1.8t - Car randomly stutters under light load

[Sirocco20348]

Hey guys, just hoping someone can point me in the right direction.

My car has started randomly stuttering/jerking under light accelerating conditions. For example while on cruise control on flat road or when driving normally.

With full boost, it doesn't stutter, but the car doesn't sound 100%, maybe like air venting into the atmosphere?

I only noticed the problem this morning while on my way to work.

Thanks

[JustCruisn]

Could be heaps of things.
I'd check for air leaks. I had a massive hole in the elbow of a line near behind throlle body, right side near the coolant sensor. I could hear the sucking air over the idling engine. It causes a strange fluctuation and sometimes hesitant acceleration.

Or the ignition control module could be dying which will drop a cylinder, that will make it run like **** and sound rough like a Subaru.

[aprr32]

Or the small vac hose that goes to the fuel press reg.

[Sirocco20348]

Thanks Guys,

I created a boost leak tester and the results are in.... my car has at least 2 leaks... I cant hold pressure at all...

1) A leak from a small pipe connecting from under the intake manifold (06A103221C)
2) Another leak somewhere near the intercooler, maybe one of the major pipes.. about to remove the front bumper and wheel etc to have a look..

I can only imagine how much power I am losing from these leaks.

Anyone who hasn't boost leak tested their car, I would strongly encourage it.

Not sure if this will fix my problem but its a good start. Ill post pictures of my Bunnings boost leak tester this afternoon. Cost $20.

[Sirocco20348]

Farout my intercooler has a hole in one of the vents... Does anyone have any recommendations on how to fix this? Or is it best to source a 2nd hand one. I don't want to buy a front mount just yet. Id rather stay with my side mount for financial reasons atm.



Also this connector was hanging down the side of the intercooler... its not a vacuum hose.. anyone know where it is meant to go?

[Sirocco20348]

For anyone that is curious about the boost leak tester... This is hooked up to my bike pump, but you could also get an attachment to hook up to a spare tyre, or even change the nozzle to fit onto a compressor...

[h100vw]

Clean with brake cleaner and araldite it up.

[Sirocco20348]

Thanks Gav

I will get some Permatex Cold Weld from super cheap and some brake cleaner.

Permatex Cold Weld Bonding Compound - 57G - Supercheap Auto Australia

Any ideas on that random connector?

Also if anyone else is interested in this link, I found a $50 silicone hose kit on AliExpress... it has Samco printed on it... Surely its upto the task.

http://www.aliexpress.com/item/VW-GO...684240293.html

[h100vw]

I'd google the part number on the sensor. It doesn't look like the outside temo sensor, but it might be?

[JustCruisn]

That random connector is just a random connector.
It should be positioned behind the driver side head light. There is a clip for it.
It does exactly nothing. If you pull off the end piece you will find it is nothing but a piece of plastic just to keep water out of the electrical connector. There is voltage in it however.
I think it might be for the MAP sensor on the intercooler, which we don't have.

[kendog]

For anyone that is curious about the boost leak tester... This is hooked up to my bike pump, but you could also get an attachment to hook up to a spare tyre, or even change the nozzle to fit onto a compressor...

Looks great! Do you have a pic of all the individual parts you got from bunnings to make it? Did you block the other end going into the throttle body too?

Also, I have a spare SMIC after just installing my FMIC..

PS - That Wiring/Plug goes to nothing on my GTI/1.8T too..

[Sirocco20348]

Looks great! Do you have a pic of all the individual parts you got from bunnings to make it? Did you block the other end going into the throttle body too?

Also, I have a spare SMIC after just installing my FMIC..

PS - That Wiring/Plug goes to nothing on my GTI/1.8T too..

Thanks for the heads up on that wiring plug, I was trawling etka last night going insane. Ill just let it hang.

I can take close up pics of it tonight, but honestly it is not very sophisticated.

- 50mm threaded piece of PVC (Thread goes about half way down)
- 50mm matching threaded cap
- 1x Air connector of choice, I used a schrauder bike valve which required me to use a 8.5mm drill bit to drill a hole. (Exact fitment). I left the harder more durable piece of rubber around the base of the valve.
- 1x roll of plumbers tape to wrap around the main thread of the 50mm threaded cap.
- Glue the valve onto the threaded cap with loctite, cold weld, whatever you like, aslong as it does not leak. (i used loctite on this occasion.

• Insert the newly constructed boost leak tester into the intake pipe.
• Remove the PCV valve from the TIP and plumb the hole with something. (I used a c02 canister as in picture). If you dont do this, apparently it pushes oil into the TIP and you will be blowing smoke afterwards.
• Remove the oil cap from the top of the engine.

No need to block off anywhere else. Start pumping with your bike pipe and listen for the dreaded hissing noises haha

If using a compressor start at 5 psi, because its pretty darn obvious when you have a leak. If its ok at 5psi, then keep raising it up to what is normal boost for your engine. If its holding that pressure fairly well, then you should be all good!

I used this page and youtube video for inspiration...

Stealth 316 - Intake pressure tester
http://www.google.com.au/url?sa=t&rc...55819444,d.dGI

[Sirocco20348]

Thanks for letting me know about your spare intercooler. I repaired mine last night with some epoxy weld, but if it doesn't work properly I will give you a PM and we can work out a deal. I haven't tested mine yet lol, apparently this epoxy weld is good for 4500psi.. so i don't think 20psi should be a problem. Will let you know.

[Sirocco20348]

Ok so I have ...
- Fixed known boost leaks
- Replaced rubber vacuum hoses around the engine, including the small one that goes to the fuel pressure regulator.

The car pulls very hard now, but every now and again I still feel a random stutter or jolt while under light load. No where near as bad as before thou.

I will have to drive it more this week to confirm that it is still there. Thanks for all your recommendations.

Out of curiostiy what are the symptoms of a failing fuel pump? Do they die slowly... or just die?

Ps. Just to add something funny/amusing for others, but not for me.... The c02 canister I was using to plug that hole, slipped down into the Turbo Intake Pipe. I nearly cried. But after a trip to Jaycar and Bunnings I had an earth magnet attached to a drain cleaner probe, and fished it out haha What a crap time that was...

[Sirocco20348]

Hey guys, I need some more brainstorming as the problem still persists.

As mentioned before, I have fixed all boost leaks and replaced the rubber hose from the plenum to the fuel pressure regulator.

Today I cleaned the MAF with MAF sensor cleaner and changed the air filter. Did not solve the problem.

I then unplugged the MAF plug, and the problem still persists. So I am pretty sure its not the MAF.

This problem is starting to wear me down a little as I just do not know what to try next.

Any other people experience this problem? Or suggestions?