2G Thought I Had Boost Leak But Something Elsee

[Ferp]

So when my engine first starts and I try to boost my turbo will feel like I have boost leak at about 75% on the stock gauge. Once my cars been at running temp for about twenty minutes this feeling goes away completely and the car will boost 100% fine. I ran a boost leak test but everything was fine. No leaks anywhere.

 

[PlanZero]

On both of my Tsis the car has to be fully warmed up to operating temp before they boost properly. Also, make sure your plugs are gapped properly for good measure.

 

[Zorak]

Just let it warm up before you push it. You really shouldn't be boosting cold anyway as it is hard on things. Someone please correct me if I'm wrong but, you are probably getting lots of blowby around the piston rings when it is cold, causing you to lose compression, which is normal. Once the car is at operating temp the rings seat tighter in the bore, allowing less blowby. Again, someone correct me if I'm wrong.

 

[pauleyman]

Nope. This is more likely timing and fuel related. Car shouldnt be sluggish cold then finelater. Ring idea sounds way off base. If rings were bad cold they would be bad hot.

 

[Ferp]

Nope. This is more likely timing and fuel related. Car shouldnt be sluggish cold then finelater. Ring idea sounds way off base. If rings were bad cold they would be bad hot.

What do you think it is? My timing belt is definitely fine.

 

[edged1g]

So when my engine first starts and I try to boost my turbo will feel like I have boost leak at about 75% on the stock gauge. Once my cars been at running temp for about twenty minutes this feeling goes away completely and the car will boost 100% fine. I ran a boost leak test but everything was fine. No leaks anywhere.

First, what does a boost leak "feel" like? Second, you can't diagnose anything with the stock boost gauge. Its an estimate. You need a real boost gauge to do any diagnosis. What are the symptoms? Do you have anything to log with? Anything to give us more insight?

What do you think it is? My timing belt is definitely fine.

What do we think what is? You are asking us to diagnose a feeling. Your timing belt? What does that have to do with anything? If your timing belt wasn't fine, the car wouldn't run.

 

[pauleyman]

I didnt say timing belt, I said timing. Meaning ignition timing. Car will feel slow if ignition timing is being pulled. You need data.

 

[Ferp]

Alright, sorry guys for the terrible post. I'm on my computer now so I'll explain it better.

When I open the throttle about 50-75% of the way my boost gauge will go about 3/4ths of the way up and the car will start to shake and the boost will not go over that 75% mark. If I WOT the shaking/boost stop occurs at about the 2/5ths to 2/4 range. I'm on the crappy stock boost gauge so I can't give any numbers and I'm really sorry about that. Like I said once the car has been at running temp for 15 or so minutes the car runs beautifully. Just the sluggish slow start.

 

[91tsiawdtalon4g63]

Do you have any fuel mods that you installed?

 

[91tsiawdtalon4g63]

http://www.dsmtuners.com/threads/fuel-cut-or-boost-cut-need-help-fast.440461/

Does this sound like your problem?

 

[Ferp]

Do you have any fuel mods that you installed?

Sorry I should have listed my mods. I have no engine or fuel mods what so ever. Just an ACT 2100 clutch, a coilover set, short shifter, 3 inch turbo back, etc. It doesn't feel like fuel cut which I've experience in other vehicles.

Everything in my engine bay is stock, spark plugs are all good. I have an NGR bov in the mail right now as a friend of mine who has more experience with turbo charged cars says he thinks thats the issue, even though it isn't leaking and works fine when warm so it doesn't make a lot of sense to me.

 

[91tsiawdtalon4g63]

Is your bov recirculated right now or vented? Have you checked the Turbo for shaft play? Can you take a video of the problem as well?

I checked your profile but wasn't sure if you may of added something recently

 

[Ferp]

Is your bov recirculated right now or vented? Have you checked the Turbo for shaft play? Can you take a video of the problem as well?

I checked your profile but wasn't sure if you may of added something recently

The bov is recirculated. And yeah the turbo runs great no scrubbing or anything.

I'll take a video of it tomorrow morning.

 

[91tsiawdtalon4g63]

Sounds good. That's just very very weird that it doesn't want to boost. I still want to say it's fuel related. Try putting some seafoam, marvel mystery oil, or Lucas fuel treatment in your gas after the video then see if that helps. Could also check your maf to see if anything is in the honey combs and if so grab some crc maf cleaner from auto zone and spray it out since it won't damage anything like brake cleaner would

 

[Ferp]

Sounds good. That's just very very weird that it doesn't want to boost. I still want to say it's fuel related. Try putting some seafoam, marvel mystery oil, or Lucas fuel treatment in your gas after the video then see if that helps. Could also check your maf to see if anything is in the honey combs and if so grab some crc maf cleaner from auto zone and spray it out since it won't damage anything like brake cleaner would

Thanks, I'll try all that. Never even thought to check my maf.

 

[91tsiawdtalon4g63]

Thanks, I'll try all that. Never even thought to check my maf.

It may not have anything to do with it but maybe something got sucked into it and isn't letting air to be filtered through til warm. Never hurts to check over everything

 

[pauleyman]

Do you have any method to log?

 

[Ferp]

Do you have any method to log?

Nope.

 

[pauleyman]

Elm adapter and torque pro is less than 40 $. Better than poking a stick in the dirt. Objective info is much easier.

 

[Ferp]

Elm adapter and torque pro is less than 40 $. Better than poking a stick in the dirt. Objective info is much easier.

Thanks, I'll check those out.

 

[Ferp]

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Sorry about the video being in portrait. It crashed in landscape (really old iphone 4). Pull is in 2nd gear. Watch the revs stutter around 4k and you can hear it too.

My battery is really old and I'm getting a new one monday, I also am installing a new bov this weekend so if any of those fix this issue I'll be sure to share.

Also at half to three quarters of the throttle open it was boosting fine.

 

[91tsiawdtalon4g63]

Check your o2 sensors. That could affect your fuel trims to being wacky while it's cold and be normal when it's warmed up and getting full voltage. They maybe dirty or wires maybe coming apart. Still tho get logging software for sure, I hate throwing a needle in a haystack with info but the more hay you toss out the better your chances of finding the needle.

 

[TSi-Rocket]

I know people use the maf cleaner on our Karman vortex airflow sensors but it says right on the can "do not use on Karman vortex mass airflow sensors". Ive gone thru all the cans on the shelf at multiple places all over my area and all read do not for Karman sensors.

Tech article
http://www.dsmtuners.com/threads/how-to-clean-your-mas.345616/

I like the idea of cleaning the our mas but never tried it due to the precaution on the can..

The coolant temp sensor will effect the car when its cold, or it could be a corroded coolant temp connector. I use the disposable finger nail files to clean them when needed.

 

[97gsxIA]

Like Paul has said, without data, you are shooting in the dark.
If you can't afford any tuning software, a wideband O2, or a aftermarket boost gauge, the only things you can do is blindly replace factory parts.

Get a boost gauge and a wideband, at the very least. They can be sourced for fairly cheap and are painless to install.

Other than that, in that rev range and stutter symptom, I'd suspect spark issues. Replace your plugs and wires and go from there.

 

[2gGst98]

I second the spark issue with the shuddering. How old are the plugs? Do they look dirty and corroded? Would replace if unknown age. +1 on boost gauge also as the factory one doesn't help much. As it just says when your positive pressure.