Hesitation + fuel economy suffering

[Robscoe]

Hey so I have a 2007 A4 Quattro 2.0T with 160,000 original km. I’ve noticed my car now hesitates, especially when flooring it from a stop or relatively low speed. No engine codes or anything, my fuel economy has been shit too. It seems to idle fine and all that. I’m also confused about my bloody boost readings. I’ll attach the link to view a chart that has my calculated boost etc. How can it be 7.5 bar? Any ideas on anything would be great . https://imgur.com/a/dLTD4IpI

[mbruveris12]

Weren't you just asking about carbon cleaning products?
Honestly, depending on how bad your carbon buildup is it could be causing some of these
issues such as decreased MPG and the engine feeling "sluggish"
In regards to your boost reading, there is clealy is an error, your not boosting 100 psi [o_o]
What are you using to calculate it?

[Robscoe]

Something tells me I don’t even have a carbon build up cause I don’t have any of the other symptoms really, maybe the catch can helped. Going to buy some crc gdi and spray it into the intake by removing the sensor. Should at the very least should show
Some signs of carbon burn off if that is the case. I just have a odb2 wifi thing plugged in and use the carscanner app on my phone
I’m going to try a different app lol. I’ve been really considering going for the stage 1 or stage 1+ Tune. Not that it’s really relevant to this LOL.

[EvolutionArmory]

Anytime you have slow performance and poor fuel economy the first thing you should do is check for vacuum or boost leaks. If those are good then go after the MAF. If the MAF is good then go after the O2 sensors.

VCDS pays for itself when trying to diagnose this. Being able to look at live fuel trim info is priceless.

[Robscoe]

i’m able to monitor my fuel trim but i’m not sure how to use it to my advantage

[EvolutionArmory]

If your LTFT is really high you can clear the codes which resets fuel trim info and start spraying down your engine with carb cleaner to try to find vacuum leaks.

When you’re looking at live fuel trim data, if you spray an area with carb cleaner and STFT spikes, you got a vacuum leak somewhere in that area. Then you fix the leak, clear codes again and take it for a drive. If LTFT goes down after a good highway drive, you fixed a leak. If it stays about the same, you gotta keep diagnosing.


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[EvolutionArmory]

The same goes if you replace a part to see if it fixed the fuel trim code. Say you had a LTFT reading of 15. You put in a new MAF or O2 sensor, clear the code and take it for a drive. If your LTFT is now like 5 after the drive, you did something that worked.

Just using random numbers.

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[Robscoe]

ohh okay thanks, and how many KM estimate would i need to
drive to get a fair and accurate reading? i actuallly just broke my turbo inlet hose as i was taking the MAF out to give it a spray down with some cleaner, i replaced the plugs the other day, i have my suspicions that the boot cover on my TB is the culprit for vacuum as it’s stupid, there’s a gap between the piping and TB that is only covered with that sleeve, and i’ve cleaned the outside and every time after i do i check it after a drive and it’s got oily residue on it, and i’m also leaking oil lol. i’m shit with mechanics so i’m slowly learning, i don’t even know what all the parts are yet. gotta get me a bloody haynes manual. oil seems to be dripping from somewhere underneath that i can’t see from just looking at the engine bay. sorry i know it’s like speaking to a toddler when it comes to me describing mechanical issues but yeah, i’m learning lol https://imgur.com/a/hYoYRXb

[EvolutionArmory]

It doesn’t take much. Just drive like 10 miles on the highway and turn back around.


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