Lacking power since cleaning MAF

[themanthatcan]

Hey peeps, hope you've all had a good bank holiday weekend?

I thought I'd make the most of the nice weather and try to get to the bottom of my lumpy idleing problem by cleaning the MAF today. I took the lid off the air box, removed the MAF sensor and cleaned it with electrical contact cleaner. I left it to dry for a couple of hours and in the meantime sprayed some carb cleaner into the TIP to clean the intake system out. I'd cleaned the throttle body a couple of weeks ago and it was a bit oily so thought the whole system could do with a flush through.

I've now put everything back together and taken the car out for a test drive and I seem to be down on power. It's almost like the turbo isn't boosting. If I rev the car above 3k RPM revving when stationary there's no ghostly big whistle when the turbo spins up and no hiss from the DV. It sounds just like a non-turbo car. If I remove the TIP from the air filter so the car is bypassing the filter and brining in air from outside things sound like they did before and the turbo spins up.

I've scanned it with Vag-Com and there's no DTC's showing up. I sat in the car with the engine ticking over monitoring measuring blocks and everything seems to be in spec, but when opening the bonnet the engine felt much hotter than normal, and the N80 valve seems to be ticking very loudly all the time.

Does anyone have any ideas what may be up? It's almost like the air filter is somehow restricting air flow into the turbo, but it's only a few weeks old and is nice and clean.

Thanks,
Andy

 

[Clach]

good luck...something small I am sure (hope so?)

 

[HTC]

Hmmm, maybe you have killed your maf?

Disconnect the battery for 30 mins, reconnect and then see how you get on.

 

[themanthatcan]

Hey matey,

Well that was my initial thought, so I unplugged the MAF and it still ran the same. It's had a good 30 min drive to work this morning and at least I can hear the turbo spooling up now, but the power just seems to be lacking. Fuel economy has improved as well, but I can't be sure if that's because the MAF is now clean and working optimally or because the turbo isn't requesting so much boost. It's almost like the car has reverted to it's pre-remap state!

Looks like I may have to pop it down to JKM for them to have a look, but as long as I'm not gonna do any damage I might leave it until next week as the improved fuel economy will be great for my drive down to Devon this weekend! Do you think it'll be ok to leave it that long?

I'll try disconnecting the battery and see what happens. One thing I did notice this morning was that there was a 3 second buzzing sound from the engine bay..throttle body re-adapting maybe? Wonder if it's worth popping that off?

 

[themanthatcan]

Well I took your advice HTC and disconnected my battery for a couple of hours. Have just been out for a drive and it seems much better now, so thanks for the suggestion matey :thumbsup: I'm not 100% sure that it's back to how it was a few days ago but it's making all the right noises, and actually seems to be pulling a bit smoother.

I'll try and get it hooked up to my laptop in a few days and see if it's making the 1.5bar of boost it should be and if not then JKM can take a look along with trying to work out why it's not idleing perfectly.

Thanks,
Andy

 

[1animal1]

woah woah woah....how do you check the boost on the laptop????

 

[themanthatcan]

You use Vag-Com measuring blocks. Can't remember exactly which ones but Lee wrote them down on my CC invoice which I have at home.

 

[1animal1]

let me know if you can mate....really appreciate that...... i know the measuring blocks.... but there are a few different ways of getting the info up isnt there?

 

[themanthatcan]

Well I finally got round to doing some Vag-Com boost level measuring and something doesn't look right to me. I'm sure Lee from Custom Code said that their map requests 1.5bar boost, and just after the remap he confirmed that was how it was working. The most I'm seeing requested is just under 1.4bar.

Problem is that my slipping clutch really isn't helping with diagnosing the problem as WOT in 3rd gear at 3k RPM (how I've been told to do a test-run) causes the clutch to slip right up to 5k RPM.

Here's my graph anyway mapping requested boost against actualt boost. As you can see the actual boost never actually reaches the level of requested boost. Boost drops off at 6k RPM as that was the best run I could manage. The roads were chokka at lunchtime today:

 

[simch]

check your connections at the throttle body, if you cleaned it, check its all done up tight.
Also, get your electrical contact cleane r(NOT carb cleaner!) on the IAT, inlet air temp sensor that is in the inlet mani near the tb. carfully remove the allen bolt and CAREFULLY remove it, it is long and easy to scrape the element on the mani. Give it a damned good clean with the contact cleaner and replace.
I reckon you have contaminated it with the carb cleaner and crap that you have removed and it is playing havoc with the ECU readings of the inlet temp. If the charge is "too hot" boost and timing will get pulled back making it run like a bag of poo!

Easy sensor to forget about, but very important on the 18T!!

 

[themanthatcan]

Excellent advice thanks mate..makes perfect sense! I didn't even know that sensor existed. I've pulled it out and it was caked in crap. It's all cleaned up and sat in the kitched drying off now.

Will plug it back in later and let you know how it goes!

 

[themanthatcan]

Ok, the sensor is back in and I've taken it for a quick drive and log. It's feels slightly better but that may be because the temp has dropped outside now compared to the 24 degrees it was at lunchtime when the last log was done.

I'm actually seeing a request for 1.5bar of boost now, although the car is still only responding with a maximum boost of 1.34bar. I'm struggling to tell if it's because of the clutch slipping or some other reason.

I'm guessing the TB will be dirty as well now so I'll remove that tomorrow and see if things improve. It was only cleaned a few weeks ago but will be worth doing again as it's such as easy job.

We'll get there sooner or later! Thanks :thumbsup:

 

[Shy19s]

Hope you get it sorted mate.

 

[themanthatcan]

Here's the latest boost graph. You can see the big lack of boost up to 3k RPM. That certainly seems to be where the power is lacking. After the remap the turbo would start spooling up just after 2k RPM and it was that early boosting which helped the car feel much quicker!

You can also see the clutch slipping badly cos the revs rise quickly then drop off again: