybe ya would feel it a little, bit not like its breaking up or somethin..

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[IcedGingerBread]

I'll do the e85 tomorrow. It seems like I wasn't educated enough between injection timing and timing pull before. When I'm WOT it feels like I go from being floored to lifted, to floored to lifted....

Do you have any other suggestions for what I should log? Thank you for the feed back.

[Jayz691]

Fuel pressures, blocks 230 & 231 with 3 for general info.

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[IcedGingerBread]

So all the gas stations near me that used to sell E85 no longer do apparently. But today I did a boost leak check and found a missing hose clamp on the crankcase breather hose. No boost leaks. I also knew my exhaust was vibrating a bit and looked into that. The downpipe was hitting a transmission bracket. I was able to correct that issue as well.
I then took it out to do the fuel logs and I cannot get the car to have power surges now. I can't help but feel like it's not fixed yet, but idk it seems to be pulling almost evenly throughout the rev range now. Below is my log.

https://docs.google.com/spreadsheets...it?usp=sharing

[Jayz691]

Well your fuel pressures look good. But if ya had an air leak, that eould cause issue. Which clamp was missing..?

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[IcedGingerBread]

Still seem unable to post an image, but in the google doc below I circled the clamp that I was missing (not my engine bay btw, pulled from google)

https://docs.google.com/document/d/1...it?usp=sharing

[Jayz691]

Oh, the rear breather. That can cause a vacuum leak, rough idle, etc.

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[IcedGingerBread]

Problem came back today so I'll be dropping the car off tomorrow evening. I will update this thread with the final diagnostic.

[Jayz691]

Ok, but don't think the power issue is directly related to the little timing pull your getting. Curious to find out what they say though..


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[IcedGingerBread]

Took a little while but I got the car back and it seems to be totally fixed. I think they smoked my clutch a bit because the release point seems so much different than I remember. Just gonna ignore that for now idk. Below is a copy paste of the shops comments. I got a new dipstick, turbo outlet gasket, flex pipe, and o2 sensor.


When the vehicle was initially pulled in there was no fault codes stored or pending in the ECM. Test drove the vehicle and verified customer complaint, no faults were present at that time. Drove the vehicle a longer period while monitoring fuel trim, in these scenarios the primary oxygen sensor readings were erratic. Inspected the intake system from potential vacuum/boost leaks, and found a small leak at the dipstick due to a missing o-ring. The exhaust system is leaking in multiple areas, this can effect oxygen sensor readings. Tested wiring for both primary and secondary oxygen sensor in order to verify proper resistance within the sensors and wiring to the ECM and relays. Found the resistance for the primary oxygen sensor was intermittent and not within spec coming from the ECM. Inspected grounds, connectors and wiring for damage, found no immediate issues. Inspected the connector at the ECM and found a loose pin within the bulk connector. Repaired the loose pin , and found the resistance is in spec. Test drove vehicle, found the primary sensor was steady but still showing a significant rich/lean spike depending on load. Pressure tested the exhaust system and found a leak at the turbo, and after the cat, the gasket used is the incorrect design and has failed prematurely. The flex pipe is also leaking. These 3 leaks are very close to the oxygen sensors and can effect the fuel trims. In order to continue testing, the exhaust leaks and small vacuum leak should be addressed.

[Jayz691]

Sounds like your took it to a good thorough garage, not just a parts swapper
Hopefully she's fixed..

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